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This work systematically reviews the complex mechanisms of CO2-water-rock interactions, microscopic simulations of reactive transport (dissolution, precipitation and precipitate migration) in porous media, and microscopic simulations of CO2-water-rock system. The work points out the key issues in current research and provides suggestions for future research. After injection of CO2 into underground reservoirs, not only conventional pressure-driven flow and mass transfer processes occur, but also special physicochemical phenomena like dissolution, precipitation, and precipitate migration. The coupling of these processes causes complex changes in permeability and porosity parameters of the porous media. Pore-scale microscopic flow simulations can provide detailed information within the three-dimensional pore and throat space and explicitly observe changes in the fluid-solid interfaces of porous media during reactions. At present, the research has limitations in the decoupling of complex mechanisms, characterization of differential multi-mineral reactions, precipitation generation mechanisms and characterization (crystal nucleation and mineral detachment), simulation methods for precipitation-fluid interaction, and coupling mechanisms of multiple physicochemical processes. In future studies, it is essential to innovate experimental methods to decouple “dissolution–precipitation–precipitate migration” processes, improve the accuracy of experimental testing of minerals geochemical reaction-related parameters, build reliable characterization of various precipitation types, establish precipitation-fluid interaction simulation methods, coordinate the boundary conditions of different physicochemical processes, and, finally, achieve coupled flow simulation of “dissolution−precipitation−precipitate migration” within CO2-water-rock systems.

Abstract The scale of propagation of hydraulic fractures in deep shale is closely related to the effect of stimulation. In general, the most common means of revealing hydraulic fracture propagation rules are laboratory hydraulic fracture physical simulation experiments and numerical simulation. However, the former is difficult to meet the real shale reservoir environment, and the latter research focuses mostly on fracturing technology and the interaction mechanism between hydraulic fractures and natural fractures, both of which do not consider the influence of temperature effect on hydraulic fracture propagation. In this paper, the hydraulic fracturing process is divided into two stages (thermal shock and hydraulic fracture propagation). Based on the cohesive zone method, a coupled simulation method for sequential fracturing of deep shale is proposed. The effects of different temperatures, thermal shock rates, and times on the scale of thermal fractures are analyzed. As well as the effects of horizontal stress difference and pumping displacement on the propagation rule of hydraulic fractures. The results show that the temperature difference and the thermal shock times determine the size and density of thermal fractures in the surrounding rock of the borehole, and the number of thermal fractures increases by 96.5% with the increase of temperature difference. Thermal fractures dominate the initiation direction and propagation path of hydraulic fractures. The main hydraulic fracture width can be increased by 150% and the length can be increased by 46.3% by increasing the displacement; the secondary fracture length can be increased by 148.7% by increasing the thermal shock times. This study can provide some inspiration for the development of deep shale by improving the complexity of hydraulic fractures.

Depression is a prevalent mental disorder that significantly diminishes quality of life and longevity, ranking as one of the primary causes of disability globally. Contemporary research has explored the potential pathogenesis of depression from various angles, encompassing genetics, neurotransmitter systems, neurotrophic factors, the hypothalamic-pituitary-adrenal axis, inflammation, and intestinal flora, among other contributing factors. In addition, conventional chemical medications are plagued by delayed onset of action, persistent adverse effects, and restricted therapeutic efficacy. In light of these limitations, the therapeutic approach of traditional Chinese medicine (TCM) has gained increasing recognition for its superior effectiveness. Numerous pharmacological and clinical studies have substantiated TCM’s capacity to mitigate depressive symptoms through diverse mechanisms. This article attempts to summarize the mechanisms involved in the pathogenesis of depression and to describe the characteristics of herbal medicines (including compounded formulas and active ingredients) for the treatment of depression. It further evaluates their effectiveness by correlating with the multifaceted pathogenesis of depression, thereby furnishing a reference for future research endeavors.

With high clay content in shale gas reservoir, the hydration is easy during hydraulic fracturing, which will affect the fracture conductivity and productivity of gas wells. The illite content of the Longmaxi formation shale in Yongchuan District is high (more than 80% of clay mineral content), and gas wells have a high productivity after fracturing and shut-in. However, the hydration effect mechanism of fracturing fluid on illite rich shale is not clear. Therefore, in this paper, core hydration experiments are performed for the illite rich shale reservoir. The water imbibition characteristic of near-fracture shale is obtained, and the micro-morphology and microfracture development characteristics of hydration are studied. Moreover, the hydration mechanism of near-fracture shale is then explored from the aspects of ion diffusion and mineral interlayer spacing variation. It is deduced that the fracturing fluid is spontaneously imbibed into small pores preferentially during well shut-in after fracturing. After the near-fracture shale is touched by water, some clay minerals peel and fall off from the fracture surface after hydration, accompanied by the development of microfractures. The interlayer spacing of clay minerals expands (smectite expands by 8.8% and illite 1.5%) after water immersion, and the ion diffusion occurs. The first 15 h is the rapid diffusion stage (surface effect), while the second 15 h is the stable rising stage (internal effect). This study systematically analyzes the hydration characteristics of near-fracture illite rich shale and reveals its hydration mechanism, which are crucial for the optimization of well shut-in time and exploitation system of shale gas reservoir after fracturing.

As a traditional Chinese medicine (TCM), Allii Macrostemonis Bulbus (AMB) is a key herb for the treatment of thoracic paralytic cardiac pain, but its quality evaluation method has not yet been fully clarified. In this study, chromatographic fingerprints of AMB were developed using solid-phase extraction–high-performance liquid chromatography–evaporative light scattering detection (SPE-HPLC-ELSD) to evaluate the quality of AMB from various origins and processing methods. This was achieved by employing chemical pattern recognition techniques and verifying the feasibility and applicability of the quality evaluation of AMB through the quantitative analysis of multi-components via a single-marker (QAMS) method. Through the analysis of the fingerprints of 18 batches of AMB, 30 common peaks were screened, and 6 components (adenosine, syringin, macrostemonoside T, macrostemonoside A, macrostemonoside U, and macrostemonoside V) were identified. Moreover, three differential markers (macrostemonoside A, macrostemonoside T, and macrostemonoside U) were screened out using chemometrics techniques, including principal component analysis (PCA), hierarchical cluster analysis (HCA), and orthogonal partial least squares discriminant analysis (OPLS-DA). Subsequently, a QAMS method was established for macrostemonoside T and macrostemonoside U using macrostemonoside A as an internal reference. The results demonstrate the method’s accuracy, reproducibility, and stability, rendering it suitable for the quality evaluation of AMB. This study provides a theoretical basis for drug quality control and the discovery of quality markers for AMB.

This paper analyzes the balanced interaction strategy of an integrated energy system (IES) operator and an industrial user in the operation process of the IES under the demand-side management (DSM) based on game theory. Firstly, we establish an electric–thermal IES, which includes a power grid, a heat grid and a natural gas grid. Secondly, a two-stage Stackelberg dynamic game model is proposed to describe the game behavior of IES operators and industrial users in the process of participating in DSM. The interactions between the IES operator (leader) and the user (follower) are formulated into a one-leader–one-follower Stackelberg game, where optimization problems are formed for each player to help select the optimal strategy. A pricing function is adopted for regulating time-of-use (TOU), which acts as a coordinator, inducing users to join the game. Then, for the complex two-stage dynamic game model established, the lower user-side constraint optimization problem is replaced by its KKT condition, so that the two-stage hierarchical optimization problem is transformed into a single-stage mixed-integer nonlinear optimization model, and the branch-and-bound method is introduced to solve it. Finally, the equilibrium strategies and income values of both sides of the game are obtained through a case simulation, and the dynamic equilibrium strategy curves under different capacity configurations are obtained through the sensitivity analysis of key parameters. The equilibrium income of the IES is USD 93.859, while the equilibrium income of industrial users in the park is USD 92.720. The simulation results show that the proposed method and model are effective.

In September 2020, the Chinese government proposed the goals to reach carbon dioxide emissions peak by 2030 and achieve carbon neutrality by 2060 (“two-carbon goals”). This brings opportunities to the development and application of CO2-enhanced gas recovery (CO2-EGR) in China. To obtain an overall understanding of the development of CO2-EGR under the two-carbon goals, this paper analyzes the significance, potential, status quo and challenges of CO2-EGR, and makes suggestions on the development of CO2-EGR in China. The research results are obtained as follows. First, the development of CO2-EGR plays a crucial role in ensuring China's energy security, accelerating the construction of the clean energy system to promote energy transition and realizing the two-carbon goals as early as possible. Second, China should clarify a path for CO2-EGR development, build a spatial layout of CO2-EGR, and promote digital inclusion in CO2-EGR, enhance the emission reduction role of CO2-EGR in the multi-energy complementary system, boost large scale application of renewable energy and deep decarbonization in the traditional coal industry, which is difficult to reduce carbon emissions. Third, China should draw lessons from European and American tax credit and innovation funds policies to accelerate the construction of a CO2-EGR policy support system. Fourth, China should carry out research on key CO2-EGR technologies to accelerate the construction of a CO2-EGR methodology and standard system and promote rapid and standardized development of the CO2-EGR industry. It is suggested to establish a CO2-EGR demonstration area in the Sichuan Basin and popularize it across China, so as to improve comprehensive economic benefits through the establishment of large-scale industrial clusters. It is concluded that the two-carbon goals bring opportunities to the development of CO2-EGR in China, which will promote gas production and demonstration of CO2 sequestration in gas reservoirs and have positive significance in ensuring energy security and realizing carbon peak and carbon neutrality in China.

The injection volume and the distribution of a proppant inside a fracture have a direct impact on the stimulation effect of fracturing. In this study, a new proppant transport model was established based on the Euler method. In this model, the proppant plugging element allows fluid to pass through. Furthermore, the proppant plugging process was successfully simulated based on this model. The proppant transport and ultimate injection concentration under different injection modes were discussed. The numerical simulation results indicate that compared with the strategy of constant concentration, the strategy of a stepwise increasing concentration can make the proppant distribution in the fracture more uniform. The strategy of injection with a stepwise increasing concentration and a periodic injection with a stepwise increasing concentration can increase the injection volume of the proppant by 25%. In the fracture network, a 67% increase in the number of branch fractures resulted in a 17% increase in the maximum proppant injection volume. If the branch fracture width is reduced by 50%, the maximum proppant injection volume is reduced by 17%.

Allii Macrostemonis Bulbus (AMB), a traditional Chinese edible and medicinal plant, is considered beneficial to health. In this study, we isolated and purified nine steroidal saponins (compounds 1–9) from AMB. Their structures were characterized using physicochemical properties, HR-ESI-MS, 1D and 2D NMR spectroscopy. Among these compounds, compounds 1–5 were newly discovered named macrostemonoside U-Y, respectively. We assessed the in vitro antioxidant properties of the nine steroidal saponins through free radical scavenging and reducing power assays. This provides options for developing natural antioxidants. Additionally, an HPLC-ELSD quantitative analysis method was developed for the nine saponins in 12 batches of AMB from different origins and processing methods. The results showed that the contents of the nine steroidal saponins in AMB varied greatly among different growing environments and processing methods.

With the depletion of conventional reservoir development, reservoir fracturing under deep high geo-stress and high geo-stress difference conditions is receiving increasing attention. Deep reservoirs typically require multi-cluster fracturing to achieve efficient reservoir transformation and development. In this paper, considering the relevant geological parameters of a certain reservoir in the southwest, three-dimensional multi-cluster reservoir fracturing models were established based on cohesive element modeling. Then, the propagation law of artificial fractures in reservoirs under the influence of the different number of fracturing clusters, injection displacement, and Young’s modulus in different regions of the 60 m fracturing well section is analyzed, and the quantitative law of parameters such as fracture length, maximum fracture width, injection point fracture width, fracture area, and tensile failure ratio during multi-cluster fracturing construction, as well as the propagation law of fracture morphology are revealed. The simulation results show that using multi-cluster fracturing can significantly improve the effectiveness of reservoir reconstruction, but as the number of fracturing clusters increases, it is also easy to form some small opening artificial fractures. These small opening artificial fractures may not be conducive to the transportation of proppants and fluids. During single cluster fracturing, the interface stiffness and rock Young’s modulus have a significant impact on the propagation of artificial fractures in the reservoir. As the number of fracturing clusters increases, the competition between artificial main fractures expands significantly, which may reduce the impact of interface stiffness and rock Young’s modulus. The fluid injection rate has a significant impact on reservoir fracturing, and in the same area, using high displacement injection can significantly increase the volume of reservoir reconstruction. This study can provide some reference for multi-cluster fracturing construction in deep reservoirs.

Abstract The intermittent access of renewable energy sources leads to a significant increase in fault short‐circuit currents in power grid. DC superconducting fault current limiters (SFCL) can limit short‐circuit currents in flexible DC transmission systems, which work in combination with direct current circuit breaker (DCCBs) to protect the grid system effectively. However, for the parameter design of DC superconducting fault current limiter (DCSFCL), it is difficult to balance the economics of the device and its adaptability to different fault situations. In this paper, a cross‐mapping design methodology for the DCSFCL is proposed and applied in the Nan'ao flexible DC transmission project, China. A cross‐mapping method is designed combining the critical parameters of DCSFCL and the system parameters. A three‐terminal simulation model of the flexible DC transmission system is constructed through MATLAB/Simulink and the design process of DCSFCL parameters is introduced. A cyclic calculation approach is proposed for the design of DCSFCL parameters through three fault conditions of the power system. Meanwhile, impact current short‐circuits test and artificial ground short‐circuit test were conducted on the prototype. Test results show that the designed DCSFCL meets the requirements of practical applications.

To understand the occurrence state of fracturing fluid in shale gas matrix-fracture system, an experimental method for evaluating fracturing fluid flow characteristics in matrix-fracture system was established. By using Nuclear Magnetic Resonance method, the flow characteristics of fracturing fluid were investigated from three processes of filtration, well shut-in and flowback. The T2 spectrum of fracturing fluid flow process and fracturing fluid saturation in matrix-fracture core model were clarified. The results demonstrate that the peak area of T2 spectra increases gradually during the filtration process, and the fracturing fluid quickly fills the fractures and matrix pores. During the well shut-in process, the fracturing fluid gradually flows from the fracture space to the matrix pores, and the signal of the matrix pores increases by 50.5%. During the flowback process, fracturing fluid flows out of the matrix and fracture. And when it reaches a stable state, the peak signal in the fracture decreases by 64.5% and the matrix signal reduces by 18.8%. The better the porosity and permeability characteristics of the core, the more likely the fracturing fluid is to stay in the formation and cannot be discharged. This paper would contribute to basic parameters for shale gas fracturing design and production strategy optimization.

There are abundant marine shale gas resources in the Sichuan Basin. After almost one decade of exploration and development, three national shale gas demonstration areas have been built in the Sichuan Basin and its periphery, and large-scale commercial development of middle and deep (above 3500 m in depth) shale gas has been successfully achieved. The volume of deep shale gas resources (3500–4500 m deep) of the upper Ordovician Wufeng Formation-lower Silurian Longmaxi Formation in the southern Sichuan Basin is 6.6 × 1012 m3, with huge exploration and exploitation potential, so it is an important area for large-scale shale gas production increase in China during the 14th Five-year Plan. Deep shale gas in the southern Sichuan Basin is influenced by complex geological engineering conditions, such as great burial depth, high temperature and pressure, and large stress and stress difference, and its high-quality development faces many challenges. After systematically summarizing the new progresses and achievements in deep shale gas exploration and development in the southern Sichuan Basin, this paper analyzes the difficulties and challenges in deep shale gas exploration and development and puts forward the next research directions. And the following research results are obtained. First, based on early practical exploration and independent innovation, key shale gas exploration and development technologies with good area selection, good well deployment, good well drilling, good well fracturing and good well management as the core are formed, and the cultivation mode of high production well is established, which supports the large-scale benefit development of deep shale gas in the southern Sichuan Basin. Second, systematical analysis indicates that the exploration and development of deep shale gas still faces a series of challenges in such three major fields as basic theory, key technology and management mode. Third, in the face of challenges, it is necessary to deepen basic theory research related to exploration and development, continuously improve key main technologies and constantly innovate mechanisms, systems and management modes. In conclusion, after years of continuous researches and pilot tests, a series of main exploration and development technologies suitable for the working conditions of deep shale gas in the southern Sichuan Basin have been basically formed, the first deep shale gas reserves of trillion cubic meters has been submitted, and the first deep shale gas production increase block of ten billion cubic meters has been selected. Thus, great progresses have been made in the exploration and development of deep shale gas, which confirms the confidence and determination in exploring and developing deep shale gas and is of great guiding significance to the rapid development of shale gas industry in China.

A representative molecular model of kerogen is the prerequisite to the study on molecular interaction of fluid molecules with organic nanopores of shale. The molecular kerogen model in Silurian deep gas shale from southern China remains to be developed. In this work, the chemical structure of the targeted deep shale kerogen is characterized by organic geochemical measurements. The derived structural parameters are utilized to build the molecular structure of the kerogen unit. The kerogen unit shows a good representation of realistic kerogen structure in shale reservoir in terms of carbon skeleton, heteroatomic compositions and groups. The kerogen matrix and a extended kerogen slit model are constructed based on the kerogen unit, which match well with the experimental results in matrix density and kerogen porosity, respectively. The kerogen matrix is overall disordered with gentle stacking of polyaromatic fragments, due to the bendable aliphatic linkages and large-size aromatic units. The kerogen nanopores are not saturated with methane at deep shale reservoir conditions. At high pressure, the absolute adsorption tends to reach a maximum, while the excess adsorption shows a decreasing trend. The effect of pressure on the dissolved gas density is not pronounced. The generated kerogen model can serve as a starting point for further theoretical investigations on fluid storage and transport in organic nanopores of deep shale reservoir at microscopic scale.

The first fractured shale gas well of China was constructed in 2010. After 10 years of development, China has become the second country that possesses the core technology of shale gas development around the world, realized the shale gas fracturing techniques from zero to one and from lagging to partially leading, and constructed the fracturing theory and technology system suitable for middle–shallow marine shale gas exploitation. In order to provide beneficial guidance for the efficient exploitation of shale gas in China in the future, this paper comprehensively reviews development history and status of domestic fundamental theories, optimized design methods, fluid systems, tools and technologies of shale gas fracturing and summarizes the research results in fundamental theories and optimized design methods, such as fracturing sweet-spot cognition, fracture network propagation simulation and control, rock hydration and flowback control, and SRV (stimulated reservoir volume) evaluation and characterization. The development and application of slick-water fracturing fluid system and new fracturing fluid with little or no water is discussed. The development and independent research & development level of multi-stage fracturing tools are evaluated, including drillable composite plug, soluble plug, large-diameter plug and casing cementing sleeve. The implementation situations of field technologies and processes are illustrated, including the early conventional multi-stage multi-cluster fracturing and the current “dense cluster” fracturing and temporary plugging fracturing. Based on this, the current challenges to domestic shale gas fracturing technologies are analyzed systematically, and the development direction of related technologies is forecast. In conclusion, it is necessary for China to continuously research the fracturing theories, technologies and methods suitable for domestic deep and ultra-deep marine shale gas, terrestrial shale gas and transitional shale gas to facilitate the future efficient development of shale gas in China.

The stress threshold of deep reservoir shale subjected to fracturing fluid immersion is an important factor affecting fracture initiation and propagation during fracturing. However, little information has been reported on the effect on shale of soaking at high temperature and high pressure (HTHP). In this study, immersion tests and triaxial compression tests were carried out at reservoir temperature and in-situ stress on the downhole cores with different mineral compositions. The characteristics of stress thresholds, i.e., crack initiation stress (σci), crack damage stress (σcd), and peak deviator stress (σp), of shale affected by the different times of soaking with low-viscosity fracturing fluid (a) and the different viscosity fracturing fluids (a, b, and c) were investigated. The results show that hydration at HTHP has a significant softening effect on the stress thresholds (σci, σcd, σp) of reservoir shale, but the softening rate varies for samples with different mineral compositions. The crack initiation stresses of quartz-rich and clay-rich shales treated with different soaking times and different soaking media remain almost unchanged in the range of 47 to 54% of the corresponding peak strength, while the crack initiation stresses of carbonate-rich shales are significantly affected. The ratio σcd/σp of quartz-rich shale is significantly affected by the different viscosity fracturing fluids (a, b) and the different times of soaking with low-viscosity fracturing fluid (a), while clay- and carbonate-rich shales are less affected. The results of this study can provide a reference for the fracturing design of deep shale gas development.

Imbibition and flowback of fracturing fluid usually occur in the shale matrix after hydraulic fracturing, which significantly impacts shale gas production and environmental protection. The rocks of deep shale gas reservoirs are under high-temperature and high-temperature conditions. There are rich micro-nano pores with various pore structures in deep shale. In addition, the flowback behavior is significantly affected by the imbibition behavior because the flowback begins after the end of the imbibition. Therefore, an accurate pore-scale description of the coupled imbibition-flowback behavior is crucial to understand the flowback mechanism and its impacts. In this paper, a pseudo-potential lattice Boltzmann method is employed to simulate the coupled imbibition-flowback behavior in a digital shale core, where the digital core is reconstructed by Markov Chain-Monte Carlo method based on scanning microscope images of deep shale cores. The microcosmic mechanism of the imbibition and flowback is studied under deep shale conditions. The influence of some factors, such as pore structure, fluid viscosity, wettability, and flowback pressure difference, on the flowback behavior of fracturing fluid is investigated. It is found that the fracturing fluid advances almost uniformly throughout the pore space during the imbibition process. The fracturing fluid is easy to adsorb on the pore wall, and the shale gas is located in the middle of the pore space. The viscous fingering is clearly observed during the flowback process, where shale gas flows through large pores to form a flow channel, and the fracturing fluid stays in tiny pores. The flowback rate increases gradually with the flowback time and eventually tends to be almost constant. The wettability, flowback pressure difference, and pore structure significantly influence the flowback behavior, while the fracturing fluid viscosity has a smaller effect on the flowback process.

IntroductionHydrometra is a common gynecological disease, especially in postmenopausal women. However, its epidemiology, harmfulness, and value in predicting gynecological tumors have not been clearly elucidated.MethodsIn this study, the prevalence rate of and risk factors for hydrometra were investigated in 3,903 women who underwent screening for gynecological diseases at Zhoupu Hospital in Shanghai from 1 January to 31 December 2021. In addition, pathological distribution of hydrometra and its predictive value in gynecological tumors were studied in another 186 patients in whom hydrometra was diagnosed sonographically at Zhoupu Hospital, from 1 January 2020 to 31 December 2021, and who underwent hysteroscopy and postoperative pathological examination.ResultsThe observed prevalence rate of hydrometra was 10.86%, which was higher than the prevalence of other gynecological diseases. Univariate and multivariate analysis indicated that advanced age (OR 1.11) and vaginitis (OR 3.18) were independent risk factors for hydrometra. Among 186 patients with a sonographic diagnosis of uterine fluid, simple hydrometra accounted for 34.41% of cases, inflammation accounted for 16.23%, and hematometra accounted for 2.15%, while gynecological tumors accounted for 5.91%. Moreover, univariate and multivariate analysis indicated that a higher body mass index (>23.92 kg/m2), greater hydrometra volume (i.e., distance between the two layers of endometrium>4.75 mm), and abnormal vaginal bleeding were high-risk predictive factors for gynecological tumors.DiscussionIn conclusion, hydrometra is a common disease, and is a risk factor for endometrial cancer and cervical cancer, especially in patients with higher hydrometra volume, higher BMI, and abnormal vaginal bleeding. It is necessary to pay more attention to hydrometra.

Design and optimization of well spacing is a key indicator for evaluating the development effect of shale gas reservoirs. On the basis of theoretical understanding, and after the verification by analogy, numerical simulation, and economic evaluation, a complete workflow from inter-well interference simulation and dynamic data diagnosis to multi-well production simulation and well spacing optimization was formed. First, a pressure detection boundary propagation model is established to simulate the response degree of inter-well interference under different connected conditions. Second, inter-well interference is identified and diagnosed depending on the inter-well interference response behaviors and the interpretation of performance data from gas wells. Third, taking the geological interpretation and dynamic analysis results as basic parameters, a multi-well numerical model for volume fracturing in gas reservoirs is established to simulate the production performance of gas field, and then well spacing is optimized in combination with the net present value model. The application in the Ning 201 well block in the Changning National Shale Gas Demonstration Area has shown that a smaller well spacing can allow a premature inter-well interference and also the enhancement of recovery in the entire block. Given the current fracturing scale and parameter system, the well spacing of 300–400 m can be optimized to 260–320 m, that is, the number of wells per unit area increases by 20%–30%. As a result, the recovery percent of reserves in the block increase by about 10%. The net present value of the block rises, but the corresponding optimal well spacing does not change, with the production period.

Two new compounds named 4,4′-bis(β-D-glucopyranosyloxy)biphenyl (1) and spirostane-25(27)-en-2α,3β-diol-3-O-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl(1→4)-β-D-galactopyranoside (2) were isolated from n-butanol extraction part of 80% ethanol extract of Allii Macrostemonis Bulbus. Alongside these, ten known compounds (3–12) were also identified, including a flavonoid glycoside (3), seven steroids (4–10), a nucleoside (11), and a phenylpropanoid glycoside (12) were found. Notably, compounds 3–6 were isolated from this plant for the first time. The structures of all compounds were confirmed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D, and 2D NMR spectroscopy. Some of these compounds showed strong antioxidant activity, and compound 1 demonstrated the most potent reduction of ferric ions (Fe3+) with an IC50 value of 0.59 ± 0.18 mg/mL. Compounds 2 and 3 exhibited the highest scavenging activity against superoxide anion radicals (O2−·) with an IC50 value of 0.02 ± 0.01 mg/mL. Additionally, compound 3 displayed substantial scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with IC50 values of 0.21 ± 0.17 mg/mL and 0.02 ± 0.01 mg/mL, respectively. The discovery of these two new compounds is a reference for identifying Allii Macrostemonis Bulbus quality markers. Moreover, their exceptional antioxidant activity offers a promising avenue for uncovering novel natural antioxidants.

The pore structure is an important factor affecting reservoir capacity and shale gas production. The shale reservoir of the Longmaxi Formation in the Changning area, Southern Sichuan Basin, is highly heterogeneous and has a complex pore structure. To quantitatively characterize the shale’s pore structure and influencing factors, based on whole rock X-ray diffraction, argon ion polishing electron microscopy observations, and low-temperature nitrogen adsorption-desorption experiments, the characteristics of the shale pore structure are studied by using the Frenkel-Halsey-Hill (FHH) model. The research reveals the following: 1) The pores of the Longmaxi Formation shale mainly include organic pores, intergranular pores, dissolution pores and microfractures. The pore size is mainly micro-mesoporous. Both ink bottle-type pores and semiclosed slit-type pores with good openness exist, but mainly ink bottle-type pores are observed. 2) The pore structure of the Longmaxi Formation shale has self-similarity, conforms to the fractal law, and shows double fractal characteristics. Taking the relative pressure of 0.45 (P/P0 = 0.45) as the boundary, the surface fractal dimension Dsf and the structural fractal dimension Dst are defined. Dsf is between 2.3215 and 2.6117, and the structural fractal dimension Dst is between 2.8424 and 2.9016. The pore structure of micropores and mesopores is more complex. 3) The mineral components and organic matter have obvious control over the fractal dimension of shale, and samples from different wells show certain differences. The fractal dimension has a good positive correlation with the quartz content but an obvious negative correlation with clay minerals. The higher the total organic carbon content is, the higher the degree of thermal evolution, the more complex the pore structure of shale, and the larger the fractal dimension. The results have guiding significance for the characterization of pore structure of tight rocks.

Ferroptosis, a new way of cell death, is involved in many cancers. A growing number of studies have focused on the unique role of ferroptosis on endometrial cancer. In this study, we made a comprehensive review of the relevant articles published to get deep insights in the association of ferroptosis with endometrial cancer and to present a summary of the roles of different ferroptosis-associated genes. Accordingly, we made an evaluation of the relationships between the ferroptosis-associated genes and TNM stage, tumor grade, histological type, primary therapy outcome, invasion and recurrence of tumor, and accessing the different prognosis molecular typing based on ferroptosis-associated genes. In addition, we presented an introduction of the common drugs, which targeted ferroptosis in endometrial cancer. In so doing, we clarified the opportunities and challenges of ferroptosis activator application in treating endometrial cancer, with a view to provide a novel approach to the disease.

Casing deformation (CD) will seriously affect the fracturing progress and stimulation effect of shale gas. Taking 105 gas wells in the Luzhou shale gas area in southern Sichuan as an example, the CD prediction model was established by introducing the fracture operation curve diagnosis method to analyze the changes in net pressure and propagation mode during fracturing. The fracturing stage induced by CD is called the excited (ET) stage, and the fracturing stage that occurs during CD is called the CD stage. It is concluded that the change of net pressure and the propagation mode are coupled with each other. By natural fracture development, formation curvature and horizontal well trajectory, natural fractures and bedding have been active by high fracturing strength, or because of the frequent crossing-layer in single stage, local stress reverse, makes the net pressure decrease and makes the formation in strike-slip stress state to reverse fault stress state, liquid leak-off and blocked fracture propagation time are increased, thus inducing CD. According to the response law induced by CD, the CD pre-control mode is formed, and the CD pre-control technology is established to quantitatively evaluate the wellbore risk and optimize the fracturing operation order and time arrangement. The CD rate is reduced from 56% in the early stage to 20%, and the integrity of the wellbore is guaranteed to be 100%. The method has strong applicability in the field and can be further popularized.

China is rich in shale gas resources and has broad prospects for development. However, the quality of shale gas resources in China is different from that in the United States, so independent unique technologies are urgently required in China. In this regard, PetroChina has carried out theoretical and technical researches systematically on shale gas in Longmaxi Formation in southern Sichuan according to its geology-engineering characteristics. Guided by the “three-control” theory for marine shale gas enrichment and high yield (i.e. sedimentary diagenesis controls reservoir, preservation conditions control accumulation, and continuous thickness of Type I reservoir controls production), six key exploration and development technologies in southern China have been innovatively developed for marine shale gas which experienced multi-stage tectonic evolution. The technologies include comprehensive geological evaluation technology, development optimization technology, optimal and fast drilling technology for horizontal well, volume fracturing technology for horizontal well, factory-like operation technology, and efficient clean production technology. These technologies have enabled the large-scale commercial recovery of shale gas. By the end of 2019, PetroChina had obtained proved geological reserves of 1.06 × 1012 m3, had built production capacity of 10 × 109 m3, and had cumulative gas production of 20 × 109 m3 in southern Sichuan. The remarkable results of application are of great significance for vigorously developing shale gas industry to reduce external dependence, ensure national energy security, and realize the strategy of “ecological priority and green development''.

In order to maximize the resource utilization rate, it is common to adopt one-time overall deployment of well pattern to develop shale gas, and the design of horizontal well spacing is the key to the deployment of shale gas well pattern. To determine the optimal well spacing, it is not only necessary to understand both geological characteristics and drilling fracturing technology, but also take into consideration the influences of economic factors, such as gas price and cost. At present, there is no reliable method for designing the well spacing of shale-gas horizontal wells at home and abroad. In this paper, a method for analyzing the well spacing of shale-gas horizontal wells based on the integration of geology, engineering and economy was established for the first time. Then, by means of geological modeling, numerical simulation and cash flow analysis, the well spacing of shale-gas development wells in Well Block Ning 209 in the Changning–Weiyuan National Shale Gas Demonstration Area in the Sichuan Basin was comprehensively evaluated by using estimated ultimate reserve (EUR), recovery factor and internal rate of return (IRR). And the following research results were obtained. First, under the current geological, engineering and economic conditions of Well Block Ning 209, the IRR of shale gas platform development can be kept greater than 8% if the well spacing is larger than 240 m. Second, when the well spacing is controlled between 330 m and 380 m, single well EUR, recovery rate of the platform and economic benefit can be considered simultaneously. In conclusion, the research results support the formulation of the shale gas development technology policy of Well Block Ning 209 and lay a foundation for the realization of its scale efficient development of shale gas.

AbstractThe optimal design of hydraulic fracturing parameters is the key to commercial exploitation of unconventional reservoirs. Hydraulic fracturing test is one of the main methods for optimizing fracturing parameters. It is known that scale effect exists between laboratory experiments and field treatments of hydraulic fracturing. However, studies on how to eliminate the scale effect are rarely reported. In this work, we conduct sensitivity analysis on rock mechanical parameters and fracturing parameters at different scales by using the dimensionless analysis method. The initiation and propagation process of field hydraulic fracturing is reproduced through laboratory tests, and fracturing parameters are analyzed by using numerical simulation. Our results show that the fracture propagation in the laboratory is inconsistent with that in the field fracturing. The fracture initiation and propagation in the field can be reproduced in experiments by using samples with high modulus and low toughness as well as high-viscosity fracturing fluid. Microcracks are created before the breakdown pressure is reached, and hydraulic fractures extend perpendicular to the direction of the minimum principal stress. The Carter’s leak-off coefficient has little effect on breakdown pressure and propagation pressure, but the injection rate and the horizontal principal stress have significant effects on breakdown pressure. This study provides a theoretical basis and guidance for the design of fracturing parameters both in the laboratory and in the field.

Abstract The performance of horizontal wells in shale gas is controlled by multiple factors, and there is a difference in gas production rate between different fracturing stages. However, the mechanism of the nonuniform gas production rate is still not clear. In this paper, a typical shale gas well in the Longmaxi formation was selected to conduct the performance evaluation based on the nonradioactive gas tracer technology. The gas production profile was obtained, and the production feature of each stage was analyzed. On this basis, the production differences between fracturing stages were compared in four aspects: reservoir physical properties, distribution of natural fracture, parameters of fracturing operation, and technology of temporary plugging re‐orientation. The effect of various factors on the contribution of each stage was analyzed. And then, the mechanism of the nonuniform gas production rate was clarified. Finally, relevance analysis was performed to determine the main controlling factors, and a mathematical model for characterizing the nonuniform gas production rate feature was established by adopting the nonlinear regression method. This study provides a reliable basis for optimal fracturing designing and reasonable production planning.

AbstractIt is excessively crucial for performing production match of parent-child wells automatically by using assisted history matching approach, especially considering the interwell interference scenario. We explored a new EDFM-AI (Embedded Discrete Facture Model-Artificial Intelligence) workflow by taking into account the multiple uncertainty parameters that were composed of fracture height, fracture half-length, fracture conductivity, fracture water saturation, fracture cluster efficiency, and natural fracture conductivity. The history matching algorithm implemented in this study is advanced machine learning model called XGBoost. It could overcome the issue that the proxy model is always imprecise due to the limited training sample data. Specifically, we established a field-scale reservoir model that includes parent-child shale gas wells with fracture hits in the Sichuan basin. By using this sophisticated workflow, two wells’ history matching results are excellent in terms of the inversed solution of the hydraulic fracture properties and natural fracture properties. And then, we perform the production forecasting for parent and child wells, respectively. Consequently, the results show that the best match value for estimated ultimate recovery (EUR) of parent well is 287.4 million cubic meters whereas the best match value for EUR of child well is 187.6 million cubic meters. The reliable reason is that effective fractured area of parent well is larger than that of child well. Besides, the natural fractures have a significant impact on the performance of shale gas wells with fracture hits observed, especially in the short-term production period.

To optimize the flowback system of shale gas horizontal wells after fracturing and to maximize the production capacity of gas wells, pipe flow and flowback models of shale gas multistage fractured horizontal wells were established based on the actual geological engineering conditions and the fracture parameters inverted from automatic history matching by combining experimental and numerical simulation methods. Optimization of the maximum choke size, reasonable opening choke size, replacement stages, and choke replacement frequency were studied. The research results show that the larger the production pressure difference in the early period, the higher the initial gas production rate but the easier the migration of proppant and the higher its stress sensitivity, which increases the permeability damage and weakens the reservoir recovery ability. Thus, the fracture conductivity gets worse and the later gas production rate and liquid production rate get lower. Specifically, the research results mainly include the following: (1) The laboratory experiment results show that the effective stress exceeding 19 MPa caused a proppant breakage and embedding phenomenon, leading to difficult recovery from reservoir permeability damage. Therefore, the maximum production pressure difference corresponding to the single-well maximum choke size shall not exceed 19 MPa. (2) A small opening choke size of a shale gas well is superior to the large one, and according to the numerical simulation, the choke size of 3 mm is recommended to be the reasonable opening choke size. (3) Under the drainage and production systems of replacing the choke size from small to large, the simulation results indicate that the production effect under the drainage and production systems of increasing the choke size incrementally stage by stage with an increase in amplitude of 1 mm is much better than that under the drainage and production systems of increasing the choke size by skipping the stage. (4) When the choke size is increased stage by stage, the research results indicate that the optimal duration of each grade of choke size is 3 days, beyond which, the increase of EUR will not be remarkable. The application of the proposed fine choke system research method in Well-CN001 indicates that the influence amplitude of the reasonable choke system on the daily gas production of Well-CN001 is in the range of 65.96%–121.67% and that on single-well EUR increase amplitude in 20 years is in the range of 5.2%–22.27%. The research results provide technical support for understanding the influence of different choke systems on the productivity of shale gas wells and optimizing the reasonable drainage and production systems of shale gas wells after fracturing.

The dried bulbs of Allii Macrostemonis Bulbus (AMB) are called “薤白” in China and are mainly distributed in Asia. The plant species included in the 2020 Edition of the Chinese Pharmacopoeia (ChP) are Allium macrostemon Bunge (called xiaogensuan in Chinese, A. macrostemon) and Allium chinense G. Don (called xie in Chinese, A. chinense), respectively. In the traditional Chinese medicine (TCM) theoretical system, AMB is warm in nature, acrid-bitter taste, and attributive to the heart, lung, stomach, large intestine meridian. AMB has the function of activating Yang and removing stasis, regulating Qi and eliminating stagnation. Modern pharmacological studies have shown that AMB has anti-platelet aggregation, hypolipidemic, anti-atherosclerotic, cardiomyocyte, vascular endothelial cell protection, anti-cancer, anti-bacterial, anti-asthmatic, and anti-oxidant effects. In some Asian countries, AMB is often used to treat coronary heart disease (CHD), angina pectoris (AP), asthma, and diarrhea. This review collates the botanical background, ethnopharmacology, phytochemistry, pharmacological activities, quality control, and toxicological studies of AMB, and provides an outlook on the current research deficiencies and future research priorities of AMB, intending to provide ideas for future research directions and commercial development.

Based on logging, seismic, fracturing and production data from 301 productive wells in Longmaxi Formation in Changning shale gas field of southern Sichuan basin, the various influence factors of shale gas stimulated potential have been analyzed to carry out the correlation study with estimated ultimate recovery (EUR) of the same fracturing operation intensity to fully clarify the main controlling factors for shale gas stimulated potential. The results show that matrix brittleness, fracture propagation and reservoir properties are the 3 key secondary potentials that control shale gas stimulation potential. The matrix brittleness is controlled by elastic modulus, Poisson’s ratio, Type I and II fracture toughness, which reflects the uniformity of hydraulic fracture propagation. Fracture propagation is controlled by critical net pressure, which reflects the scale of hydraulic fracture propagation. Reservoir properties are controlled by porosity, total organic carbon content (TOC) and horizontal interval differences, which reflect the enrichment conditions and dynamic production capacity of reservoir resources. The matrix brittleness index, fracture propagation index, reservoir properties index and their combined stimulated potential index were formed by using the above 7 parameters to verify and apply the wells in Changning shale gas field. Results show that the matrix brittleness index and length-width ratio of hydraulic fracture was significantly negative correlation, the fracture propagation index and stimulated reservoir volume (SRV) were significantly positive correlation, stimulated potential index was developed taking into account enrichment & exploitation potential. In areas where the value is greater than 0.5, increasing the fracturing scale can effectively improve the well productivity; in areas less than 0.5, increasing the fracturing scale has an upper limit on the increase of productivity, so the physical properties of the reservoir itself play a significant role in controlling the production of shale gas wells.

Abstract The pores and throats of coal seam are narrow, and the permeability is very low. It is a porous medium with complicated deformation mechanism. In the process of gas production, the change of stress, pore pressure, gas adsorption and desorption will lead to the change of grains, pore volume, and the seepage capacity of coal seam. Based on the theory of poroelastic and seepage mechanics, a physical model of fractured horizontal well and a coupled mathematic model of coal deformation and gas flow are established. The dynamic change model of permeability is deduced too. The development characteristics and laws of coalbed methane are numerically simulated by using numerical analysis software Comsol Multiphysics. Finally, the sensitivity of the key parameters in the model and the influence of the fracture parameters are analyzed. The results show that the application of fractured horizontal well is an effective measure to increase production of coalbed reservoirs; with the increase of Langmuir volumetric strain constant, fracture half‐length, and the numbers of fracture, the production of coalbed methane is increasing. In the case of constant total fracture length, number, and spacing, when fracture half‐lengths are long and short interlaced distribution, the production is the highest and it is the best fracture distribution pattern. The study provides a theoretical basis for the further study of coalbed deformation, gas migration, efficient, and rational development of coalbed methane reservoirs.

In this paper, shale samples of Lower Silurian Longmaxi Fm, taken from the Changning–Weiyuan area in the Sichuan Basin, were selected to figure out the influence of reservoir primary water on the adsorption laws and the flow capacity of shale gas. Experimental samples with different water saturations were prepared using the adsorption equilibrium method. Then, high-pressure isothermal adsorption experiments were carried out, and the isothermal adsorption effects and mechanisms of shale under different water saturations were discussed. Finally, the flow capacity of shale gas under different water saturations was tested using the independently developed steady-state flow test device. And the following research results were obtained. First, the presence of primary water in micron–nanometer pores of shale reservoirs reduces the adsorption capacity of shale. When the water saturation is 40%, the simulated total gas content is 18% lower than that in the conventional calculation result. Second, the apparent shale permeability is a function of pressure. Due to the effect of Knudsen diffusion, the apparent shale permeability increases significantly with the decrease of pressure under low pressure. When the average pressure is 5 MPa and the water saturation reaches 50%, the apparent shale permeability is about 70% lower than that of a dry sample. Third, when the water saturation is lower than the critical value, water is mainly presented as non-movable water in micropores and mesopores, and it has less effect on the flow capacity of shale gas. When the water saturation is greater than the critical value, the lodging point of water is changed, resulting in significant reduction of the shale gas flow capacity. It is concluded that an accurate understanding of the original water saturation and critical water saturation of shale reservoirs helps to calculate shale gas reserves accurately and predict gas well production rate rationally. Keywords: Shale gas, Reservoir, Water saturation, Isothermal adsorption, State of occurrence, Flow capacity, Reserves, Gas production rate

An appropriate well spacing plan is critical for the economic development of shale gas reservoirs. The biggest challenge for well spacing optimization is interpreting the subsurface uncertainties associated with hydraulic and natural fractures. Another challenge is the existence of complex natural fractures. This work applied an integrated well spacing optimization workflow in shale gas reservoirs of the Sichuan Basin in China with both hydraulic and natural fractures. The workflow consists of five components: data preparation, reservoir simulation, estimated ultimate recovery (EUR) analysis, economic calculation, and well spacing optimization. Firstly, the multiple realizations of thirteen uncertain parameters of matrix and fractures, including matrix permeability and porosity, three relative permeability parameters, hydraulic fracture height, half-length, width, conductivity, water saturation, and natural fracture number, length, and conductivity, were captured by the assisted history matching (AHM). The fractures were modeled by the embedded discrete fracture model (EDFM) accurately and efficiently. Then, 84 AHM solutions combining with five well spacing scenarios from 517 ft to 1550 ft would generate 420 simulation cases. After reservoir simulation of these 420 cases, we forecasted the long-term gas production for each well spacing scenario. Gas EUR degradation and well interference would imply the critical well spacing. The net present value (NPV) for all scenarios would be calculated and trained by K-nearest neighbors (KNN) proxy to better understand the relationship between well spacing and NPV. In this study, the optimum well spacing was determined as 793 ft, corresponding with a maximum NPV of 18 million USD, with the contribution of hydraulic fractures and natural fractures.

Although great success has been achieved in the shale gas industry, accurate production dynamic analyses is still a challenging task. Long horizontal wells coupling with mass hydraulic fracturing has become a necessary technique to extract shale gas efficiently. In this paper, a comprehensive mathematical model of a multiple fractured horizontal well (MFHW) in a rectangular drainage area with a rectangular stimulated reservoir volume (SRV) has been established, based on the conceptual model of “tri-pores” in shale gas reservoirs. Dimensionless treatment and Laplace transformation were employed in the modeling process, while the boundary element method was used to solve the mathematical model. The Stehfest numerical inversion method and computer programing techniques were employed to obtain dimensionless type curves, production rate, and cumulative production. Results suggest that 9 flow stages can be observed from the pseudopressure derivative type curve when the reservoir and the SRV are large enough. The number of fractures, SRV permeability, and reservoir permeability have no effect on the total production when the well is abandoned. As SRV and reservoir permeability increases, the production rate is much higher in the middle production stage. Although the SRV scale and its permeability are very important for early and intermediate production rates, the key factors restricting the shale gas production rate are the properties of the shale itself, such as adsorbed gas content, natural fractures, and organic content. The proposed model is useful for analyzing production dynamics with stimulated horizontal wells in shale gas reservoirs.

The formation mechanism and propagation behaviors of a three-dimensional hydraulic fracture network in fractured shale reservoirs remain unclear, especially when the scale of hydraulic fractures is much larger than that of natural fractures. In this study, taking the well XH in the Longmaxi shale reservoir in the Sichuan Basin, China as an example, we develop a fully three-dimensional numerical model for hydraulic fracturing coupled with microseismicity based on the discrete lattice method. We introduce a randomly generated discrete fracture network into the proposed model and explore the formation mechanism of the hydraulic fracture network under the condition that the hydraulic fractures are much larger than natural fractures in scale. Moreover, microseismic events are inversely synthesized in the numerical model, which allows the evolution of the fracture network to be monitored and evaluated quantitatively. In addition, we analyze the effects of injection rate, horizontal stress difference, and fluid viscosity on fracture propagation. Our results show that when the scale of hydraulic fractures is much larger than that of natural fractures, the fracture morphology of “main hydraulic fractures + complex secondary fractures” is mainly formed. We find that a high injection rate can not only create a complex fracture network, but also improve the uniform propagation of multi-cluster fractures and enhance far-field stimulation efficiency. Optimizing the horizontal wellbore intervals with low horizontal stress differences as the sweet spots of hydraulic fracturing is also beneficial to improve the stimulation efficiency. For zones with a large number of natural fractures, it is recommended to use an injection schedule with high viscosity fluid early and low viscosity fluid late to allow the hydraulic fractures to propagate to the far-field to maximize the stimulation effect.

In recent years, great progress has been made in geologic evaluation, engineering test and development optimization of the Lower Cambrian Wufeng Fm–Lower Silurian Longmaxi Fm shale gas in the Sichuan Basin, and the main shale gas exploitation technologies have been understood preliminarily. In addition, scale productivity construction has been completed in Jiaoshiba, Changning and Weiyuan blocks. In this paper, the Wufeng Fm–Longmaxi Fm shale gas wells in Changning Block were taken as the study object to provide technical reference for the development design of similar shale-gas horizontal wells. The technology combining geology with engineering, dynamic with static, and statistical analysis with simulation prediction was applied to quantify the main factors controlling shale-gas well productivity, develop the shale-gas well production prediction model, and optimize the key technical parameters of geologic target of shale-gas horizontal wells in the block (e.g. roadway orientation, location and spacing, horizontal section length and gas well production index). In order to realize high productivity of shale gas wells, it is necessary to maximize the included angle between the horizontal section orientation and the maximum major stress and fracture development direction, deploy horizontal-well roadway in top-quality shale layers, and drill the horizontal section in type I reservoirs over 1000 m long. It is concluded that high productivity of shale gas wells is guaranteed by the horizontal-well wellbore integrity and the optimized low-viscosity slickwater and ceramsite fracturing technology for complex fracture creation. Based on the research results, the technical policies for shale gas development of Changning Block are prepared and a guidance and reference are provided for the shale gas development and productivity construction in the block and the development design of similar shale-gas horizontal wells.

This paper presents two representative models to analyze the flow dynamic of multi-scale porous medium in hydraulic fractured horizontal shale gas wells. In this work, considering the characteristic mechanisms (multi-scale porous space, desorption and diffusion), flow equations in shale are established. After that, two representative models (discrete fracture model and dual-porosity model) are tailored to our issues. Solved by the control-volume finite element method (CVFEM), influences of fracture network system on productivity in shale reservoirs are analyzed in detail. Based on the analysis, the effects can be summarized as follow: at the beginning of production, high conductivity fracture network means more free gas could be produced; at the later part of production, high conductive fracture network can form a large low pressure region, which can not only stimulate the desorption of adsorbed gas, but also reduce the flow resistance to the well. Finally, the sensitivities of characteristic parameters in shale are discussed.

To effectively monitor the atmospheric quality of small-scale areas, it is necessary to optimize the locations of the monitoring sites. This study combined geographic parameters extraction by GIS with fuzzy matter-element analysis. Geographic coordinates were extracted by GIS and transformed into rectangular coordinates. These coordinates were input into the Gaussian plume model to calculate the pollutant concentration at each site. Fuzzy matter-element analysis, which is used to solve incompatible problems, was used to select the locations of sites. The matter element matrices were established according to the concentration parameters. The comprehensive correlation functions KA (xj) and KB (xj), which reflect the degree of correlation among monitoring indices, were solved for each site, and a scatter diagram of the sites was drawn to determine the final positions of the sites based on the functions. The sites could be classified and ultimately selected by the scatter diagram. An actual case was tested, and the results showed that 5 positions can be used for monitoring, and the locations conformed to the technical standard. In the results of this paper, the hierarchical clustering method was used to improve the methods. The sites were classified into 5 types, and 7 locations were selected. Five of the 7 locations were completely identical to the sites determined by fuzzy matter-element analysis. The selections according to these two methods are similar, and these methods can be used in combination. In contrast to traditional methods, this study monitors the isolated point pollutant source within a small range, which can reduce the cost of monitoring.

To effectively and accurately detect and classify network intrusion data, this paper introduces a general regression neural network (GRNN) based on the artificial immune algorithm with elitist strategies (AIAE). The elitist archive and elitist crossover were combined with the artificial immune algorithm (AIA) to produce the AIAE-GRNN algorithm, with the aim of improving its adaptivity and accuracy. In this paper, the mean square errors (MSEs) were considered the affinity function. The AIAE was used to optimize the smooth factors of the GRNN; then, the optimal smooth factor was solved and substituted into the trained GRNN. Thus, the intrusive data were classified. The paper selected a GRNN that was separately optimized using a genetic algorithm (GA), particle swarm optimization (PSO), and fuzzy C-mean clustering (FCM) to enable a comparison of these approaches. As shown in the results, the AIAE-GRNN achieves a higher classification accuracy than PSO-GRNN, but the running time of AIAE-GRNN is long, which was proved first. FCM and GA-GRNN were eliminated because of their deficiencies in terms of accuracy and convergence. To improve the running speed, the paper adopted principal component analysis (PCA) to reduce the dimensions of the intrusive data. With the reduction in dimensionality, the PCA-AIAE-GRNN decreases in accuracy less and has better convergence than the PCA-PSO-GRNN, and the running speed of the PCA-AIAE-GRNN was relatively improved. The experimental results show that the AIAE-GRNN has a higher robustness and accuracy than the other algorithms considered and can thus be used to classify the intrusive data.