Asphaltenes, key components of petroleum systems with high molecular weight and strong polarity, pose significant challenges during hydrocarbon extraction and recovery. In the Tarim oilfield, asphaltenes exhibit highly condensed polycyclic aromatic hydrocarbon structures, necessitating the development of targeted inhibitors. This study designed a molecular structure for asphaltene dispersion using molecular dynamics simulations, analyzing radial distribution functions (RDFs), mean square displacement (MSD), and hydrogen bond probabilities. A novel ternary polymer inhibitor (SMN) was synthesized using low‐toxicity butyl acetate instead of conventional aromatic solvents (e.g., toluene). Experimental results demonstrate that SMN enhances the dispersibility of Tarim archipelago‐type asphaltenes by 71.49%, delays precipitation onset by 50%, and reduces particle size from 1704.4 nm to 431.5 nm. For Qinghai island‐type asphaltenes, dispersibility improves by 62.96%, precipitation onset delays by 24%, and particle size decreases from 1421.3 nm to 415.8 nm. This work advances an efficient, eco‐friendly asphaltene inhibition system by elucidating dispersion mechanisms and molecular interactions, offering theoretical and practical insights to optimize hydrocarbon recovery and mitigate asphaltene‐related operational challenges.

Hydroxypropyl guar gum (HPG) is a critical thickener to increase viscosity and lubrication to improve the water-based hydraulic fracturing efficiency. However, current crosslinkers require a large amount of HPG (>0.3 wt%) to form gel with sufficient viscosity, and high concentrations of HPG may cause adverse effects to the production and the environment. In this study, a novel starch microsphere silica‑boron crosslinker (SMSB) was developed using starch microspheres as a carrier and γ-aminopropyl triethoxy silane (KH550) as a modifier with an in-house method. Both the rheology and surface reactions of the SMSB-HPG crosslinking system were studied using multiple laboratory experiments and molecular dynamics simulation. The results showed that SMSB crosslinker caused multi-site cross-linking with low concentration (only 0.2 wt%) of HPG molecules, reducing the twisting of single molecular chain in the crosslinking system, enhancing the cross-linking strength between molecular chains, and making HPG molecular chains stretcher in the aqueous solution. The apparent viscosity and viscoelasticity of the HPG system were substantially higher than the organoboron crosslinker, and the temperature resistance of the SMSB-HPG crosslinking system was up to 140 °C. This study provides an alternative green crosslinker for more sustainable industrial applications and provides theoretical basis for the modification of biomaterials.

The treatment of boron in fracturing backflow fluid is a widely studied issue in oil and gas resource extraction. In this work, the material of canola straw-derived biochar composite graphene oxide (BC@GO) was produced and used for boron removal. Then, a series of characterization and batch adsorption experiments were conducted on the material. The results show that the composite material has good adsorption capacity, and the maximum adsorption capacity is 168mg/g at the initial concentration of 300 mg/L at pH = 7. The results of kinetic and thermodynamic fitting showed that the boron adsorption by BC@GO conforms to the pseudo-second-order kinetics model and Freundlich model. In addition, it was found that the material still has a good adsorption capacity in batch adsorption experiments of hydraulic fracturing simulated water. Therefore, BC@GO is a new boron removal material with good application prospects.

Hydraulic fracturing (HF) has substantially boosted global unconventional hydrocarbon production but has also introduced various environmental and operational challenges. Understanding the interactions between abundant and diverse microbial communities and chemicals, particularly polymers used for proppant delivery, thickening, and friction reduction, in HF water cycles is crucial for addressing these challenges. This review primarily examined the recent studies conducted in China, an emerging area for HF activities, and comparatively examined studies from other regions. In China, polyacrylamide (PAM) and its derivatives products became key components in hydraulic fracturing fluid (HFF) for unconventional hydrocarbon development. The microbial diversity of unconventional HF water cycles in China was higher compared to North America, with frequent detection of taxa such as Shewanella, Marinobacter, and Desulfobacter. While biodegradation, biocorrosion, and biofouling were common issues across regions, the mechanisms underlying these microbe-polymer interactions differed substantially. Notably, in HF sites in the Sichuan Basin, the use of biocides gradually decreased its efficiency to mitigate adverse microbial activities. High-throughput sequencing proved to be a robust tool that could identify key bioindicators and biodegradation pathways, and help select optimal polymers and biocides, leading to more efficient HFF systems. The primary aim of this study is to raise awareness about the interactions between microorganisms and polymers, providing fresh insights that can inform decisions related to enhanced chemical use and biological control measures at HF sites.

The harsh underground conditions often lead the CO 2 -oil minimum miscible pressure too high to be attainable. In previous studies, nonionic surfactants polyoxypropylene alkyl ether (C i PO j ) and tri-isobutyl citrate (TBC) were utilized to enhance CO 2 -crude oil miscibility. Both of them have a hydroxyl at the terminal. The effects of surfactant terminal hydroxyl acetylation on CO 2 -crude oil miscibility deserves investigation and microscopic mechanisms need to be explained. In this work, four surfactants, C 6 PO 3 , acetylated C 6 PO 3 , TBC and acetylated TBC, were selected for the CO 2 -surfactant-crude oil system and dynamics simulations were carried out at 358.15 K with NVT ensemble. The density profile and fluid properties such as interfacial tension (IFT), minimum miscible pressure (MMP), CO 2 solubility in alkane, oil volume expansion factor and CO 2 extraction efficiency were calculated for systems with and without surfactants. The study found that those surfactants can reduce CO 2 - crude oil MMP although they prefer dissolving into the oil phase. The addition of surfactant enhances CO 2 solubility in the alkane phase, thus resulting in a larger oil volume expansion factor. There exists an approximate linear relationship between the volume expansion factor and CO 2 solubility. Compared with C 6 PO 3 and TBC, the surfactant with terminal hydroxyl acetylation further reduces MMP by 1.18 MPa and 0.43 MPa, respectively. Among the four surfactants selected in this research, acetylated TBC outperforms the other three in increasing CO 2 solubility due to the reinforcement of CO 2 -alkane interaction and the reduction of alkane -alkane interaction. The system with acetylated C 6 PO 3 yields the largest CO 2 extraction efficiency because of the weakened CO 2 -CO 2 interaction.

Enhancing the spreading performance of organic solvents at the gas-water interface is crucial for creating large-area polymer barriers at the gas-water interface in gas reservoirs. Surfactants, recognized for their prominent role in modulating interfacial characteristics, induce marked alterations in the interfacial tension between oil and water phases. The alteration impacts the mechanical equilibrium at the triphasic contact boundary, ultimately influencing the spreading behavior of surfactant-laden oil droplets on water surfaces. In this investigation, we present a novel method for bestowing high-speed spreading attributes upon oil droplets on water surfaces, potentially offering a more effective approach to establishing extensive artificial barriers at the gas-water interface through a spreading-polymer coupling technique. Initially, we selected six surfactants (OP-4, OP-7, AOT, Span20, Span80, Span85) with high solubility in cyclohexane, based on their solubility parameters. Subsequently, the surfactant concentration gradient was set at 5 × 10-7, 5 × 10-6, 5 × 10-5, 5 × 10-4, 5 × 10-3, and 5 × 10-2 mol/L and we measured the surface tension and interfacial tension for each surfactant solution at concentrations ranging from 5 × 10-7 to 5 × 10-2 mol/L, from which we calculated the spreading coefficients. Ultimately, we evaluated the spreading radius as a function of time, and the temporal evolution curves of the spreading radius (R) on the water surface were computed using an inter-correlation algorithm to determine the spreading velocity (v) of the surfactant-cyclohexane solutions. This assessment allowed us to pinpoint the optimal surfactant type and concentration for maximizing cyclohexane spreading performance.

This study clarified the high-efficiency mechanism of enhancement of the spreading performance of oil by allowing a droplet of an organic solvent to spread over the surface of water with the addition of oil-soluble surfactants. Firstly, the effect of Span 85, Span 80, Span 20, octylphenol polyoxyethylene (4) ether (OP-4), and sodium dioctyl sulfosuccinate (AOT) on the interfacial parameters of an n-decane droplet was evaluated by measuring the surface tension and interfacial tension. Then the spreading coefficient was calculated to determine whether the surfactant-laden oil droplets could spread at the air-water interface. Moreover, the law governing the spreading of the surfactant-laden oil droplets over water was systematically studied. Furthermore, the characteristics of the dynamic behavior of the surfactants were investigated by molecular dynamics simulations to elucidate the spreading mechanism. The results of the experiments and simulations explained how the oilsoluble surfactants Span 85, Span 80, Span 20, OP-4, and AOT significantly improved the spreading performance of oil droplets over the water surface.

The discharge of chromium-containing wastewater in industrial production causes resource loss and damage to the ecological environment. Currently, various phenolamine materials have been used to remove chromium, but their harsh adsorption conditions bring many difficulties. For example, ideal chromium removal is only achieved at low pH. In this study, we synthesized catechol/m-phenylenediamine nanospheres (CMN) and combined CMN with Fe(II) for Cr removal from aqueous solutions, and Fe(II) comes from FeSO4 & BULL;7H(2)O. CMN was characterized and analyzed by field-emission scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron (XPS). The adsorption performance was studied through a series of adsorption experiments. When C-0 = 900 mg/L and pH = 6, the maximum adsorption capacity obtained in the experiment was 977.1 mg/g. It maintains excellent adsorption properties in acidic, neutral and alkaline environments. The results of the adsorption mechanism showed that the ultra-high adsorption capacity of CMN and Fe(II) for Cr was the result of the synergistic effect of adsorption and reduction, including electrostatic attraction, reduction and coprecipitation. CMN is expected to be an ideal adsorbent for Cr removal in aqueous solution due to its low cost, high biocompatibility and high efficiency in Cr removal.

Surfactants are often used to change the structure of natural polysaccharide polymers and improve their properties for industrial applications. However, implementing surfactants to boost the Welan gum has yet to be studied. This study prepared the compound system HWG-A by Sodium alcohol ether sulphate (AES) with hydrophobic modified Welan gum (HWG). Compared with HWG, the critical association concentration of HWG-A they have decreased from 3.8 x 103 mg L-1 to 2.8 x 103 mg L-1. The viscosity of 2 x 103 mg L-1 HWG-A remained at 244 mPa s when the salinity was 96,670 mg L-1. The rheological test showed that HWG-A still maintained the characteristics of pseudoplastic fluid under different polysaccharide concentrations, pH and salinity. The viscoelastic test showed that the elasticity of HWG-A was interdependent with the concentration of polysaccharides. When HWG-A was higher than the critical association concentration, the elasticity dominated the whole system. The temperature resistance test showed that the viscosity of HWG-A was still much higher than that of Welan gum and HWG when the salinity was 19,334 mg L-1 at 140 celcius and lower than the critical association concentration, and the viscosity remained above 350 mPa s. SEM showed that HWG-A presented a regular large network structure when the concentration was lower than its critical association concentration. Otherwise, HWG-A presented a gel shape. Our study promotes the industrial potential of Welan gum in such as Enhanced Oil Recovery (EOR) process. It suggests that the interaction between surfactants and natural polysaccharides is essential in determining the functional properties of the fluid system.

目的 针对尕斯油藏地层水矿化度大,凝析油含量分布广的情况,研制一种能耐高矿化度和高凝析油的固体洗井剂,以满足尕斯油藏洗井.方法 基于尕斯油田水分析结果,水中C a2+含量较大,对阴离子起泡剂的起泡能力和泡沫稳定性影响很大.非离子、阳离子、两性离子起泡剂的抗盐能力优良,使用韦伯搅拌法对这3类抗盐能力优良的起泡剂进行耐盐性筛选.结果 最终选出CAO-30(两性离子氧化铵型)、CAB(两性离子甜菜碱型)、YN-1(非离子烷基糖苷型)3种耐盐能力优良的表面活性剂.并对3种表面活性剂进行复配,优选出表面张力低、泡沫体积大、泡沫稳定性强的组合,其中,两性离子甜菜碱型与非离子烷基糖苷类起泡剂复配具有协同增效作用,使用羟丙基胍胶作为稳泡剂,稳泡效果良好.起泡剂的最佳质量比为:m(CAB):m(YN-1):m(HPG)=6:9:5.使用尿素为固定剂制成固体起泡剂,对固体起泡剂进行性能评价.结论 该起泡剂与地层水配伍性良好,最大耐凝析油质量分数为30％,最大耐温能力为80℃,洗油污能力优良.

Herein, we report the preparation of Fe(III) complexed polydopamine modified Mg/Al layered double hydroxides composite material (LDHs@PDA-Fe(III)) and its application to the removal of Cr(VI) in aqueous solution. LDHs@PDA-Fe(III) was characterized and analyzed by field-emission scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDS), Fourier transformed infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron (XPS). The adsorption performance was studied through a series of adsorption experiments. Investigate the effects of pH, time, temperature, concentration and other factors. When C0 = 800 mg/L, T = 308 k and pH 3, the maximum adsorption capacity obtained in the experiment was 683.4 mg/g. In addition, after 5 adsorption cycles, LDHs@PDA-Fe(III) still shows excellent adsorption capacity and stability. Combining adsorption experiments and characterization analysis, it is inferred that the adsorption of Cr(VI) by LDHs@PDA-Fe(III) is the result of the synergistic effect of multiple adsorption mechanisms. Therefore, the efficient removal capacity and excellent stability make LDHs@PDA-Fe(III) an ideal adsorbent for removing Cr(VI) from aqueous solutions.

The application of oil-based drilling fluids in high temperature deep well drilling and the other complex well drilling process has been severely restricted due to the limited types and poor high-temperature high-pressure (HTHP) fluid loss (FL) control capability of fluid loss control additives (FLCAs). Aiming at the issue, a kind of slightly amphiphilic polymer microspheres, i.e., poly (acrylamide-co-divinylbenzene) (PACD) microspheres, with mean diameter 3.2 μm and polydispersity 1.82, were selected as the FLCA for oil-based drilling fluids in the study. The performance of PACD microspheres in terms of FL control and the structure of filter cake was compared with the traditional additives including oxidized asphalt and nano-CaCO3. The results showed that PACD microspheres have superior HTHP FL control capability. The HTHP FL of oil-based drilling fluids at 180 °C can be controlled within 10 mL as the addition of PACD microspheres was kept at 5 kg/m3. The FL control mechanism of PACD microspheres was analyzed based on the physical properties of PACD microspheres, the rheological properties of oil-based drilling fluids and the macro-appearance and microstructure of the filter cake. It was concluded that the superior HTHP FL control capability of PACD microspheres is due to the finite deformation property and the slight amphipathy of the microspheres.

In this study, a salt-tolerant friction reducer was proposed on the basis of dispersion polymerization to recycle high-salinity produced water. A dispersion polymerization friction reducer (DPFR) was synthesized using an acrylamide copolymer in an ultra-high-salinity solution, and its friction reduction performance was simulated in produced water. The gel permeation chromatography revealed that DPFR exhibited high molecular weight and low dispersity could stretch rapidly and show hydration in 2 s. Thus, the proposed reducer exhibits considerable potential for fracturing friction reduction. These performance tests were primarily conducted using a closed-loop flow system at various bulk velocities, dosages, and salt contents; therefore, the experimental results revealed that 2000 ppm DPFR exhibited the maximum slickwater friction reduction efficiency (FRe ) of approximately 80% at 40 L/min. Furthermore, DPFR retained a high friction reduction performance of more than 75% at concentration of 120 g /L Na+, 100 g/L Ca2+, 20 g/L Fe-3+,Fe- 180 g/L Cl-, and 100 g/L SO4 (2-) solutions. Functional tests revealed that novel DPFR exhibited a high salt tolerance in various high-salinity produced waters. Furthermore, DPFR is economical, environment-friendly and operationally efficient, because no additional organic additive is required in the synthesis and application process.

The minimum miscible pressure （MMP） of CO2 flooding is a crucial parameter to judge whether miscible flooding is attainable. In order to reduce the application threshold of miscible flooding, the MMP between CO2 and crude oil needs to be reduced urgently. Adding miscible flooding assistants to oil reservoir is an effective means for minimum miscible pressure reduction. At present, according to the elements contained, the miscible flooding assistants can be divided into three categories including fluorocarbon, siloxane, and hydrocarbon （oxygenated）. In order to reduce the cost and improve the MMP reduction performance, the hydrocarbon structure should be added to the fluorocarbon assistants to make the assistants develop in the direction of mixing type. The hydrocarbon assistants have sound MMP reduction performances and room for improvement. The key is to find a suitable CO2-phlic structure. Computer simulation is also a vital means to study micro mechanism and assist structure designing. Compared with fluorocarbon and siloxane, the cost of hydrocarbon （oxygenated） is lower, and it has the most application potential from the prospective of cost. At present, the main factor affecting the large-scale application of miscible assistants is the limitation of cost. The promotion and application in the future needs the close cooperation of petroleum and chemical practitioners. In this paper, the mechanisms of CO2 miscible flooding assistants reducing MMP are introduced. The structures of existing miscible flooding assistants, MMP reduction effectiveness are summarized, and the influencing factors on MMP reduction efficiency are analyzed. The developing directions CO2 miscible flooding assistants designing are prospected.

Summary Hydraulic fracturing has extended to both deep-terrestrial and deep-sea reservoirs because hydrocarbons in shallow subsurface are depleting. However, the density of common inorganic weighting agents may not give sufficient column pressure, which may compromise the efficiency of hydraulic fracturing fluids (HFF) and present potential risks to facilities and the environment. Here, we investigated hydroxypropyl guar (HPG)-based HFF (HPG-HFF) using potassium formate (PF) as a weighting agent with and without a hydroxy carboxylate acid (citric acid, abbreviation FW was used througout this study) as an additional dispersion stabilizer. Analyses included stability investigations, macro- and microrheology assessments, Fourier transform infraredspectroscopy (FTIR) analyses, molecular dynamic simulations, and screening of crosslinking points. Our results showed that increased concentrations of PF substantially reduced the stability and viscosity of HPG solutions, but adding citric acid mitigated these drawbacks. Molecular dynamic modeling suggested that formate acid ions formed hydrogen bonds with HPG and water, resulting in reduced hydrophilicity and coiling of the HPG molecular chain. When citric acid was added, less formate ions surrounded the HPG molecule, and the forming FW ions primarily interacted with the HPG molecule through hydrogen bonding. Besides, the hydroxyl group of the citric acid may improve the hydrophilicity of the whole complex. Thus, the original nature of the HPG molecular chain could be compensated. Atomic force screening showed more crosslinking points with stronger intensity and an even distribution in the HPG-PF-citric acid gel system, compared to that in the HPG-PF gel system (without citric acid). Furthermore, thermal stability tests showed that the proposed PF-citric acid-HPG-HFF system could resist temperatures up to 120°C. Our study demonstrates the potential application of formate-based weighting agents, highlighting the effects of hydrogen bonding in complex HFF. This benchtop study provides a foundation for future research to understand the application of formate-FW-based weighting HPG-HFF in downhole high temperature conditions.

Using a chemical water shutoff method is one of the most effective ways to control formation water and enhance gas recovery. Numerous water shutoff agents have been applied to successfully address water influx in gas fields. Basically, according to the differences in plugging mechanisms, the water shutoff agents can be divided into nine categories: inorganic salts, resins, particles, polymer bridge bond adsorption agents, polymer gels, foams, wetting alteration agents, micro-emulsions, and composite water plugging agents. The typical water shutoff agents and corresponding water plugging mechanisms, materials, properties, and adaptability analysis have been summarized to identify water shutoff agents suitable for gas reservoirs. A systematic performance evaluation of water shutoff agents has been conducted from the perspectives of plugging strength, temperature tolerance, salt tolerance, corrosion tolerance, long-term stability, selectivity of water plugging, migration capability, convenience of construction, and gas reservoir adaptability. We identified four types of water shutoff agents—polymer bridge adsorption agents, polymer gels, micro-emulsions, and composite water plugging agents—along with innovative construction techniques that satisfy the results for water shutoff in gas reservoirs. The concept of water shutoff for gas reservoirs is proposed, namely, optimizing water shutoff agents and construction techniques to establish a large-area barrier layer with a high compressive strength and good tolerance of temperature and salinity in gas-water interface to inhibit formation water flow around the barrier layer.

Advanced industrial (e.g., hydraulic fracturing) and environmental demands necessitate the development of natural products with excellent properties. This study developed a new polysaccharide product by hydrophobically modifying welan gum by using 1-bromohexadecane under NaOH catalysis. This is the first study reporting the introduction of a long hydrophobic chain into welan gum to enhance its viscosity in saline solutions. Comparative analyses showed that hydrophobically modified welan gum (HWG) displayed higher solution viscosity (225.58 mPa.s) than welan gum (110.34 mPa.s) with 85,000 mg.L-1 mixed salts. Moreover, the viscosity of HWG solution (20.58 mPa.s) remained higher than that of welan gum (16.39 mPa.s) at 120 degrees C and 170 s(-1) shear stress, with 85,000 mg.L-1 mixed salts. The scanning electron microscopy images suggested network structure formation by inferring the altered surface morphology of HWG after the modification of the original welan gum structure. The Fourier transform infrared spectroscopy analysis demonstrated that the bands of the C-H and C-O-C associated with the 1-bromohexadecane increased in HWG. The changed molecular structure was confirmed using the altered diffraction bands of X-ray diffraction spectra and the decreased decomposition rate (1.08 times lower) of HWG compared with those of welan gum obtained from thermogravimetric analysis and differential thermogravimetry analysis. The pyrene-based fluorescence analysis revealed the presence of the hydrophobic microdomains of HWG. Our study suggested HWG to be a promising candidate for fabricating highly viscous and saline fluids for hydraulic fracturing fluids and other potential applications and highlighted the vital role of macromolecular structures in determining the functional properties.

CO2驱最小混相压力(MMP)是衡量能否达到混相驱的重要参数,因此,为提高混相驱的应用率,迫切需要降低CO2与原油间的最小混相压力,而油藏中加入助混剂是降低最小混相压力的有效手段.目前助混剂按照所含元素可分为碳氟、硅氧烷、碳氢(含氧)三大类.为了降低成本,提高助混效果,应在碳氟类助混剂加入碳氢类结构,向混合型的方向发展,而碳氢类助混剂具有良好的助混效果,并且有提升的空间,关键是找到合适的亲CO2结构,计算机模拟是研究微观机理,辅助结构设计的重要手段.相比于碳氟类和硅氧烷类,碳氢类助混剂的成本较低,从成本的角度看最有应用潜力.目前影响助混剂规模化应用的主要因素是成本上的限制,未来推广应用需要石油与化工从业者的密切配合,重点介绍助混剂降低MMP的机理,总结了目前已有助混剂的结构以及助混效果,分析了助混效果的影响因素,展望了助混剂设计的发展方向.

以油菜秸秆为原料,通过厌氧热裂解和磁性明胶改性制得磁性明胶改性生物炭GXBC,并用于双氯芬酸钠(DFC)的去除.结果表明,改性后的材料对DFC拥有优异的吸附能力,在pH=5,初始浓度15 mg/L,t=240 min达到吸附平衡,吸附量为266 mg/g.动力学和热力学拟合结果表明,GXBC对DFC的吸附是符合准二级动力学模型和Langmuir模型的自发放热化学吸附过程.

To address the poor injectivity of conventional chemicals, and the drawbacks of existing nanoparticles (NPs) in in-depth conformance control in low-permeability reservoirs, a hydrophilic cross-linked polystyrene NPs named as CPSAs was fabricated via emulsion polymerization in this study. The reaction conditions were determined through orthogonal experiments, and the influence of each condition on the particle size of CPSAs was investigated with single factor experiments. The results showed that CPSAs with the mean diameter ranging from 73 to 95 nm could be readily produced by moderately changing the polymerization conditions, and the yield could be larger than 80%. The property evaluation results indicated that CPSAs can disperse well under reservoir conditions and was able to properly propagate to deep formation and block breakthrough regions, revealing the good injectivity and in-depth conformance control capability in low-permeability reservoirs.