Petroleum Science最新文献

{"title":"Microscopic oil occurrence in the Permian alkaline lacustrine shales: Fengcheng formation, Mahu Sag, Junggar basin","authors":"Jia-Hao Lv ,&nbsp;Tao Hu ,&nbsp;Wang Zhang ,&nbsp;Fu-Jie Jiang ,&nbsp;Jing Xue ,&nbsp;Chen-Xi Zhang ,&nbsp;Zhen-Guo Qi ,&nbsp;Ren-Da Huang ,&nbsp;Mei-Ling Hu ,&nbsp;Shu Jiang","doi":"10.1016/j.petsci.2025.01.005","DOIUrl":"10.1016/j.petsci.2025.01.005","url":null,"abstract":"<div><div>Alkaline lacustrine shale is highly heterogeneous, and the complex relationship between the organic-inorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development. Herein, we investigated the Fengcheng Formation (P₁f) in Mahu Sag. This study integrated geochemistry, Soxhlet extraction, scanning electron microscopy, gas adsorption, and nuclear magnetic resonance T₁-T₂ spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales. Results indicate the presence of felsic shale, dolomitic shale, lime shale, and mixed shale within the P₁f. Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P₁f. Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals, while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes. Variations exist in the quantity and distribution of shale oil accumulation across different scales, where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm, respectively. Shale oil occurrence characteristics are influenced by organic matter, pore structure, and mineral composition. Felsic shale exhibits a high abundance of dominant pores, possesses the highest oil content, predominantly harbors free oil within these dominant pores, and demonstrates good mobility. Fluid occurrence in dolomitic shale and lime shale is intricate, with low oil content and a free oil to adsorbed oil ratio of 1:1. Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores. Moreover, ineffective pores contain increased bound water, resulting in medium oil content and limited mobility predominantly due to adsorption. Presently, shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state. During the exploration and development of alkaline lacustrine shale oil resources, emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1407-1427"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143917209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ball-sealer transport characteristics and plugging performance in vertical wells","authors":"Ying Liu ,&nbsp;Hai Qu ,&nbsp;Mao Sheng ,&nbsp;Hai-Zhu Wang ,&nbsp;Ting-Xue Jiang ,&nbsp;Shi Wang","doi":"10.1016/j.petsci.2025.01.002","DOIUrl":"10.1016/j.petsci.2025.01.002","url":null,"abstract":"<div><div>Ball-sealer plugging is a cost-effective method for hydraulic fracturing in vertical wells, yet the transport and plugging behavior of ball sealers remains poorly understood. This paper investigates ball-sealer plugging using both experimental and numerical approaches. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) model simulates ball transport under field conditions, validated by experiments in inclined pipes. Results show that plugging performance improves with a higher flow rate ratio of the perforation, allowing effective plugging even when the ball is far from the target perforation. There exists a threshold distance between the ball and the perforation under specific conditions. The closer the ball is to the wellbore wall, the higher the likelihood of successful plugging. Low-density balls can enhance plugging performance to some extent. At high flow rates, ball inertia along the wellbore axis increases, reducing the ball's ability to redirect and weakening plugging performance. Ball interactions also affect their positioning and plugging success. In vertical wells with multiple clusters, prioritizing higher flow rates to the first fracturing cluster optimizes overall plugging performance and minimizes excessive plugging in lower, under-stimulated clusters. These findings offer valuable insights for optimizing ball-sealer deployment in well completions, improving operational outcomes.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1686-1698"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enlightenment of geochemistry for ultra-deep petroleum accumulation: Coupling of secondary processes and filling events","authors":"Rong-Zhen Qiao ,&nbsp;Mei-Jun Li ,&nbsp;Dong-Lin Zhang ,&nbsp;Hong Xiao","doi":"10.1016/j.petsci.2025.02.019","DOIUrl":"10.1016/j.petsci.2025.02.019","url":null,"abstract":"<div><div>Light oil and gas reservoirs are abundant in the Ordovician marine carbonate reservoir in Shunbei Oilfield, Tarim Basin. This presents a compelling geological puzzle, as ultra-deep reservoirs undergo intense alteration and complex petroleum accumulation processes. A comprehensive suite of geochemical analyses, including molecular components, carbon isotope composition, homogenization temperature of saline inclusions, and burial-thermal history of single wells, was conducted to elucidate the genesis of these ancient reservoirs. Three petroleum filling events have been identified in the study area: Late Caledonian, Hercynian-Indosinian, and Himalayan, through analysis of homogenization temperatures of brine inclusions and burial-thermal histories. Additionally, the oil in the study area has undergone significant alteration processes such as biodegradation, thermal alteration, mixing, evaporative fractionation, and gas invasion. This study particularly emphasizes the influential role of Himalayan gas filling-induced evaporation fractionation and gas invasion in shaping the present petroleum phase distribution. Furthermore, analysis of light hydrocarbon and diamondoid parameters indicates the oil within the study area is at a high maturity stage, with equivalent vitrinite reflectance values ranging from 1.48% to 1.99%. Additionally, the analysis of light hydrocarbons, aromatics, and thiadiamondoids indicates that TSR should occur in reservoirs near the gypsum-salt layers in the Cambrian. The existence of the Cambrian petroleum system in the study area is strongly confirmed when considering the analysis results of natural gas type (oil cracking gas), evaporative fractionation, and gas invasion. Permian local thermal anomalies notably emerge as a significant factor contributing to the destruction of biomarkers in oil. For oil not subject to transient, abnormal thermal events, biomarker reliability extends to at least 190 °C. In conclusion, examining the special formation mechanisms and conditions of various secondary processes can offer valuable insights for reconstructing the history of petroleum accumulation in ultra-deep reservoirs. This research provides a scientific foundation for advancing our knowledge of petroleum systems and underscores the importance of hydrocarbon geochemistry in unraveling ultra-deep, complex geological phenomena.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1465-1484"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multidisciplinary insights into the origin of natural gas from hydrocarbon generation and charging history of Permian dolomite reservoir in Sichuan Basin","authors":"Yan-Xian Zhu ,&nbsp;Zhi-Liang He ,&nbsp;Xiao-Wen Guo ,&nbsp;Long Li ,&nbsp;Kamaldeen O.L. Omosanya ,&nbsp;Jian Gao ,&nbsp;Ze Tao ,&nbsp;Xue-Song Lu","doi":"10.1016/j.petsci.2025.02.004","DOIUrl":"10.1016/j.petsci.2025.02.004","url":null,"abstract":"<div><div>Understanding the origin of natural gas in deep and ultra-deep reservoirs with multiple potential source rocks remains challenging due to the complex thermal evolution of hydrocarbons at high temperatures and multi-stage accumulation processes. This study investigates the origin of natural gas in deep hydrothermal dolomite reservoirs of the Maokou Formation, eastern Sichuan Basin, using hydrocarbon inclusion analysis, radiometric U-Pb dating of calcite cements, maturity modeling of potential source rocks, and constraints on reactivation periods of the nearby No. 15 Fault System. Results indicate an oil charging event at approximately 246.9 Ma, followed by two episodes of gas charging at 222.4 Ma and 175.2 Ma. Furthermore, the oil and gas charging events occurred synchronously with activities of the No. 15 Fault System, suggesting that its reactivation induced episodic hydrocarbon migration. Maturity modeling indicates that during the oil charging period, source rocks in the Qiongzhusi, Wufeng-Longmaxi, and first member of the Maokou formations reached the stages of dry gas generation, significant oil generation, and the threshold of oil generation, respectively. During the subsequent two-episode gas charging periods, the Qiongzhusi and Wufeng-Longmaxi formations progressed to dry and wet gas generation stages, respectively, while the first member of the Maokou Formation attained the oil generation stage. The hydrocarbon charging time and maturity history of potential source rocks indicate that: 1) oil in hydrothermal dolomite reservoirs predominantly originated from the Wufeng-Longmaxi Formation at approximately 246.9 Ma; 2) during the subsequent gas charging episodes, the Wufeng-Longmaxi Formation could contribute wet gas, while the Qiongzhusi Formation likely supplied cracking gas from kerogen and residual liquid hydrocarbon; 3) all oil in the hydrothermal dolomite reservoirs underwent thermal cracking to gas at approximately 110 Ma. This study indicates that gas pools in (ultra-)deep carbonate reservoirs of the Sichuan Basin have mixed genetic origins, with contributions from multiple sources. The multidisciplinary approach, combining direct dating of hydrocarbon charge events and simulation of hydrocarbon generation, proves robust and effective in identifying the origin of natural gas in (ultra-)deep reservoirs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1428-1445"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative insight into fracture distribution during supercritical CO2 fracturing in tight sandstone formation","authors":"Bing Yang ,&nbsp;Hai Huang ,&nbsp;Qian-Qian Ren ,&nbsp;Hai-Zhu Wang ,&nbsp;Bin Wang ,&nbsp;Jun Ni ,&nbsp;Yong Zheng ,&nbsp;Wen-Tong Zhang","doi":"10.1016/j.petsci.2025.02.006","DOIUrl":"10.1016/j.petsci.2025.02.006","url":null,"abstract":"<div><div>Supercritical CO₂ (SC-CO₂) fracturing stands out a promising waterless stimulation technique in the development of unconventional resources. While numerous studies have delved into the induced-fracture mechanism of SC-CO₂, the small scale of rock samples and synthetic materials used in many studies have limited a comprehensive understanding of fracture propagation in unconventional formations. In this study, cubic tight sandstone samples with dimensions of 300 mm were employed to conduct SC-CO₂ fracturing experiments under true-triaxial stress conditions. The spatial morphology and quantitative attributes of fracture induced by water and SC-CO₂ fracturing were compared, while the impact of in-situ stress on fracture propagation was also investigated. The results indicate that the SC-CO₂ fracturing takes approximately ten times longer than water fracturing. Furthermore, under identical stress condition, the breakdown pressure (BP) for SC-CO₂ fracturing is nearly 25% lower than that for water fracturing. A quantitative analysis of fracture morphology reveals that water fracturing typically produces relatively simple fracture pattern, with the primary fracture distribution predominantly controlled by bedding planes. In contrast, SC-CO₂ fracturing results in a more complex fracture morphology. As the differential of horizontal principal stress increases, the BP for SC-CO₂ fractured rock exhibits a downward trend, and the induced fracture morphology becomes more simplified. Moreover, the presence of abnormal in-situ stress leads to a further increase in the BP for SC-CO₂ fracturing, simultaneously enhancing the development of a more conductive fracture network. These findings provide critical insights into the efficiency and behavior of SC-CO₂ fracturing in comparison to traditional water-based fracturing, offering valuable implication for its potential applications in unconventional reservoirs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1670-1685"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of casing failure risk locations under multi-stage hydraulic fracturing inter-well interference in “well factory” mode","authors":"Yu-Heng Tuo,&nbsp;Tie-Jun Lin,&nbsp;Hao Yu,&nbsp;Zhang-Hua Lian,&nbsp;Fang-Xin Chen","doi":"10.1016/j.petsci.2025.02.016","DOIUrl":"10.1016/j.petsci.2025.02.016","url":null,"abstract":"<div><div>The “well factory” mode's high-density well placement and multi-stage hydraulic fracturing technology enable efficient development of unconventional oil and gas resources. However, the deployment of platform wells in the “well factory” model results in small wellbore spacing, and the stress disturbances caused by fracturing operations may affect neighboring wells, leading to inter-well interference phenomena that cause casing deformation. This study investigates the issue of inter-well interference causing casing deformation or even failure during multi-stage hydraulic fracturing in the “well factory” model, and predicts high-risk locations for casing failure. A flow-mechanics coupled geomechanical finite element model with retaining geological stratification characteristics was established. Based on the theory of hydraulic fracturing-induced rock fragmentation and fluid action leading to the degradation of rock mechanical properties, the model simulated the four-dimensional evolution of multi-well fracturing areas over time and space, calculating the disturbance in the regional stress field caused by fracturing operations. Subsequently, the stress distribution of multiple well casings at different time points was calculated to predict high-risk locations for casing failure. The research results show that the redistribution of the stress field in the fracturing area increases the stress on the casing. The overlapping fracturing zones between wells cause significant stress interference, greatly increasing the risk of deformation and failure. By analyzing the Mises stress distribution of multi-well casings, high-risk locations for casing failure can be identified. The conclusion is that the key to preventing casing failure in platform wells in the “well factory” model is to optimize the spatial distribution of fracturing zones between wells and reasonably arrange well spacing. The study provides new insights and methods for predicting casing failure in unconventional oil and gas reservoirs and offers references for optimizing drilling and fracturing designs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1611-1624"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exact P-wave reflection and transmission coefficients for horizontal transversely isotropic media at an imperfectly welded contact interface under in-situ horizontal stress","authors":"Xin-Peng Pan ,&nbsp;Cheng-Xu Lu ,&nbsp;Hao-Wen Xu ,&nbsp;Da-Zhou Zhang","doi":"10.1016/j.petsci.2025.02.005","DOIUrl":"10.1016/j.petsci.2025.02.005","url":null,"abstract":"<div><div>A comprehensive understanding of exact seismic P-wave reflection and transmission (<em>R</em>/<em>T</em>) coefficients at imperfectly welded or non-welded contact interfaces holds paramount importance in the realm of seismic exploration. Nonetheless, scant attention has been devoted in previous literature to the investigation of stress-dependent exact <em>R</em>/<em>T</em> coefficients in horizontal transversely isotropic (HTI) media, characterized by a horizontal symmetry axis, at such interfaces. Addressing this scholarly gap, we present exact <em>R</em>/<em>T</em> coefficient formulations specifically tailored to an imperfectly welded contact interface separating two HTI media under the influence of in-situ horizontal stress. We begin by deriving the equation of motion for a stressed HTI medium, utilizing the theoretical framework of acoustoelasticity to examine the impact of in-situ horizontal stress on the overarching elastic properties of HTI media. Precise boundary conditions are then established at the imperfectly welded contact interface by applying generalized stress-strain relationships and linear-slip theory, with the influence of in-situ horizontal stress on the interface further explored through the linear-slip model. By integrating these elements with the seismic wave displacement equation, we derive exact <em>R</em>/<em>T</em> coefficient formulations applicable to an imperfectly welded contact interface between two HTI media. Numerical analyses are conducted to elucidate the effects of in-situ horizontal stress on critical parameters such as rock density, seismic wave velocity, Thomsen-type anisotropy parameters, <em>R</em>/<em>T</em> coefficients, and seismic reflection responses at the imperfectly welded contact interface. Furthermore, the proposed formulations are frequency-dependent, with the imperfectly welded contact interface acting as a frequency-selective filter for both reflected and transmitted waves. Notably, under conditions of sufficiently large incident angles, the sensitivity of <em>R</em>/<em>T</em> coefficients to key influencing factors increases significantly. The derived <em>R</em>/<em>T</em> coefficient formulations and the accompanying numerical results offer valuable insights for fracture characterization, stress-dependent parameter inversion, and in-situ stress detection.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1497-1512"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics, controlling factors and mechanisms of natural fractures formation in lacustrine shale oil reservoirs: The Chang 7 member in Ordos Basin, China","authors":"Xiao-Yu Du ,&nbsp;Zhi-Jun Jin ,&nbsp;Lian-Bo Zeng ,&nbsp;Guo-Ping Liu ,&nbsp;Shi-Xiang Li ,&nbsp;Mehdi Ostadhassan ,&nbsp;Xin-Ping Liang ,&nbsp;Guan-Ping Wang ,&nbsp;Guo-Qing Lu","doi":"10.1016/j.petsci.2025.03.005","DOIUrl":"10.1016/j.petsci.2025.03.005","url":null,"abstract":"<div><div>Lacustrine shale oil reservoirs of the Upper Triassic Chang 7 Member in the Ordos Basin have demonstrated significant potential for hydrocarbon resources. Natural fractures play a crucial role in hydrocarbon enrichment and production. Outcrops, cores, borehole image logs, thin sections, and FE-SEM images were used to investigate the types and characteristics of natural fractures in the Chang 7 Member. The factors controlling fracture development and the mechanisms of bedding-parallel fracture formation were revealed by integrating TOC analysis, XRD analysis, and rock pyrolysis. Results show that natural fractures in the study area include high-angle tectonic fractures and nearly horizontal bedding-parallel fractures. Brittle minerals and bed thickness control the occurrence and attributes of tectonic fractures. High TOC content and thermal maturity positively affect the development of bedding-parallel fractures, formed through the conversion of organic matter to hydrocarbons or the smectite-to-illite transformation. Additionally, the dominant orientations of tectonic fractures intersect the present-day maximum horizontal principal stress at a small angle, resulting in large apertures and good effectiveness. Bedding-parallel fractures contribute to enhance porosity and provide favorable pathways for lateral hydrocarbon migration. Collectively, this study could provide valuable insights for finding promising exploration areas in lacustrine shale oil reservoirs in the Ordos Basin and worldwide.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1391-1406"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143917207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomass thermal decomposition induced hydrogen sulfide blooming in thermal recovery reservoirs","authors":"Ying-Jia Zhu,&nbsp;Yun-Yang Wan,&nbsp;Yan Tian,&nbsp;Hong-Mei Mu,&nbsp;Tong-Gang Zhang","doi":"10.1016/j.petsci.2025.03.044","DOIUrl":"10.1016/j.petsci.2025.03.044","url":null,"abstract":"<div><div>High concentration of secondary hydrogen sulfide (sH₂S) in thermal recovery reservoirs of Liaohe Oilfield, NE China was concluded to originate from thermochemical sulfate reduction (TSR), and no biotic source of H₂S under abundant biomass has been reported in these presumed steam sterilized reservoirs ever before. In this study, we propose a new mechanism, biomass thermal decomposition for sulfur compounds (BTDS), to interpret the increasing of sH₂S. Sulfur of cells’ dry weight took 0.20%–1.92% of the active strains isolated from the <em>in-situ</em> thermal recovery reservoirs of Liaohe Oilfield. When microbial organic sulfur compounds (MOSC) in biomass were exposed to injected steam, it resulted in the BTDS process. The isolated <em>Bacillus subtilis</em> D3 (G+) and <em>Pseudomonas aeruginosa</em> XJ14 (G−) were chosen to simulate this process. About 36% of sulfur in MOSC emitted as H₂S in steam chamber by BTDS. The <em>δ</em>³⁴S of H₂S from produced gas ranged from 8.7‰ to 17.0‰, close to the <em>δ</em>³⁴S of H₂S 11.2‰ from BTDS simulation experiment. It provides new insight into the contribution and sulfur cycle made by subterranean microorganisms on H₂S formation.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1802-1810"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in shale microstructure and fluid flow under high temperature: Experimental analysis and fluid–structure interaction simulation","authors":"Xiang-Ru Chen ,&nbsp;Xin Tang ,&nbsp;Rui-Gang Zhang ,&nbsp;Heng Yang ,&nbsp;Qiu-Qi Chen ,&nbsp;Zhang-Ping Yan ,&nbsp;Lei Zhang","doi":"10.1016/j.petsci.2025.02.025","DOIUrl":"10.1016/j.petsci.2025.02.025","url":null,"abstract":"<div><div>Oil shale is characterized by a dense structure, low proportion of pores and fissures, and low permeability. Pore-fracture systems serve as crucial channels for shale oil migration, directly influencing the production efficiency of shale oil resources. Effectively stimulating oil shale reservoirs remains a challenging and active research topic. This investigation employed shale specimens obtained from the Longmaxi Formation. Scanning electron microscopy, fluid injection experiments, and fluid–structure interaction simulations were used to comprehensively analyze structural changes and fluid flow behavior under high temperatures from microscopic to macroscopic scales. Experimental results indicate that the temperature has little effect on the structure and permeability of shale before 300 °C. However, there are two threshold temperatures within the range of 300 to 600 °C that have significant effects on the structure and permeability of oil shale. The first threshold temperature is between 300 and 400 °C, which causes the oil shale porosity, pore-fracture ratio, and permeability begin to increase. This is manifested by the decrease in micropores and mesopores, the increase in macropores, and the formation of a large number of isolated pores and fissures within the shale. The permeability increases but not significantly. The second threshold temperature is between 500 and 600 °C, which increases the permeability of oil shale significantly. During this stage, micropores and mesopores are further reduced, and macropores are significantly enlarged. A large number of connected and penetrated pores and fissures are formed. More numerous and thicker streamlines appear inside the oil shale. The experimental results demonstrate that high temperatures significantly alter the microstructure and permeability of oil shale. At the same time, the experimental results can provide a reference for the research of in-situ heating techniques in oil shale reservoir transformation.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 4","pages":"Pages 1699-1711"},"PeriodicalIF":6.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}