Journal of Petroleum Geology最新文献

{"title":"The Unexpected Discovery of Paleocene? Coals in Outcrops Thought to Be Cambrian, Al Huqf, Oman","authors":"Mohammed H. Al Kindi,&nbsp;Alan P. Heward,&nbsp;Lorraine B. Eglinton,&nbsp;Steve R. Packer,&nbsp;Darrin T. Stead","doi":"10.1111/jpg.70078","DOIUrl":"https://doi.org/10.1111/jpg.70078","url":null,"abstract":"<p>Two brown organic deposits were encountered whilst investigating kaolinitic claystones thought to occur at the base of a Cambrian formation at outcrop. The age of these organic deposits is probably Paleocene from palynology. Organic petrography shows that they are subbituminous coals with some oil source potential. Vitrinite reflectance measurements of 0.53–0.56%<i>R_o</i> indicate a thermal maturity that is approaching the early oil window and imply burial to about 1600 m and subsequent uplift back to near surface. The kaolinitic claystones are interpreted to have been weathered from the outcrops of the Cambrian Thumaylah Formation and to have accumulated in small terrestrial basins along with organic matter of both allochthonous and autochthonous origin. These kaolinitic claystones and coals may be equivalent to terrestrial deposits which occur at the base of the early to middle Paleocene Shammar Member of the Umm er Radhuma Formation in northwest Oman. They may also be equivalent to kaolinite deposits of Paleocene age which occur on Masirah Island. It seems likely that further evidence of Paleocene organic deposits will be discovered in Oman where there are the conditions for preservation from erosion and oxidation.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1179-1194"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpg.70078","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic Geochemistry of Source Rock and Crude Oil in the Paleozoic and Mesozoic Petroleum Systems in SE Anatolia (Türkiye): Oil–Source Rock Relationships With Biomarker Approaches","authors":"E. Ağırman-Aktürk,&nbsp;R. Kara-Gülbay","doi":"10.1111/jpg.70066","DOIUrl":"https://doi.org/10.1111/jpg.70066","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;This study investigates the source rock and organic geochemical properties of Paleozoic and Mesozoic petroleum systems in southeastern (SE) Anatolia. It focuses on the Bedinan and Dadaş (Paleozoic) and the Derdere, Karababa, Karaboğaz, and Sayındere (Mesozoic) formations. Total organic carbon (TOC)/Rock Eval, gas chromatography (GC), and gas chromatography-mass spectrometry (GC-MS) analyses were performed on crude oil and source rock samples, and the oil–source rock and oil–oil relationships were determined using the &lt;i&gt;n&lt;/i&gt;-alkane, isoprenoid, and biomarker data obtained from these analyses. Measured TOC values for the Bedinan and Dadaş formations are 0.59–2.5 wt.% and 1.47–3.64 wt.%, respectively. Mesozoic formations showed TOC ranges of 0.76–1.48 wt.% (Derdere), 0.42–0.82 (Karababa), 0.90–3.36 wt.% (Karaboğaz), and 1.06–1.74 wt.% (Sayındere). The Paleozoic Bedinan and Dadaş formations constitute active source rocks exhibiting variable quality, ranging from poor to good. These units predominantly generate natural gas, with subordinate oil generation. Their organic matter (OM) is characterized by Type II, II/III, and III kerogen, and their thermal maturity corresponds to conditions within the oil window. The Mesozoic Derdere Formation is fair, while the Karababa, Karaboğaz, and Sayındere formations are good source rocks. Source rocks from the Mesozoic era have the capacity to generate oil due to their Type II kerogen content, and these formations are active source rocks with maturity levels within the oil formation window. The source rocks of the Paleozoic petroleum system (Bedinan and Dadaş formations) differ significantly from the source rocks of the Mesozoic petroleum system (Derdere, Karababa, Karaboğaz, and Sayındere formations) and crude oil samples, exhibiting higher higher pristane (Pr)/phytane (Ph), Ts/(Ts+Tm), diasterane/sterane, C&lt;sub&gt;24&lt;/sub&gt;/C&lt;sub&gt;23&lt;/sub&gt; tricyclic terpane (TT), C&lt;sub&gt;29&lt;/sub&gt; norhopane (NH)/C&lt;sub&gt;30&lt;/sub&gt; hopane (H), secohopane (SH)/C&lt;sub&gt;30&lt;/sub&gt; hopane (H), C&lt;sub&gt;26&lt;/sub&gt;/C&lt;sub&gt;25&lt;/sub&gt;TT ratios, C&lt;sub&gt;29&lt;/sub&gt; sterane (S), C&lt;sub&gt;29&lt;/sub&gt; monoaromatic steroid (MAS), C&lt;sub&gt;30&lt;/sub&gt; diahopane (C&lt;sub&gt;30&lt;/sub&gt;*) contents, and lower C&lt;sub&gt;22&lt;/sub&gt;/C&lt;sub&gt;21&lt;/sub&gt;TT, C&lt;sub&gt;35&lt;/sub&gt;/C&lt;sub&gt;34&lt;/sub&gt; homohopane (HH), and dibenzothiophene/phenanthrene (DBT/P) ratios. Crude oil samples are characterized by biomarker parameters such as low Pr/Ph, absence of C&lt;sub&gt;30*&lt;/sub&gt;, high C&lt;sub&gt;28&lt;/sub&gt;/C&lt;sub&gt;29&lt;/sub&gt; sterane ratios and C&lt;sub&gt;35&lt;/sub&gt;/C&lt;sub&gt;34&lt;/sub&gt;HH, and others, which align closely with Mesozoic formations, especially Karababa, Karaboğaz, and Sayındere. Biomarker distribution suggests that the crude oils originated from a Cretaceous carbonate source rock deposited in an anoxic marine environment with low clay content. Cluster analysis of biomarker data confirms a strong correlation between the Mesozoic formations and the crude oils, particularly with Karababa, Karaboğaz, and Sayındere. Pa","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1054-1087"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the Effective Stress Coefficient for Porosity in Sandstone Reservoirs Considering Clay Filling Patterns","authors":"Yi-Long Li,&nbsp;Zhen-Ya Teng,&nbsp;Zhi-Peng Ou,&nbsp;Xiao-Hua Tan,&nbsp;Xiao-Ling Xu,&nbsp;Zi-Yi Chen,&nbsp;Cai-Shen Li,&nbsp;Xing-Hao Li","doi":"10.1111/jpg.70086","DOIUrl":"https://doi.org/10.1111/jpg.70086","url":null,"abstract":"<div>\u0000 \u0000 <p>Porosity attenuation from effective stress changes during sandstone mining restricts reserve assessment accuracy. The traditional Terzaghi theory assumes that the effective stress coefficient is always 1, ignoring the heterogeneous influence of clay minerals on the pore structure. This article proposes two types of clay filling modes: clay shell-shaped filling model and clay granular filling model. Through theoretical modeling and physical experiment verification, the regulation mechanism of clay content on the effective stress coefficient for porosity is revealed. The research results show that (1) the effective stress coefficient for porosity in the granular model is significantly higher than that in the shell-shaped model, and the difference stems from the mechanical action mode of the clay. (2) The effective stress coefficient for porosity shows a trend of first increasing and then decreasing with the increase of clay content. The peak position is controlled by porosity and is positively correlated with the Poisson ratio of the skeleton and negatively correlated with the Poisson ratio of the clay minerals. (3) Experimental verification shows that the chlorite-dominated samples are more in line with the shell-shaped model (error &lt;0.1%). This article provides theoretical support for the precise assessment of heterogeneous sandstone reservoirs.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1336-1356"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary Environment and Mechanisms of Differential Organic Matter Enrichment of the Lucaogou Formation in the Eastern Junggar Basin","authors":"Hu Dong,&nbsp;Zhenglu Xiao,&nbsp;Yong Li,&nbsp;Chaowei Liu,&nbsp;Luchuan Zhang,&nbsp;Quiyu Wang,&nbsp;Jungang Lu","doi":"10.1111/jpg.70081","DOIUrl":"https://doi.org/10.1111/jpg.70081","url":null,"abstract":"<div>\u0000 \u0000 <p>The Middle Permian Lucaogou Formation in the Junggar Basin hosts a suite of organic-rich fine-grained sedimentary succession of continental lacustrine facies, whose deposition was prominently governed by volcanic-hydrothermal activities. Most prior investigations have predominantly focused on deciphering the dominant controls on organic matter (OM) enrichment in the vertical profile, whereas systematic research on the sedimentary settings and differential OM enrichment mechanisms of the Lucaogou Formation source rocks across distinct sags remains poorly documented. To fill this critical research gap, this study reconstructs the sedimentary paleoenvironments of the Lucaogou Formation source rocks in the Dongdaohaizi Sag, Fukang Sag, and Jimsar Sag of the Junggar Basin and clarifies the driving mechanisms of differential OM enrichment in these sags, using an integrated dataset of organic geochemical, major and trace element analyses. Our results demonstrate that the source rocks in the Jimsar Sag are classified as high-quality intervals with strong hydrocarbon generation potential, whereas those in the Fukang and Dongdaohaizi sags are generally of moderate to poor quality. In terms of paleoenvironmental conditions, all three sags were characterized by an arid to semi-humid paleoclimatic background, formed in a deep lacustrine depositional environment, and maintained high paleoproductivity levels during the Lucaogou Formation depositional period. Specifically, the Jimsar Sag featured higher water salinity and stronger reducing conditions, whereas the Dongdaohaizi Sag recorded higher paleoproductivity than the other two sags, which is attributed to more intense volcanic-hydrothermal alteration. Furthermore, two distinct OM enrichment models, namely, the high productivity-anoxic preservation model and the high productivity-oxidative consumption model, are proposed under the synergistic effect of volcanic-hydrothermal activities and lacustrine water salinization. This model framework reveals the intrinsic mechanism of differential OM enrichment among different sags and provides a novel theoretical basis for high-quality source rock evaluation and hydrocarbon exploration in intracontinental rift lacustrine basins affected by volcanic-hydrothermal activities.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1291-1312"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2D Petroleum System Modeling of the Early Cretaceous Sembar Formation in the Southern Indus Basin, Pakistan: Insights for Petroleum Generation, Migration, and Accumulation Histories","authors":"Waqas Naseem,&nbsp;Irfan U. Jan,&nbsp;Mohammed Hail Hakimi,&nbsp;Yousif T. Hadad,&nbsp;Ali Y. Kahal,&nbsp;Khairul Azlan Mustapha,&nbsp;Zubair Zubair,&nbsp;Igor Ognev,&nbsp;S. M. Talha Qadri","doi":"10.1111/jpg.70088","DOIUrl":"https://doi.org/10.1111/jpg.70088","url":null,"abstract":"<div>\u0000 \u0000 <p>In Pakistan's southern Indus Basin, the Early Cretaceous Sembar Shale Formation is a principal source rock, but the petroleum system with its essential elements and processes has not been defined yet. This study presents the first 2D petroleum system modeling of the Sembar source rock system, and its essential elements were studied, in order to determine the timing of hydrocarbon generation, migration, and accumulation using Schlumberger PetroMod software. The 2D model integrates bulk geochemical data and a depth-converted 2D seismic line across three exploration wells. The organic-rich shale of the Sembar Formation has been identified as the most important petroleum-source rock, with total organic content (TOC) between 0.76 and 3.07 wt.% and hydrogen index (HI) values in the range of 47–463 mg HC/g TOC. The Sembar shale source rock reached the main oil window (0.7–1.1%VRo) during the Late Cretaceous to early Paleocene (90–60 Ma), and the wet-gas window thereafter occurred with VRo of up to 1.23%. 2D modeling results also indicate that the transformation ratio (TR) of kerogen reached 80%–100% in the depocenter, and the oil and gas migration and accumulation began at ∼90 Ma, with lateral migration through microfractures into Sembar sandstone and vertical migration along faults upward to the Lower Goru sandstone reservoirs. The Upper Goru limestone and shale units provide effective seal capacity. These findings reduce exploration risk and highlight the remaining potential in deeper stratigraphic levels of the Southern Indus Basin.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1313-1335"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geological Feasibility for CO2 Storage and Utilization Potential of the Risha Gas Field, Jordan","authors":"Mohamed Arafat,&nbsp;Fayez Ahmad,&nbsp;Abdelrahman Qteishat,&nbsp;Shu Jiang,&nbsp;Khaled Al-Kahtany,&nbsp;Sherif Farouk","doi":"10.1111/jpg.70076","DOIUrl":"https://doi.org/10.1111/jpg.70076","url":null,"abstract":"<div>\u0000 \u0000 <p>This study evaluates the feasibility of repurposing the depleted Risha Gas Field in northeastern Jordan for carbon storage through integrated analysis of seismic, petrophysical, geochemical, geomechanical, pressure–volume–temperature (PVT), and production data spanning three decades. The Risha sandstone reservoir (depth 2610–2695 m) exhibits porosity of 6%–15% and permeability below 1 mD, with localized fractures enhancing injectivity. The gas composition (CH₄ = 90.6%, CO₂ = 7.5%) indicates a thermogenic, dry system that is favorable for CO₂ reinjection. The CO₂ storage capacity of the Risha Gas Field was evaluated using two complementary approaches: material-balance analysis based on PVT data and reservoir pressure depletion, and a static volumetric assessment derived from seismic interpretation and petrophysical characterization. Both methods yielded an original gas in place (OGIP) of approximately 149 Bcf. On the basis of pressure depletion and volumetric replacement calculations, the material-balance-based CO₂ storage capacity is estimated at 186.5 Bcf (approximately 10.4 Mt [million tonnes]) of CO₂. The overlying Silurian Mudawwara Shale (&gt;100 m thick) acts as an effective regional caprock, providing robust vertical containment. At the same time, the present-day stress regime characterized by a maximum horizontal stress (Shmax) oriented ENE–WSW (060°–070°) and a minimum horizontal stress (Shmin) trending WNW–ESE (330°–340°) indicates a strike-slip to transitional tectonic setting favorable for mechanically stable injection operations.Therefore, the Ordovician Risha Formation sandstone reservoir is an excellent candidate for CO₂ storage. Preliminary CO₂-enhanced gas recovery (CO₂-EGR) estimates suggest the recovery of 5%–10% of residual gas (5–7 Bcf of methane) while securely storing up to 10 Mt of CO₂. These results confirm that the Risha Gas Field is a technically feasible and strategic site for coupling carbon sequestration with EGR, contributing to Jordan's decarbonization strategy and serving as a regional CCUS model for Paleozoic basins.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1195-1218"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical Composition–Driven Modeling of Rheological Properties in Sustainable Oil Well Cement Using Individual Oxides and Indices With Micro- and Nano-Silica Additives","authors":"Mohammed Ariwan Jamal,&nbsp;Ahmed Salih Mohammed,&nbsp;Jagar A. Ali","doi":"10.1111/jpg.70077","DOIUrl":"https://doi.org/10.1111/jpg.70077","url":null,"abstract":"<div>\u0000 \u0000 <p>Yield stress and plastic viscosity (PV) are key rheological parameters controlling the flow behavior, placement efficiency, and zonal isolation of oil well cement slurries. Maintaining these properties within API standards is essential for well integrity. This study investigates the effect of the chemical composition of cement, particularly silicon dioxide (SiO₂), on yield stress across three systems: base cement, nano-silica (NS)-modified cement, and silica fume (SF)-modified cement. In modified systems, total SiO₂ includes contributions from both cement and additives. A dataset of 224 entries was analyzed alongside 358 entries from the literature to examine the relationship between yield stress and PV. Four quartic regression models were developed using different chemical descriptors: individual oxides (IOs), alumina-ferric ratio (AFR), silicate–metallic ratio (SMR), and lime modulus (LM). Results show that in base cement, the IO model achieved the highest accuracy (<i>R</i>² = 0.98, RMSE = 2.49), whereas the LM model performed worst (<i>R</i>² = 0.80, RMSE = 8.88). For NS cement, IO, and AFR models showed strong performance (<i>R</i>² = 0.96), whereas all models performed similarly well for SF systems (<i>R</i>² ≈ 0.97). Overall, models based on IOs outperformed combined indices. These findings highlight the critical role of oxide composition, particularly SiO₂, in controlling cement rheology and support incorporating detailed chemical parameters into predictive models of oil well cement performance.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1219-1240"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GC × GC–ToF–MS Insights Into the Molecular Signatures of Early Permian Coals and Their Implications for Organic Matter Source, Deposition Conditions, and Maturity","authors":"Santanu Ghosh,&nbsp;Tanu Priya,&nbsp;Tushar Adsul,&nbsp;Akhandal Sahoo,&nbsp;Suryendu Dutta","doi":"10.1111/jpg.70068","DOIUrl":"https://doi.org/10.1111/jpg.70068","url":null,"abstract":"<div>\u0000 \u0000 <p>The present investigation reports the detailed saturated and aromatic biomarker distributions in seven Early Permian coal samples using the conventional gas chromatography–mass spectrometry (GC–MS) and comprehensive GC × GC–time-of-flight (ToF)–MS techniques to reveal new insights into organic matter (OM) source, deposition conditions, and thermal maturity. The coal samples from the Karharbari and Barakar Formations of the Ib-Valley Basin, Odisha, India, reveal a predominance of intermediate chain-length <i>n</i>-alkanes (51.83%–63.61%) and low odd-over-even carbon preference (OEP = 0.31–1.91), likely suggesting OM derivation from aquatic plants and/or terrestrial shrubs/herbs. The identification of saturated bicyclic (C₁₆–C₁₈), tricyclic (abietane, norabietane, 4β(H)-19-norisopimarane), and tetracyclic diterpanes (16β(H)-phyllocladane, 16β(H)-<i>ent</i>-kaurane, 16α(H)-<i>ent</i>-kaurane, norkaurane), along with isohexyl alkylnaphthalenes, retene, tetrahydroretene, and bisnorsimonellite in the aromatic fraction, suggests a significant contribution from <i>Glossopteris</i> flora and/or primitive conifers. High abundances of C₂₉ regular steranes and diasteranes further support the contribution from terrestrial swamp vegetation. Redox-sensitive parameters, including pristane/phytane ratios, Pr/<i>n</i>-C₁₇ versus Ph/<i>n</i>-C₁₈, alkylated dibenzothiophenes, dibenzofurans, and methyltrimethyltridecylchromans (MTTCs), with MTTC index values of 0.32–0.58 and α-/γ-MTTC ratios of 0.61–2.10, reflect peat accumulation under fluctuating oxic–anoxic conditions within a marginal marine environment. Thermal maturity assessments based on biomarker parameters, such as C₃₁ 17β(H),21β(H)-homohopane, C₂₉ diasterane/sterane ratios, methylphenanthrene indices, and methyldibenzothiophene isomer ratios, suggest that the coals have attained peak catagenetic maturity, with estimated equivalent vitrinite reflectance values ranging from 0.57% to 0.68%. These molecular-level insights provide a comprehensive understanding of the origin, depositional environment, and maturation history of Early Permian coals from the Ib-Valley Basin.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1088-1107"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geological Characteristics and Resource Potential of the Leping Formation Shale Gas in the Qingjiang Basin, Southern Poyang Depression, China","authors":"Songyang Wan,&nbsp;Weiwei Liu,&nbsp;Liang Liao,&nbsp;Yuping Ouyang,&nbsp;Yonghui Yan,&nbsp;Hu Li,&nbsp;Kun Zhang","doi":"10.1111/jpg.70069","DOIUrl":"https://doi.org/10.1111/jpg.70069","url":null,"abstract":"<div>\u0000 \u0000 <p>Despite limited geological data availability in the Qingjiang Basin (southern Poyang depression), evaluating the shale reservoir of the Permian Leping formation (LP FM) in the Fengcheng–Gao'an area is of great significance for identifying new shale gas exploration targets. To investigate its shale gas potential, this study builds upon previous research and conducts organic matter content, kerogen type, and maturity analyses, whole-rock x-ray diffraction (XRD) experiments, and low-temperature gas adsorption experiments. The results show that the LP FM in the study area consists mainly of gray to gray-black mudstone, shale, and siltstone, interbedded with coal seams. Vertically, the sedimentary environment experienced multiple cycles from deep to shallow, shallow to deep, and then deep to shallow. The mudstone and shale thickness in coastal-shallow marine facies ranges from 40 to 85 m. Total organic carbon (TOC) content ranges from 0.37% to 13.52%, with an average of 2.12%. Kerogen is predominantly type II₂ and type III. Organic matter maturity (Ro) ranges from 1.2% to 1.8%, averaging 1.54%, indicating a high-mature stage. The average brittle mineral content is 48%. Porosity is mainly concentrated around 7%, with an average permeability of 9 mD, indicating good porosity and permeability. The maximum desorbed gas content reaches 2.10 m³/t. Gas composition is dominated by methane and nitrogen, with a high dryness coefficient. Compared with the Wufeng–Longmaxi Formation shale, the study area's dark mudstone/shale has greater thickness and good porosity/permeability. However, organic matter is dominated by Type II₂–III kerogen with poorly developed organic pores, and faulting/uplift may have caused gas escape. Thus, deeply buried synclines with weak faulting are preferred targets. The Qujiang syncline (242 km² of high-quality shale) holds an estimated 1043.44 × 10⁸ m³ of shale gas.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1017-1033"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation of Elastoplastic Wellbore Surrounding Stress Field Model Coupling Thermal-Hydro-Mechanical-Adsorption (THMA) in Coalbed Methane Wells","authors":"Ziheng Ye,&nbsp;Weian Huang,&nbsp;Zizhen Wang,&nbsp;Yong Ouyang,&nbsp;Mingyang Liu,&nbsp;Wuzhen Gong","doi":"10.1111/jpg.70041","DOIUrl":"https://doi.org/10.1111/jpg.70041","url":null,"abstract":"<div>\u0000 \u0000 <p>Existing studies on coalbed methane wellbore stability have inadequately addressed the systematic consideration of coal's elastoplastic constitutive behavior and matrix shrinkage/swelling stresses induced by gas adsorption–desorption. It perturbs the initial wellbore stress equilibrium and incurs risks of borehole collapse and formation instability. This study, based on the stress equilibrium equation of elastoplastic mechanics and combined with seepage mechanics, Langmuir theory, and thermodynamic equations, thoroughly considers the heterogeneity of circumferential stress around coal–rock gas wellbores, and finally establishes a thermal-hydraulic-mechanical-adsorption coupling elastoplastic circumferential stress field model for coalbed methane wells. As verified, the model satisfies the Krisch formula. This study analyzed the influence of coal–rock adsorption and various stress fields on wellbore stability. Results show that: (1) after considering adsorption stress, in the plastic zone, the radial stress increases; the circumferential stress decreases when <i>r</i> &gt; 0.10537 m. In the elastic zone, the radial stress increases while the circumferential stress decreases. (2) Furthermore, after introducing thermal stress, compared with the original model, in the plastic zone, the radial stress increases significantly; the circumferential stress decreases when <i>r</i> &gt; 0.13407 m. In the elastic zone, the radial stress increases and the circumferential stress decreases. (3) Specifically, the influence of the adsorption parameter <i>ε_L</i> is analyzed. In the plastic zone, as <i>ε</i>_L increases, the radial stress increases accordingly; the circumferential stress decreases when <i>r</i> &gt; 0.10538 m. In the elastic zone, the radial stress increases and the circumferential stress decreases. Moreover, considering different parameters has an impact on the plastic radius, wellbore circumferential stress. This study reveals the law of variation in the stress distribution state around the wellbore under multi-field coupling effects, providing a solid theoretical foundation for the accurate determination of the safe density window of drilling fluid and the maintenance of wellbore stability in coal–rock gas well drilling engineering.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 3","pages":"578-595"},"PeriodicalIF":1.7,"publicationDate":"2026-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148215109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}