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14C, a radionuclide, which is widely used in all works of life, such as medical research and determination of PM2.5, has been realized autonomous production in China. It relied on imports, which was expensive and unstable supply in the past time. At present, Qinshan Nuclear Power has started 14C production to completely solve the problem of the serious shortage of 14C independent supply in China. Aluminum nitride powder is the main raw material for the preparation of 14C, whose elemental aluminum directly affects the safety and quality of 14C isotopic targets in nuclear reactors. Aluminum nitride is very stable in an inert high temperature environment. But a lot of elemental aluminum will react with water producing hydrogen in a high temperature environment which can result in the expansion of component rods or it will react with cladding tubes producing hydrogen embrittling effect, and these can affect the quality of 14C isotopic target. According to the characteristic of aluminum nitride insoluble in acid, this study researched different dissolution effect of elemental aluminum in aluminum nitride nano-powder by nitric acid, hydrochloric acid and sulfuric acid. It was found that the above mentioned acid can only dissolve a small amount of aluminum nitride powder, and there was a small amount of aluminum nitride powder suspending in solution, which would seriously interfere the determination of elemental aluminum. At present, microwave digestion, laser ablation, X-ray fluorescence and other methods are used to dissolve or determinate aluminum nitride, but they are not suitable for the determination of elemental aluminum. The determination of elemental aluminum is generally used in pharmaceutical, soil, tea and other samples, but most of the aluminum in the above samples exists as an impurity element, or aluminum is combined with organic matter, which is easy to separate from elemental aluminum. However, it is difficult to achieve complete separation of elemental aluminum(unbound elemental aluminum) and the aluminum nitride matrix in the aluminum nitride powder. This study used replacement reaction to selectively dissolve elemental aluminum. Then the suspended aluminum nitride powder was separated by filter membrane filter. By this method, it could solve the determination interference to elemental aluminum. This study established the determination of elemental aluminum in aluminum nitride nanoparticles by inductively coupled plasma mass spectrometer(ICP-MS), which has the advantages of low determination limit, high accuracy, fast determination speed and small matrix effect. This method’s linear range is 10-100 μg/g and the relative standard deviation is 3.8%(n=6). Using high purity alumina powder to verify the established determination method, the dissolution efficiency can reach 96%-98%.

Brachytherapy can kill cancer cells more effectively and make the normal tissues around the tumor free or less irradiated. It has become an effective means for the treatment of malignant tumors. 103Pd has a half-life of 16.96 days and a significant advantage in the field of brachytherapy due to its unique decay properties. In order to achieve the large-scale production of 103Pd, the preparation process based on Cyclone-30(C30) cyclotron was studied. The rhodium metal was electroplated on the copper target base by pulse electroplating method. The rhodium-plated target was transferred to C30 solid target station for irradiation with beam energy of 16-18 MeV, and the beam current was 200 μA. In order to obtain Curie-level 103Pd, the beam integral should be more than 10000 μA•h. After irradiation, the target was transferred to the separation and purification hot cell, the rhodium plating was separated from the target base first, then was ground into powder, and dissolved by high temperature melting of potassium bisulfate. The rhodium was converted into soluble rhodium sulfate, and the 103Pd nuclide was separated and purified by AG1-X8 resin. The impurities of Rh, Fe, Cu and Zn were rinsed with 6 mol/L hydrochloric acid and 0.03 mol/L hydrochloric acid, respectively. At last, 103Pd was desorbed with a mixed solution of ammonium chloride-ammonia mixed solution(volume ratio 1∶1). The radioactive activity, radionuclide purity and specific activity of 103Pd were measured respectively. The preparation of sealed seed core was studied by using the prepared 103Pd feed solution. The results show that the rhodium plating layer is smooth and dense, and firmly bonded with the copper plate, the rhodium layers mass thickness is greater than 150 mg/cm2. The production capacity of 103Pd is greater than 37 GBq, the radionuclide purity is greater than 99.9%, and the specific activity is greater than 875 GBq/mg, and activity concentrations greater than 6.2 GBq/mL. The preparation field of 103Pd brachytherapy sources is more than 90%, it can meet the requirements. The 103Pd preparation process is stable, and the quality is controllable. The large-scale production capacity has been reached, and it provides a stable source for the research of 103Pd brachytherapy sources.

Inert gas argon has important applications in the fields of daily life, industrial manufacture and nuclear environmental monitoring. The key to its application is to selectively and efficiently separate and purify Ar from complex gas components. However, the separation of O2 and Ar at normal temperature is full of challenge due to their similar molecular sizes and adsorption properties as well as their close boiling point. In industry, high purity Ar is mainly produced by low temperature rectification, which is mature technology, but the equipment is large, high-energy consumption and explosive. Adsorption separation is a common method of gas separation. Molecular sieves are the most widely used material due to their huge specific surface area, aboudant pore structure and excellent adsorption properties. The silica tetrahedron in molecular sieve is electrically neutral, while the aluminum tetrahedron is electronegative, which makes it necessary to use H+ or Na+ outside the molecular sieve skeleton to maintain electrical neutrality. In actual application, the interaction between adsorbent and adsorbent can be enhanced by ion-exchange modification of molecular sieve material, so as to effectively improve the O2/Ar separation capacity of molecular sieve. In this paper, the application of ion-exchange modified molecular sieve materials in the field of O2/Ar adsorption separation was systematically summarized and reviewed. The results show that the O2/Ar separation coefficients of molecular sieves modified by alkaline earth metal ions like Ca2+, Sr2+ and Ba2+ can reach about 2.0, while that of Ce3+-exchanged X-type molecular sieve is as high as 5.9, it is an ideal adsorption material for O2/Ar separation. However, the high separation coefficient is limited to the range of low partial pressure, and the O2/Ar separation coefficient under normal pressure is below 2.0. The Ag+-exchanged molecular sieves, namely silver-loaded molecular sieves, have excellent Ar adsorption selectivity. At present, the O2/Ar separation coefficients of silver-loaded molecular sieve materials at atmospheric pressure are around 2.0, but the preparation cost of silver-loaded molecular sieves is high, and it is more suitable for small-scale separation applications, it means that the efficient separation of O2 and Ar at normal temperature and pressure is still challenging. The development of novel ion-exchange modified molecular sieve materials with high adsorption capacity and high adsorption selectivity for the separation of O2 and Ar is still one of the focuses and trends of future research projects.

In order to accurately simulate the large-scale migration of plutonium in groundwater(a three-phase system), it is necessary to understand the interaction mechanisms between plutonium(Ⅳ), natural colloid, and granite(immobile media). The experimental results show that plutonium pseudo-colloids(i.e., Pu(Ⅳ) sorbed on the surfaces of soil colloids) have the strong mobility(i.e., the recovery percentage of plutonium after plutonium pseudo-colloids transported through columns filled with pore media, R). The mobility R increases with soil colloid concentration ρ(0≤ρ≤375.4 mg/L, 1.3%≤R≤52.5%). The master complexation speciation of Pu(Ⅳ) on the surfaces of soil colloids is \begin{document}$\equiv {\text{SOPu}} $\end{document}(OH)3. The speciation percentage(＞95%) is positively correlated with the colloid concentration. The results of experiments and surface complexation calculations confirm that plutonium pseudo-colloids enhance the mobility of Pu(Ⅳ) and thus pose a greater risk of contaminating far-field waters than the dissolved Pu(Ⅳ). The calculations of DLVO interaction potential indicate that the trough depth of the second energy minima(Фmin2) between colloids and media deepens with increasing colloid concentrations. This attractive interaction potential results in an increase in the adsorptive deposition efficiency of plutonium pseudo-colloids on the media surfaces. The DLVO calculations are consistent with the observation: the mobility of plutonium pseudo-colloids become weak(375.4 mg/L＜ρ≤2017.8 mg/L, 52.5%＜R≤12.7%).

Radioactive TBP/kerosene(OK) organic waste liquid is produced in the process of uranium purification and spent fuel retreatment. In order to avoid the safety risks caused by the accumulation of radioactive organic waste liquid over the years, it is urgent to treat it. In this paper, the conventional Fenton oxidation method and microwave synergistic Fenton method were used to treat simulated radioactive TBP/OK waste liquid, and the effects of mass fraction of Fenton’s reagent ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document}) and ρ(\begin{document}$ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}} $\end{document}), initial pH and oxidation time(t) on the removal of chemical oxygen demand(COD) was experimentally investigated. The results of the conventional Fenton oxidation method show that: at the optimal process conditions, ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document})=20 mg/L，ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document})/ρ(\begin{document}$ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}} $\end{document})=1∶10, initial pH=1.90，t=15 min, the COD removal can reach up to 72.01%; the most important factor is the ratio of ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document})/ρ(\begin{document}$ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}} $\end{document}), followed by ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document}), initial pH, and oxidation time. The microwave synergistic Fenton method is superior to the conventional heating Fenton method, and even better than the conventional Fenton oxidation method, when under the same optimal reaction conditions. As for the microwave synergistic Fenton method, the COD removal can be increased to 95.80%. The dosage of Fenton reagent is also reduced from ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document})=20 mg/L，ρ(\begin{document}$ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}} $\end{document})=200 mg/L to ρ(\begin{document}$ {\text{Fe}}^{\text{2+}} $\end{document})=10 mg/L，ρ(\begin{document}$ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}} $\end{document})=100 mg/L. It can be seen that the microwave synergistic Fenton method not only further improves the COD removal, but also reduces the dosage of Fenton reagent.

In recent years, semiconductor photocatalytic methods have made great progress in the reduction and extraction of uranium from water. In recent years, due to its advantages of less pollution, low energy, and high material reuse efficiency, photocatalysis has become an important direction in the study of reduction and extraction of uranium in water, and it also has the potential to treat nuclear wastewater and extract uranium from seawater. This article reviews the mechanism of photocatalytic reduction of uranium, and the characteristics, synthesis and classification methods of catalyst materials. In order to make the classification more intuitive and specific, classification is based on composition rather than structure, and it is divided into titanium dioxide and its modified composite materials, graphite phase carbon nitride and its derivatives, bismuth photocatalysts, metal sulfide photocatalysts, etc. The advantages and disadvantages of different photocatalysts were analyzed and a series of comparisons were made to provide reference and basis for research on uranium extraction through photocatalytic reduction.

The separation and recovery of uranium from natural water is of great significance to the exploitation of unconventional uranium resources. In our paper, a novel polyacrylonitrile(PAN)/Hummers oxidized lotus seedpod carbon composite was prepared, and adsorption of U(Ⅵ) ion from U(Ⅵ)-CO3 solution under weakly alkaline condition was also studied. Batch adsorption experimental results show that at room temperature, pH=8.0, ρ(U(Ⅵ))=50 mg/L, cT(CO3)=2 mmol/L, the adsorption reaches equilibrium after 840 min, and the maximum adsorption capacity is about 51.92 mg/g. The increase of the pH values, calcium ion concentration, magnesium ion concentration and carbonate concentration inhibit the U(Ⅵ) adsorption. Thermodynamic results indicate that it is a spontaneous, endothermic chemical adsorption process. Characterization results show that the composite displays good structure stability during U(Ⅵ) adsorption process, meanwhile, the phenolic —OH and —COOH(C=O) are the main adsorption sites on the composite surfaces. In the presence of calcium/magnesium ions, the order of adsorption affinity of U(Ⅵ) on the composite material is as follows: Mg-U(Ⅵ)-CO3 system＞Ca-U(Ⅵ)-CO3 system. The results can provide the new materials for the separation and extraction of uranium from natural uranium-containing water.

Uranium-zirconium alloy is an important nuclear fuel in Integral Fast Reactor, which is of great significance to study its basic physical properties at high temperature by using advanced calculation methods. This work used deep potential molecular dynamics method, which combines the high accuracy of the first principles with the high efficiency of the classical molecular dynamics, to perform an evaluation of the static and thermophysical properties of body-centered cubic phase zirconium, uranium, and uranium-zirconium alloy. Firstly, the deep potential(DP) models of body-centered cubic zirconium(Zr-BCC), body-centered cubic uranium(U-BCC), and body-centered cubic uranium-zirconium alloy(U-Zr（BCC）) were trained by using deep neural network machine learning. Secondly, the DP models were used to predict equilibrium state equation, lattice constant, elastic properties, and phonon spectrum of the three systems, and the predicted results can reach the accuracy of the first principles. Then, the variation of heat capacity and density at constant pressure of Zr-BCC, U-BCC, and U-Zr（BCC） with temperature were predicted by using DP models, and the results are in good agreement with the experimental values. The research results show that the machine learning method provides an important path for successfully exploring more complex nuclear fuel properties.

As a reactor which can reusing low-abundance 235U resources, fast reactor construction is an important part of China’s three-step nuclear energy process. Due to high burnup and strong irradiation of the spent fuel oxides of fast reactor, the dry reprocessing method based on molten salt electrolytic refining has unique advantages such as the ability to handle the widest range of fuel types and higher stability of the reaction system. Before the electrolytic refining step, the oxide spent fuel needs to be reduced to metal through electrical or thermal reduction. Thermal reduction requires the use of calcium, lithium, and magnesium as reducing agents. Compared with other alkali metal reduction process, lithium reduction process at high temperature has the advantages of simple recovery process, moderate temperature and lower equipment requirements, it may become the future tendency of thermal reduction. In this paper, the research progress of lithium high-temperature chemical reduction of spent fuel in dry reprocessing and compared the characteristics of lithium thermal reduction processes in various countries was investigated. The mechanism of high-temperature reduction with lithium was deduced based on thermodynamic calculation, and the influencing factors of reaction were discussed from the perspective of kinetics. Finally, the relevant research on the electrolytic recovery of residual salt from thermal reduction was described. The different reaction routes and technological process of lithium thermal reduction were summarized. The shortcomings of existing research were summarized, and the trend of lithium thermal reduction in the future was prospected. It gave a reference for the research of the process flow in China’s dry reprocessing.

Due to anthropogenic and long-term geological factors, radionuclide leakage may occur in deep geological repositories of radioactive waste when groundwater infiltrates a failed waste canister. The released radionuclides can migrate to near and far field regions through groundwater, posing a serious threat to the ecological environment and human health. As a consequence, knowledge of radionuclide speciation in groundwater is essential for understanding their transport behavior. Uranium is one of the key elements of significant concern for deep geological disposal of high-level radioactive waste. In this study, the uranium species in groundwater from boreholes BS03(pH=9.43) and BS05(pH=7.51) located at the Beishan area(Gansu province) were calculated by the hydrogeochemical software PHREEQC(version 3). The effects of pH, temperature, and initial uranium concentrations on ternary uranyl species are presented. The results indicate that UO2CO3(aq) and (UO2)2CO3(OH)\begin{document}$_3^- $\end{document} are the dominant species in a mildly acidic condition, while CaUO2(CO3)\begin{document}$_3^{2-} $\end{document} and Ca2UO2(CO3)3(aq) are the major species in neutral and weakly alkaline conditions. In BS05 groundwater, the concentration of Ca2+(5.11 mmol/L) is about three times higher than that of Mg2+(1.58 mmol/L). However, the concentration of calcium uranyl carbonate is estimated to be about 250 times higher than that of magnesium uranyl carbonate(MgUO2(CO3)\begin{document}$ _3^{2-}$\end{document}). With an increase of temperature, Ca2UO2(CO3)3(aq), CaUO2(CO3)\begin{document}$_3^{2-} $\end{document} and UO2(CO3)\begin{document}$_3^{4-} $\end{document} concentrations progressively diminish. At uranium concentrations between 4×10−4 and 1×10−1 mmol/L (25 ℃), the dominant uranium species, in order of decreasing concentration are: Ca2UO2(CO3)3(aq)(x＞62%)＞CaUO2(CO3)\begin{document}$_3^{2-} $\end{document}(x≈35%)＞MgUO2(CO3)\begin{document}$_3^{2-} $\end{document}/UO2(CO3)\begin{document}$_3^{4-} $\end{document}(x≈1%), irrespective of the concentrations of Ca2+, Mg2+, and Na+. In the near-neutral and slightly alkaline conditions, the results suggest that the formation of neutral Ca2UO2(CO3)3(aq) and anionic CaUO2(CO3)\begin{document}$_3^{2-} $\end{document} in Beishan groundwater reduces the distribution coefficient between uranium and environmental geo-medium, thereby enhancing the mobility and migration potential of uranium. The research findings contribute to understanding the transport and release mechanisms of uranium, as well as interactions between uranium species and engineered and natural barriers.

In view of the geological characteristics and development contradictions of different types of heavy oil reservoirs in Shengli Oilfield， a set of development technologies for heavy oil reservoirs have been developed， and remarkable development achievements have been obtained. In this paper， the progress of development technologies for different types of heavy oil reservoirs was summarized in the theoretical basis and the field application. For heavy oil reservoirs after many rounds of huffing and puffing， the well pattern infilling technology was formed based on the non-Darcy flow theory. For sensitive heavy oil reservoirs， the adverse impact of water sensitivity on development was reduced based on the proposed theory of near heat and remote prevention. For extra-heavy oil reservoirs， HDCS technology was applied through the synergistic viscosity reduction and energy enhancement due to the expansion to solve the development problem of difficult injection and production. For inefficient water-flooding heavy oil reservoirs， the flow lines of infilled corner wells and water wells were changed by turning to steam flooding to enhance oil recovery. For deep heavy oil reservoirs， the multi-thermal composite oil displacement theory was formed， and deep heavy oil reservoirs were effectively produced based on the understanding of the synergistic interaction mechanism of gas-heat synergy for heat retention and enhancing steam chamber， heat-agent synergy for replacing viscosity reduction and improving flooding， and gas-agent synergy for thermal front equilibrium. For thin heavy oil reservoirsthe steam absorption capacity and production ranges were improved through the thermal and horizontal well composite development model. For shallow extra-heavy oil reservoirs， HDNS technology was used to enhance the energy， reduce viscosity， and expand the spread， realizing efficient development. The application of development technologies for heavy oil reservoirs in Shengli Oilfield provides technical support for the beneficial development and green development of heavy oil in Shengli Oilfield.

Water-flooding reservoirs are the mainstay in developing mature oilfields in eastern China， and they have entered the ultra-high water cut stage as a whole after long-term water injection development. Laboratory studies and field practice show that there is still potential for significantly enhancing oil recovery. However， the difficulty of scientific and efficient development has increased due to the heterogeneity of reservoirs and development dynamics， and further research is needed to enhance oil recovery technology. Uncompartmentalized reservoirs face challenges such as severe extreme water consumption in the later stage of ultra-high water cut， affecting stable production and enhanced oil recovery through water flooding. Therefore， the theory of high water consumption zones was deepened， and the development technology of near-resistance layer recombination， the vector development technology of ultra-high water cut reservoirs， and the development technology of flow field adjustment in the later stage of ultra-high water cut were developed through innovation， achieving water consumption control and reduction， with an average oil recovery of 43.7%. In response to the characteristics of fault block reservoirs with numerous faults and small fault blocks， as well as the challenges of small remaining oil reserves and difficult exploitation during the ultra-high water-cut stage， understanding of the accumulation patterns of remaining oil and hydrodynamic regulation mechanisms was deepened. A series of leading development technologies were developed through innovation， such as artificial peripheral water flooding and stereoscopic development， improving reserve control and water flooding efficiency， with an average oil recovery of 29.4%. These technologies have supported the stable and profitable production of fault block reservoirs. Given the poor physical properties of low-permeability reservoirs and the difficulty of effective water flooding， nonlinear flow mechanisms and pressure flooding development mechanisms were researched， supporting development technologies were formed， and the development limits were constantly broadened. A series of differential development technologies have been innovated， such as water injection of simulated horizontal wells in ultra-low permeability reservoirs， well pattern adaptation for enhanced oil recovery in general low-permeability reservoirs， and pressure flooding in low-permeability and tight reservoirs， with an average oil recovery of 15.7%， realizing rapid and efficient development of low-permeability reservoirs. Through the above technical research， the efficient development of water-flooding reservoirs in ultra-high water cut stage is realized. According to the development characteristics and situation of different types of reservoirs， the directions for further enhancing oil recovery of water-flooding reservoirs are being put forward.

The shale oil in the continental faulted basins in eastern China，represented by Jiyang shale oil，has made a breakthrough in production capacity. However，Jiyang shale oil faces great challenges in achieving high and stable production due to the large burial depth and thickness，low maturity，high formation temperature and pressure，and poor oil flow capacity. Based on the production practice of more than 90 horizontal wells and 10 000-meter cores，the ternary-element storage and flow theory of “storage，fracture，and pressure” was deepened，and the key technology system of Jiyang shale oil development，such as three-dimensional fine evaluation of sweet spots of shale oil development，policy optimization for three-dimensional development technology，and three-dimensional balanced fracturing technology，was formed under the guidance of the theory. Theoretical research and practice show that pores and multi-scale and multi-type micro-fractures constitute a double reservoir system，which is the material basis for high and stable production and controls the reservoir space and the law of oil and gas accumulation. The support fractures and the hydraulic fractures are coupled to form a double fracture system with a scale of nanometer to centimeter. It has the characteristics of a cascade start-up and is the flow path of high and stable production. Energy increase by fracturing can effectively improve the flow capacity of pores and increase the imbibition displacement efficiency under the premise of good formation pressure retention. At the same time，fine pressure control can realize collaborative coupling of energy fields，which can further release the production capacity of shale oil reservoirs. The double pressure coordination of pressure retention and pressurization is the energy guarantee for high and stable production. The key development technology system guided by the theory of ternary-element storage and flow provides effective technical support for the production capacity breakthrough of multi-sag multilayer systems，which is of great significance for promoting the large-scale beneficial development of shale oil in continental faulted basins in eastern China.

Chemical flooding is one of the essential means to enhance oil recovery and has played an important role in the efficient development of oilfields. Based on the current development status of chemical flooding technology in China and abroad，the theory and technology of chemical flooding for enhanced oil recovery in Shengli Oilfield were systematically summarized in response to the harsh conditions of high temperature and high salinity reservoirs. This article reviewed the theoretical and technical challenges overcome in the development of chemical flooding technology from indoor research to field application and introduced the development process of chemical flooding in high-temperature and high-salinity reservoirs of Shengli Oilfield over the past 60 years. By understanding the interaction and structure-activity relationships between oil displacement agents and between oil displacement agents and crude oil，Shengli Oilfield iteratively created the theory of “equal emphasis on viscoelasticity and expansion” for polymers in high-temperature and high-salinity reservoirs，the theory of “similar enrichment of oil agents and anionic non-ionic additive efficiency enhancement” for surfactants，and the theory of “control flooding by deformation” for viscoelastic particles. Shengli Oilfield also developed polymer flooding technology，alkali-free binary composite flooding technology，and heterogeneous composite flooding technology for high-temperature and high-salinity reservoirs with the characteristics of Shengli Oilfield and overcame the problem of significantly enhancing oil recovery in reservoirs with a temperature of 85 °C and a mineralization of 30 000 mg/L. The annual oil production of 96 chemical flooding projects implemented in the field has accounted for over 11% of the oilfield’s production for 20 consecutive years. This series of technologies has made important contributions to the stable production and sustainable development of the Shengli Oilfield.

Reservoir numerical simulation technology is an important means of reservoir analysis， and it is a powerful tool for oilfield developers to design development schemes， proceed with dynamic tracking adjustment， and enhance oil recovery of reservoirs. In order to clarify the future development directions of reservoir numerical simulation technology in Shengli Oilfield， this paper reviewed the development process of reservoir numerical simulation application technology and independent intellectual property software in Shengli Oilfield over the past 60 years and summarized the innovative progress in numerical simulation application technology in many fields since the “13th Five-Year Plan in 2011-2015” period， which is applicable to current development and geological characteristics of Shengli Oilfield. The fields covered fine reservoir description in ultra-high water-cut stage， pressure flooding development in low-permeability reservoirs， heterogeneous combination flooding， multiple thermal combination flooding in heavy oil reservoirs， high-pressure CO2 miscible flooding， and integrated development of shale oil by large-scale fracturing. Then， this paper introduced the development and application of several reservoir numerical simulation software with Shengli characteristics， involving water flooding， chemical flooding， and micro and intelligent simulation. Finally， it was pointed out that under the current development situation of Shengli Oilfield， the reservoir numerical simulation is facing great challenges in terms of refinement， scale， efficiency， and collaboration approach， and the numerical simulation of reservoirs should be further developed towards integration， parallelization， and intelligence， so as to provide technical support for improving the quality and efficiency of Shengli Oilfield development.

Shengli Oilfield has entered the middle and later development stages， and higher requirements for development seismic technologies have been set to develop reservoirs and further enhance oil recovery finely. The distribution and connectivity of conventional reservoirs in Jiyang Depression are complex due to different buried depths， multi-stage tectonic movements， various sedimentary types， and other factors. At the same time， constrained by seismic recognition， the well-seismic correspondences of some reservoirs are unclear， limiting the accuracy of fine reservoir characterization. In response to the development needs of different types of conventional reservoirs in Shengli Oilfield， a series of development seismic technologies have been formed through practice. These technologies include multi-method integrated reservoir prediction technology for middle and shallow fluvial facies reservoirs， integrated fine description technology for fracture systems in complex fault block reservoirs combing fine fault edge depiction and multiple attributes， prediction technology for middle-deep reservoirs with low permeability， and description technology of buried hill reservoirs fusing multiple parameters of “fault-fracture-dissolution composite storage space.” These technologies provide strong support for reservoir development. However， as the target reservoirs for development get deeper， thinner， and smaller and expand into unconventional reservoirs， the development seismic technologies faces higher requirements and challenges. It is necessary to accelerate the integration process of processing and interpretation， strengthen the theoretical research of rock physics， promote the application of OVT domain pre-stack inversion in the description of multi-type oil reservoirs， tackle the fine description technologies of complex fault block-lithofacies reservoirs， break through the technical bottleneck of well-ground joint acquisition and gravity-magnetic-electric-seismic technology， and realize the application of artificial intelligence technology in the development seismic field， so as to further promote reservoir development.

As shale oil exploration and development intensifies， the experimental technologies for shale oil development have been continuously improved while inheriting the experimental technologies and methods of conventional reservoirs and shale gas reservoirs， and a set of experimental technology systems of reservoir physics and flow mechanisms has been initially formed， which provides strong technical support for geological evaluation of shale reservoirs， reservoir engineering optimization design， and enhanced oil recovery. The development status of six experimental technologies in China and abroad， including porosity， permeability， oil-water saturation， wettability， relative permeability， and imbibition， was systematically summarized. In view of the characteristics of continental shale oil， such as low maturity， strong heterogeneity， and well-developed lamina and micro-fractures， the measurement methods and principles， key influencing factors， control conditions of experiments， advantages and disadvantages and technical applicability of experiment methods were analyzed. The main problems， development trends， and research direction of these experimental technologies were put forward. The results show that ① unifying the cleaning agent and cleaning time of rock samples is the key to improving the comparability of different measurement methods of porosity， and nuclear magnetic resonance measurement of porosity is the technological development direction to meet the needs of rapid analysis in mining fields； ② the irregular and multi-directional permeability measurement technology capable of simulating formation pressure changes is the future technological development direction； ③ the alcohol soaking method and two-dimensional nuclear magnetic resonance （T1-T2） method are the technological development direction of the determination of shale oil-water saturation， but they still face the problem of the influence of clay bound water and adsorbed oil on the determination accuracy； ④ the droplet morphology method is one of the future development directions of measurement technology of shale reservoir wettability， which requires further research and unified standards in experimental methods and comprehensive evaluation methods for surface wetting and spontaneous imbibition processes； ⑤ the combination of experimental measurement and numerical method is an effective way to obtain the relative permeability of shale reservoirs， and the micro-oil and water metering， end-effect correction， as well as technologies and methods considering the time-varying pressure are the key directions； ⑥ pressure imbibition measurement method should be used to evaluate imbibition effect and optimize well kill time in elastic development after fracturing. Pressure imbibition measurement methods based on nuclear magnetic resonance T2 spectrum， stratification T2 spectrum， and T1-T2 spectrum will be one of the essential technological development directions.

Shengli Oilfield is a typical continental compound oil and gas area with various reservoir types， many oil-bearing strata， and complex fault systems. It entered the extra-high water cut development stage with a water cut of more than 90% in the early 90s of the 20th century. The basis for enhanced oil recovery in mature oilfields with high water cuts is how to accurately characterize the changes of underground reservoirs and accurately recognize the remaining oil according to different types of reservoirs and development stages. To this end， the oilfield has carried out the fine reservoir description for the remaining oil potential in mature oilfields since 1996. A set of fine reservoir description technologies aligning with Shengli Oilfield characteristics has been formed through breakthroughs in critical technologies such as the fine characterization of reservoir architectures， fine description of low-sequence faults， phase division and connectivity evaluation of glutenites， prediction of thin beach dam sand reservoirs， three-dimensional geological modeling， and the fine description of the remaining oil， as well as multiple rounds of iterations of reservoir description technologies， and the technical specifications of fine reservoir description have been compiled. As of 2023， more than 600 development units have been described， covering 43.6 × 108 t of original oil in place. The modeling technology has been widely used in the adjustment of mature areas and the scheme preparation of new areas， which effectively supports the large-scale production of oilfields and stable production with benefits. This paper systematically analyzed the development process of reservoir description technologies in Shengli Oilfield， summarized the characteristic technologies of different types of reservoirs， analyzed five challenges faced by fine reservoir description in mature oilfields in the late stage of extra-high water cut， and expounded on five development directions of reservoir description technologies in the next step， which had guiding and reference significance for promoting fine reservoir description technologies in continental oilfields.

Underground natural gas storage is an essential infrastructure for strategic reserves， emergency peak shaving， and national energy security. It is also one of the directions for optimizing the industrial layout of mature oilfields and promoting green and low-carbon transformation and development. The geological conditions of Shengli Oilfield are complex， with shallow gas reservoirs， small scale， scattered distribution， and abundant oil and water trap resources. However， it is difficult to evaluate the sealing property. In view of these characteristics， significant progress has been made in research related to gas storage since the “Thirteenth Five-Year Plan in 2016-2020” period. Different types of gas storage， such as loose sandstone gas reservoirs， gas cap oil reservoirs， and aquifers， have been studied and designed， and the first gas storage in abandoned water-flooded gas reservoirs in China， Y21 Gas Storage， has been built. Key technologies such as target screening and evaluation of gas storage in aquifers， injection and production operation optimization design of gas storage in aquifers， sealing evaluation of gas storage traps， and tracking evaluation of gas storage have been developed， which align with characteristics of Shengli Oilfield. At present， the construction of other types of gas storage still faces challenges such as limited data， small scale， poor efficiency， and difficulty in evaluating the dynamic sealing of traps. It is necessary to propose corresponding technical countermeasures and research directions in the site screening and evaluation of gas storage in oil reservoirs， the construction of gas storage in combination with scattered gas sand bodies， and the collaborative construction of gas storage in oil reservoirs with high water cut， to provide technical support for the large-scale construction and green development of gas storage in Shengli Oilfield.

Shengli Oilfield has a large scale of undeveloped reserves， which is an important backup for the sustainable production of the oilfield. However， many years of development practice show that there are lots of problems in the overall development of these reserves， which restricts the economic development and production of the reservoir. In view of the characteristics of some reservoirs with low grade， difficult production， and poor development effect， the types and distribution characteristics of undeveloped reserves in Shengli Oilfield were systematically sorted out， and the main types of undeveloped reserves and key research objectives were defined. Based on the development practice in recent years in the reservoirs such as glutenites， beach bar sands， and deep low-permeability heavy oil， the paper analyzed three main technologies for undeveloped reserves， including large-scale fracturing of wells with high inclination in glutenite reservoirs， pressure flooding in low-permeability beach bar sand reservoirs， and cold production of heavy oil reservoirs by chemical viscosity reduction. The large-scale fracturing technology of wells with long sections and high inclination combined engineering sweet spots and geological sweet spots through the geology and engineering integration， and its application in the glutenite oil reservoirs with low grade has greatly improved reservoir productivity. The innovative development concept of pressure-driven water injection technology has achieved a breakthrough in replenishing energy and increasing the production of beach bar sand reservoirs with low-permeability. The development technology of viscosity reduction combined with pressure flooding has achieved a breakthrough in the economic development of deep heavy oil reservoirs with low-permeability by changing the development idea. These three reservoir types have been effectively produced of undeveloped reserves from single well production， reservoir energy replenishment， and low-cost development and have achieved good development results. The breakthrough of development technologies and the change of development concept are the only ways for the effective development of undeveloped reserves， which has an important demonstration and guiding significance for the development of other undeveloped reserves in Shengli Oilfield.

This paper systematically investigated the progress of laboratory research and field application of biochemical composite enhanced oil recovery technology in the past 10 years in China and abroad. The synergistic mechanism between oil recovery bacteria， biosurfactants， biopolysaccharides， and chemical oil recovery agents such as surfactants， polymers， and nanoparticles was discussed in terms of improving displacement efficiency and expanding swept volume， respectively. In addition， the system construction and field application effects were analyzed. The results show that the combination of biological bacteria and their metabolites with chemical oil recovery agents has synergistic effects on interfacial tension reduction， emulsification dispersion， mobility ratio control， and viscosity reduction of heavy oil， and the field application has achieved good application results. Bacteria polymer composite profile control and microbial desulfurization and viscosity preservation technologies were explored in Shengli Oilfield， and estimated recoveries reached 9% and 10.3%， respectively. Biological ASP composite technology was applied in Daqing Oilfield， and the recovery of the pilot area has been improved to 22%. The biochemical composite enhanced oil recovery technology has great potential for application in the exploitation of difficult-to-recovery reserves in mature oilfields. The next step is to continue to deepen the synergistic mechanism between biological and chemical systems， innovate the integration and implementation process of biological and chemical oil recovery systems according to the differences between reservoir planes and inter- and intra-layers， refine the implementation plan for different development stages and reservoir spaces， and maximize the advantages of biological and chemical synergistic efficiency enhancement technologies through the three-dimensional balanced development of reservoirs to satisfy the demand for sustainable development of mature oilfields.

CO2 capture， utilization， and storage （CCUS） can achieve a win-win situation of carbon emission reduction and oil production increase， and it is a key technology for the green and low-carbon transformation of the fossil energy industry. The petroleum and petrochemical industries have accelerated the large-scale application of CCUS technology after China proposed the goals of “peaking carbon emissions before 2030 and achieving carbon neutrality before 2060” in September 2020. It has gradually been revealed that CO2 flooding has contradictions such as a low impact， short effective time， and rapid increase in the gas-oil ratio in the field practices of SINOPEC Shengli Oilfield and CNPC Jilin Oilfield. It is necessary to strengthen the optimization design of reservoir engineering further. This article systematically analyzed field practices of CO2 flooding to enhance oil recovery in sandstone reservoirs in China and abroad and key issues in the optimization design of reservoir engineering， such as the matching between reservoir pressure maintenance level and miscible pressure， between well pattern direction and formation stress direction， between well spacing and reservoir permeability， and optimization of gas-water alternative displacement methods combined with the research results of the million-ton CCUS demonstration project in Shengli Oilfield. Then， the article summarized the latest progress in reservoir engineering research， such as reservoir pressure maintenance level during CO2 flooding， well network， well spacing， and gas-water alternative displacement， and analyzed the increasing pressure method， well pattern， well spacing， and gas-water alternative displacement optimization design for high-pressure miscible flooding. Finally， it indicated that the research direction of CO2 flooding reservoir engineering design should focus on the phase and flow laws of crude oil， CO2， and water in porous media under high-pressure conditions， the synergistic mechanism of CO2 flooding and storage， and the gas channeling mechanism of CO2 flooding under complex reservoir conditions. This article provides technical support for large-scale CO2 flooding in China.

Shengli Oilfield has abundant low-permeability oil reservoirs with proven reserves of 1.18 billion tons， presenting a good prospect for development. However， there is a problem of inability to inject and produce during the development process of the oil reservoirs due to the low porosity， poor permeability， and strong heterogeneity of the low-permeability oil reservoir. A systematic review was conducted on the prediction and analysis methods for low-permeability oil reservoirs in Shengli Oilfield to achieve efficient development of low-permeability oil reservoirs， as well as efficient development technologies， and the advantages and disadvantages of existing technologies were analyzed to provide an outlook for the development technologies of low-permeability oil reservoirs. Based on research and practice， the following conclusions are drawn： ① Shengli Oilfield has developed fine reservoir characterization technologies such as reservoir prediction， in-situ stress prediction， and evaluation of reservoir heterogeneity. ② Based on theoretical and technological innovation， the physical limit of reserve production was constantly broken， forming differential development technology series， such as water injection development technology of horizontal wells in ultra-low permeability oil reservoirs， long well section multi-stage fracturing development technology of horizontal wells in tight oil reservoirs， well pattern adaptation technology for enhanced oil recovery of general low-permeability oil reservoirs， pressure flooding technology in low-permeability tight oil reservoirs， and viscous emulsion-surfactant flooding technology. Good development results have been achieved. ③ Combined with the actual needs of high-quality development and speed and efficiency improvement development of low-permeability oil reservoirs in Shengli Oilfield， the well pattern reconstruction technology of dual control streamline variation， CCUS technology， and nanobubble flooding technology were proposed， pointing out the development direction for improving oil recovery of low-permeability oil reservoirs.

The influence of fractures on the mechanical properties of shale rocks is prominent. Accurately characterizing the changes in the mechanical properties of fractured shale is an essential basis for precisely depicting the four-dimensional in-situ stress field during the fracturing and production process of shale reservoirs. Existing studies on four-dimensional in-situ stress often attribute stress changes primarily to alterations in pore pressures， neglecting the impact of changes in the mechanical properties of rocks on four-dimensional in-situ stress. The relationship between the pore pressure and the volume of shale pores and fractures was clarified by utilizing online CT experiments. Theoretical relationships among fracture volume， Poisson’s ratio， and elastic modulus of shale rocks were derived based on strain energy theory. Furthermore， a time-varying theoretical model was established with pore pressure， Poisson’s ratio， and elastic modulus as variables. The results indicate that the opening of bedding fractures is the primary cause of the time-varying nature of the mechanical parameters of shale rocks. The number of fractures opening increases， and the fracture space exhibits exponential growth as pore pressure increases. With the increase in fracture volume， the Poisson’s ratio of shale rocks rapidly increases， while the Young’s modulus rapidly decreases， leading to a significant reduction in shale strength. An analysis of the shale in Jiyang Depression reveals that Young’s modulus decreases from 37.5 GPa to 15.06 GPa， and the Poisson’s ratio increases from 0.22 to 0.35 when the proportion of fracture volume increases to 1%. The influence of the time-varying nature of mechanical parameters of rocks on the evolution of four-dimensional in-situ stress is comparatively analyzed through numerical simulation methods. The four-dimensional in-situ stress simulation， considering the time-varying characteristics of rock mechanics， can better characterize the law of stress evolution and direction deflection during shale fracturing and production. It is more consistent with the evolution law of four-dimensional in-situ stress in the process of fracturing and production， and the simulation results are more reliable. The research results can provide theoretical support for the rational deployment， optimal design， and risk warning of three-dimensional well groups of shale oil.

Shengli Oilfield has abundant chemical flooding resources. However， the implementation of chemical flooding technologies is difficult due to strong reservoir heterogeneity， high reservoir temperature， high formation water mineralization， high calcium and magnesium ion content， and high crude oil viscosity. After years of research and development， the theory of chemical flooding for high-temperature and high-salinity reservoirs has been established， forming a series of chemical flooding technologies such as polymer flooding， alkali-free binary compound flooding， heterogeneous compound flooding， and viscosity-reducing compound flooding. These technologies have significantly enhanced oil recovery in reservoirs with a formation temperature of 85 °C， a formation water mineralization of 30 000 mg/L， a calcium and magnesium ion concentration of 1 500 mg/L， and a crude oil viscosity of 1 000 mPa·s. In terms of basic theory， the mechanism of heterogeneous compound flooding was elucidated with “deformation passage， fluid flow diversion， balanced displacement， and coordinated transfer and washing” to enhance oil recovery， and an essential understanding of “simultaneously increasing viscosity and elasticity” and “significantly reducing adhesion work” was obtained during chemical flooding in high-viscosity reservoirs. In terms of technical application， in response to the technical difficulties of significantly enhancing oil recovery in offshore oilfields， an efficient binary compound oil displacement system was constructed， and a fully enclosed injection process was designed， forming a binary compound flooding technology for offshore oilfields. For reservoirs after polymer flooding and high-temperature and high-salinity reservoirs， a viscoelastic particle oil displacement agents were invented， and a heterogeneous compound flooding system was constructed. In addition， heterogeneous compound flooding technology was developed. For high-viscosity reservoirs， highly viscoelastic polymers and efficient surfactants were developed， and a viscosity-reducing compound flooding system was constructed， forming an alkali-free binary compound flooding technology. As of October 2023， the chemical flooding technologies have achieved the produced geological petroleum reserve of 6.3 × 108 t， an accumulated oil production of 7 701 × 104 t， and an accumulated oil increase of 3 604 × 104 t for high-temperature and high-salinity reservoirs in Shengli Oilfield， providing significant support for the sustained and high-quality development.

Jiyang shale oil resources have enormous potential. However， there is a lack of systematic understanding of seepage mechanism and development laws in the multi-scale spaces after fracturing due to the influence of complex geological conditions， making it difficult to achieve large-scale beneficial development. In order to clarify the formation mechanism of the development law of Jiyang shale oil， the multi-scale fracture characteristics of Jiyang shale oil were analyzed. The formation mechanism and combination mode of fracture networks after fracturing were studied using physical experiments and numerical simulations. In addition， seepage mechanisms in multi-medium spaces were researched， including the stress sensitivity of multi-scale fractures， nonlinear flow in multi-scale pores and fractures， and imbibition displacement of pore-fracture systems. According to the differences in the distribution of multi-scale fracture networks and their flow laws after fracturing， a three-zone flow pattern of “easy flow-slow flow-difficult flow” for shale oil was established. Finally， the flow characteristics and production laws of Jiyang shale oil at different flow stages were clarified. The research results indicated that the developed bedding fractures could improve the physical properties of reservoirs， enhance imbibition displacement efficiency， and reduce start-up pressure gradient. During the elastic development stage， the flow channels reduce， and the fracture network conductivity decreases as the formation pressure declines， resulting in significant stress sensitivity. In the development process of Jiyang shale oil， the initial flow state is mainly dominated by linear flow and elliptical flow of fractures supplied by the easy flow zone. In the middle stage of development， the slow flow zone supplies energy to the easy flow zone， and the flow state changes to elliptical flow in the formation. Moreover， the shale oil in the difficult flow zone is gradually produced， and the flow state changes to boundary-controlled flow in the later stage of development. Due to the influence of geological conditions and production systems， there are significant differences in the energy change， water cut decrease， and production change law of different horizontal wells. Reasonably optimizing the shut-in time and production system can ensure imbibition displacement efficiency， efficiently utilize formation energy， and improve shale oil production capacity.

In order to realize the effective development of shale oil with low maturity in continental faulted basins in Jiyang Depression， systematic evaluations have been carried out simultaneously in Boxing， Niuzhuang， and Minfeng sags since 2019， based on the 10 000 meters of systematic coring and more than 100 000 core tests. Significant breakthroughs have been made in single well evaluation and stereoscopic development of well groups. A pilot test of eight wells in three layers was conducted in Boxing Sag， and the first 100 000-ton shale oil development well group of SINOPEC was built. A large-platform stereoscopic development test of well groups was carried out with 20 wells in five layers， and all wells were put into production in Niuzhuang Sag. A comprehensive overall evaluation and stereoscopic development test was launched in Minfeng Sag， following the mode of “overall deployment of a large platform and step-by-step implementation of a small well group.” Peak daily oil production exceeded one hundred tons in 28 wells， including Wells FYP1 and FY1-1HF ternary-element （storage， fracture， and pressure） storage and flow theory of shale oil in Jiyang Depression was proposed. The technologies of shale oil development， stereoscopic fine evaluation of development sweet spots， integrated modeling and numerical simulation， and stereoscopic development optimization were developed. A theoretical and technical system of stereoscopic development of shale oil in continental faulted basins with Shengli characteristics was initially constructed. It effectively supported the construction of the shale oil national demonstration area in Jiyang Depression， Shengli Oilfield.

Since the 1990s， Shengli Oilfield has integrated fluctuations in international oil prices， exploration and development trends， and technological advancements and developed a technical system for development planning that closely aligns with the strategic needs of each stage of oilfield development. Based on the practice of formulating mid-to-long-term development plans for Shengli Oilfield， this paper traced the evolution of development planning technologies in Shengli Oilfield and introduced the historical background， technical approaches， and challenges encountered by the development planning technologies during each stage. Through persistent research and practical application， the development planning technologies in Shengli Oilfield have progressed through four primary stages： scheme optimization， production planning， beneficial planning， and uncertainty planning. The development planning technologies developed during these stages have effectively supported the formulation of development planning strategies， guiding the oilfield’s development. With a focus on the sustainable development goals of Shengli Oilfield， it has been identified that there are three key issues for the development planning technologies to address： the challenge of mastering the economic principles of new field development， the need to reinforce the integration of mid-to-long-term planning with annual production schedules， and the requirement to elevate the strategic and forward-looking aspects of plans. In response to these challenges， the development planning technologies in Shengli Oilfield will prioritize uncertainty and multi-objective planning， alongside advancements in intelligence and precision， as well as strategic and futuristic development， so as to provide technical support for the strategic decision-making of oilfields.

Shengli beach-shallow sea oilfields are located at the junction of sea and land， with Chengdao Oilfield and Xinbei Oilfield as representatives. They have the characteristics of diverse reservoir types， complex ground conditions， and significant investments in ocean engineering facilities， so it is difficult to develop beneficially. Based on the development practice of the Shengli beach-shallow sea oilfield， this paper focused on the technical achievements since the “11th Five-Year Plan.” The efficient development technologies for characteristic Shengli beach-shallow sea oilfields were formed through continuous technical research， with the cores of subdivision and comprehensive adjustment of beach-shallow sea oilfields， overall injection and production regulation of beach-shallow sea oilfields， efficient development of offshore oil production， effective utilization of beach-shallow sea marginal oilfield， and development of complex fractured buried hill oil reservoir. The first beach-shallow sea oilfield of four million tons， Chengdao Oilfield， was built in China， realizing the crossing from land to sea. The challenges in the efficient production construction in the new area and the technical support of enhanced oil recovery in the mature area were clarified by analyzing the problems facing the high-quality development of the beach-shallow sea oilfield. By considering the important position for the continuous production of Shengli Oilfield， the development direction of “fewer wells， high yield， high speed， and high efficiency” was proposed to alleviate the contradiction between the production demand and low grade of unproduced reserves， as well as the stable production foundation and restrictive liquid production in the mature area faced by the beach-shallow sea oilfield in the future. In other words， it is necessary to continue to study critical technologies， such as the beneficial utilization of multiple oil and gas reservoirs in beach-shallow sea， the reconstruction of secondary well pattern under the “3 + 2” development mode based on platform intensification， and the intelligent injection and production control based on a big model， to support the high-quality and sustainable development of Shengli beach-shallow sea oilfield.

The extraction of uranium from nuclear wastewater through photocatalysis represents a highly viable, environmentally friendly, and sustainable approach, contributing significantly to mitigating environmental degradation while facilitating the efficient recovery of uranium resources. Nonetheless, the development of highly efficient photocatalysts with rapid charge carrier migration and surface reaction kinetics for the effective removal of U(Ⅵ) from uranium-containing wastewater remains a formidable challenge. This study successfully employed template-free self-assembly techniques to fabricate hollow tubular g-C3N4(TCN) and synthesized a tubular donor-acceptor(D-A) organic semiconductor photocatalyst, B-TCNx, by incorporating hydroquinone into the framework of TCN. This innovative photocatalyst was utilized for the photocatalytic removal of U(Ⅵ) under ambient air conditions. The construction of an intra-molecular D-A system enables the separate accumulation of electrons and holes in the acceptor and donor moieties, thereby significantly reducing electron-hole recombination. Furthermore, the spatial separation of electrons and holes in the acceptor and donor moieties leads to the formation of an intrinsic electric field, which facilitates the migration of charge carriers. The research findings indicate that B-TCN60 achieved a remarkable removal rate of 96.8% for U(Ⅵ) within 120 minutes, with a kinetic constant(0.03114 min−1) that is 2.58 times higher than that of TCN(0.01215 min−1). Moreover, negligible performance variation was observed after five consecutive cycles, demonstrating the excellent stability and reproducibility of the photocatalyst. The enhanced performance of B-TCN60 can be attributed to its unique structural and electronic properties. The hollow tubular structure of TCN provides a high surface area, which is beneficial for the adsorption of uranium ions. Additionally, the incorporation of hydroquinone into the TCN framework not only improves the light absorption properties of the photocatalyst but also plays a crucial role in the formation of the D-A system. The effective separation of charge carriers within the D-A system minimizes recombination losses and maximizes the efficiency of the photocatalytic process. The study’s findings underscore the potential of D-A organic semiconductor photocatalysts in addressing environmental challenges associated with nuclear waste, while also enhancing the recovery of valuable uranium resources. The novel approach of utilizing a D-A system in the photocatalyst design opens new avenues for the development of advanced materials with superior photocatalytic performance. The innovative use of template-free self-assembly techniques to fabricate hollow tubular g-C3N4 and the successful synthesis of the B-TCNx photocatalyst represent significant advancements in the field. The high removal efficiency, stability, and reproducibility of B-TCN60 highlight its potential for practical applications in environmental remediation. This work not only contributes to the field of environmental remediation but also offers a sustainable solution to the global issue of nuclear waste management.

The development and application of nuclear energy is often considered as a potential solution to meet the increasing energy demand. However, it is important to acknowledge that the utilization of nuclear energy resources and the treatment of nuclear waste pollution pose significant challenges that require careful consideration and management. Therefore, it is crucial to address the challenges of uranium pollution treatment and uranium resource recovery to ensure the sustainable development of nuclear energy. The technology of photocatalytic reduction has been found to have a synergistic adsorption reduction ability, which allows it to overcome the thermodynamic limitations of single adsorption removal. As a result, photocatalytic reduction technology is widely recognized as having great potential in the removal and recycling of uranium in nuclear waste liquid. One of the key factors for the effective application of this technology is the acquisition of a catalyst with high photocatalytic reduction ability. Nitride carbon materials are considered an ideal photocatalyst for photocatalytic reduction of U（Ⅵ） due to their excellent photochemical properties, excellent physicochemical adjustability, and good chemical stability. However, the pure g-C3N4 photocatalyst still suffers from its low separation efficiency of photogenerated charge carriers, which results in unsatisfactory photocatalytic activity. In recent years, research on modifying and applying carbon nitride has provided in-depth insights into the reduction of uranium through photocatalysis. Discussing the strategy of modifying C3N4, constructing heterojunction nanostructures, and utilizing them for the photocatalytic reduction of uranium, along with the mechanisms involved. This review summarizes the recent significant progress on the design of g-C3N4-based heterostructure photocatalysts and their special separation/transfer mechanisms of photogenerated charge carriers. On the one hand, according to the key steps of photocatalytic uranium reduction, modification strategies using g-C3N4 photocatalysts can be classified into the following groups: morphology modification, band-structure regulation, and heterostructure construction. Moreover, according to the different transfer mechanisms of photogenerated charge carriers between g-C3N4 and the coupled components, the g-C3N4-based heterostructure photocatalysts can be divided into the following categories: g-C3N4-based conventional Type-Ⅱ heterojunction, g-C3N4-based Z-scheme heterojunction, g-C3N4-based S-scheme heterojunction, and g-C3N4/metal heterostructure. We also focused on the structure-activity relationship between the modification of photocatalytic materials based on carbon nitride and their photocatalytic reduction performance for U（Ⅵ）, as well as the mechanism of their catalytic reduction removal. Finally, this section offers concluding remarks and prospects for exploring the challenges and opportunities faced by advanced carbon nitride-based photocatalytic materials in the removal of uranium pollution and the recovery of uranium resources. It also provides directions for future breakthroughs.

With the rapid development of nuclear energy, uranium as the main element of nuclear energy production, its source has been widely explored. At present, uranium resources mainly come from uranium mining, and a lot of radioactive uranium containing wastewater is produced in the process of uranium mining. Until now, the treatment technology of uranium mine wastewater is still in the research and development stage in China, which leads to the storage of a large amount of uranium mine wastewater and the discharge of nuclear waste liquid, which poses a threat to human health and the environment due to the comprehensive effect of chemical toxicity and radiation toxicity. On the other hand, other metal cations in uranium wastewater, such as Ca2+ and Mg2+, compete with U(Ⅵ) for active sites, making it difficult for most treatment methods to effectively recover uranium resources from uranium wastewater. Therefore, how to effectively treat radioactive uranium mine wastewater is full of challenges. Photocatalysis is a kind of green environmental protection technology with natural selectivity to non-variable valence ions, which can precipitate the soluble U(Ⅵ) in wastewater. The photocatalysis technology is expected to overcome the competition between metal cations and uranium for active sites, and realize the efficient extraction of U(Ⅵ) in uranium mine wastewater. In this study, ZIF-8-derived Zinc@iron oxide(D-ZnO@FexOy) heterostructures were prepared by impregnation of metal salt solution and high-temperature pyrolysis using ZIF-8 as a precursor for photoassisted reduction of U(Ⅵ) in uranium ore wastewater. The electron transport mode of D-ZnO@FexOy in S-scheme heterojunction is deduced by calculating the work function and band structure. Under photoexcitation, the direction of electron flow changes, the useless electrons and holes recombine at the interface, and the electrons and holes with strong redox ability are retained and participate in the photocatalytic reaction. Compared with D-ZnO and FexOy, this kind of spatially separated photogenerated electrons and holes have stronger redox ability and longer electron lifetime. Meanwhile, the internal electric field formed at the heterojunction interface can effectively enhance the directional electron migration, providing a strong power for promoting the photoassisted reduction of uranium. Therefore, compared with iron oxide(FexOy) and ZIF-8-derived ZnO(D-ZnO), the S-type heterostructure D-ZnO@FexOy exhibits stronger photoassisted uranium reduction ability(>95%) in the presence of multiple competing ions, and the material has good anti-interference and stability. High U(Ⅵ) removal performance(above 86%) is maintained after 5 cycles. The mechanism study shows that hydroxyl radical and superoxide radical are the main active species of photocatalytic reduction of U(Ⅵ). U(Ⅵ) is deposited on the surface of the material in the form of (UO2)O2•2H2O crystals. This study provides a valuable way to explore the photocatalyst with high efficiency photoelectron separation to reduce U(Ⅵ).

Extracting uranium from seawater is an effective strategy for sustainable nuclear fuel supplementation. Uranium in seawater mainly exists in the form of hexavalent uranyl(U(Ⅵ)), although the total amount is large, the mass fraction of U(Ⅵ) is only 3.3×10−9, and many metal ions coexist with uranium. Extracting uranium from seawater is extremely challenging. Electrochemical seawater uranium extraction has become an emerging method for seawater uranium extraction due to its advantages over physical and chemical adsorption processes, such as fast reaction rate, strong anti-interference ability, and simple desorption. However, due to the lack of research on the structure-activity relationship between catalysts and uranium extraction performance, the rational design of highly active electrocatalysts remains a challenge. In this work, we proposed an interface bonding strategy by using a simple hydrothermal method to bond the {2 2 2} fact of octahedral Fe3O4 to the {0 0 2} fact of MoS2. This significantly improves the electron transfer rate at the interface and the cycling stability of Fe3O4, verifying the feasibility of interface bonding for the electrochemical extraction of uranium from seawater. After 7 hours of electrochemical extraction in a simulated solution, the extraction efficiency of uranium can reach 96%. Meanwhile, the experimental results of coexisting ion extraction of uranium indicated that MoS2/Fe3O4 has good selectivity for uranium and anti-interference ability against coexisting ions. Electrochemical extraction is also performed in 10 L natural seawater with a yield of 27.2 μg. The extraction amount of uranium is 5.44 mg/g. A series of characterizations such as XPS and HRTEM, show that Fe3O4 is dispersed on the surface of MoS2 and effectively bound through interfacial interactions. This dispersion effectively solves the aggregation problem of Fe3O4, and the stability of MoS2 structure ensures the cycling stability of Fe3O4. By combining the MoS2 and Fe3O4 at the interface, an efficient electron transfer channel can be constructed, accelerating electron transfer and achieving the goal of simultaneously improving the selectivity, stability, and electron transfer rate of the catalyst. Therefore, the interfacial regulation strategy proposed in this work utilizes the synergistic effects of different components in the composite material to achieve stability and the cyclicity of the catalyst in seawater uranium extraction. At the same time, the interface control strategy will also provide a feasible solution for achieving efficient reduction and extraction of uranyl in a series of complex environments such as seawater. And the electron transfer path and the species change of uranium during catalytic reduction need to be further explored in the mechanism analysis in this work.

In this work, the coordination chemistry of the uranyl ion(\begin{document}${\mathrm{UO}}_2^{2+} $\end{document}) with N, N-dimethyl-diglycolamic acid(HDMDGA, HLI) and N, N-diethyl-diglycolamic acid(HDEDGA, HLII) has been systematically studied through thermodynamic and structural analysis, by means of both potentiometric and spectroscopic titration, as well as Raman spectroscopy and X-ray diffractometry. The protonation constants of L−(L=LI, LII) and the stability constants of the uranyl complexes were determined by potentiometric and spectroscopic titrations in 1.0 mol/L NaClO4, with the molar absorption spectra of all species deconvoluted in the process of the latter titration. Besides, the standard Raman spectra of various complexes were confirmed by Raman spectroscopic titration. Furthermore, the single crystal of compound \begin{document}${\mathrm{UO}}_2{\mathrm{L}}^{{\mathrm{II}}}_2 $\end{document} was obtained by slow evaporation of aqueous solution containing uranyl ion and LII ligands at room temperature. X-ray diffraction analysis shows a monoclinic crystal system in P21/c space group, with lattice parameters: a=15.5096(6) Å（1 Å=0.1 nm）, b=7.7934(3) Å, c=11.3732(4) Å, α=90°, β=97.388(4)°, γ=90° and Z=2. Although both ligands show a similar structure and protonation constant, the different values of stability constant in aqueous solution and the different bond length of U-O in two complexes indicate the distinct coordination ability for two ligands with \begin{document}${\mathrm{UO}}_2^{2+} $\end{document}, where HDEDGA performs better. Like the crystal structure of \begin{document}$ {\mathrm{UO}}_2{\mathrm{L}}^{{\mathrm{I}}}_2$\end{document}, the ligand LII in the \begin{document}${\mathrm{UO}}_2{\mathrm{L}}^{{\mathrm{II}}}_2 $\end{document} complex coordinates with \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} in a tridentate manner, with three oxygen atoms(amide oxygen, ether oxygen and carboxylic acid oxygen) coordinating with the linear \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} at the equatorial plane. In addition, the diffuse reflectance spectra of the \begin{document}${\mathrm{UO}}_2{\mathrm{L}}^{{\mathrm{II}}}_2 $\end{document} crystal show characteristics significantly different from the absorption spectra of the corresponding complex in the aqueous solution. Meanwhile, the Raman shift of the characteristic peak of uranyl ion between hydrated uranyl ion and the 1∶1 complex(U∶ LII) is significantly larger than that between 1∶1 and 1∶2. Therefore, it is speculated that the structure of the 1∶2 complex in aqueous solution is supposed to be different from that in the solid crystal.

Photocatalytic technology can use photogenerated electrons to reduce easily soluble U(Ⅵ) to insoluble U(Ⅳ). In this work, hierarchical macro/mesoporous g-C3N4-TiO2 composites were synthesized without the introduction of organic templates or auxiliary additives, and were used for photocatalytic reduction of U(Ⅵ). The morphology, structure and optical properties of g-C3N4-TiO2 composites were studied by X-ray diffractometer(XRD), scanning electron microscope(SEM), automatic specific surface area physical adsorption instrument(BET), ultraviolet-visible diffuse reflectance spectrometer(UV-vis DRS) and other advanced characterization equipment. The photocatalytic reduction of U(Ⅵ) of g-C3N4-TiO2 composites was studied by photocatalytic experiments. The results show that g-C3N4-TiO2 composites have the advantages of hierarchical macro/mesoporous TiO2 and g-C3N4, not only have a large specific surface area(174.68 m2/g) and pore channels, but also have a wider light absorption range. Therefore, the removal rate of g-C3N4-TiO2 composites on U(Ⅵ) is as high as 98.4% within 15 min. This work provides new ideas for the treatment of uranium-containing radioactive wastewater.

Photocatalytic assisted uranium extraction technology is a rapidly developed technology for uranium extraction from wastewater and seawater in recent years, which can significantly improve the extraction capacity and extraction rate of uranium. However, the activity of most photocatalysts in air atmosphere is inhibited, which hinders the practical application of this technology. Based on this, this paper discusses the latest progress of photocatalytic assisted uranium extraction technology in air atmosphere, focusing on the analysis of different mechanisms and product characteristics of photocatalytic assisted uranium extraction in air atmosphere, especially the photoreaction and chemical reaction mechanism in the absence of catalyst. There are mainly two mechanisms for the photocatalysis assist uranium extraction. The first one is based on the photocatalytic reduction of U(Ⅵ) to U(Ⅳ). Under illumination, electrons and holes pairs are generated on photocatalysts, and the electrons could reduce the soluble \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} to insoluble uranium oxide(UO2). However, under air atmosphere, at the presence of oxygen, the newly formed UO2 could be oxidated back to \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} and dissolved into solution, resulting in the decrease of uranium extraction performance. Therefore, this mechanism is usually applied under inert atmosphere. Although with proper design of photocatalyst, the oxygen could be covert to \begin{document}${ · {\mathrm{O}}_2^- } $\end{document} to further reduce \begin{document}${\mathrm{UO}}_2^{2+} $\end{document}, the performance is still not comparable with that under inert atmosphere. The other recently developed photocatalysis assisted extraction mechanism is based on the convert of soluble \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} to uranium peroxide((UO2)O2•xH2O), which can work well under air atmosphere. Under light illumination, hydrogen peroxide(H2O2) can be first produced with the assist of efficient photocatalysts or the photoactivity of \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} itself. Then H2O can react with to \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} form insoluble uranium peroxide. As uranium peroxide is stable under air and oxygen may contribute to the formation of H2O2, this mechanism can obtain excellent performance under air. Researchers have developed composite materials such as carbon nitride, carbon dots, graphene aerogels, and metal-organic frameworks(MOFs), which exhibit superior uranium removal performance under aerobic conditions. Besides, research on uranium extraction via photocatalysis under air is still in its infancy, and the specific reaction mechanisms may vary under different environments, necessitating further investigation. Based on the mechanism of uranium extraction via the photo-assisted transformation to uranium peroxides, the design of catalysts and uranium extraction materials will be greatly broadened. Combined with the discussion of the reaction mechanism of uranium extraction under light conditions and the design of catalyst materials, we hope to provide inspiration for researchers to develop highly efficient uranium extraction catalyst and mechanism research under air atmosphere.

In this work, molten salt method was used to prepare highly dispersed graphitic carbon nitride(WSGCN), and chemical reduction method was used to load Cu nanoparticles on WSGCN to prepare Cu-WSGCN composites. FTIR, XRD, XPS, TEM, SEM, ICP-AES, UV-vis DRS, PL spectroscopy, ESR and EIS characterization methods were carried out to investigate the structure and photoelectric properties of the photocatalyst. The results show that compared with WSGCN, Cu-WSGCN has a larger light absorption range and a narrower band gap. In addition, the presence of Schottky barriers at the interface between Cu nanoparticles and WSGCN promotes charge transfer and separation of photogenerated carriers, which improves the photocatalytic ability. The uranium removal rate of Cu-WSGCN composite is relatively high(81.07 %) when the load of Cu nanoparticles is 1%. After three cycles of photocatalytic uranium reduction experiments, the uranium removal rate by 1%Cu-WSGCN can still reach 75.96%, which provides a useful reference for the development of novel materials with high efficiency photocatalytic removal of uranium.

Uranium is the main fuel of nuclear power, and the removal of uranium from uranium-containing wastewater is important for environmental protection and resource recovery. Photo-induced uranyl ion removing is an economical and efficient method to remove U(Ⅵ) from uranium-containing wastewater. Many materials have been used for photo-induced reduction of U(Ⅵ). However, the practical application of most materials is still limited by many factors, such as the complexity of its synthesis process, the harsh conditions required, and the poor selectivity and reusability in the photocatalytic process. More importantly, most materials can only be photocatalyzed under the protection of an inert atmosphere. In the presence of oxygen, the photocatalytic product uranium dioxide(UO2) is unstable and easily oxidized resulting in reduced removal effect, so it becomes particularly vital to find an effective catalyst. Carbon dots(CDs) are a new type of carbon-based materials with excellent fluorescence performance, good water solubility and biocompatibility. However, due to the small size and hydrophilicity of the CDs, it is difficult to separate from water. It needs to be combined with other solid materials when applied. The application of CDs to the photocatalytic removal of uranyl ions in water has rarely been studied. Silica(SiO2) is an ideal loader due to its excellent mechanical strength and irradiation stability, as well as its large specific surface area and easy modification. In this paper, a blue carbon dot was prepared by solvothermal method and CDs/SiO2 composites were synthesized by sol-gel method. The morphology of the composite was characterized by scanning electron microscopy(SEM) and transmission electron microscopy(TEM) technologies, and their application in photocatalytic removal of uranium were studied. Under visible light irradiation, CDs/SiO2-b can remove more than 95% of uranium in 100 min. Experiments have found that the photo-precipitation rate of silica to uranium after the introduction of carbon dots is about 5.8 times of that of the pure silica, and uranium can be transformed into solid product of (UO2)O2•2H2O under air atmosphere, with a removal capacity of more than 800 mg/g. The morphology and structure of the photocatalytic products were characterized by SEM and XPS technology, and the solid products were easy to separate and remove. In order to evaluate the practical application of CDs/SiO2 light-induced reduction of uranium under visible light irradiation, pH and other influencing factors were systematically studied. Moreover, the removal efficiency of uranium is higher 85% after 5 cycles of recycling, showing excellent recycling performance. CDs/SiO2 composites are simple to prepare and can efficiently remove uranyl ions in water through photoinduction, which provides a new method and material for photoinduced removal of uranium.

The photocatalytic conversion of soluble U(Ⅵ) to insoluble U(Ⅳ) is regarded as an effective method for the separation of solution uranium. During the photocatalytic reactions, the design of photocatalyst plays a role. As a metal free polymer semiconductor, carbon nitride(CN) has attracted increasing attentions in photo-catalytic reduction of U(Ⅵ) under visible light irradiation due to its low cost, easy preparation, excellent physicochemical stability and adjustable structure. However, the application of carbon nitride in photocatalytic U(Ⅵ) reduction is limited by its low photocatalytic reduction efficiency, which is caused by the poor reactive sites low separation rate of charge carriers, and slow transport efficiency of electrons. This study aimed to evaluate the transformation of U(Ⅵ) in aqueous solution over Y-doped CN(YCN). YCN photocatalysts with different amount of Y3+ were prepared by in situ doping to modify the energy band structure and physicochemical properties of carbon nitride. It was revealed that the presence of Y3+ changed the in-plane periodic topology and inter-layer stacking structure of the tri-s-triazine unit of carbon nitride, resulting in the incomplete polymerization of the tri-s-triazine unit. The doping of Y3+ lead to the formation of porous structure in YCN, which increases the specific surface area and the active sites. Comparing with pristine CN, YCN showes enhanced absorbance for light and increases separation rate of charge carriers. The average fluorescence life is subsequently increased under light irradiation, which is 1.8 times for YCN2 than the pristine CN. The EPR spectra demonstrates that, compared to CN, significantly more \begin{document}$ · {\mathrm{O}}_2^- $\end{document} radicals and less \begin{document}$· {\mathrm{OH}} $\end{document} radicals are generated on YCN2 under light irradiation. The free radical trapping experiments verifies that \begin{document}$ · {\mathrm{O}}_2^- $\end{document} radicals act as the dominant reactive species for the reduction of U(Ⅵ) and the small amount of other radicals do not bring obvious influence. The enhanced generation of \begin{document}$ · {\mathrm{O}}_2^- $\end{document} radicals on YCN2 therefore provides favorable conditions for the photocatalytic reduction of U(Ⅵ). When using methanol as a sacrificial agent, it can remove about 95% of U(Ⅵ) within 20 min for the YCN2-containing system under light. The rate of the photocatalytic reduction of U(Ⅵ) on YCN2(0.112 min−1) is 5.3 times higher than CN(0.021 min−1). Analysis of the products reveals that water-soluble U(Ⅵ) is reduced in the photocatalytic reaction, with approximately 80% U(Ⅳ) and 20% U(Ⅵ). The soluble U(Ⅵ) is mainly reduced to insoluble UO2+x deposited on the surface of YCN by \begin{document}$ { · {\mathrm{O}}_2^- } $\end{document} radicals. This study improves the photocatalytic performance of CN for the reduction of U(Ⅵ) by Y3+ doping.

Uranium, as the most important fuel for nuclear power operation, is crucial to ensure the sustainable development of nuclear power. However, the supply-demand contradiction of uranium resources in China has become increasingly prominent, and the gap needs to be filled by overseas development and international market procurement. The photoreduction and electroreduction of uranium under complex conditions are mainly targeted at uranium containing radioactive wastewater, real seawater, and other systems. Uranium containing radioactive wastewater comes from the processes of uranium mining, uranium enrichment, uranium conversion, and manufacture of nuclear fuel elements, with the characteristics of complex interfering ions. Although the total amount of uranium in seawater is very large, the concentration of uranium in seawater is low, making the extraction of uranium from seawater extremely challenging. On the one hand, the reserves of uranium in seawater are nearly a thousand times higher than those on land; on the other hand, the entire application process of the nuclear industry produces a large amount of uranium containing radioactive wastewater. If efficient separation of uranium from seawater and uranium containing radioactive wastewater can be achieved, it can promote the secondary supply of uranium resources and alleviate the supply-demand contradiction of uranium resources in China. Therefore, the development of uranium recovery and extraction technology from seawater and uranium containing radioactive wastewater is important for the sustainable development of the nuclear industry. This paper reviews the recent research progress in separating uranium in complex environments such as seawater and uranium containing radioactive wastewater. In terms of uranium speciation analysis, it describes the coordination environment of complex environmental uranyl and summarizes the advantages of photocatalysis and electrocatalysis in the fields of uranium extraction from uranium containing radioactive wastewater and seawater. In terms of designing photocatalysts, strategies such as element doping, metal loading, defect engineering, and introducing heterojunctions have been summarized for the preparation of photocatalytic semiconductor materials. The modification of functional groups on heterojunctions to regulate their energy band structure had introduced, which improved the overall performance of the material. The integration of selective adsorption and catalytic reduction, electrochemical methods can reduce soluble uranyl ions to neutral and insoluble products for separation, with advantages such as fast kinetics, wide extraction concentration range, and large separation capacity. However, there are also many key technical challenges in the practical application process, such as the competition between multiple cations and uranyl ions in complex systems, and the problem of excessive energy consumption caused by the competing reaction of water splitting during the cathodic uranium extraction process. In terms of electrocatalysis, various aspects such as electrode carrier selection, electrochemical device design, defect engineering, surface engineering, interface engineering, and microbial electrochemistry have been summarized to design electrocatalytic materials. In terms of key technical bottlenecks, combining photocatalysis and electrocatalysis technology with challenges in complex scenarios such as uranium speciation analysis, material functionalization design, intermediate reaction species analysis, uranium extraction mechanism analysis, cost control, and real-world application outcomes, relevant research have focused on challenges such as efficient photocatalytic reduction of uranium under natural light, identification of intermediate uranium species, uranium extraction from uranium containing radioactive wastewater, and seawater extraction from real ocean environments.

In this work, a novel graphite-based electrochemical filter was developed for the efficient and environmentally friendly treatment of uranium tailings leachate. The filter utilizes graphite particles as filler and carbon felt as a conductor, powered by a DC power supply and driven by a peristaltic pump. In a non-circulating continuous operation filter experiment, uranium tailings leachate was tested for uranium removal efficiency under different operating parameters such as voltage and residence time, using both synthetic wastewater and actual uranium mine wastewater. This study is based on the fundamental principles of metal electrochemical reduction. The efficacy of this device for the continuous flow treatment of uranium tailings leachate was systematically investigated. The mechanism of uranium tailings leachate treatment by the electrochemical filter was elucidated through electrochemical analysis and product characterization. The results highlight that voltage and hydraulic retention time are critical factors influencing the efficiency of electrochemical filter treatment. Specifically, 4.0 V and 10 hours were identified as the optimized voltage and suitable hydraulic residence time, respectively, for the treatment of uranium tailings leachate using the electrochemical filter, resulting in a uranium removal rate exceeding 97%. In actual uranium tailings leachate applications, the maximum extraction rate can reach 5275 μmol/(m3∙h), confirming the feasibility of electrochemical filter in removing uranium from actual uranium tailings leachate and its good selectivity in complex water quality applications, the device can be quickly applied to uranium tailings leachate collection facilities and achieve in-situ uranium extraction. The voltage increase can significantly enhance the uranium extraction performance and can be portablely deployed in uranium mine water. In-situ uranium processing and recovery is achieved in processing and collection facilities. Characterization techniques such as field emission scanning electron microscope-energy spectrum analyzer(FESEM-EDS) and X-ray photoelectron spectrometer(XPS) were employed to analyze the reaction products on the graphite particles, revealing that uranium was evenly distributed on the surface of graphite particles and exhibits a stable crystal structure, the main mechanism responsible for uranium removal was adsorption-reduction, with uranium recovery products deposited on the electrode surface in the form of a mixture of U(Ⅳ) and U(Ⅵ). A cost estimation shows that the operational cost of extracting uranium from uranium tailings leachate using this device falls within the range of 176.6 ￥/kgU to 587.5 ￥/kgU. This cost is significantly lower than that of conventional land-based uranium resource development, making it economically viable. This research provides both theoretical and technical support for the efficient and environmentally friendly treatment of uranium tailings leachate.

Due to large burial depths， ultra-deep clastic rock reservoirs have poor physical properties and low oil and gas productivity. However， the newly drilled Well Zheng10 in Shawan Sag， Sinopec exploration area， has encountered high-quality thick reservoirs in the Triassic Karamay Formation at a buried depth of 6 700 m， and conventional tests have obtained high industrial oil and gas flow. To reveal the characteristics of this set of reservoirs and favorable main controlling factors， clarify the direction of ultra-deep clastic rock exploration， and reduce the risk of further oil and gas exploration in this area， this paper comprehensively analyzed the data of core， well logging， cast thin sections， physical properties， scanning electron microscopy， and diagenetic evolution of the reservoirs， and discussed the petrological， physical， and pore characteristics of reservoirs in the Triassic Karamay Formation in this area. The results show that the ultra-deep clastic rocks of the Triassic Karamay Formation in Well Zheng10 area are deposited in the front of the braided river delta. The lithology is dominated by glutenites， gravel-bearing fine sandstones， and fine sandstones， and the rock types are mainly feldspar lithic sandstones with low composition maturity. The remaining primary pores and solution pores dominate the reservoir space. The average porosity of the reservoirs is 9.1%， and the average permeability is 2.85 mD. The reservoir belongs to the ultra-low porosity and ultra-low permeability type and low porosity and low permeability type as a whole. Favorable sedimentary facies zones， constructive diagenesis， and abnormal high-pressure control the development and distribution of favorable reservoirs in this area. Among them， sedimentary microfacies are the basis of favorable reservoir development. The fine sandstones deposited in the underwater distributary channel at the front of the braided river delta are better sorted and rounded. The contents of the muddy matrix are low， and the physical properties of the reservoir are better， which are the dominant phase zones for favorable reservoir development. The sodium feldspar cements generated in the early diagenetic process are dissolved by acids in the later period， which increases the dissolution pores and is an essential constructive diagenesis. The abnormal high-pressures formed by continuous oil and gas charging form early and develop continuously for a long time， playing an important construction role. The research results have a guiding role for the subsequent ultra-deep oil and gas exploration in this area.

Deep source rocks undergo high degrees of evolution， leading to a significant decrease in biomarker content in crude oil as maturity increases. The decrease affects the reliability of the oil source correlation with conventional biomarker parameters. To better use the δ13CPDB value for identifying deep crude oil sources， authors analyzed the δ13CPDB values of four group components in the soluble organic matter from naturally evolved source rock profiles in Dongying Sag， Jiyang Depression， Bohaiwan Basin and the products of physical experiments on hydrocarbon generation and expulsion. Considering the relative content of alkane， authors discussed the carbon isotope fractionation effects in the crude oil from deep source rock. Additionally， authors proposed the working thought and procedure for identifying the source of deep oil with the δ13CPDB values. The carbon isotope fractionation effects resulting from high thermal maturity are obvious in deep source rocks. The δ13CPDB values of the four group components of soluble organic matter from source rocks （alkane， aromatics， non-hydrocarbon， and asphaltene） exhibit a significant elevation with increasing burial depth. Specifically， the δ13CPDB values of alkane exhibit the most pronounced change， exceeding 5‰， while aromatics show a change of around 4‰. The changes in the δ13CPDB value of non-hydrocarbon and asphaltene are relatively small， ranging from 2‰ to 3‰. As burial depth increases， the alkane contents in soluble organic matter increase from around 40% to over 80%. Correspondingly， the δ13CPDB values of alkane increase from around -30‰ to over -24‰， and the alkane contents show a great correlation with the variations of its δ13CPDB values. Similar results can also be observed from the δ13CPDB values of group components from physical experiments on hydrocarbon generation with the same type of source rock samples. In these experiments， the variations in the δ13CPDB values of alkane can reach 4‰， while those in aromatics， non-hydrocarbon， and asphaltene are relatively low， ranging from 1‰ to 3‰. When utilizing carbon isotopes to identify the source of deep oil， it is essential to first check the correlation between alkane contents and their δ13CPDB values to identify if the carbon isotope fractionation effects derived from thermal maturation exists. Subsequently， the δ13CPDB values of alkane should be properly recovered before utilizing it to identify the source of the oil. According to the abovementioned methods， authors identified the source of light oil from Chepaizi Uplift in the Western region of Junggar Basin. It confirmed the presence of carbon isotope fractionation effects in the light oil derived from thermal evolution. It shows a great possibility that the light oil is sourced from the underlying high-maturity source rock of the Permian， which is of important practical significance in the evaluation and deployment of the petroleum exploration target in this area.

The occurrence characteristics and mobility are essential aspects of shale oil evaluation， as well as exploration and development. However， there are still significant challenges in characterizing the occurrence characteristics and mobility of shale oil due to the strong heterogeneity， as well as the complex pore structure and fluid properties of shale. New research methods and experimental techniques have emerged in recent years with the intensifying exploration and development of shale oil in China and abroad. Therefore， progress in research methods and experimental techniques were summarized for evaluating shale oil occurrence characteristics and mobility， and issues were proposed that need to be considered in the research on shale oil occurrence characteristics and mobility. The most direct method for qualitative evaluation of shale oil occurrence characteristics is the advanced high-resolution imaging techniques for image observation among existing techniques. The oil saturation index method and classification evaluation method based on statistical analysis have advantages in evaluating shale oil mobility in mature exploration areas. At present， the multi-temperature stage pyrolysis parameter method is a fast and efficient method to characterize the shale oil quantity in different occurrence states quantitatively， and it has a good application prospect in the evaluation of shale oil content， shale oil mobility， and resource quantity. The following issues should be fully considered while studying the occurrence characteristics and mobility of shale oil in the future： ① developing highly simulated shale oil enrichment， flow， and development simulation experiments to ensure similarity between experimental conditions and underground geological conditions； ② conducting microscopic flow experiments of micro- and nano-scale shale oil to explore the microscopic flow mechanism and control factors of shale oil； ③ dissecting the differences in occurrence characteristics and mobility of shale oil in different basic thin layers， as well as the contributions of different basic thin layers to shale oil content and mobility； ④ combining the microscopic occurrence form， fluid mechanism， and macroscopic geological parameters of shale oil to determine and evaluate the macroscopic geological conditions and parameters.

Jiyang Depression is rich in petroleum resources. However， as the exploration degree intensifies， the exploration difficulty of the Paleogene conventional petroleum reservoirs is increasing. Therefore， exploring new fields and ensuring the effective supplement of resources is urgent. The strata in Jiyang Depression is well developed， and the pre-Paleogene buried hill is widely distributed， with a great thickness and significant exploration potential. However， the exploration results are unsatisfactory due to the early formation of deep buried hills， complex geological evolution history， and poor quality of deep seismic data. In recent years， with continuous breakthroughs in experimental technologies， deepening research on basic geology， and massive seismic data processing methods， the exploration of buried hills has yielded many promising leads. This has led to an understanding of petroleum exploration in buried hills characterized by multiple periods of structures contributing to hills， multiple sets of source rocks supplying hydrocarbons in conjunction， multi-element control of advantageous reservoir formation， and various modes of orderly controlling the reservoir. The risk direction and exploration targets for deep buried hills were clarified， and the ways for further petroleum potential exploration in Jiyang Depression were pointed out through an in-depth dissection of the discovered reservoirs， coupled with the exploration experience of neighboring areas. Specifically， the risk exploration directions for each stratum were as follows： fault-fractured bodies， fault-dissolved bodies， and other enclosures within the buried hills of the Archean； concealed fault block traps and internal grain beaches， as well as lithologic traps formed by layer-following dissolution of the lower Paleozoic； deep coal-measure gas reservoirs with a burial depth of greater than 2 000 meters of the upper Paleozoic； lithologic traps controlled by fractures and sand bodies of the Mesozoic.

After more than 60 years of exploration and development， the conventional oil and gas in the middle and shallow layers of the oil-rich sag in Jiyang Depression and in the ultra-denudation zones at the western edge of Junggar Basin have been in the mature exploration stage， which are the main body of reserve increase in Shengli exploration area. The exploration targets are becoming increasingly complex and subtle， and the difficulty of large-scale reserve increase continues to rise. It is urgent to strengthen the research and judgment of the exploration situation and resource potential evaluation， formulate targeted exploration and development strategies， and ensure the sustainable development of exploration in Shengli Oilfield. The exploration condition and situation resource potential， and areas with reserve increase were analyzed， and the remaining resource potential and favorable exploration directions were clarified in the eastern and western parts of Shengli exploration area. It was believed that Shengli exploration area still had a resource foundation for sustainable development， with deep and ultra-deep layers having the potential for large-scale reserve increase， peripheral low exploration areas having greater exploration potential， and unconventional oil and gas being the real resource replacement field. The implementation of the “three major exploration strategy transformations” was proposed， which included a shift from conventional oil and gas focus to equal emphasis on both conventional and non-conventional oil and gas in types， a shift from middle and shallow layers to deep and ultra-deep layers in stratigraphic systems， and a shift from mature oil areas to comprehensive exploration of the whole exploration area in the regions. An exploration development strategy of “focusing on the whole area， successfully exploring deep layers， emphasizing both conventional and non-conventional oil and gas， and implementing coordinated promotion” was developed. The development path was proposed of “persisting in tackling difficulties in low exploration areas to achieve breakthroughs， continuing deep and ultra-deep layer exploration to form a new position for large-scale reserve increase， emphasizing both conventional and non-conventional oil and gas to achieve stable reserve increase， and maintaining efficient management to promote high-quality exploration development”， which pointed out the direction for high-quality exploration development of Shengli Oilfield and provided ideas and directions for exploration in similar exploration areas in Bohai Bay Basin and Junggar Basin.

Shengli Oilfield has abundant oil and gas resources， with multiple types of reservoirs， and logging evaluation plays an essential role in exploration and development. The development history and the characteristics of logging evaluation technologies for reservoirs were systematically reviewed to celebrate the institute's 60th birthday. Summarizing experience and predicting the future have positive significance for the development and application in the professional logging field. A series of mature evaluation technologies formed in three types of reservoirs， including conventional sandstone reservoirs， complex reservoirs， and unconventional shale reservoirs， were systematically summarized according to the characteristics and evaluation difficulties of reservoirs. For conventional sandstone reservoirs， a highly applicable identification technology for oil layers was systematically developed， and an innovative method for establishing electrical standards constrained by the lower limits of lithology and oil potential was developed under multi-layer joint testing conditions. In addition， a pioneering logging modeling technology was proposed based on different diagenetic zones. Various technologies were developed for complex reservoirs， including logging identification of sandstone lithology in steep slope zones， effectiveness evaluation of low-permeability sandstone reservoirs， and identification and evaluation of oil layers with low resistivity. For unconventional shale reservoirs， a logging evaluation technology of reservoir parameters was preliminarily developed to evaluate the storage properties and oil potential mainly based on two-dimensional nuclear magnetic resonance experiments. These logging evaluation technologies for different types of reservoirs reflected the combination of wellbore data and geological understanding， as well as the integration of rock physics and logging models， and they demonstrated the ability of logging to serve geology and reservoirs and achieved good application results. In the future， the remaining resources will mainly be distributed in hidden oil and gas reservoirs and deep layers. In order to meet the needs of exploration and development， it is necessary to strengthen the analysis of experimental data， gas logging， and testing production data， combine logging evaluation and geology， intensify the application of new logging technologies such as logging while drilling， imaging， and nuclear magnetic resonance， carry out comprehensive research and evaluation， and expand the evaluation and prediction of production capacity of oil layers from the perspective of evaluation objectives. Moreover， it is necessary to fully rely on expert experience to select samples and deepen the application of big data/artificial intelligence on the basis of conventional technologies， which will definitely achieve good results.

Shale oil in Jiyang continental faulted basin is a realistic new field for subsequent resource， with enormous exploration potential. It is an important resource base for the sustainable development of Shengli Oilfield. The results of geological research and exploration of shale oil were analyzed in Jiyang continental faulted basin in recent years， and the new progress was systematically reviewed in shale sedimentation， reservoir formation， hydrocarbon generation， shale oil enrichment theory， and supporting fracturing stimulation technologies for Jiyang continental faulted basin. The results show that ① A shale lithofacies classification scheme is proposed based on mineral composition， sedimentary structure， crystallization， and abundance of organic matter ， which can be summarized as “four elements and three ends.” The mechanism of “four paleo-environment factors control shale lithofacies” is revealed， and the orderly “ring-shaped” distribution of shale lithofacies is confirmed. ② The core micro/nano CT scanning， argon ion polishing scanning electron microscopy， FIB-FESEM， nuclear magnetic resonance freeze-thaw， and small-angle X-ray scattering are integrated to form the quantitative characterization technologies of multi-scale shale pore and fracture systems. It is clear that the spaces of the shale reservoir in Jiyang continental faulted basin are divided into both pores and fractures， mainly inorganic pores and fractures. It is revealed that calcite recrystallization， dissolution， and conversion from illite/smectite to illite are the most critical reservoir formation mechanisms， and a reservoir model of shale pore and fracture network is established. ③ The oil content evaluation method of organic-rich shale is developed， which reveals the characteristics of high paleo-productivity， early generation， and early enrichment of organic-rich shale in the saline lake basin. The shale oil resources in Jiyang continental faulted basin are estimated to be more than 1010 t. ④ The shale oil enrichment is controlled by the spatiotemporal coupling of hydrocarbon generation and reservoir formation of bedded/laminated shale， which is characterized by “early formation of saline source rock， inorganic pore， and fracture reservoirs， microscopic source-reservoir integration， and dual coupling enrichment.” ⑤ The comprehensive evaluation system and target selection process for shale oil exploration in continental faulted basins are established， which involves four characteristics and four determinations. ⑥ The fracturing stimulation technologies are developed of “combined fracture network fracturing” and “horizontal well multistage fracturing” suitable for Jiyang continental faulted basin. According to the actual situation of Shengli Oilfield， the exploration idea is proposed of “increasing storage and production in main subsags， exploring new positions in small oil-rich subsags， implementing resources in peripheral small subsags， and taking into account the optimization of mineral rights，” to orderly promote the large-scale increase in storage and production of shale oil in Jiyang continental faulted basin. The relevant achievements and supporting technologies are significant for shale oil exploration and development in similar oilfields.

Oil and gas reservoir modeling integrates multidisciplinary information from logging， geology， and seismic data through geostatistics and other methods， and it is a powerful tool for oil and gas field development. The geological model of reservoirs can quantitatively characterize the variation and distribution of various geological features of the reservoir in three-dimensional space and is a high generalization of the type， geometry， scale， internal structure of the oil and gas reservoir， reservoir parameters， and fluid distribution. The geological model of reservoirs is the core of the geological model of oil and gas reservoirs， which can comprehensively characterize the sedimentary characteristics， heterogeneity， physical properties， and fluid characteristics. However， it is difficult to characterize reservoir distribution under the condition of a large-scale sedimentary system and sparse well pattern in the exploration stage， covering ① quantitative representation of geological knowledge， including how to represent the experience of geological experts digitally； ② it is impossible to accurately and quantitatively describe the development scale， distribution direction， and structural characteristics of geological bodies directly with logging data and construct geological models under the condition of sparse well pattern， and complex sedimentary systems in large-scale space cannot be characterized by simple mathematical functions； ③ traditional geostatistics and other methods can not realize the fusion of seismic， logging， geological， reservoir， and other multi-dimensional data in the construction of exploration model. Therefore， the theory and technology of reservoir modeling based on deterministic modeling and stochastic modeling， such as traditional geostatistics， have met great challenges. On the basis of systematic analysis of traditional reservoir modeling technology processes and methods， the authors constructed a multidisciplinary big data knowledge base of geoscience covering geology， logging， seismic， analytical， and laboratory information and carried out the characterization of the sedimentary facies pattern library by hierarchical clustering through multi-dimensional data condensation and the intelligent modeling based on the generation network. In addition， a multidisciplinary collaborative modeling technology strategy and system are proposed for oil and gas reservoir exploration， which quantitatively characterized the matching relationship among structure， sediment， and reservoir. This technology system has been systematically applied in the exploration and deployment of steep slope and subsag belts in the north of Dongying Sag， and the geological models of lithofacies， physical properties， and oil and gas migration and accumulation has been constructed， which integrates multiple information such as paleogeomorphology， paleoprovenance， transport channels， logging， and seismic attributes. Based on the new paradigm of the model， the deployment of well locations has been guided， and the exploration practice of complex glutenites and shale oil in continental faulted basins has been supported. The authors further discuss the development trend and application prospect of oil and gas reservoir exploration and modeling technology in the future by deeply analyzing the practical difficulties and accuracy of exploration and modeling in the north belt of Dongying Sag.

Geothermal resources are widely distributed in Jiyang Depression， with great potential. They would be essential directions for the development and utilization of geothermal resources of Shengli Oilfield in the future. The geothermal geological conditions were systematically sorted out， such as thermal reservoir， thermal cover， and heat source of hydrothermal geothermal resources and geothermal resources of dry-hot rocks in Jiyang Depression， and the amounts of two types of geothermal resources were calculated respectively to reveal their geothermal resource potential to develop and utilize geothermal resources in Jiyang Depression scientifically and efficiently，. The results show that hydrothermal geothermal resources in Jiyang Depression are mainly deposited in the Guantao Formation， Dongying Formation， and Lower Paleozoic strata. Among them， Guantao Formation is the strata with the largest potential for hydrothermal geothermal resources， featuring a wide distribution and massive resources. It is the critical stratum for exploration and utilization in the next step. Jiyang Depression is a sedimentary basin with a cold crust and hot mantle and has a high geothermal flow value. The thermal reservoirs in the geothermal resources of dry-hot rocks are mainly magmatic rocks and metamorphic rocks of the Archean. The heat flow in the deep mantle is the main heat source. The distribution area of thermal reservoirs is large and has high temperatures， and the resources are primarily distributed in Bohai Bay Basin. Geothermal resources are rich in Jiyang Depression. It is suggested that the relationship between hydrothermal geothermal resources and oil and gas， as well as the evaluation of resource zoning， should be strengthened to accelerate the development and utilization of geothermal resources. The exploration and development of geothermal resources of dry-hot rock is still in the initial stage. Research on the selection of thermal reservoir types and heat source mechanisms should be strengthened in the future.