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In this paper, the ionic liquids Met-1, Met-2, Asp-1 and Asp-2 were prepared by acid-base neutralization reactions with different molar ratios of amino acids (methionine and aspartic acid) and concentrated sulfuric acid as raw materials. Four ionic liquids were formulated into different concentrations of inhibitors, and their hydration inhibition and inhibition mechanism were investigated by anti-expansion experiment, linear swelling experiment and flocculation experiment. The results showed that when the molar ratio of aspartic acid to concentrated sulfuric acid was 1:1.5, which was named Asp-2, and the concentration of Asp-2 was 1.0%, the inhibitor achieved the best hydration inhibition performance on clay with 91.95% anti-swelling rate and 21.37% linear swelling rate. Infrared spectra (FT-IR) analysis, thermogravimetric analysis (TGA), and laser particle size analysis were used to investigate the inhibition mechanism of Asp-2. The results showed that the average particle size of the hydrated soil samples increased by 0.282 μm and the median particle size increased by 2.101 μm after the addition of Asp-2 inhibitor, indicating that Asp-2 inhibitor played a good inhibitory role in the drilling fluid. [ABSTRACT FROM AUTHOR]

High‐voltage electric pulse rock breaking has excellent potential for exploiting deep geothermal resources. Numerous researchers have conducted experimental studies on this topic, particularly in rock mechanics, where the breakdown occurs. However, there has been limited scholarly research on drilling fluid. Therefore, the study focuses on the drilling fluid suitable for electric pulse drilling, considering the characteristics of electric pulse rock breaking, which differ from traditional rock breaking. The study focused on the impact of various drilling fluid parameters on the effectiveness of electric impulse rock breaking using red sandstone as the experimental material. This was investigated using the finite element method, and indoor electric rock‐breaking tests were conducted in a drilling fluid environment. The results indicate that the plasma channel mainly grows in the permeable layer of the drilling fluid, resulting in shallow rock breaking depth in the drilling fluid environment. The pore permeated by drilling fluid guides the growth of the plasma channel. The higher the conductivity of the drilling fluid, the closer the ion channel of rock breaking by electric pulse is to the rock surface. This results in a smaller crushing volume and shallower damage depth, which is more detrimental to rock breaking by an electric pulse. The viscosity of drilling fluid can impede the breakdown to some extent. In this paper, the influence of drilling fluid parameters on electro‐pulse rock‐breaking technology is preliminarily studied, which has significant reference value for the selection of actual drilling fluid. [ABSTRACT FROM AUTHOR]

Shale hydration and expansion during drilling can lead to wellbore instability, sticking, and frequent leakage accidents. To prevent these issues, an ionic liquid (IL) inhibitor solution was synthesized using DL‐alanine and 98% concentrated sulphuric acid as raw materials. The optimum composition and effect of the synthesized inhibitor in oilfield water‐based drilling fluids were evaluated through anti‐expansion, linear expansion rate, water washing resistance, and clay hydration dispersion experiments. The inhibition mechanism was investigated by thermogravimetric analysis, infrared spectroscopy, zeta potential, contact angle, and X‐ray diffraction analysis. The results show that the optimum IL consists of a 1:1 molar ratio of DL‐alanine to concentrated sulphuric acid synthesized under a reaction temperature and time of 70°C and 18 h, respectively. The resulting DL‐alanine IL exhibited the best inhibitory effect on the hydration, dispersion, and expansion of clay at a concentration of 0.5% in aqueous solution, and its linear expansion rate was only 18.49%. After adding a quantitative amount of clay to different concentrations of DL‐alanine IL aqueous solution, the expansion volume of the clay decreased and the water washing resistance significantly improved. These results provide a theoretical basis for improving the safety and efficiency of shale horizontal well drilling operations. [ABSTRACT FROM AUTHOR]

Rate of drilling bit penetration into the subsurface formations, referred to as rate of penetration (ROP), is considered as the main optimization parameter in the drilling operation. ROP optimization results in a faster and cheaper operation. The rate of bit penetration depends on several factors, including but not limited to rock properties, fluid characteristics and drilling operational parameters. Due to the diversity of affecting parameters, prediction of rate of penetration is a challenging task. There are various mathematical relations in the literature to estimate ROP. However, these relations are developed based on specific conditions, where data from a field or experimental tests are used to develop the relations. In this work, drilling data of three wells from one onshore oil fields are gathered and then the performances of some common ROP models are investigated. Results show that the simplified Bourgoyne and Young model can accurately predict the ROP in the mentioned field, which makes the model applicable for planning of the new offset wells in the future. It should be noted that the model requires fewer input data, which makes it more applicable. The results show the average R2 coefficient for the model is 0.91, which is higher than other models. The results confirmed the applicability of the model. [ABSTRACT FROM AUTHOR]

In view of the extremely developed bedding of shale formations, which are dominated by micro-nano pores and fractures, traditional sealing agents make it difficult to produce a tight seal on shale formations due to their huge particle sizes. Combining the bridging effect of inorganic nanoparticles and the deformation properties of organic particles, this article synthesized a core-shell structure nano-blocking agent through emulsion polymerization, which was called P(MMA-St-BD)/KH570-SiO2. The structure of the synthesized nano-plugging agent was characterized utilizing Fourier transform infrared spectroscopy (FT-IR), particle size distribution, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Performance characterization was carried out through the effect of nano-blocking agents on emulsion stability, rheological properties, microporous filter membrane plugging experiments, and core pressure-bearing capacity tests. The findings demonstrate that P(MMA-St-BD)/KH570-SiO2's structure satisfies design specifications, and that the nano-plugging agent has outstanding thermal stability, homogeneous particle size distribution, and good dispersion. Its decomposition temperature also exceeds 400 °C. This study analyzed the plugging efficiency of nano-blocking agents from the temperature perspective, indicating that the nano-blocking agents seal shale formations tightly. Ultimately, through mechanism analysis, nanomaterials can squeeze and deform through the polymer shell and enter the shale micropores and micro-cracks for sealing, forming a high-strength sealing zone. [ABSTRACT FROM AUTHOR]

The implication of nano-additives in drilling fluids introduces a promising avenue for enhancing sustainability in the oil and gas industry. By upgrading the properties of drilling fluids, nano-additives can contribute to mitigating the drilling costs, improving wellbore stability, and minimizing the environmental impact. For example, the use of nano-additives can diminish the amount of drilling fluid required, thus reducing the volume of waste generated. Also, nano-additives can enhance the efficacy of drilling operations, leading to reduced energy consumption and greenhouse gas emissions. This review researches the potential of nano-additives in enhancing sustainable drilling practices, emphasizing the environmental advantages and economic advantages associated with their usage. Specifically, this comprehensive review will elucidate the most recent developments in drilling fluids by evaluating the impact of nano-additives. Referring to the conclusions, adding nanoparticles to drilling fluids significantly improves their characteristics. At 0.2 parts per billion (ppb), for example, the yield stress increases by 36% and the plastic viscosity increases by 17%. In addition, the inclusion of nanoparticles at a concentration of 0.6 ppb led to a significant decrease of 60% in the loss of filtrate. The measured enhancements highlight the capacity of nano-additives to augment the properties of drilling fluid, necessitating additional investigation into their prospective applications for enhancing competitiveness in the gas and oil industry. This study methodically examines the effects of these breakthroughs on scientific, commercial, and industrial sectors. It intends to provide an inclusive understanding of the possible advantages of nano-additives in drilling operations. [ABSTRACT FROM AUTHOR]

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Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules. As an additive to the drilling fluid, the BDTPM can minimize drilling fluid intrusion by plugging the reservoir during drilling and afterwards maximize permeability recovery by degrading the material. The particle size distribution was in the range of 1–130 μm. The optimal mass ratio between modified ceramic particles, ethyl cellulose and epoxy resin was found to be 4:2:1. The plugging rate was 100% when ethyl cellulose and epoxy resin were mixed to coat the ceramic particles to form BDTPM, and the plugging performance was the best. At a temperature close to the typical hydrate reservoir environment (5 °C), 0.02 wt% low-temperature complex enzyme can degrade BDTPM, and the permeability recovery rate is 64.66%. The efficient reservoir protectant developed in this work could play an important role in the successful drilling of natural gas hydrate reservoirs. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules. As an additive to the drilling fluid, the BDTPM can minimize drilling fluid intrusion by plugging the reservoir during drilling and afterwards maximize permeability recovery by degrading the material. The particle size distribution was in the range of 1–130 μm. The optimal mass ratio between modified ceramic particles, ethyl cellulose and epoxy resin was found to be 4:2:1. The plugging rate was 100% when ethyl cellulose and epoxy resin were mixed to coat the ceramic particles to form BDTPM, and the plugging performance was the best. At a temperature close to the typical hydrate reservoir environment (5 °C), 0.02 wt% low-temperature complex enzyme can degrade BDTPM, and the permeability recovery rate is 64.66%. The efficient reservoir protectant developed in this work could play an important role in the successful drilling of natural gas hydrate reservoirs.

The evaluation of the use of sawdust in drilling fluid formulation is covered in this study. The investigation focused on the physicochemical and rheological properties of water-based mud (WBM) drilling fluids that included four different dosages of sawdust. These properties included yield stress, plastic viscosity, rheological behavior, gel strength, filtration test (API filtrate; American Petroleum Institute), and pH. The sawdust was employed as a substitute for the polymers commonly used in water-based muds (WBMs) to serve either as a viscosifier or as a fluid loss controller. The current study set out to evaluate how sawdust (diameter ≤630 µm) affected the primary characteristics of the drilling muds. Sawdust was utilized in place of carboxymethyl cellulose polymer (CMC) as a viscosifier and polyanionic cellulose polymer (PAC) as a filtrate reducer at several dosages (0, 10, 20, 50, and 100 g/L). It was found that the sawdust dosage and its role had a significant impact on the rheological characteristics of the drilling fluids. At amounts between 20 and 50 g/L, the sawdust was added as a viscosifier to the drilling fluids under study, resulting in a significant improvement in their physicochemical and rheological parameters (yield stress, plastic viscosity, and gel strength). However, the drilling fluids showed extremely high rheological properties and a viscosity that can slow down fluid circulation in the well when 100 g/L of sawdust were used, totally substituting for the polymers. [ABSTRACT FROM AUTHOR]

This study was conducted on bentonite deposits in Um Al Rozm and Ain Al Ghazala areas that lie between Latitudes º32 “00 ‘30 and º32 “33 ‘30 N and Longitudes º23 “00 ‘30 and º23 “20 ‘30 E in Northeast Libya. The objective of this study is the assessment of geological, physiochemical, mineralogical, and rheological properties and the potentiality of utilizing these rocks as drilling fluids for oil and gas wells. Chemical and mineralogical analyses were performed by XRF and XRD, respectively. Rheological properties are investigated before and after the treatment process by adding additive materials such as Na2CO3 and CMC. The chemical analysis results of bentonite showed a discrepancy in the proportions of the major components. The results after the treatment process for bentonite in Um Al Rozm exhibit rheological properties consistent with those stipulated by API and other standard bentonites, but for Ain Al Ghazala, the results are unsatisfactory. Mineral analysis of bentonite from the two areas revealed a difference in the mineral composition. The bentonite of the Um Al Rozm area is Na-bentonite, while the bentonite of the Ain Al Ghazala area is Ca-bentonite, whose rheological properties aren’t acceptable as drilling fluid properties stipulated by API.

In the process of unconventional oil and gas exploitation, the invasion of a large amount of drilling fluid into the formation is one of the most critical reasons leading to wellbore instability. A temperature‐sensitive polymer (AOS) was synthesized from acrylamide, oligo (ethylene glycol) methyl ether methacrylate (OEGMA), and sodium p‐styrene sulfonate by emulsion polymerization. The material is a solid‐free fluid with good fluidity at room temperature, after injection into the formation, the fluid is gradually transformed into hard gel above the lower critical solution temperature (LCST) (90°C), thus blocking micro‐fractures and improving wellbore stability. Infrared and NMR characterization confirmed the successful preparation of the target product. The transmittance of AOS with ambient temperature was measured by UV–vis spectrophotometer, and the LCST behavior of AOS was verified by rheological and viscoelastic measurements. The interaction mechanism between AOS and sodium bentonite was evaluated according to the American Petroleum Institute standard. The results show that after aging at 180°C, the filtration loss is reduced by 93%, and the medium permeability (100, 200 mD) formation is effectively plugged, with a plugging efficiency is as high as 74.7%. [ABSTRACT FROM AUTHOR]

Addressing the increasing demand for green additives in drilling fluids is essential for the sustainable development of the oil and gas industry. Fluid loss into porous and permeable formations during drilling presents significant challenges. This study introduced an innovative, environmentally sustainable drilling fluid known as nano-biodegradable drilling fluid (NBDF). The NBDF formulation incorporates greenly synthesized zinc nanorods (ZNRs) and gundelia seed shell powder, with ZNRs derived from Cydonia oblonga plant extracts using an eco-friendly method. The research developed multiple drilling fluid variants for experimentation: a reference drilling fluid (BM); biodegradable drilling fluid (BDF) with particle sizes of 75, 150, 300, and 600 µm at concentrations ranging from 0.5 to 1 wt% (GSMs); a drilling nanofluid (DNF) with ZNRs at a 0.1 wt% concentration (ZNR); and NBDF combining both nano and gundelia waste (GS-ZNR). Experimental tests were conducted under various temperature and pressure conditions, including low temperature and low pressure (LTLP) and high temperature and high pressure (HTHP). Rheological and filtration measurements were performed to assess the impact of the nano-biodegradable additives on flow behavior and fluid loss. Results indicated that incorporating 1 wt% of gundelia seed shell powder with a particle size of 75 µm led to a 19.61% reduction in fluid loss compared to BM at 75 °C and 200 psi. The performance of the same GSM improved by 31% under identical conditions when 1 wt% of zinc ZNRs was added. Notably, the GS-ZNR formulation demonstrated the most effective performance in reducing fluid loss into the formation, decreasing mud cake thickness, and enhancing the flow behavior of the non-Newtonian reference drilling fluid. This study highlights the relevance of particle size in the effectiveness of biodegradable additives and underscores the potential of NBDF to address environmental concerns in the oil and gas drilling industry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During reservoir development process, the permeability of near wellbore zone decreases, and filtration characteristics of productive formations deteriorate due to anthropogenic impact for the primary and secondary improved oil recovery process and other technological operations. To restore and improve the productivity of wells in heterogeneous low-permeability terrigenous reservoirs, classic acid treatments are recommended. Aggressive secondary sedimentation or in other words, precipitation occurs during acid treatments in terrigenous reservoirs, confirming the effectiveness of putting wells into operation through the proposed chemical composition as the cleaning and stimulating operations. Therefore, a comprehensive approach and methods of impact on the near wellbore zone are necessary, as these are multifactorial processes. This research is focused on developing effective technologies to improve technical means or compositions that restore well productivity by decolmatizing the formation and substantiating effective chemical compositions. The results of this work show that the proposed method and chemical reagent highly improved the permeability of near wellbore zone and as a result increased the productivity index of the well. [ABSTRACT FROM AUTHOR]

In underground diaphragm wall and pile foundation engineering operations, calcium ions from the concrete continually invade into the drilling fluids because of the frequent contact of the drilling fluids with the concrete, leading to gradual deterioration of the basic properties of the drilling fluids and large amount of waste muds after the operations. To improve the calcium resistance of the drilling fluids and minimize the amount of waste drilling fluids produced, the natural bentonite used to formulate the drilling fluids needs to be modified. A calcium-resistant compound bentonite ACB-16 is synthesized with natural bentonite purified through high-speed centrifuging and monomers for polymerization, such as a hydrophilic monomer BX with double carbon bonds, hydrophilic monomers AS and AP with sulfonic acid groups. In the polymerization reaction, the monomers enter into the crystal spaces of the purified bentonite, reacting with each other through in-situ free radical polymerization. Studies on the polymerization products with FT-IR, particle size distribution test, SEM and TEM show that the monomers successfully in-situ polymerize in the crystal spaces of the bentonite. The quality of ACB-16 exceeds the quality of the OCMA bentonite. A drilling fluid formulated with ACB-16 has an apparent viscosity of 26 mPa∙s, an API filter loss of 7.6 mL, a good rheology and filtration property as well as a good calcium resistance. When contaminated with 1% calcium chloride, the rheology and filtration property of the drilling fluid are still stable. The limit of calcium resistance of a drilling fluid formulated with ACB-16 is 6,300 mg/L (equivalent to 1.75% CaCl2 ), perfectly satisfying the requirements for a drilling fluid to resist calcium contamination in foundation engineering. Using particle size analysis and SEM, the working mechanism of ACB-16 is studied. The high molecular weight polymers located on the networking structures of the bentonite hinder the ion exchange between the calcium ions and the bentonite, thereby maintaining the thickness of the hydration membrane and the c-spacing of the bentonite and supporting the network structures generated by the hydrated bentonite. Direct mixing of ACB-16 with water can obtain a calcium-resistant drilling fluid with excellent properties. ACB-16 is easy to use, it will have good application prospects in foundation engineering and other fields, and it can also be used in formulating anti-sloughing drilling fluids for high calcium environment such as salt and gypsum drilling. [ABSTRACT FROM AUTHOR]

Two wells, the well Long-XX and the well Ning-XX, in Longdong area are recently tested, and the target zone located in the bauxite formation has been found an important alternative resource for the Changqing Oilfield. Significant findings were obtained in exploring the bauxite formation through these two wells. Technical difficulties, such as prevailing of dissolution pores and fractures, borehole wall collapse, mud losses and poor hole cleaning etc. have been encountered in drilling the target bauxite formation. The main factors contributing to borehole wall collapse were found in analyzing and testing the bauxite samples for physical properties, chemical properties, mechanical properties and sensitivity characteristics, and a fast-plugging, inhibitive drilling fluid for safe drilling of the bauxite formation was developed. This drilling fluid has high temperature (170 ℃) high pressure filter loss of less than 10 mL and percent secondary cuttings recovery of greater than 91%. After soaking the bauxite samples in the drilling fluid and fresh water respectively for 15 days, the compressive strength of the samples tested in the drilling fluid is 81.8% higher than that of the samples tested in the fresh water. This drilling fluid has been tried in drilling the first horizontal Long-4XX well targeted the bauxite reservoir in Changqing, a horizontal section of 700 m was successfully drilled. The daily flowing production rate of this well is 3.53 × 106 m³, a new record made in developing the upper Paleozoic resources in the Erdos basin in the last 50 more years. This technology has provided a technical support to the development of the similar reservoirs. [ABSTRACT FROM AUTHOR]

The effect of silicon dioxide nanoparticles on the rheology of aqueous solutions of xanthan gum was studied. Tests were carried out on a rotational viscometer and by the oscillatory method on an Anton Paar rheometer. Additions of nanoparticles up to 2 wt.% to solutions containing up to 1 wt.% gum were analyzed. In the studied concentration ranges, the influence of nanoparticles maintains the shape of the flow curves and viscosity curves, introducing small changes. It was shown that with increasing concentration of nanoparticles, the elastic modulus of suspensions, the values of their yield strengths and flow points increase. At the same time, the pseudoplasticity index practically does not increase, leading to the manifestation of a brittle rupture with increasing load in the oscillatory test of the suspension. The storage modulus at a nanoparticle concentration of 1% takes on a two-stage form, and at a concentration of 2% it forms a hysteresis curve, indicating a brittle rupture of the material. It was shown that the effect of the conformational transition is about 30% and decreases with increasing flow shear rate. [ABSTRACT FROM AUTHOR]

Ultrasonic wave propagates with strong penetration, high stability, and has non-contact nature, therefore it is widely used in the petroleum industry. As an application example, an ultrasonic flowmeter can accurately measure the annular flow rate of water-based drilling fluid. According to the outlet flow rate, it can be noticed if there is an abnormal situation in the well to avoid accidents such as well kick and blowout. However, due to the attenuation of ultrasonic wave in the drilling fluid, the relevant research results are not reliable. Herein, based on the theory of acoustics, the influences of water-based drilling fluid density, solid particle size and solid particle number on the ultrasonic attenuation characteristics under different frequencies are studied by numerical simulation. First, the propagation characteristics of ultrasonic wave in water-based drilling fluid are systematically analyzed, then the accuracy of the above results is verified by laboratory tests. The results show that the ultrasonic attenuation rate is positively correlated with the solid particle size, solid particle number and ultrasonic frequency in water-based drilling fluid, while it is negatively correlated with the density of water-based drilling fluid. Furthermore, it is established that the ultrasonic energy decreases with increasing propagation distance. The results of this study can provide a theoretical basis and practical guidance for using an ultrasonic flowmeter to accurately measure the annulus return flow rate of drilling fluid and develop an intelligent drilling system, so as to improve the efficiency of field operation and drilling success rate. [ABSTRACT FROM AUTHOR]

While drilling an oil well, the bit will penetrate different geological formations, and these formations will contaminate the drilling fluid either through rocky crumbs or formation water. The amount of alternation caused in the drilling fluid depends on the lithological type of the drilled formation and the percentage of ions in the formation water. Water is the main component of drilling mud, especially water-based mud, and it can be fresh water or salt water. One of the most important duties of the mud engineer when preparing drilling mud is to do a water test to measure the salinity: chloride (Cl–) and calcium (Ca2+). This study relied on field information for oil well in southern Iraq, which was adopted as a model for this case study. The study concluded that the presence of some ions in drilling mud such as Cl, sodium (Na) and Ca either reduces or increases the rheological properties of the mud system and in turn affects the rate of penetration, and it could also lead to serious drilling problems. The results proved that one of the most important indicators of mud contamination is a rise in the proportions of magnesium (Mg), Ca, carbonate (H2CO3) bicarbonate (HCO3), in addition to a low potential hydrogen (H). The rheology of the mud was also affected by contamination, depending on the type of ion polluting the drilling mud and the amount of its percentage. On the other hand, neglecting the treatment and monitoring of mud properties lead to serious problems. The results showed that adding silica dust contributed to treating drilling mud contaminated with calcium ions by 20%, as an increase in the value of the mud's viscosity was observed after adding silica. When the concentration of sodium chloride (NaCl) was about 8% or less, an increase in the rheological properties of the clay was observed, and the opposite was observed at concentrations of 10% or more. [ABSTRACT FROM AUTHOR]

In the development of ultra-deep wells, extremely high temperatures can lead to inefficiency of additives in drilling fluids. Hence, there is a need to prepare additives with a simple preparation process and good effects at ultra-high temperatures to ensure stable drilling fluid performance. In this study, a high temperature resistant filtration loss polymer (LY-2) was prepared using γ-methacryloyloxypropyltrimethoxysilane (KH570), N,N-dimethylallyl ammonium chloride (DMDAAC), sodium p-styrenesulfonate (SSS), and β-cyclodextrin (β-CD). The impact of the different monomer ratios on particle size, rheology, and filtration performance was systematically investigated. Infrared spectroscopy afforded the structural features. Thermogravimetric Analysis detected the temperature stability, and scanning electron microscopy characterized the polymer micromorphology. LY-2 was completely decomposed at a temperature above 600 °C. Experiments showed FLAPI of the drilling fluid containing 3% LY-2 aged at 260 °C/16 h was only 5.1 mL, which is 85.4% lower compared to the base fluid. This is attributed to the synergistic effect of the polymer adsorption through chemical action at high temperatures and the blocking effect of carbon nanoparticles on the filter cake released by cyclodextrin carbonization at high temperatures. Comparing LY-2 with commercial filter loss reducers shows that LY-2 has excellent temperature resistance, which exhibited five times higher filtration performance and relatively low cost, making it possible to be applied to ultra-high temperature drilling operations in an industrial scale-up. [ABSTRACT FROM AUTHOR]

Laponite® (LAP) is an intensively studied synthetic clay due to the versatility given by its layered structure, which makes it usable in various applications. This review describes the multifaceted properties and applications of LAP in aqueous dispersions and gel systems. The first sections of the review discuss the LAP structure and the interactions between clay discs in an aqueous medium under different conditions (such as ionic strength, pH, temperature, and the addition of polymers) in order to understand the function of clay in tailoring the properties of the designed material. Additionally, the review explores the aging phenomenon characteristic of LAP aqueous dispersions as well as the development of shake-gels by incorporating LAP. The second part shows the most recent studies on materials containing LAP with possible applicability in the drilling industry, cosmetics or care products industry, and biomedical fields. By elucidating the remarkable versatility and ease of integration of LAP into various matrices, this review underscores its significance as a key ingredient for the creation of next-generation materials with tailored functionalities. [ABSTRACT FROM AUTHOR]

As the deep hole drilling environment becomes more and more complex, the phenomenon of well wall instability during the implementation of rope coring drilling technology becomes more and more prominent. In order to solve this technical issue, the factors leading to well wall instability in the process of rope coring were discussed in detail from both geological and engineering factors. Taking the key investigation hole DZK4 in a major water supply project as an example, the synergistic anti-collapse theory of "cation-high adhesion-wetting reversal-chemical inhibition-reasonable density support" was proposed in combination with the actual situation of deep hole and complex rock formation, and the drilling fluid formula was formed in combination with this theory. The application shows that the density of drilling fluid, water loss and other related indexes meet the control standard of drilling fluid, and the performance of drilling fluid is more stable. [ABSTRACT FROM AUTHOR]

The effective determination of pressure losses depends on accurate knowledge of the drilling fluid rheology. As the fluid circulates deeper around the wellbore, its rheological behavior undergoes significant alterations due to the variations in downhole conditions encountered. The present study investigates the effects of the rheological properties of Yield-power law fluid at various pressures and temperatures on annular pressure losses and velocity profiles. Simulations were performed using Computational Fluid Dynamics to examine the fluid flow in turbulent and laminar regimes. Comparison between numerical, experimental and slot approximation model results showed a good agreement. Results indicated that pressure losses have reduced in both regimes with increasing temperature, at a constant pressure. However the pressure has the opposite effect at a constant temperature. For a drilling fluid flow velocity of 1 m/s, the elevation of temperature from 25 °C to 90 °C, decreases the pressure drop gradient by (31% to 48%) at low and high- pressure conditions respectively. Whereas, the influence of increasing pressure on pressure losses is more apparent at 25 °C. Earlier transition from laminar to turbulent is observed with temperature rise. Therefore, the temperature effect on pressure losses in the turbulent region; is shown for different Generalized Reynolds numbers. [ABSTRACT FROM AUTHOR]

Deep oil and gas are essential alternative resources for future energy sources, but the lack of high temperature and high salt resistance mechanisms and agents significantly limits their development. Copolymers of six commonly used high-temperature and salt resistance monomers and acrylamide with similar molecular weights were prepared to improve oil recovery in deep reservoirs. The effects of different functional groups on the high-temperature and salt resistance of polymers were revealed by the drilling fluid and elemental analysis, TOC test, Zeta potential, particle size, and other analytical methods. Experimental results indicate that the pyrrole ring groups, quaternary amine groups, long-chain sulfonate groups, and benzenesulfonic acid groups can effectively improve the high-temperature stability of polymers in an aqueous solution. Quaternary ammonium groups and pyrrole rings can enhance the polymer adsorption with clay under high temperatures and high salinity conditions due to charge attraction. However, these functional groups hinder the clay dispersion and reduce the stability of drilling fluids. Hydration groups, such as sulfonic and carboxylic acid groups, can better maintain the colloidal stability of drilling fluids under high temperatures and high salinity, and benzene sulfonic acid groups are the optimal hydration groups. After the polymer is adsorbed on the clay surface, the benzene sulfonic acid group assists in forming a thicker hydration film on the clay surface, effectively hindering the damage of high temperature and high salinity on the clay. The findings and observations of this study provide theoretical support for the development of high-temperature and salt resistance polymers for water-based drilling fluids of ultra-deep wells. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University / Shanghai Daxue Xuebao is the property of Journal of Shanghai University (Natural Sciences) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract It is very important to clarify the reservoir damage characteristics and damage characteristics and damage mechanism of tight sandstone gas reservoirs in Jinhua-Zhongtai mountain area of central SiChuan Basin, and put forward the technical countermeasures of “Double protection” drilling fluid to protect the reservoir and the environment, which is very important for the efficient well construction in this area. Through X-ray diffraction, scanning electron microscopy, casting thin sections and other testing methods, the mineral composition and microstructure characteristics of the block were analyzed, and the potential damage factors of the reservoir were clarified. Based on the sensitivity evaluation, it was revealed that the overall sensitivity damage of the block was weak. The main damage type was salt-sensitive damage, and the critical salinity was 9472.5 mg/L. On the basis of the environmental protection drilling fluid system used in this block, the surfactant which can effectively prevent gas invasion and reduce surface tension is selected, and the “Double protection” drilling fluid system is constructed. Through comprehensive performance test and reservoir protection performance evaluation, the core permeability damage rate of the optimized drilling fluid system is reduced from 88.77 to 18.66%, and the cuttings recovery rate is increased to more than 66%, and the cuttings expansion rate is reduced to less than 3.2%, which can effectively solve the problem of reservoir damage in drilling in Jinhua-Zhongtai mountain block in central Sichuan.

Abstract In drilling operations, the formation of a filter cake is crucial for well stability, but its removal post-drilling is essential to restore rock formation productivity. This study focuses on hematite-based filter cakes and investigates factors influencing their solubility and removal, addressing a significant knowledge gap in the field. The research methodology involves examining the effects of various factors, including types and concentrations of reducing agents, temperature, particle size, and treatment duration, on the dissolution process. Notably, Nuclear Magnetic Resonance (NMR) tests are employed to assess the treatment's impact on core porosity. Among the diverse reducing agents examined, ferrous chloride emerges as the optimal choice for effectively enhancing hematite solubility. Particularly, a composite solution of ferrous chloride (10 wt.%) and hydrochloric acid (6 wt.%), was highly efficient demonstrated by exhibiting rapid solubilization of hematite filter cakes. A removal efficiency of approximately 99%, with a parallel enhancement in core permeability was achieved. NMR tests reveal the treatment's success in reinstating the porosity system, which had undergone reduction due to drilling fluid particles. Crucially, the solution exhibits a considerably lower corrosion rate than concentrated hydrochloric acid, highlighting its potential to mitigate environmental concerns while ensuring efficient filter cake removal. The findings of this research provide valuable insights into optimizing post-drilling operations, balancing environmental sustainability and operational efficiency. The identified composite solution offers a promising approach to efficient filter cake removal while mitigating environmental concerns associated with corrosion. Overall, this study contributes to advancing the understanding and practice of well productivity enhancement in the oil and gas industry.

The wellbore instability problem has always been a global technical challenge in drilling engineering. The development of weak planes and the high clay mineral content in laminated shale increases the risk of borehole collapse. In the process of drilling construction, the invasion of a large number of drilling fluids gradually deteriorates the strength of shale oil and causes wellbore instability, leading to several engineering problems (e.g., diameter reduction, stuck drilling, and hole expansion) and greatly restricting the efficient development of shale horizontal wells. Therefore, to study the invasion characteristics of drilling fluid into laminated shale, displacement experiments and nuclear magnetic scanning were conducted to determine the depth of drilling fluid invasion into laminated shale under different displacement times. This method directly and accurately studies the process of drilling fluid invading laminated shale oil. With the increase in intrusion time, the pore sizes of small and large pores increase continuously, and the increase in various pore sizes causes the separation between the grain sizes of the rock skeleton to produce micro-cracks and eventually leads to rock failure. The influence of striation is not considered in the mathematical model established by most scholars due to the development of striation in shale oil and the fact that striation is the main advantageous channel for fluid intrusion. In this study, a new mathematical model of shale oil liquid intrusion is established by considering the joint action of end-face intrusive and striated intrusive fluids. Under constant total water absorption, the model can determine the depth of drilling fluid invasion into laminated layers and total intrusion based on the invasion time. The accuracy of the model was verified based on experimental results. The numerical model established using the finite-discrete element method is used to simulate the influence of different displacement times, different numbers of layers, and different layer openings on the invasion depth under certain displacement pressure. The results show that the depth of drilling fluid invasion into laminated shale increases logarithmically with invasion time under a fixed volume of drilling fluid. As the invasion time and the opening of the laminated layers increase, the invasion depth gradually increases, but the growth slows down in the later stages and eventually stabilizes. Moreover, the invasion depth gradually decreases as the number of laminated layers increases. The primary aim of this study is to reveal the invasion mechanism of drilling fluid into laminated shale under invasion and provide a theoretical basis for selecting safe drilling fluid density and wellbore stability.

The ionic liquid, as a new treatment agent, has been increasingly applied in oil fields due to its strong temperature resistance, good solubility and high surface activity. In this paper, we systematically discuss the action mechanism and application effect of ionic liquids in oilfield chemistry. Ionic liquids can inhibit shale hydration expansion and reduce fluid loss through adsorption and intercalation, inhibit the formation of natural gas hydrate through imidazole five-membered ring structure as a space barrier, reduce viscosity of heavy oil by breaking chemical bonds of heavy oil macromolecules and charge transfer, improve oil displacement efficiency by forming ions pairs with carboxyl groups in crude oil, demulsify by forming channels between dispersed water droplets, acidify the formation by reacting with water to produce acid, interacts with organic material through weak hydrogen bonds and extracts it from oilfield wastewater, desulphurize by inserting sulfide molecules into the “stack” structure and form liquid inclusion complex, inhibit corrosion by forming a protective film on the metal surface. Based on the above aspects, the development direction of ionic liquids is proposed. The application of ionic liquids in oilfield chemistry is still in its infancy. It is urgent to fully explore the application performance of ionic liquids in oilfield chemistry, which also provides theoretical and technical supports for efficient reservoir development.

It is very important to clarify the reservoir damage characteristics and damage characteristics and damage mechanism of tight sandstone gas reservoirs in Jinhua-Zhongtai mountain area of central SiChuan Basin, and put forward the technical countermeasures of "Double protection" drilling fluid to protect the reservoir and the environment, which is very important for the efficient well construction in this area. Through X-ray diffraction, scanning electron microscopy, casting thin sections and other testing methods, the mineral composition and microstructure characteristics of the block were analyzed, and the potential damage factors of the reservoir were clarified. Based on the sensitivity evaluation, it was revealed that the overall sensitivity damage of the block was weak. The main damage type was salt-sensitive damage, and the critical salinity was 9472.5 mg/L. On the basis of the environmental protection drilling fluid system used in this block, the surfactant which can effectively prevent gas invasion and reduce surface tension is selected, and the "Double protection" drilling fluid system is constructed. Through comprehensive performance test and reservoir protection performance evaluation, the core permeability damage rate of the optimized drilling fluid system is reduced from 88.77 to 18.66%, and the cuttings recovery rate is increased to more than 66%, and the cuttings expansion rate is reduced to less than 3.2%, which can effectively solve the problem of reservoir damage in drilling in Jinhua-Zhongtai mountain block in central Sichuan. [ABSTRACT FROM AUTHOR]