China Geology最新文献

{"title":"Machine learning supervised algorithms for gas hydrate identification and saturation estimation in marine reservoirs using well log data: A case study of NGHP-01-19B","authors":"Yi-fan Wu,&nbsp;Zheng Su,&nbsp;Takeshi Tsuji,&nbsp;Dai-dai Wu,&nbsp;Guang-rong Jin,&nbsp;Chao Yang,&nbsp;Chuang-ji Feng,&nbsp;Neng-you Wu","doi":"10.31035/cg2025078","DOIUrl":"10.31035/cg2025078","url":null,"abstract":"<div><div>Gas hydrates are increasingly recognized as a significant unconventional energy resource and a key factor in marine geohazards and the global carbon cycle. However, accurately identifying and quantifying hydrate-bearing formations remains challenging due to complex geophysical signatures and heterogeneous distribution. This study evaluates twelve supervised machine learning (ML) algorithms for two key tasks: Classification of hydrate-bearing layers and regression-based estimation of hydrate saturation, using well log and pore-water geochemical data from Site NGHP-01-19B. Two physically independent labeling frameworks are employed: One based on Archie’s law using resistivity (1350 samples, 29% hydrate-bearing), and another based on a three-phase velocity model (890 samples, 25% hydrate-bearing). A diverse set of models, including tree-based ensembles (Decision Tree, Random Forest, GBDT, XGBoost, LightGBM, CatBoost, Bagging, AdaBoost), kernel methods (SVM, SVR), instance-based learning (KNN), neural networks (MLP), and Gaussian Process models (GPR, GPC), are systematically compared using cross-validation and grid search. Ensemble methods consistently performed best in classification, with AdaBoost and GBDT, achieving test accuracies above 0.94 (Archie) and 0.98 (velocity-based). For regression, GPR delivered the most accurate hydrate saturation estimates (<em>R</em>² &gt; 0.99), while GBDT and Random Forest provided a strong balance of accuracy and computational efficiency. Notably, depth below seafloor (TDEP), though not a direct geophysical input, significantly enhanced model performance by acting as a proxy for stratigraphic and thermodynamic conditions. Group-based validation confirmed that random-sample splitting overestimates performance due to depth-wise autocorrelation, highlighting the importance of geologically informed model assessment. Overall, the consistent performance of ML models across both labeling schemes and input feature sets underscores their robustness and transferability, supporting their use as a reliable toolset for offshore gas hydrate reservoir characterization.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 519-534"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Natural gas hydrate resource development: Prospects, technical bottlenecks, and research pathways","authors":"Neng-you Wu,&nbsp;Yan-long Li,&nbsp;Zi-guo Hao (Editor-in-Chief)","doi":"10.31035/cg2026026","DOIUrl":"10.31035/cg2026026","url":null,"abstract":"","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 443-444"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Fluid invasion-induced geological risks during drilling in marine natural gas hydrate reservoirs: A mini review","authors":"Lin Dong,&nbsp;Yan-long Li,&nbsp;Neng-you Wu","doi":"10.31035/cg2024021","DOIUrl":"10.31035/cg2024021","url":null,"abstract":"<div><div>Geological risks are the main obstacles encountered during drilling in marine natural gas hydrate reservoirs. This review aims to provide a primary insight into the geological risks in the process of drilling in marine hydrate reservoirs. Different geological risks and their characteristics will be analyzed, together with a discussion of possible influencing factors. Geological risks occurring in the marine natural gas drilling process have a close association with uncontrollable drilling fluid invasion and hydrate dissociation. Finally, the mechanisms of drilling risks and control strategies for safe drilling are highlighted. Results can give a reference to drilling risk prediction and control for drilling in marine natural gas hydrate reservoirs efficiently.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 652-658"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Effect of reservoir goaf on methane recovery and carbon dioxide sequestration in sandy and clayey hydrate reservoirs: An experimental study","authors":"Yun-shuang Zeng,&nbsp;Dong-bin Pan,&nbsp;Chen Chen,&nbsp;Yu Xie,&nbsp;Yang Zhou","doi":"10.31035/cg2025070","DOIUrl":"10.31035/cg2025070","url":null,"abstract":"<div><div>Carbon dioxide (CO₂) replacement is a promising technique for extracting natural gas hydrate (NGH, a promising clean energy source), capable of promoting energy development while mitigating the greenhouse effect. However, the improvement of NGH extraction efficiency in field engineering is hindered by the difficulty of CO₂ injection and diffusion. To overcome these difficulties, this study proposes combining CO₂ replacement with the solid fluidization method for the exploitation of NGH. The effects of solid fluidization mining goaf on methane (CH₄) recovery and CO₂ sequestration were experimentally investigated. The results indicate that the presence of a goaf in a sandy hydrate reservoir improves the CH₄ recovery ratio and CO₂ storage capacity due to its ability to provide a higher replacement driving force. However, the CO₂ sequestration ratio in the goaf-containing reservoir is lower than that in the intact hydrate reservoir due to the influence of free water content. Besides increasing the replacement driving force, the goaf in the clayey hydrate reservoir can also enhance the diffusion of the replacement medium. The enhancement of CH₄ recovery and CO₂ storage amount per unit sediment volume is 5.3% and 22.8%, respectively. Moreover, the CO₂ sequestration ratio in the goaf-containing hydrate reservoir is higher than that in the intact hydrate reservoir. These results provide theoretical support for the extraction of NGH via the CO₂ replacement method.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 624-634"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Editorial Committee of China Geology","authors":"","doi":"10.1016/2096519226000418","DOIUrl":"10.1016/2096519226000418","url":null,"abstract":"","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 663-666"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Permeability evolution and model of methane hydrate-bearing sediments under coupled shear strain, effective confining pressure, and hydrate saturation","authors":"Tian-xiang Ao,&nbsp;Le Zhao,&nbsp;Ming-zhong Gao,&nbsp;Meng Xu,&nbsp;Yi-kun Yang,&nbsp;Ming-zhu Qi","doi":"10.31035/cg2025111","DOIUrl":"10.31035/cg2025111","url":null,"abstract":"<div><div>The permeability of methane hydrate-bearing sediments (MHBS) is a key parameter for evaluating reservoir exploitation potential and formulating efficient production strategies. In actual field development, MHBS exists in a complex environment characterized by stress-seepage coupling. Research on the permeability model of methane hydrate-bearing sediments under multi-factor coupling conditions remains scarce, limiting the assessment of methane hydrate (MH) reservoir hydrocarbon production potential and efficient development. This study used quartz sand and deep-sea clay from the South China Sea as matrix materials to generate MH, simulating MHBS. Systematic triaxial seepage experiments were conducted to assess the influence of multiple factors, including triaxial shear process, effective confining pressure, and hydrate saturation, on the permeability characteristics of MHBS. The results demonstrate the following: (1) During triaxial compression, permeability exhibits a nonlinear variation—first decreasing and then stabilizing or rebounding—with increasing shear strain, reflecting stress-induced pore structure evolution; (2) the permeability of MHBS decreases nonlinearly with increasing effective confining pressure, showing higher sensitivity in the low-pressure range. Effective confining pressure reduces sample permeability by compressing seepage channels, and this effect is more significant at the initial stages of stress growth; (3) hydrate saturation is negatively correlated with permeability, with the cementing effect of hydrates being the primary cause for the decrease in permeability of MHBS, also reducing the impact of effective confining pressure; (4) effective confining pressure, hydrate saturation, and shear strain have a coupled effect, jointly influencing the permeability of MHBS, but their relative weights vary and require specific consideration; (5) based on experimental data, a permeability prediction model considering the coupling effects of shear strain, effective confining pressure, and hydrate saturation was established. This model demonstrates excellent predictive accuracy and can be applied to forecast the hydrocarbon yield potential of MHBS under varying geological and engineering conditions, providing quantitative basis for reservoir evaluation and gas production prediction. This study bridges the gap between laboratory permeability characterization and field production capacity forecasting, offering critical theoretical and technical support for the sustainable development of marine gas hydrate resources.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 584-595"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"A thermoresponsive temporary plugging agent for drilling fluids in marine gas hydrate reservoirs: Synthesis, performance, and reversible plugging mechanism","authors":"Jin-tang Wang,&nbsp;Ke Zhao,&nbsp;Bo Liao,&nbsp;Lei Liu,&nbsp;Kai-he Lü,&nbsp;Jin-sheng Sun,&nbsp;Shu-qiang Shi","doi":"10.31035/cg2025145","DOIUrl":"10.31035/cg2025145","url":null,"abstract":"<div><div>During drilling in marine gas hydrate reservoirs, drilling-fluid invasion can induce hydrate dissociation, wellbore instability, and reservoir damage, thereby compromising drilling safety and reservoir protection. To address the low-temperature agglomeration and limited self-unplugging capability of conventional temporary plugging agents, a water-soluble thermoresponsive temporary plugging agent (TRP) was synthesized via free-radical copolymerization. Its structural characteristics, phase-transition behavior, plugging performance, reversible unplugging capacity, and underlying mechanism were systematically investigated through laboratory experiments and low-field nuclear magnetic resonance (NMR) imaging. The results show that TRP exhibits a lower critical solution temperature (LCST) of approximately 15°C, matching the thermal conditions of marine hydrate reservoirs. Above the LCST, TRP rapidly aggregates to form a dense plugging layer, effectively suppressing drilling-fluid invasion; below the LCST, it redissolves and restores formation permeability, with a maximum permeability recovery of 96.8%. Sand-disk filtration tests further demonstrate that TRP provides more effective fluid-loss control than ultrafine CaCO₃ and nano-emulsion under the tested conditions. Low-field NMR imaging directly visualizes the invasion–plugging–unplugging process. Mechanism analysis indicates that plugging originates from hydrophobic association of polymer chains above the LCST, which enhances filter cake compactness and increases the rock-surface contact angle from 41.5° to 77.4°. This reversible thermoresponsive strategy provides a practical basis for intelligent reservoir protection during deep-sea hydrate drilling.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 553-566"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Zircon LA-ICP-MS U-Pb age of the newly identified Majiawan mafic-ultramafic intrusion in the Hannan complex: Implications for the Cu-Ni mineralization in the northwest Yangtze craton","authors":"Guo-chao Zhou,&nbsp;Hong-jing Xie,&nbsp;Yu-wang Wang,&nbsp;Yu Shi","doi":"10.31035/cg2024107","DOIUrl":"10.31035/cg2024107","url":null,"abstract":"","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 659-660"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Cenozoic fault system and its control on gas hydrate accumulation in the eastern Dongsha Island area, northern South China Sea: Insights from high-resolution 3D seismic data","authors":"Gang Dong,&nbsp;Yun-bao Sun,&nbsp;Zhi-lei Sun,&nbsp;Ang Li,&nbsp;Di Luo,&nbsp;Qing Li,&nbsp;Dong Zhang,&nbsp;Feng Cai,&nbsp;Bin Zhai,&nbsp;Gui-jing Yan,&nbsp;Jian-ming Gong","doi":"10.31035/cg2025120","DOIUrl":"10.31035/cg2025120","url":null,"abstract":"<div><div>The enrichment and accumulation of natural gas hydrates depend on sufficient gas supply and effective migration pathways. The upward migration of deep thermogenic gases through fault systems is critical for seepage-type hydrate formation. This study aims to elucidate the developmental characteristics of Cenozoic fault systems in the eastern offshore area of Dongsha Island and their influence on natural gas hydrate formation. Utilizing high-resolution 3D seismic data, this study conducted a detailed structural interpretation and seismic attribute analysis to systematically investigate the spatial distribution, developmental stages, and dynamic mechanisms of the Cenozoic fault systems in this region. In addition, this study explored the role of these fault systems in facilitating the migration of deep thermogenic gases to the shallow strata. The study area is dominated by extensional and transtensional normal faults characterized by inherited development and relatively small fault displacements. The Cenozoic strata exhibit a tectonic framework of block-faulted uplift and subsidence with alternating highs and lows. Faults on either side of the central uplift dip in opposite directions and commonly exhibit parallel, step-like patterns. Differences in fault system attitudes were observed between the southern and northern parts of the study area. In the south, fault strikes remained consistent from deep to shallow levels, predominantly trending NE and NEE. In the north, fault strikes varied significantly with depth, transitioning from predominantly NEE in deeper strata to EW and NWW in shallower strata. The study identifies two distinct phases of Cenozoic fault activity: (1) 66–10 Ma, a regional extensional tectonic regime controlled fault development, resulting in the formation of NEE-trending normal faults; (2) 10–2.6 Ma, the Dongsha Movement influenced fault activity, during which EW- and NW–W-trending transtensional faults with dextral strike-slip characteristics developed in the Miocene strata of the northern region. The Cenozoic fault system played a significant positive role in facilitating the migration of deep thermogenic gas to shallow levels, thereby enabling the formation of natural gas hydrates.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 3","pages":"Pages 489-501"},"PeriodicalIF":5.1,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148746675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Prolonged super-orogens during Gondwana assembly contributed to the formation of a habitable Earth: Insights from big data","authors":"Peng-yuan Cui ,&nbsp;Jin-long Yao ,&nbsp;Guo-chun Zhao ,&nbsp;Yi-gui Han ,&nbsp;Qian Liu ,&nbsp;Dong-hai Zhang ,&nbsp;Hang Yang","doi":"10.31035/cg2025068","DOIUrl":"10.31035/cg2025068","url":null,"abstract":"<div><div>Since the initiation of plate tectonics on Earth, the evolution of tectonic regime and supercontinent cycles (Nuna, Rodinia and Pangea) have been the first order factors that contributed to Earth surficial environmental changes and thus development of Earth habitability. In particular, the Neoproterozoic to Cambrian eras recorded dramatic evolution in solid earth and surficial systems, including the breakup of the Rodinia supercontinent and the assembly of the Gondwana (680–430 Ma) landmasses, the Neoproterozoic Oxidation Event (NOE) and Cambrian life diversification. However, the key tectonic factors that were responsible for the evolution of Earth surficial systems during this period remain highly debated and are largely confined to conceptual models. The authors reconstructed the temporal trends of continental orogenic belts, using detrital zircon europium anomalies (Eu/Eu*) and orogen length big data database. The quantitative results indicate that the sustained orogens over 200 Ma formed prolonged super-mountains during the Gondwana assembly period. This might have occurred due to the initiation of modern type plate tectonic regime since the Neoproterozoic time, which allowed large-scale continental deep-subduction for the first time in Earth history. This coincides well with the large-scale Himalaya type collision orogenic belt during Gondwana assembly, along with the sudden drops of the global thermobaric ratio (T/P) and the large-scale occurrence of high-pressure and ultrahigh-pressure metamorphism. This suggests that orogenic elevation and scales were comparable to those of modern Earth. The high topographic relief of terrestrial systems during this time likely resulted in intense weathering and erosion of low-latitude orogenic belts, supplying huge continental sediments to the ocean, consistent with the seawater Sr isotope variation. Huge sediments and nutrients supply profoundly changed ocean composition and increased ocean productivity, triggering Neoproterozoic oxygenation events and providing environmental triggers for the Ediacaran–Cambrian explosion. Overall, multiple factors, with orogens being the most important one, contributed to the genetic, environmental and ecological conditions for Ediacaran life radiation and Cambrian life explosion.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"9 2","pages":"Pages 231-242"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147994703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}