Marine and Petroleum Geology最新文献

{"title":"Application of nuclear magnetic resonance technology in reservoir characterization and CO2 enhanced recovery for shale oil: A review","authors":"Lu Wang ,&nbsp;Yi Du ,&nbsp;Gang Wu ,&nbsp;Xiaofei Fu ,&nbsp;Chenlu Xu ,&nbsp;Zhejun Pan","doi":"10.1016/j.marpetgeo.2025.107353","DOIUrl":"10.1016/j.marpetgeo.2025.107353","url":null,"abstract":"<div><div>The reservoir characterization and development for shale oil faces significant challenges due to low porosity, low permeability, multi-scale pore space, and complex fluid composition. Nuclear magnetic resonance (NMR)technologies applied in shale oil reservoirs include one-dimensional (1D) NMR T₂ map, two-dimensional (2D) NMR T₁-T₂ map, nuclear magnetic imaging (MRI) technology, and stratified T₂ technology. The 1D T₂ map nondestructively characterizes the full-scale pore size distribution (PSD) of shale oil reservoirs and can be combined with other experimental methods to extend the functions: (1) Through combining with centrifugation and thermal treatment, the NMR T₂ cutoff value can be determined to quantitatively distinguish movable fluid, capillary bound fluid, and immovable fluid; (2) In conjunction with a confining core holder, stress sensitivity of the shale matrix and fracture systems can be characterized; (3) Through combining with spontaneous imbibition experiments, the spontaneous imbibition characteristics and wettability can be quantitatively evaluated; (4) Based on an online high-temperature and high-pressure CO₂ enhanced shale oil recovery (CO₂-ESOR) apparatus, dynamic oil recovery factors can be quantitatively calculated. Furthermore, the 2D T₁-T₂ map has unique advantages in the identification of various fluid types and in-situ content of fluids in different occurrence states in shale oil reservoirs. MRI technology has significant potential to characterize the spatial distribution of the gas-liquid interface during the CO₂-ESOR process. However, current resolution capabilities are generally inadequate for imaging shale oil reservoir samples, particularly those with low porosity and permeability. The stratified T₂ technology provides spatially resolved T₂ distributions and profiles of oil saturation in shale oil reservoirs. However, these applications still face challenges, such as developing novel probes, mitigating the impact of paramagnetic minerals on NMR measurement, and enhancing the resolution capabilities of MRI technology. The continuous advancement of NMR technology will further enhance the applications in the exploration and development of shale oil reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107353"},"PeriodicalIF":3.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inconsistencies in stratigraphic interpretation and correlation – Comments on “depositional cyclicity of lower Cambrian strata in the NW Himalayas: Regional sequence stratigraphy of the Indian passive margin” by Mahmood et al. (2024)","authors":"Malik Muhammad Saud Sajid Khan ,&nbsp;Bing Pan ,&nbsp;Maoyan Zhu","doi":"10.1016/j.marpetgeo.2025.107351","DOIUrl":"10.1016/j.marpetgeo.2025.107351","url":null,"abstract":"<div><div>This article comments on a recent study by Mahmood et al. (2024) on the lower Cambrian strata across the NW Himalaya. While providing a detail sequence stratigraphic framework, the authors fail to adequately considered recent developments in the Cambrian chronostratigraphic framework of the Himalaya and misinterpreted the age of rock successions, which currently range from late Cryogenian to middle Cambrian, as “Lower Cambrian” (ca. 538-512 Ma). This stratigraphic discrepancy introduced considerable confusion, disrupting the recently revised and established late Neoproterozoic to early Cambrian stratigraphic framework across the Himalaya. Consequently, this necessitates a reevaluation of their inferred depositional history and sequence stratigraphic interpretation, as these misinterpretations directly impact the timing, duration, and correlation of depositional events and sea-level changes they described. Present comments seek to address key stratigraphic uncertainties identified in the study by Mahmood et al. and offer clarity to the conflicting interpretations based on more appropriate references related to the chronostratigraphic aspects of the commented paper. This effort not only contextualized rock units being discussed within their established stratigraphic context but also facilitated future research on more precise correlation and subdivision of the late Neoproterozoic-early Cambrian strata at both regional and global scales.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107351"},"PeriodicalIF":3.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-scale pore network fusion and upscaling of microporosity using artificial neural network","authors":"Abolfazl Moslemipour ,&nbsp;Saeid Sadeghnejad ,&nbsp;Frieder Enzmann ,&nbsp;Davood Khoozan ,&nbsp;Sarah Hupfer ,&nbsp;Thorsten Schäfer ,&nbsp;Michael Kersten","doi":"10.1016/j.marpetgeo.2025.107349","DOIUrl":"10.1016/j.marpetgeo.2025.107349","url":null,"abstract":"<div><div>Digital Rock Physics can significantly enhance our understanding of rock behavior. However, modeling heterogeneous rocks remains challenging because of the trade-off between resolution and field of view. To address this, researchers have developed multi-scale pore network models (PNMs), which integrate PNMs from different scales to create unified multi-scale PNM. Various methodologies exist for merging PNMs from different resolutions, but they often suffer from inaccuracy, high runtime and significant memory consumption, particularly when microporosity is integrated into larger scales. This study introduces a novel fusion and an innovative upscaling approach for efficient multi-scale PNM reconstruction of rocks containing microporosity. Our methods separate resolved and unresolved porosities using different voxel sizes from CT scans at multiple resolutions. Resolved regions have larger voxel sizes, while unresolved areas retain smaller voxel sizes. We extract macro-PNM from the resolved regions and generate stochastic micro-PNM for the unresolved areas. An artificial neural network (ANN), trained on micro-PNM, links micro- and macro-PNMs. The multi-scale PNMs generated using the ANN method had an average permeability of 252 ± 3 mD, closely matching the laboratory-measured permeability of the rock (257 mD). In contrast, the average permeability of multi-scale PNMs reconstructed using the statistical method was significantly higher, at 308 ± 38 mD. Consequently, the ANN-based reconstruction method, owing to the proper connection between scales, improved the accuracy of permeability prediction by approximately 90% compared to the statistical reconstruction method. In the next step, each micro-PNM is upscaled to a base pore based on its effective hydraulic conductance. These base pores are then connected to the macro-PNM using a novel approach. We utilized synchrotron CT images of an Indiana limestone rock at two resolutions as our training dataset. The single- and multi-phase flow analysis of the fused PNM demonstrated excellent agreement with laboratory-measured rock properties. Our upscaling method also reduced runtime by up to 40% (from 312 to 190 CPU-seconds) and memory consumption by approximately 68% (from 25 GB to 8 GB), all without compromising predictive accuracy.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107349"},"PeriodicalIF":3.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagenetic evolution in marine carbonate rocks based on the typical case studies: Review and perspectives","authors":"Li Deng ,&nbsp;Chenlin Hu ,&nbsp;Xin Li ,&nbsp;Hongmei Su ,&nbsp;Jonathan Atuquaye Quaye ,&nbsp;Qiuxia Yuan","doi":"10.1016/j.marpetgeo.2025.107352","DOIUrl":"10.1016/j.marpetgeo.2025.107352","url":null,"abstract":"<div><div>Oil and gas derived from marine carbonate rocks are critical energy resources worldwide. The diagenetic process plays a pivotal role in controlling reservoirs, which is essential for understanding reservoir genesis and enhancing oil and gas exploration. Considering the complexity of carbonate rock diagenesis, this review examines the diagenetic mechanisms and stages of marine carbonate rock reservoirs for the first time, with the aim of enhancing the understanding of reservoir evolution and improving oil and gas exploration. This review elucidates the significance of carbonate diagenesis, summarizes the stages of diagenesis, delineates the diagenetic evolution of various types of carbonate rocks, describes the technical methods employed to investigate diagenetic evolution, examines the factors affecting the reservoir, and discusses potential future developments. These findings indicate that compaction, cementation, dissolution, neomorphism, and metasomatism are the primary diagenesis of carbonate rocks. Diagenetic evolution is typically divided into syngenetic, early, intermediate, late, and epigenetic stages. This study employed a basin dynamics perspective to examine the fluid-rock interactions that drive diagenesis. Furthermore, it provided a summary of the diagenesis of microbial and cool-water carbonate rocks. The control of reservoirs through karstification, hydrothermal dissolution, dolomitization, and cementation is dual. In the future, artificial intelligence and artificial neural networks will play significant roles in identifying thin sections and diagenesis. The integration of micro-elements, micro-isotopes, and various techniques is highly significant for studying the diagenetic evolution of carbonate rocks. The storage of CO₂ in marine carbonates is considered a future development trend. This study offers a theoretical basis for the exploration and development of marine carbonates by examining advancements in the diagenetic evolution of marine carbonates, as well as the theoretical and technological aspects.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107352"},"PeriodicalIF":3.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controls on storage capacity in mudstones. Cementation before sediment compaction and preservation of porosity in lithified rock","authors":"Daniel Minisini,&nbsp;Toni Simo,&nbsp;Joe H.S. Macquaker,&nbsp;Mark D. Rudnicki","doi":"10.1016/j.marpetgeo.2025.107350","DOIUrl":"10.1016/j.marpetgeo.2025.107350","url":null,"abstract":"<div><div>This contribution tackles the origin of porosity and cements in organic-rich mudstones, both important factors in the production of energy resources from unconventional reservoirs. A thorough chronology of sedimentary processes and early diagenesis depicts how most of the porosity (storage capacity) was preserved by 1) bottom current delivery of sand-size coccolith-rich pelagic fecal pellets to the seafloor, 2) limitation of pervasive early calcite cementation by reverse weathering, 3) cementation of pre-compaction microcrystalline quartz that stiffened the rock and limited the compactional porosity loss.</div><div>The presence and chronology of early cements, dissolution fabrics, and migrated oils indicate that significant volumes of fluid flowed through these sediment/rocks, and that fluid transport had a dramatic effect on the evolution of the pore filling histories because much of the cementation occurred prior to compaction. The preservation of porosity due to early cementation enabled subsequent flow of both aqueous and hydrocarbon fluids with consequential impacts on diagenesis and the ability of these mudstones to act as reservoir rather than seal facies.</div><div>The results emphasize that the prediction of facies in organic-rich mudstones should be based on pre-compaction diagenetic processes, which can significantly enhance or occlude porosity. In fact, facies in organic-rich mudstones are not satisfactorily predicted by the traditional methods that investigate solely environments of deposition and sequence stratigraphy.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107350"},"PeriodicalIF":3.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143600749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Petrophysical implications of stromatolite morphologies in the Dam Formation, Saudi Arabia","authors":"Jaber Muharrag ,&nbsp;Hassan A. Eltom ,&nbsp;Fawwaz M. AlKhaldi ,&nbsp;Ammar El-Husseiny ,&nbsp;Fatma Maandouche ,&nbsp;Moaz Salih","doi":"10.1016/j.marpetgeo.2025.107348","DOIUrl":"10.1016/j.marpetgeo.2025.107348","url":null,"abstract":"<div><div>This study examines how stromatolite morphologies influence the porosity and permeability of carbonate strata, focusing on columnar (CF) and laterally linked (LL) forms. By emphasizing the critical role of morphology in shaping porosity, permeability, and pore system architecture, the research integrates field observations with laboratory analyses of 40 core plug samples collected from the Miocene-aged Dam Formation in Saudi Arabia. These analyses include petrographic and Nuclear Magnetic Resonance (NMR) techniques to assess rock texture, laminae characteristics, pore types, and pore size distribution. Porosity and permeability measurements were analyzed in conjunction with detailed rock characterization derived from both field and laboratory data. The findings reveal that both CF and LL stromatolite forms can be classified as coarse-grained stromatolites, comparable to examples from both modern and ancient settings. Both forms exhibit alternating dense, micrite-rich laminae and highly porous, grain-rich laminae. The grain-rich laminae are primarily composed of ooids, peloids, skeletal grains, and quartz, with well-preserved interparticle, intraparticle, and moldic porosity. In contrast, the micrite-rich laminae are characterized by clotted micrite, clotted peloids, and sinuous biofilms preserved on lamina tops. Fenestral and vuggy porosity are present in both lamina types. Despite having relatively narrow porosity ranges—33.93%–48.04% for CF stromatolites and 32.28%–54.90% for LL stromatolites—both forms exhibit wide permeability ranges. Permeability in CF stromatolites ranges from 1.38 mD to 1900.50 mD, whereas LL stromatolites range from 13.31 mD to 2017.78 mD. Notably, LL stromatolites display less variable permeability compared to the highly variable CF forms. Although petrographic and NMR analyses provided valuable insights into the factors influencing permeability, the results demonstrate that these techniques alone cannot fully explain the observed permeability variability especially in the LL form. The findings suggest that additional factors, such as pore connectivity and laminae orientation, might play a significant role in controlling permeability. Proposed scenarios of laminae configuration in the samples suggest that these configurations may be the most critical factor influencing the measured permeability in stromatolites. This research has significant implications for reservoir characterization, providing a deeper understanding of fluid flow behavior in carbonate systems containing stromatolites.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107348"},"PeriodicalIF":3.7,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-stage dolomitization controlled by sedimentary facies and basement faults: Insights from the Middle Permian Maokou Formation of the Eastern Sichuan Basin, SW China","authors":"Rong Yang ,&nbsp;Xiyan Yang ,&nbsp;Yang Li ,&nbsp;Cunhui Fan ,&nbsp;Yue Li ,&nbsp;Zisang Huang ,&nbsp;Fei Huo ,&nbsp;Xingzhi Wang ,&nbsp;Xiangyu Fan","doi":"10.1016/j.marpetgeo.2025.107334","DOIUrl":"10.1016/j.marpetgeo.2025.107334","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Middle Permian Maokou Formation in China's eastern Sichuan Basin has undergone multiple episodes of dolomitization, recrystallization, and cementation. However, a consensus on the controlling factors for dolomite formation has yet to be reached. This study adopted a multidisciplinary approach, encompassing petrological, geochemical (C-O-Sr stable isotopes, trace elements, and rare earth elements), and fluid inclusion thermometry analyses to determine the spatial distribution characteristics and diagenetic influencing factors of various dolomite types. Core, outcrop, and thin-section observations have identified three types of replacive dolomites and one type of cementing dolomite: very fine crystalline, nonplanar-a to planar-s dolomite (RD1); fine to coarse crystalline, nonplanar-a to planar-s dolomite (RD2-a); fine to coarse crystalline, planar-e dolomite (RD2-b); and medium to coarse crystalline, nonplanar saddle dolomite (CD). All dolomites exhibit more negative δ&lt;sup&gt;13&lt;/sup&gt;C and δ&lt;sup&gt;18&lt;/sup&gt;O values than the host limestone, with &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr ratios exceeding the range of Permian seawater. RD1 has negative or no anomaly in the Eu element and shows higher Sr content with lower Ba content, indicating that it was not affected by hydrothermal fluids. RD2-a and CD show positive anomalies in Eu, with lower Sr content and higher Ba content, indicating that both were affected by hydrothermal fluids. RD2-b, although showing negative or no anomaly in Eu, has fluid inclusion homogenization temperatures comparable to CD and also has less Sr with more Ba, suggesting that its formation also involved hydrothermal fluids. All dolomites exhibit a clear negative anomaly in the Ce element. By synthesizing petrological and geochemical findings, a multi-stage dolomitization model was proposed, which includes seepage-reflux, thermal convection, and hydrothermal dolomitization, reflecting the formation mechanisms of various dolomite types. Before the activation of the basement faults (SQ1 ∼ SQ2-TST), RD1 was formed by limited seepage-reflux dolomitization in low-energy shoals and small-scale confined environments on the periphery of open seas, with dolomitization fluids being contemporary seawater and a small amount of meteoric water. In the early stage of basement fault activity (SQ2-HST), abnormal geothermal temperatures promoted the thermal convection dolomitization between hydrothermal fluids and external cold contemporary seawater in high-energy and low-energy shoals, leading to the formation of RD2-a, with dolomitization fluids being contemporary seawater and a small number of hydrothermal fluids. In the middle stage of basement fault activity (SQ3), silica-rich hydrothermal fluids rose along the faults and mixed with contemporary seawater, replacing the previously formed dolostones and host limestone to form RD2-b. In the peak stage of basement fault activity (the end of Guadeloupe), deep hydrothermal fluids were fully tra","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107334"},"PeriodicalIF":3.7,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New method for logging identification of natural fractures in shale reservoirs: The Fengcheng formation of the Mahu Sag, China","authors":"Song Wang ,&nbsp;Guiwen Wang ,&nbsp;Lianbo Zeng ,&nbsp;Peng Liu ,&nbsp;Yuyue Huang ,&nbsp;Shiqian Li ,&nbsp;Zhishi Wang ,&nbsp;Yuanlong Zhou","doi":"10.1016/j.marpetgeo.2025.107346","DOIUrl":"10.1016/j.marpetgeo.2025.107346","url":null,"abstract":"<div><div>Natural fractures are one of the critical types of reservoir space in lacustrine shale formations. The enrichment, preservation, and production of shale oil are closely related to these natural fractures. However, the development of various sedimentary structures in lacustrine shale can interfere with fracture identification. In this study, we combined image logging and array sonic logging methods to examine the response characteristics of natural fracture development zones in the borehole, near-wellbore, and far-wellbore regions. We integrated a new logging identification method for natural fractures and explored the relationships among mineral composition, fracture types, and reservoir quality, providing a reference for selecting sweet spots in lacustrine shale reservoirs. Core samples, thin sections, and scanning electron microscope observations of the Fengcheng Formation shale reveal characteristics of multi-scale natural fracture development. High-angle and oblique fractures, which are relatively easy to identify, were recognized using core-calibrated image logs and appear as sinusoidal features on image logs. Low-angle fractures, however, require correlation with core observations for accurate identification. Using array acoustic logging data, including shear leaky and reflected waves, we obtained radial profiles of fast and slow shear waves based on dispersion variations, enabling the determination of fracture development zones. The crossing of slowness curves of fast and slow shear waves along the radial direction and strong responses of red energy clusters in radial profiles indicate the presence of fractures. Additionally, processing of shear-wave reflected wave information remote acoustic reflection imaging profiles, allowing the identification of reflectors distant from the borehole. This resulted in a new multi-scale observation method for natural fracture identification by coupling acoustic and electrical imaging data. Applying this method, we identified natural fractures and established relationships among mineral composition, fracture types, and reservoir quality. The study indicates that high-angle and oblique fractures tend to develop in interbedded felsic shale and mudstone, while low-angle fractures are more likely to form in interbedded felsic shale, dolomitic shale, and mixed shale. Reservoir quality deteriorates with increasing clay mineral content but improves with higher felsic minerals and dolomite content. The findings of this research provide a valuable reference for improving natural fracture logging identification methods and offer guidance for achieving efficient development of lacustrine shale oil.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107346"},"PeriodicalIF":3.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of lithofacies categories on inflection-point behaviors in micro-nano pore-structure evolution: Implications for differential reservoir-forming mechanisms and “sweet-spot intervals” identification for marine gas shales","authors":"Wei Yang ,&nbsp;Rui Yang ,&nbsp;Min Wang ,&nbsp;Shujing Bao ,&nbsp;Leilei Yang ,&nbsp;Haodong Hou ,&nbsp;Yan Song ,&nbsp;Zhenxue Jiang ,&nbsp;Ke Miao ,&nbsp;Liang Xu","doi":"10.1016/j.marpetgeo.2025.107336","DOIUrl":"10.1016/j.marpetgeo.2025.107336","url":null,"abstract":"<div><div>Pore structure evolution characteristics and the controlling factors of organic-rich shales have received considerable attention, with recent investigations have focused on pore-type heterogeneity and pore-structure variations during the thermal maturation. A still controversially discussed issue concerns the potential inflection points of the microscopic reservoir parameters occurring at specific thermal evolution stages, and a deeper understanding and reasonable interpretation of the differential pore-structure evolution trajectory for marine shale-gas reservoirs remains a challenging task. In this study, we focus on black shale reservoirs in the Wufeng-Longmaxi Formations (Upper Ordovician-Lower Silurian) from Southwest China. An integrated analytical approach is employed utilizing lithofacies classification, FE-SEM observation and digital image extraction, fluid injection techniques, calculation of innovatively proposed predominant direction coefficients of migrated organic matter (CMOM), as well as FIB-SEM microscopy and three-dimensional (3D) reconstruction. We offer new perspectives on and constraints particularly regarding the potential effect of lithofacies on differential inflection-point behaviors in the evolution of multi-scale and organic-matter pore structures during thermal maturation. Additionally, we offer a unique perspective on the differential reservoir-forming mechanisms of the heterogeneous shale-gas reservoirs. The significant time-lag effect observed at the identified inflection points trending toward the high-quality siliceous shale reservoirs is confirmed, suggesting the strongest storage capabilities of migrated organic matter, and a most sustainable and advantageous window period for organic matter-hosted pore development. The optimal genetic conditions for disadvantageous argillaceous shales are also uncovered by assessing sensitive parameters to evaluate pore-throat connectivity. This highlights the importance of interconnected micropores facilitating adsorbed-gas micro-reservoirs and seepage properties at the appropriate thermal maturity stage in heterogeneous and porous medium. Our findings may fill significant gaps in identifying “sweet-spot” categories and “sweet window” intervals, as well as assessing favorable exploration and commercial exploitation targets for marine shale-gas reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107336"},"PeriodicalIF":3.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas hydrate in the Faroe-Shetland Basin, offshore United Kingdom","authors":"Fawz Naim,&nbsp;Ann E. Cook","doi":"10.1016/j.marpetgeo.2025.107347","DOIUrl":"10.1016/j.marpetgeo.2025.107347","url":null,"abstract":"<div><div>We conduct the first comprehensive assessment of the hydrate system in the Faroe-Shetland Basin, offshore United Kingdom using well and seismic data from the petroleum industry and find that the hydrate systems in the Faroe-Shetland Basin are primarily microbial in origin. We also argue that there are hydrate systems similar to the Faroe-Shetland Basin across Europe's continental margins. In the Faroe-Shetland Basin, we find evidence for hydrate in 19 out of 20 wells (95%), however hydrate is mostly accumulated in discrete intervals at low concentrations. In addition, hydrate is not concentrated at the base of the hydrate stability zone. These observations from well data suggest that the hydrate system has a microbial source of gas. We identify and describe the first bottom simulating reflection (BSR), which is a seismic indicator of hydrate, in the United Kingdom. The BSR is spread across an area of 66 km² and has both continuous and discontinuous characteristics. We observe that the BSR is associated with normal faults that are not deep seated. The BSR is intersected by two low concentration hydrate bearing wells. Moreover, we observe that the root mean square amplitude values within the hydrate stability zone at the wells and in the area above the BSR is consistently low. This does not suggest a significant accumulation of hydrate above the BSR indicating that the gas source for the hydrate system is likely microbial origin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"176 ","pages":"Article 107347"},"PeriodicalIF":3.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}