Geofluids最新文献

{"title":"Dynamic Evolution Mechanism and Law of Hydrogeological Parameters of Roof Aquifer Under Mining Stress-Seepage Coupling Effect","authors":"Ke Zhou,&nbsp;Chong Li","doi":"10.1155/gfl/5123428","DOIUrl":"https://doi.org/10.1155/gfl/5123428","url":null,"abstract":"<p>In the process of deep mining in the Jurassic coalfield of the Ordos Basin, the key bottleneck in preventing and controlling roof water inrush disasters is the unclear dynamic evolution mechanism of hydrogeological parameters of the roof aquifer under the coupling of mining stress and seepage. Existing studies mostly focus on a single process—either mining-induced overburden failure or seepage field evolution—and lack systematic clarification of the quantitative evolution law of hydrogeological parameters throughout the full mining cycle, as well as the intrinsic response mechanism between overburden failure and seepage field evolution, with insufficient engineering-scale in situ verification results. Taking the No. 3-1 coal seam of Mudu Chaideng Coal Mine in the Hujierte Mining Area of the Ordos Basin as the research object, this study adopted a combination of in situ hydrogeological tests, long-term sequential monitoring, FLAC³D numerical simulation, Visual MODFLOW flow field inversion, and multifield coupling theoretical analysis to systematically reveal the spatiotemporal evolution law of hydrogeological parameters of the roof aquifer under the coupling of mining stress and seepage. The research results indicate that the sandstone aquifers at the bottom of the Zhiluo Formation and in the Yan′an Formation are the main water-filling aquifers, which can be connected by the mining-induced water-conducting fracture zone (WCFZ). The WCFZ has a maximum development height of 95.80 m, with a “saddle-shaped” spatial distribution, and its development process exhibits three-stage characteristics, forming a dominant channel for groundwater seepage. After mining, the cumulative water level drop of the target aquifer exceeds 400 m, and the average increase rate of the permeability coefficient reaches 54.77%. The mine water inflow shows three-stage evolution characteristics, with lateral runoff of the aquifer as the core recharge source during the stable period. This study clarifies the whole-chain response mechanism from mining-induced overburden failure to mine water inflow evolution, improves the theory of mining-induced seepage evolution in Jurassic thick-bedded sandstone aquifers, and provides a scientific basis for the precise prevention and control of roof water hazards and dynamic prediction of water inflow in fully mechanized mines with Jurassic near-horizontal medium-thick coal seams at a buried depth of 600–700 m.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/5123428","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149206119","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":"Formation Mechanism and Accurate Identification of Spontaneous Combustion Hazard Zones in Gob-Side Entry Driving Goafs Under Small Coal Pillar Damage","authors":"Jiace Guo,&nbsp;Gang Wang,&nbsp;Weizhi Zhao","doi":"10.1155/gfl/1018583","DOIUrl":"https://doi.org/10.1155/gfl/1018583","url":null,"abstract":"<p>Mining-induced damage to a narrow retained coal pillar can establish preferential air leakage pathways between an active goaf and an adjacent previously mined goaf, thereby altering oxygen transport and the spatial distribution of residual coal oxidation regions. Taking the 31119 gob-side entry driving panel of Nalinhe No. 2 Coal Mine as the engineering background, this study combined buried tube monitoring, gob-side directional borehole sampling, and CFD porous medium simulations to investigate the effects of retained coal pillar damage on airflow and oxygen migration. A coal pillar damage–air leakage–oxygen transport model was established, and steady-state simulations were conducted for different prescribed coal pillar damage conditions. Field monitoring showed that the oxygen-defined oxidation zone in the 31119 goaf extended from 37.5 to 83.9 m on the intake side and from 16.2 to 49.0 m on the return side, whereas the corresponding simulated ranges were 35–84 m and 16–51 m, respectively. More importantly, in the adjacent 31120 goaf, the monitored oxidation zone range along the gob-side strike direction was approximately −45 to 14 m, compared with a simulated range of −48 to 13 m. With increasing retained coal pillar damage, fracture connectivity and equivalent permeability increased, promoting deeper oxygen penetration and progressive expansion of the oxidation zone in the adjacent goaf, whereas the three-zone distribution in the 31119 active goaf changed only slightly. These results indicate that damage to the retained coal pillar primarily controls the reactivation of oxygen-accessible oxidation conditions in the adjacent goaf. The proposed approach provides a basis for identifying potential spontaneous combustion–prone regions and for targeted leakage sealing, gas monitoring, and fire prevention measures in gob-side entry driving panels.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/1018583","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149205653","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":"Creep Behaviors of High Fly Ash Content Cemented Backfill and Its Permeability Enhancement Effect of Overlying Strata","authors":"Shuokang Wang,&nbsp;Jingjing Yan,&nbsp;Zihui Dong,&nbsp;Yuanzhong Yang,&nbsp;Naseer Muhammad Khan","doi":"10.1155/gfl/7712799","DOIUrl":"https://doi.org/10.1155/gfl/7712799","url":null,"abstract":"<p>The evolution laws of overlying strata permeability under the creep effect of backfill constitutes a critical environmental protection and safety challenge for deep mining. To address the aforementioned challenge, this study develops fly ash–cement backfill materials with a fly ash content exceeding 70.0% from the perspective of improving the utilization rate of coal-based solid waste resources, conducts conventional triaxial graded creep tests on the backfill, and investigates the creep characteristics of backfill mass. Based on numerical simulations of fluid–solid coupling in heterogeneous rocks, a global permeability calculation model for overlying strata in deep backfill mining is established, and the evolution law of overlying rock permeability is elucidated. The main conclusions are summarized as follows: (1) When the stress level reaches 0.9 times the peak deviatoric stress, the backfill exhibits three complete creep stages. The average total creep duration is approximately 660 min, and creep deformation accounts for roughly 20% of the total deformation upon failure. (2) According to the series connection characteristics of rheological mechanical elements, a creep constitutive model for backfill under equal confining pressure loading is established. Nonlinear fitting and verification are performed on the model parameters, with the coefficient of determination (<i>R</i>²) no less than 0.97 and 0.80, respectively. (3) A numerical calculation method for fluid–solid coupling of heterogeneous rocks is proposed. On this basis, the horizontal and vertical zoning characteristics of overlying rock permeability evolution subjected to backfill creep are revealed. The results provide theoretical support for safe deep coal mining and groundwater resource protection, as well as fundamental experimental data for further investigations on the creep behaviors of coal-based solid waste backfill materials.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/7712799","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145686","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":"A Generalized Hamiltonian Variational Framework for Water–Particle Flow and Grain-Size Segregation in Alluvial-Fan Porous Media","authors":"Jie Chi,&nbsp;Guangzheng Zhao,&nbsp;Haoran Zhang","doi":"10.1155/gfl/2012097","DOIUrl":"https://doi.org/10.1155/gfl/2012097","url":null,"abstract":"<p>Grain-size segregation in alluvial-fan porous media governs depositional architecture and reservoir heterogeneity, but existing models rely on empirical resistance terms and lack a first-principles framework, leaving the coupling among sediment transport, porosity evolution, and flow unclear. Here, we establish a fully coupled dynamic model for single-phase sediment-laden flow and pore-space evolution in saturated alluvial-fan porous media using the generalized Hamiltonian variational principle with dissipation. Starting from the energy and dissipation functionals, we derive a closed set of field equations—mass conservation, generalized Darcy′s law, particle number conservation, and particle force balance—and obtain an explicit analytical expression for the particle transport velocity, which yields an explicit segregation criterion separating fine grains carried in suspension from coarse grains subject to frictional settling. This criterion reveals an autogenic positive feedback: Coarse-grain deposition constricts pore throats, which raises friction and promotes further proximal retention, spontaneously generating ordered zonation under constant boundary conditions. Simulations reproduce the steady three-zone porosity structure—clogging core, transitional zone, and distal background—together with the complete cascading coarse–medium–fine sequence, with <i>d</i>₁₀, <i>d</i>₅₀, and <i>d</i>₉₀ decreasing downstream and the sorting coefficient peaking in the transition zone. The framework thus offers a quantitative first-principles tool for self-organized sedimentary segregation.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/2012097","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146722","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":"Stress Transfer Law of the Floor of Overlying Residual Coal Pillars and Roadway Surrounding Rock Deformation and Support Technology When Crossing Residual Coal Pillars","authors":"Peng Sun,&nbsp;Hao Lan,&nbsp;Jing Chai,&nbsp;Dingding Zhang,&nbsp;Jianfeng Yang,&nbsp;Wenli Ji,&nbsp;Yongliang Liu,&nbsp;Kuiying Gao","doi":"10.1155/gfl/7067361","DOIUrl":"https://doi.org/10.1155/gfl/7067361","url":null,"abstract":"<p>To address severe mining hazards such as intense ground pressure, roof fragmentation, and support instability encountered when longwall faces pass beneath residual coal pillars in close-proximity coal seams, this study investigates the mining conditions of an inclined residual coal pillar in a shallow-buried, close-spaced coal seam at the Daliuta Coal Mine in the Shendong Mining Area. A comprehensive approach integrating theoretical analysis, numerical simulation, fiber-optic monitoring, and field measurements was employed to investigate the stress evolution of surrounding rock and mining-induced pressure response. A floor stress transfer model beneath the upper residual coal pillar was established, revealing stress transmission characteristics into the underlying strata, and numerical simulations confirmed that the stress-enhanced zone exhibits an ellipsoidal distribution and gradually attenuates with depth. Full-process simulations of the working face during the “entry–passage–exit” stages showed that stress concentration on the right side of the pillar consistently exceeded that on the left, whereas horizontal stress in the underlying coal wall increased with advance distance and peaked during the exit stage. The maximum stress concentration reached 12.83 MPa in the pillar and 15.74 MPa in the lower coal seam. Meanwhile, the peak advance abutment pressure increased from 6.47 MPa during the entry stage to 11.44 MPa during the exit stage, following the pattern of “exit &gt; passage &gt; entry.” Fiber-optic borehole monitoring indicated that the stress peak beneath the residual coal pillar reached 2.72 MPa, significantly higher than that beneath the goaf, and exhibited a dynamic “rise–peak–fall” evolution. Field monitoring further confirmed that the exit stage represents the most critical risk zone, with hydraulic support resistance peaking at 18,455 kN per support and a maximum pressure influence range of 7.5 m. Finally, integrating the theory of rock beam structures in shallow-buried coal seams, this study proposes that the rated working resistance of supports during the coal pillar extraction phase should not be less than 15,000 kN per frame. It further recommends implementing proactive control measures such as coal pillar reinforcement support to enhance load transfer. This study systematically elucidates the dynamic stress response mechanism of surrounding rock during the process of mining through residual coal pillars in close-to-the-face coal seams. It identifies the characteristics of intense mining pressure and key prevention and control priorities during the coal pillar extraction phase, providing theoretical foundations and engineering practice references for safe and efficient mining in similar geological conditions.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/7067361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048482","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":"A High-Temperature Stable Weighted Self-Generating Acid System and Its Field Application in 10,000-Meter Ultradeep Reservoir Wells","authors":"Xin Qiao,&nbsp;Ying Gao,&nbsp;Junyan Liu,&nbsp;Jv Liu,&nbsp;Jianxin Peng,&nbsp;Liwei Wang,&nbsp;Zhanwei Yang,&nbsp;Rui Huang","doi":"10.1155/gfl/3783359","DOIUrl":"https://doi.org/10.1155/gfl/3783359","url":null,"abstract":"<p>Conventional acidizing systems for ultradeep carbonate reservoirs face dual challenges: rapid acid-rock reactions limiting penetration depth and severe corrosion of injection strings under extreme conditions. To address these issues, this study develops a high-temperature self-generating acid system with density weighted to 1.2 g/cm³ for deep-well stimulation. By integrating acid-generating agents, corrosion inhibitors, and friction reducers, the system achieves an equivalent acid concentration of 10%–12% HCl while reducing the reaction rate to 1/20–1/30 of conventional HCl, significantly improving retardation. Even under simulated distal-fracture conditions at 195°C, etched fracture channels remain clearly visible, and the slow acid-generation kinetics combined with specialized corrosion inhibitors meet stringent corrosion standards at 180°C. Furthermore, the system achieves a friction reduction rate exceeding 60% at 90 L/min—comparable with conventional guar gum fracturing fluids. The system was successfully applied in Well Shendi Take-1, the world′s first 10,000-meter-deep well. Compared with the gelled acid stage, the effective treatment area of the self-generating acid is increased by 1.8 times, validating its effectiveness for ultradeep, high-temperature reservoir stimulation. This work provides a scalable solution for challenging carbonate reservoirs globally.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/3783359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994456","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":"Sonic Dispersions of P-Waves of Two Types: Fractured Safaniya Sandstone","authors":"Guangquan Li,&nbsp;Xiang Li,&nbsp;Zhongyuan Liu","doi":"10.1155/gfl/6165629","DOIUrl":"https://doi.org/10.1155/gfl/6165629","url":null,"abstract":"<p>As P-waves propagate in fractured porous rock, fluid pressure in fractures may be distinct from that in the contiguous matrix; the fluid pressure differential can drive a viscous squirt between them, which substantially attenuates the waves. A double porosity model of P-waves is constructed based on this mechanism and under the major assumption of isotropic fractures. As a second assumption, matrix permeability between two neighboring rock units is set to zero, whereas fracture permeability is not vanishing to allow the existence/propagation of slow P-wave. The resulting wavenumber equation has two eigenvalues representing two types of P-waves. The P-wave of the first type is the fast P-wave in acoustics, whereas the P-wave of the second type is the slow P-wave in hydrogeology. Safaniya sandstone of the Wasia Formation is used for illustration. The parameters of the sandstone are calibrated by the phase velocity and quality factor of the fast/acoustic P-wave, measured at 10 kHz from a sonic log in Saudi Arabia. Thus, the dispersions/attenuations of P-waves of the two types are determined. The results reveal that fast P-wave dispersion in the low-frequency (seismic) regime is small, whereas that in the high-frequency (sonic) regime is extraordinarily large. The small fracture Biot dispersion at low frequencies arises from interfracture viscous flow, whereas the large dispersion at high frequencies arises from fracture–matrix squirt. The clear separation of the two mechanisms in the frequency domain is the novelty of this study.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/6165629","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994487","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":"Time-Dependent Mechanical Degradation and Constitutive Modeling of Longmaxi Shale Under Different pH Soaking Conditions","authors":"Yongzhou Wei,&nbsp;Guodong Feng","doi":"10.1155/gfl/5509112","DOIUrl":"https://doi.org/10.1155/gfl/5509112","url":null,"abstract":"<p>Fluid-rock interaction can weaken shale during drilling, stimulation, and prolonged wellbore exposure. Longmaxi Formation shale was soaked for 5–20 days in solutions with pH values of 2, 4, 7, 9, and 12, and was examined using physical-property measurements, P-wave testing, scanning electron microscopy, and uniaxial compression. After 20 days at pH = 2, the soaking-induced mass change reached −15.43 g, porosity increased by 1.06 percentage points, P-wave velocity decreased by 6.31%, peak strength decreased by 69.49%, and apparent elastic modulus decreased by 78.65%. Degradation was consistently strongest at pH = 2 and weakest near neutral conditions, whereas the relative severity of pH = 4 and pH = 12 depended on the selected indicator. Because the modulus-based index includes wetting, hydration, chemical reaction, and specimen variability, it is redefined as an equivalent soaking-induced stiffness damage index rather than a pure chemical-damage measure. An endpoint-constrained exponential function is used only to interpolate its evolution over the tested 0–20 day interval. To represent the initial nonlinear pore-compaction stage, axial strain is normalized and a threshold logistic mechanical-damage function is introduced. Unlike common damage formulations that permit damage growth from the onset of loading, the threshold function keeps mechanical damage close to zero during early crack closure and reproduces the compaction, hardening, peak, and postpeak portions of representative pH = 2 and pH = 12 curves. The model is a phenomenological curve representation for outcrop shale under ambient uniaxial conditions; replicated mechanical tests, quantitative chemical characterization, and triaxial validation are still required.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/5509112","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994024","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":"Fluid-Driven Evolution of Deep In-Situ Stress Field in the Kuqa Depression: Insights From Seismic Monitoring and Stress Inversion","authors":"Hui Zhang,&nbsp;Zhimin Wang,&nbsp;Xin Wang,&nbsp;Bin Wang,&nbsp;Lei Liu,&nbsp;Haoyang Zan,&nbsp;Yu Zhang,&nbsp;Hongxiang Gao,&nbsp;Kezhen Zuo","doi":"10.1155/gfl/4488739","DOIUrl":"https://doi.org/10.1155/gfl/4488739","url":null,"abstract":"<p>The Kuqa Depression hosts deep, high-pressure, fractured tight sandstone gas reservoirs within a critically balanced compressional tectonic regime. Long-term gas extraction and subsequent water breakthrough cause widespread pore-pressure perturbations and gas–water fluid substitution, offering a natural laboratory for studying fluid-driven stress evolution in compressional foreland systems. This study integrates multitemporal seismic catalogs, focal mechanism solutions, seismic velocity tomography, and stress inversion to decipher the spatiotemporal evolution of deep in-situ stress throughout the full production cycle. Gas depletion systematically alters P-wave velocity (<i>V</i>_<i>p</i>), S-wave velocity (<i>V</i>_<i>s</i>), and the <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i> ratio. Spatially, core-producing blocks show elevated <i>V</i>_<i>p</i> and <i>V</i>_<i>s</i> but reduced <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i>, whereas peripheral zones exhibit increased <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i>. These contrasting anomalies reflect coupled poroelastic compaction and fluid substitution under variable effective stress. Subsurface mechanical deformation migrates from east to west, with the 4–10 km interval confirmed as the primary stratigraphic layer modified by anthropogenic fluid activities. The in-situ stress field evolves through three stages. Pore-pressure drawdown and fluid displacement drive westward stress migration and pronounced stress localization in the KS8 block. We propose a cascaded geomechanical coupling pathway: gas extraction → fluid redistribution → rock compaction → stress re-equilibration. Our findings clarify sequential stress perturbations triggered by production and water influx in near-critical foreland thrust belts, providing practical insights into fluid-induced stress heterogenization and fault stability assessment for deep tight-gas reservoirs.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/4488739","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943203","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":"Pore Development, Connectivity, and Their Controlling Factors in Shahejie Formation Shales, Bonan Sag, Jiyang Depression","authors":"Baojian Shen,&nbsp;Xiaoqi Xu,&nbsp;Peng Li,&nbsp;Huimin Liu,&nbsp;Suping Yao","doi":"10.1155/gfl/4012065","DOIUrl":"https://doi.org/10.1155/gfl/4012065","url":null,"abstract":"<p>Shale oil exploration in the Paleogene Shahejie Formation of eastern China has advanced substantially in recent years. Geological investigations and exploration practice have shown that pore structure and pore connectivity are fundamental controls on shale reservoir quality and shale oil productivity. This study is aimed at quantifying pore structure and pore connectivity across lithofacies in organic-rich shales from the lower submember of the third member of the Shahejie Formation (Es₃^L) in Well Luo-69, Bonan Subsag, Jiyang Depression. An integrated workflow combining Wood′s metal (WM) injection, scanning electron microscopy (SEM), small-angle and very-small-angle neutron scattering (SANS/VSANS), and x-ray computed tomography (X-ray CT) was applied. WM injection labels pores connected to the exterior of the sample, SEM identifies pore types and WM-filled pathways, SANS/VSANS constrains nanometer-scale porosity and connectivity, and X-ray CT reconstructs micrometer-scale three-dimensional pore and fracture networks. This integrated workflow provides complementary constraints on pore morphology, pore size distribution, connected pore volume, and pore architecture, with the combined investigated pore size range extending from 2 nm to 200 <i>μ</i>m. The results reveal pore systems controlled by lithofacies. The massive lithofacies is dominated by clay mineral-related nanopores and shows relatively weak connectivity because most nanopores are isolated or only weakly connected. The laminated lithofacies contains abundant carbonate laminae, dissolution pores, bedding fractures, and microfractures, forming a better connected pore and fracture network, especially at the micrometer scale. The bedded lithofacies displays transitional pore structure and connectivity characteristics. These differences are mainly controlled by depositional structure and mineral composition: Clay minerals promote nanoscale storage pores, whereas carbonate laminae and bedding structures favor dissolution pores and fracture connectivity. The results indicate that reservoir quality evaluation in the Shahejie Formation should integrate porosity, pore size distribution, pore morphology, and pore-fracture connectivity rather than relying on total porosity alone. Laminated intervals with high carbonate mineral content in the lower Es₃^L are interpreted as favorable targets for shale oil sweet spot evaluation and engineering stimulation.</p>","PeriodicalId":12512,"journal":{"name":"Geofluids","volume":"2026 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1155/gfl/4012065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943290","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}