Journal of Natural Gas Geoscience最新文献

{"title":"Geochemical characteristics and source of Cambrian natural gas in the Longdong area, Ordos Basin, China","authors":"Junping Huang ,&nbsp;Jianwu Zhang ,&nbsp;Yan Zhang ,&nbsp;Junfeng Lin ,&nbsp;Lingyin Kong ,&nbsp;Jianglong Shi ,&nbsp;Xiangbo Li","doi":"10.1016/j.jnggs.2026.05.001","DOIUrl":"10.1016/j.jnggs.2026.05.001","url":null,"abstract":"<div><div>In recent years, significant progress has been made in Cambrian natural gas exploration in the Longdong area of the Ordos Basin. However, the genetic types and sources of Cambrian gas remain unclear, severely constraining the exploration and development of deep natural gas in the basin. This study presents a detailed analysis of the composition and carbon isotope characteristics of Cambrian natural gas in the Longdong area and compares them with Upper Paleozoic coal-type gas from the Sulige area and Taiyuan Formation bauxite gas in the Longdong area. The genetic types and maturity characteristics of Cambrian natural gas are investigated, and its sources are analyzed in combination with the characteristics of potential source rocks. The results show that the Cambrian natural gas in the Longdong area is predominantly oil-type gas. Only Well L20 exhibits higher carbon isotope values of ethane and propane, indicating distinct coal-type gas characteristics, whereas other Cambrian gas samples show lower ethane and propane isotope values, characteristic of typical oil-type gas. Except for Well L20, methane, ethane and propane carbon isotopes, together with compositional characteristics, further demonstrate that Cambrian natural gas in the Longdong area mainly represents secondary cracking gas of oil and wet gas. All Cambrian natural gas in the Longdong area has reached the over-mature dry gas stage and shows significant carbon isotope reversal features. Based on geochemical characteristics, including genetic types and maturity of natural gas, combined with the distribution of potential source rocks, it is concluded that Cambrian oil-type gas in the Longdong area primarily originates from high-abundance marine source rocks in the Cambrian Dongpo Formation of the Fuping–Luochuan Gulf in the southern part of the basin, whereas the coal-type gas in Well L20 is derived from overlying Permian coal source rocks.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 2","pages":"Pages 103-114"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fine characterization and favorable area prediction of Changxing Formation reef-shoal reservoir in the central Sichuan Basin, China","authors":"Hu Zhao ,&nbsp;Shijie Ou ,&nbsp;Rongrong Zhao ,&nbsp;Jingyun Dai ,&nbsp;Wei Chen ,&nbsp;Hongyi An ,&nbsp;Juzheng Li ,&nbsp;Qianwen Mo","doi":"10.1016/j.jnggs.2026.05.002","DOIUrl":"10.1016/j.jnggs.2026.05.002","url":null,"abstract":"<div><div>The Changxing Formation in the central Sichuan Basin developed on a central isolated gentle-slope platform, where multiple rows of high-energy reef-shoal bodies occur. In some local areas, dolomitized reservoirs are well developed, indicating significant exploration potential. However, strong reservoir heterogeneity and the pronounced characteristic of “one reef, one reservoir” have resulted in challenges such as unclear delineation of internal reservoir boundaries and ambiguous seismic response characteristics. Therefore, further refined delineation of reef-shoal body boundaries are required. Based on geological and logging data, the petrological and seismic response characteristics of reef-shoal reservoirs in the Changxing Formation were first clarified. Combined with the results of forward modeling, a seismic identification model for reef-shoal reservoirs was then established. Subsequently, by integrating paleogeomorphic restoration, seismic attribute analysis, and related techniques, a method for delineating internal boundaries—namely, the Three-Determination Method—was proposed. Finally, through the combined application of seismic inversion, seismic facies analysis, and related techniques, the vertical and lateral distribution characteristics of reef-shoal reservoirs were defined. The results indicate that, vertically, reef-shoal reservoirs in the study area are mainly developed in the Chang 1 Member and the middle-upper part of the Chang 2 Member, with thicknesses ranging from 10 to 60 m. Laterally, they are primarily distributed along the platform margin and at local paleogeomorphic highs within the platform, and the characteristic of “one reef, one reservoir” is evident. Reef-shoal bodies in the platform-margin zone, characterized by clear seismic response patterns and relatively large individual extents, still exhibit considerable exploration potential.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 2","pages":"Pages 79-90"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rethinking the Ordos world-class super energy basin","authors":"Caineng Zou ,&nbsp;Shixiang Li ,&nbsp;Zhi Yang","doi":"10.1016/j.jnggs.2026.04.001","DOIUrl":"10.1016/j.jnggs.2026.04.001","url":null,"abstract":"<div><div>Under the global energy transformation driven by the “dual-carbon” strategy, the Ordos Basin—a national strategic resource enrichment zone—is transitioning toward an integrated carbon-neutral energy system. This shift is critical for ensuring national energy security and promoting green development. Based on the new development phase since the “14th Five-Year Plan”, this paper re-evaluates the basin's resources, theories and technologies, and strategic positioning from the perspectives of “Energy Power”, “Whole-Energy Integrated System” theory, and “Energy Equivalent” concept. It comprehensively analyzes the resource foundation, technological readiness, strategic orientation, and implementation pathways for the basin's transformation from a fossil energy production base into a world-class “carbon-neutral super energy basin.” The study concludes that the Ordos Basin possesses unique advantages, including abundant fossil and renewable energy resources, excellent CO₂ source-sink matching, and well-developed infrastructure. It is recognized as a “triple-super” basin, encompassing a super fossil energy basin, a super new energy basin, and a super CCUS basin. By implementing the “Seven Major Projects”—clean production of billions of tons of coal, green production of hundreds of millions of tons of oil and gas, production of associated resources such as thousands of tons of uranium, installation of hundreds of gigawatts of wind and photovoltaic power, development of hundreds of millions of square meters of clean heating, industrialization of billions of tons of CCUS/CCS, and establishment of a national energy strategic reserve and regulation hub—the basin is expected to become a world-class demonstration project of a carbon-neutral super energy basin. This initiative will integrate secure energy supply, green and low-carbon transition, and coordinated regional development, providing a systematic pathway and a leading example and demonstration for China to accelerate the building of a new-type energy system and even for the green leap forward in the transition of resource-dependent regions worldwide.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 2","pages":"Pages 67-78"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics and openness evaluation of natural fractures in deep marine shale gas reservoirs: A case study of the Longmaxi Formation in Zigong area, Sichuan Basin, China","authors":"Shihao Wen ,&nbsp;Jin Wu ,&nbsp;Fancheng Zeng ,&nbsp;Lei Gong ,&nbsp;Xiaopin Zou ,&nbsp;Yu Liu ,&nbsp;Jie Tian ,&nbsp;Liang Tang ,&nbsp;Zhaolong Liu","doi":"10.1016/j.jnggs.2026.04.002","DOIUrl":"10.1016/j.jnggs.2026.04.002","url":null,"abstract":"<div><div>The Zigong area in the southern Sichuan Basin has been subjected to multi-stage and multi-directional tectonic stresses, resulting in the development of natural fracture systems with multiple scales and types. These fractures have a significant impact on the enrichment, preservation, and development of shale gas. By comprehensively utilizing data from core samples, thin sections, dipole sonic logs, and image logs, the types and development characteristics of natural fractures in the first sub-member of the Long 1 Member (S₁<em>l</em>₁¹) shale reservoir in the Zigong area were quantitatively characterized. Combined with experimental analyses, including fluid inclusion analysis and acoustic emission testing, the fracture formation mechanisms were clarified, and a comprehensive evaluation of fracture openness was conducted. The results indicate that the S₁<em>l</em>₁¹ shale reservoir in the study area has developed structural fractures, diagenetic fractures, and overpressure fractures. Among these, high-angle structural fractures trending in the NNE and NEE directions are dominant, exhibiting a high degree of development and good effectiveness. Across different tectonic units, fracture development patterns show systematic variation. The S₁<em>l</em>₁¹ shale has undergone three stages of fracturing and three stages of cementation. The early two stages of structural fractures experienced multiple episodes of filling and thus exhibit relatively poor effectiveness, whereas the late-stage structural fractures are minimally filled and demonstrate relatively good effectiveness. The Coulomb Failure Function (<em>CFF</em>) values of fractures in the study area are generally less than 0, indicating that, under the in-situ stress conditions, the fractures remain in a stable state. Spatially, the <em>CFF</em> values increase progressively from the northwest to the southeast and then to the north, reflecting a corresponding increase in fracture openness. Two principal stress mechanisms—normal faulting and strike-slip faulting—are predominant in the study area. Under different stress mechanisms, the orientations of preferentially opened fractures vary. Under the normal faulting stress mechanism, NWW–SEE trending fractures, which are parallel to the current maximum principal stress direction, are preferentially opened. Under the strike-slip faulting mechanism, high-angle fractures trending NEE–SWW and NW–SE, oriented at approximately 30° to the current maximum principal stress, are preferentially opened. These findings provide a theoretical basis for optimizing shale gas sweet spot selection, preventing and controlling fracture stringing and casing deformation, and optimizing horizontal well trajectories in the study area.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 2","pages":"Pages 91-102"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent advances in machine learning and deep learning for total organic carbon (TOC) estimation: A comprehensive review","authors":"Alidu Rashid ,&nbsp;Abdul Halim Abdul Latiff ,&nbsp;John Oluwadamilola Olutoki ,&nbsp;B. Venkateshwaran ,&nbsp;Md. Mahmodul Islam ,&nbsp;Manoj Joseph Mathew ,&nbsp;Joshua Nsiah Turkson ,&nbsp;Misbahu Abdullahi ,&nbsp;Oluwaseun Daniel Akinyemi ,&nbsp;Muhammad Rafi ,&nbsp;Ahmad Dedi Putra","doi":"10.1016/j.jnggs.2026.04.003","DOIUrl":"10.1016/j.jnggs.2026.04.003","url":null,"abstract":"<div><div>Accurate estimation of total organic carbon (TOC) is central to source rock evaluation, reservoir characterization, and unconventional resource assessment. While laboratory measurements provide reliable TOC values, their high cost and sparse availability motivate the use of well logs and data-driven predictive models for continuous subsurface characterization. This review presents a comprehensive and critical synthesis of conventional TOC estimation methods and recent advances in artificial intelligence (AI), encompassing machine learning (ML), deep learning (DL), and hybrid optimization frameworks. A wide range of algorithms, including ensemble learners, kernel-based methods, neural networks, graph-based models, and evolutionary optimization techniques, are systematically compared in terms of predictive performance, data requirements, computational characteristics, interpretability, and geological applicability. The review further examines the influence of input log combinations, feature engineering strategies, lithofacies, mineralogy, kerogen type, and thermal maturity on model behavior and transferability. Although ensemble models such as Random Forest and XGBoost often demonstrate strong performance across many case studies, optimized Support Vector Regression and Gaussian Process Regression provide advantages in error minimization and uncertainty quantification, respectively. Deep learning architectures, including Convolutional Neural Networks, Long Short-Term Memory networks, and Graph Neural Networks, enable advanced feature extraction and spatial dependency modeling but remain constrained by data scarcity and interpretability challenges. Beyond performance comparison, the review critically evaluates data quality, validation practices, and generalization risks, highlighting the impact of small sample sizes, inconsistent train–test splitting, potential data leakage, laboratory measurement uncertainty, depth mis-tie between logs and cores, and limited cross-formation benchmarking. The analysis confirms that no single model is universally optimal and that reliable deployment requires geology-aware validation, uncertainty-aware evaluation, and standardized benchmarking. Future directions emphasize hybrid and physics-informed learning, expanded open-access datasets, explainable AI, transferable model architectures, and tighter integration with reservoir modeling and automated interpretation workflows.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 2","pages":"Pages 115-145"},"PeriodicalIF":0.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148103755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of hydrocarbon accumulation in Upper Cambrian carbonate rocks of the Yingdong structural belt, eastern Tarim Basin, China: Insights from fluid inclusion analysis of Well Yingdong-1","authors":"Weihong Liu ,&nbsp;Hao Li ,&nbsp;Yong Peng ,&nbsp;Honggang Cheng ,&nbsp;He Wang","doi":"10.1016/j.jnggs.2026.01.001","DOIUrl":"10.1016/j.jnggs.2026.01.001","url":null,"abstract":"<div><div>The Cambrian strata in the eastern Tarim Basin (Tadong area) possess favorable geological conditions for hydrocarbon accumulation; however, the exploration degree remains low, and no major breakthroughs have been achieved for an extended period. The limitation lies in an insufficient hydrocarbon accumulation and evolution processes, which leads to ambiguous exploration directions. To address this issue, this study integrates data from drilling, core samples, and fluid inclusion thin section analyses, combined with burial history reconstruction, hydrocarbon generation evolution, and structural evolution analyses. The characteristics of fluid inclusions in the Paleozoic reservoirs from Well Yingdong-1 in the Yingdong structural belt of the Tadong area were systematically investigated. The homogenization temperature and salinity of the inclusions were determined, and a burial-thermal evolution simulation was conducted. The results indicate that the fluid inclusions can be divided into two distinct periods: Period I inclusions formed in the middle stage of the Late Ordovician, which corresponds to the initial oil generation stage of the source rocks; Period II inclusions formed from the Late Permian to the Early Triassic and represent the destruction and adjustment phase of the oil and gas reservoirs. Combined with the structural evolution history of the Yingdong structural belt, the results suggest that oil reservoirs were primarily formed toward the end of the Ordovician, while the main gas generation phase occurred during the Silurian to Devonian. By the end of the Devonian, the oil reservoirs had largely cracked into gas reservoirs. Subsequently, by the end of the Triassic, the Yingdong-1 oil and gas reservoir experienced significant destruction and adjustment as a result of the Indosinian tectonic movement. Based on these findings, it is recommended that the future exploration targets focus on areas where ancient carbonate rocks have not been breached by faulting or on traps that have undergone structural adjustments and preservation.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 1","pages":"Pages 31-41"},"PeriodicalIF":0.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Construction and geological application of comprehensive evaluation indices for biomarker characteristics: A case study of the Yanchang Formation in the Ordos Basin, China","authors":"Kaiming Su ,&nbsp;Jingyi Li ,&nbsp;You Zhou ,&nbsp;Wanglin Xu ,&nbsp;Yaohui Xu ,&nbsp;Yang Li ,&nbsp;Gang Yan ,&nbsp;Taohua He","doi":"10.1016/j.jnggs.2026.02.001","DOIUrl":"10.1016/j.jnggs.2026.02.001","url":null,"abstract":"<div><div>In response to the issue of numerous, redundant, and complexly interpreted biomarker parameters in molecular geochemistry, this paper proposes a novel comprehensive index evaluation method. Focusing on the Yanchang Formation in the Ordos Basin, factor analysis is employed to screen biomarker parameters that are most closely related to organic matter maturity, parent material type, and water salinity. Based on the selected parameters, three comprehensive indices—the Maturity Index (MI), Parent Material Index (PMI), and Water Salinity Index (WSI)—are constructed through linear combinations. Applications of these indices to different stratigraphic layers and structural blocks of the Yanchang Formation demonstrate their ability to represent the geochemical characteristics of organic matter more concisely and clearly, with higher accuracy and reliability than single biomarker parameters. Research findings based on these indices reveal that the maturity of organic matter in the Yanchang Formation gradually increases with burial depth, that the Chang 7 oil group exhibits a significant contribution from aquatic organic matter, and that deeper oil groups, such as Chang 9 and Chang 10, are associated with relatively higher water salinity. Additionally, the planar distribution patterns of maturity, parent material type, and water salinity across different blocks are complex, reflecting the heterogeneity of geological conditions. Overall, the comprehensive index evaluation method proposed in this paper provides a new analytical framework for molecular geochemistry research and has important implications for oil and gas exploration under complex geological settings.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 1","pages":"Pages 43-56"},"PeriodicalIF":0.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microscopic coupling mechanisms between helium and carrier gas molecules and their influence on accumulation and retention behavior","authors":"Wentao Zhang ,&nbsp;Yifei Liu ,&nbsp;Ping Li ,&nbsp;Chunhui Zhao ,&nbsp;Zhe Ding ,&nbsp;Huifei Tao ,&nbsp;Jianjun Liang ,&nbsp;Zhuanhong Lu ,&nbsp;Dongqi Wang ,&nbsp;Qiaohui Fan","doi":"10.1016/j.jnggs.2026.01.002","DOIUrl":"10.1016/j.jnggs.2026.01.002","url":null,"abstract":"<div><div>Helium (He) is an indispensable strategic resource for global high-technology industries, and its migration and preservation during accumulation are strongly governed by synergistic interactions with fluid carrier gases such as methane (CH₄), carbon dioxide (CO₂), and nitrogen (N₂). To elucidate the microscopic coupling mechanisms between He and carrier gas molecules, as well as their environmental dependence, this study employs quantum chemical calculations combined with molecular configuration screening to systematically evaluate coupling energies and the stability of He-carrier coupled structures under anhydrous and hydrous conditions. The results show that, under anhydrous environments, the coupling affinity between He and carrier molecules follows the order CO₂&gt;CH₄&gt;N₂&gt;He. In contrast, under hydrous conditions, the interactions of He with CO₂ and CH₄ are weakened, whereas the coupling stability with N₂ is significantly enhanced, accompanied by a spatial reorganization of coupling sites. Solvation effects induced by water molecules strengthen He–N₂ interactions, indicating that pore water within mineral matrices facilitates the co-existence of He and N₂. In multi-molecular systems, He–H₂O complexes exhibit the highest stability, followed by He–CO₂, He–CH₄, and He–N₂. Moreover, owing to their relatively large molecular sizes and their propensity to form molecular clusters, carrier gas molecules can physically block caprock pore throats, thereby enhancing sealing efficiency and reducing He leakage. Based on these findings, three key microscopic contributions of carrier gases to He accumulation are identified, namely aggregation in water, cooperative transport through fractures, and effective retention by caprocks. From a molecular-scale perspective, this study reveals the cooperative role of the He-carrier system in helium accumulation and provides a theoretical basis for elucidating accumulation mechanisms and predicting He-rich sweet spots.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 1","pages":"Pages 57-66"},"PeriodicalIF":0.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accumulation characteristics and models of low-rank multi-source coal-rock gas in the Jurassic of Junggar Basin, China","authors":"Honglin Liu ,&nbsp;Huaichang Wang ,&nbsp;Ze Deng ,&nbsp;Daojun Huang","doi":"10.1016/j.jnggs.2025.12.001","DOIUrl":"10.1016/j.jnggs.2025.12.001","url":null,"abstract":"<div><div>The Junggar Basin is a large Jurassic low-rank coal-bearing basin in western China, mainly comprising the Xishanyao Formation and the Badaowan Formation, which are characterized by substantial coal measure thickness and stable spatial distribution. The coal-rock gas resources in the whole basin exceed 3 × 10¹² m³, and with a maximum daily gas production of 57 × 10³ m³. However, the accumulation characteristics and enrichment laws of coal-rock gas remain insufficiently understood. Subsequent to this development, this paper comprehensively analyzes coal quality, reservoir characteristics, and gas-bearing properties of coal seams, and concludes that: (1) The southeastern margin of the Junggar Basin has superior conditions for coal-rock gas accumulation, characterized by wide distribution of Jurassic coal seams with large thickness, good coal quality, moderate to poor reservoir physical and adsorption properties, and rich coal-rock gas resources. (2) Reservoir formation is jointly controlled by multiple factors, including gas source conditions, structural conditions, and preservation conditions. The identified reservoir types include exogenous fault-occlusion type, exogenous anticlinal type, endogenous pore type, formation pinch-out type, and exogenous fracture type. (3) The enrichment of coal-rock gas shows distinct characteristics of plane distribution, being more favorable in the south than in the north and better in the west than in the east. The main controlling factors include coal quality, thermal evolution degree, coal seam roof and floor sealing and hydrogeological conditions. (4) Using the volumetric method, coal-rock gas resources in the weathered zone shallower than 5000 m across the basin were estimated. In the Urumquqi to Fukang area at depths shallower than 2000 m, the estimated resource volume is 1623.82 × 10⁹ m³, while resources at depths between 2000 and 5000 m amount to 1316.36 × 10⁹ m³. Based on an optimal selection index system of advantageous areas, Urumqi–Dahuangshan and Baijiahai are identified as advantageous exploration targets, covering a total area of 2630 km² with a predicted resource volume of 320 × 10⁹ m³, indicating abundant resources and favorable reservoir-forming conditions.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 1","pages":"Pages 15-30"},"PeriodicalIF":0.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrocarbon accumulation differences and exploration directions among sub-sags of the Taibei Sag, Tuha Basin, China","authors":"Jianzhong Li ,&nbsp;Fan Yang ,&nbsp;Dongsheng Xiao ,&nbsp;Xuan Chen ,&nbsp;Chao Wu ,&nbsp;Hua Zhang ,&nbsp;Haiyue Yu ,&nbsp;Xueli Jia ,&nbsp;Gang Chen","doi":"10.1016/j.jnggs.2025.12.002","DOIUrl":"10.1016/j.jnggs.2025.12.002","url":null,"abstract":"<div><div>The Taibei Sag of the Tuha Basin contains three major hydrocarbon-generating sub-sags—Shengbei, Qiudong, and Xiaocaohu—in the Shuixigou Group. Although these sub-sags share similar tectonic–sequence–sedimentary evolutionary backgrounds, they exhibit distinct petroleum geological characteristics and hydrocarbon accumulation patterns as a result of differential uplift between the southern and northern orogenic belts. Based on a comprehensive analysis of structural evolution, source rocks, sedimentary reservoirs, and accumulation condition differences among the three sub-sags are identified mainly in four aspects. (1) During the Early to Middle Jurassic, the Taibei Sag maintained a relatively unified tectonic–sedimentary framework, internally segmented by local uplifts, with the Xiaocaohu sub-sag in the east serving as the primary depocenter. By the Late Jurassic, eastern uplift shifted the depositional focus to the Shengbei sub-sag. (2) During the main hydrocarbon accumulation stage of the Xiaocaohu sub-sag, source rocks had already reached a highly mature stage. Subsequently, as the Shengbei sub-sag deepened, both sags reached a mature to highly mature stage. Overall, the source rocks of the Shuixigou Group in the Taibei Sag are generally characterized by mature to highly mature hydrocarbon evolutionary stage. (3) The Shengbei sub-sag developed three provenance systems, among which the northwestern long-axis provenance system transported well-sorted sediments over long distances. In contrast, the Qiudong and Xiaocaohu sub-sags are dominated by bidirectional NS braided river delta systems. The southern provenance systems across all three sub-sags contain rigid clasts with strong compressive resistance, which is favorable for high-quality reservoir formation. (4) The Shuixigou Group experienced at least three stages of hydrocarbon accumulation. The Shengbei and Xiaocaohu sub-sags underwent slightly earlier hydrocarbon charging compared to the Qiudong sub-sag. Favorable exploration areas were assessed on the basis of accumulation patterns in the three sub-sags. Three key exploration frontiers are identified: tight sandstone reservoirs in sub-sags, lithologic–stratigraphic reservoirs in slope zones in the south, and structural reservoirs in piedmont buried zones in the north. These areas represent prioritized directions for near-term hydrocarbon exploration in the Taibei Sag.</div></div>","PeriodicalId":100808,"journal":{"name":"Journal of Natural Gas Geoscience","volume":"11 1","pages":"Pages 1-14"},"PeriodicalIF":0.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147420431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}