Marine and Petroleum Geology最新文献

{"title":"Feldspar dissolution controlled by coal-measure fluids and the impacts on pore structure of tight sandstone reservoirs: The case of the Jurassic Badaowan Formation in the Junggar Basin, Northwestern China","authors":"Zhi-Cheng Cui ,&nbsp;Ke-Lai Xi ,&nbsp;Ying-Chang Cao ,&nbsp;Xiang Shan ,&nbsp;Wei-Kai Huang ,&nbsp;Hua-Jun Guo ,&nbsp;Bo Peng ,&nbsp;Nian-Ming Zan","doi":"10.1016/j.marpetgeo.2025.107419","DOIUrl":"10.1016/j.marpetgeo.2025.107419","url":null,"abstract":"<div><div>Diagenetic fluids from coal measures are crucial for feldspar dissolution within feldspar-rich reservoirs. The intensity of feldspar dissolution and the distribution of kaolinite and quartz collectively shape reservoir pore structures, thereby influencing their quality. This study innovatively quantifies the impact of varying degrees of diagenetic alteration by coal-derived organic acids on pore structures and reservoir properties, employing petrographic and geochemical methodologies in the Mobei and Mosuowan uplifts. The results reveal that authigenic minerals predominantly originate from K-feldspar dissolution facilitated by coal-measure organic acid fluids. They tend to precipitate in situ within intergranular pores through diffusion in a relatively closed diagenetic system. Detailed analysis indicates that feldspar dissolution exerts a limited impact on porosity improvement, with permeability reduction primarily attributed to authigenic mineral precipitation blocking pore throats. The Mobei reservoirs exhibit high porosity and permeability characteristics, driven by well-developed network pore structures featuring effectively connected pore-throat systems, contributing 88.8 % to permeability. In contrast, the Mosuowan reservoirs, closer to coal-measure source rocks, undergo more intensive diagenetic modification, resulting in lower compositional and structural maturity. They primarily exhibit relatively high-porosity but low-permeability reservoirs, dominated by tree-like pore structures associated with clay minerals. This study constructed models of reservoir property evolution and pore structure modification, highlighting the critical role of distance from coal seams in shaping differences in feldspar dissolution and authigenic mineral distribution, contributing to the comprehensive research of coal-measure tight sandstones.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"178 ","pages":"Article 107419"},"PeriodicalIF":3.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834809","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":"Flexible X-ray computed tomography for multiscale and dynamic imaging of geological materials","authors":"Armin Afrough ,&nbsp;Rasoul Mokhtari,&nbsp;Ming Li,&nbsp;Karen L. Feilberg","doi":"10.1016/j.marpetgeo.2025.107415","DOIUrl":"10.1016/j.marpetgeo.2025.107415","url":null,"abstract":"<div><div>X-ray Computed Tomography (CT) methods can be used to study the internal structure of geomaterials non-destructively and with minor sample preparation. Previously, such methods have been utilized in the characterization of petroleum reservoirs, underground water resources, soil, ores, and carbon storage in aquifers. We describe the development of a flexible scripting system, <em>FLEX</em>T, to control the components of a non-commercial multiscale X-ray CT scanner for geological applications. This X-ray CT system, with allied hardware and software, can characterize geomaterials at multiple length scales and as a function of time – in the dynamic imaging mode. This multiscale and dynamic imaging system enables flexible imaging of geomaterials with open hardware and software architectures that permit programming, scripting, and modifications. The modifiable custom-built X-ray CT scanner is capable of imaging objects as large as 20 cm to smaller than 1 mm with three stages. Flow equipment that may be integrated into the software system permits realistic dynamic imaging experiments. Imaging of three rock samples at the 120-mm, 40-mm, and 2-mm length scales are presented as well as two dynamic evaporation experiments in a model glass-bead pack and a natural chalk core plug. The developed imaging system accelerates hardware and software modifications and permits new applications and discoveries in geosciences.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"178 ","pages":"Article 107415"},"PeriodicalIF":3.7,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824105","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":"Tide to river-dominated changes in the early Miocene mixed-energy paralic western shelf of the Pearl River Mouth Basin, northern South China Sea","authors":"Mingxuan Tan ,&nbsp;Yanlei Dong ,&nbsp;Jiawang Ge ,&nbsp;Lianpu Sun ,&nbsp;Hehe Chen ,&nbsp;Shunli Li","doi":"10.1016/j.marpetgeo.2025.107407","DOIUrl":"10.1016/j.marpetgeo.2025.107407","url":null,"abstract":"<div><div>Many modern paralic depositional systems are characterized by complicated morphologies mixed with the river, tide, and wave processes. However, the prediction of hydrodynamic processes within their ancient counterparts is challenging from the subsurface data due to the limitation of resolution and coverage. This study illustrates an integrated work on the mixed-energy paralic deposits of the lower Miocene Zhujiang Formation in the western shelf of the Pearl River Mouth Basin, northern South China Sea. Through a synthesis of grain size and heavy mineral analysis, well-based facies interpretation, and seismic stratigraphic study, it generally shows a vertical change from the dominance of tidal strait deltas and tide-influenced deltas to a river-dominated delta with the wave-dominated shelf throughout three members, in response to the evolution from semi-closed to open marine settings. Tidal, river, and wave signals were recognized from the mixed-energy paralic deposits, albeit with alternative interpretations and non-negligible limitations. Tidal processes, which were interpreted from grain size distribution unmixing and statistical heavy mineral comparison, intensified towards the distal reach in the Member 2, and they generally declined after the drowning of paleo-Highs in the Member 1–2. Fluvial processes, which were reflected by heavy mineral evidence and sedimentary response, significantly enhanced from Member 2 to Member 1-1 with more extensive drainages and increased sediment supply, despite the long-term transgression. The presence of large-scale shoreline-parallel shelf sand ridges in the Member 1-1 was mostly controlled by the wind-driven Guangdong Coast Currents and intrusion of the South China Sea Branch of Kuroshio Current, which were coupled with the maximum East Asian Monson intensity and the Indonesian Seaway shoaling before the final closure. We demonstrated that a multidisciplinary approach presented can be effectively used to assess the changes in hydrodynamic processes of mixed-energy depositional systems, which unravel more paleogeographic, paleoclimatic, and paleoceanographic information from depositional records.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"178 ","pages":"Article 107407"},"PeriodicalIF":3.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824442","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":"Geological controls on shale gas accumulation in a synclinal reservoir and implications for natural gas migration","authors":"Yong Ma ,&nbsp;Zhiyuan Xin ,&nbsp;Junbei Song ,&nbsp;Dahua Li ,&nbsp;Daiduo Zhu ,&nbsp;Haipeng Zhang ,&nbsp;Ningning Zhong","doi":"10.1016/j.marpetgeo.2025.107404","DOIUrl":"10.1016/j.marpetgeo.2025.107404","url":null,"abstract":"<div><div>Shale gas exploration in the marine systems of southern China has predominantly targeted anticlines, while synclines have been regarded as high-risk areas due to potential gas loss along shale layers governed by structural morphology. Recently, commercial shale gas production has been identified in the Upper Ordovician Wufeng and Lower Silurian Longmaxi shales within the Baima Syncline, Southeast Sichuan Basin, sparking significant interest in exploring the geological controls on shale gas accumulation and migration in synclinal settings. Here, we characterize the shale microstructure, free and adsorbed gas capacities, and the chemical and isotopic composition of shale gas in relation to the tectonic evolution of the syncline, based on a sample set from five wells in the structurally isolated Baima Syncline. Total gas contents decrease from the center of the syncline (5.2 m³/t) through the limb (4.9 and 4.8 m³/t) towards the margin (3.8 and 2.4 m³/t), primarily due to a reduction in free gas content. Seismic profiles and microstructural analysis of organic matter (OM)-hosted pores reveal increasing structural deformation from the syncline core to its margins. This strong deformation reduces the free gas content through two mechanisms: (1) porosity loss due to compression of OM-hosted pores caused by structural deformation, and (2) lower pressure coefficients and reduced gas saturation at the syncline margins, where bedding-parallel microfractures formed by strong tectonic stress and enhance permeability and facilitate gas escape. Variations in δ¹³C₁ values and the wetness of shale gas indicate minimal gas migration along shale layers within the syncline, typically less than 2 km, even over a geological timespan of approximately 90 million years. These findings suggest that the core and limb areas of synclines with weak structural deformation and adequate distance from faults could serve as promising targets for shale gas exploration, even in tectonically complex regions. Moreover, the limited gas flow along shale layers provides valuable insights into the CO₂ storage potential of shale reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"178 ","pages":"Article 107404"},"PeriodicalIF":3.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143815654","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":"Effects of outcrop-scale structural and diagenetic heterogeneities on flow and mass transport in a porous sandstone aquifer","authors":"Marco Antonellini ,&nbsp;Leonardo Del Sole ,&nbsp;Pauline Nella Mollema","doi":"10.1016/j.marpetgeo.2025.107406","DOIUrl":"10.1016/j.marpetgeo.2025.107406","url":null,"abstract":"<div><div>We apply outcrop-based structural and <em>in-situ</em> petrophysical properties measurements for the construction of flow and mass transport calibrated numerical models in a porous sandstone aquifer. The hydraulic conductivity in this aquifer is influenced by the presence of deformation bands and related carbonate nodules. These heterogeneities are shown to decrease the hydraulic conductivity of the host rock by 2–3 orders of magnitude. The result obtained is robust, given that the models were calibrated with hydrologic field data. Our upscaling methodology for hydraulic conductivity allows inclusion of outcrop-scale structures and diagenetic features by means of inversion of the advective velocity for conservative particles. This approach can be used for easily implementing field data in aquifers or other geofluids reservoir simulators. Our experiments show that the use of an equivalent isotropic hydraulic conductivity approach fails to correctly account for mass transport in porous sandstone aquifers and we recommend implementing, as much as possible, the local heterogeneities and anisotropies in hydraulic conductivity within the model to be able to have a more realistic and conservative estimate of advection and dispersion. Our findings should be helpful to those scientists dealing with geofluids modeling and groundwater pollution.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107406"},"PeriodicalIF":3.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791773","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":"Re-Os geochronological evidence for oil generation during the early Oligocene in the South Llanos basin of Colombia: Insights into the Understanding of giant heavy oil accumulations in northwestern South America","authors":"Sebastian Jimenez-Rodriguez ,&nbsp;Andrés Mora ,&nbsp;Robert A. Creaser ,&nbsp;Julián Naranjo-Vesga ,&nbsp;Nelson Sánchez ,&nbsp;Víctor Caballero","doi":"10.1016/j.marpetgeo.2025.107401","DOIUrl":"10.1016/j.marpetgeo.2025.107401","url":null,"abstract":"<div><div>The Southern Province of the onshore Llanos Basin of Colombia is characterized by accumulations of heavy-biodegraded oils (&lt;20°API gravity oils) sourced from Upper Cretaceous rocks localized in the adjacent Eastern Cordillera. There are some uncertainties regarding the precise age of oil generation in this sector of the Llanos Basin, however, previous time-temperature models have restricted the timing of oil generation to the Paleogene. Re-Os geochronology in crude oils has shown promising potential to directly determine the age of hydrocarbon generation, migration, or charge in basins with complex tectono-sedimentary settings. Here, we conducted Re-Os isotopic analyses in 29 oil samples from the Castilla, Peguita, and Rubiales oilfields to constrain the timing of hydrocarbons generation in the Southern Province of the Llanos Basin. The Re-Os isotopic data yield an isochron age of 28.9 <strong>±</strong> 4.4 Ma, consistent with basin evolution models that support a maximum thermal maturity reached by source rocks of the Eastern Cordillera in the Early Oligocene. This age also seems to precede the onset of exhumation of the Eastern Cordillera at ca. 25 Ma, providing new chronological controls to constrain the timing of cessation of oil generation by Upper Cretaceous rocks. This study highlights the applicability of the Re-Os geochronometer to (1) constrain the temporal evolution of petroleum systems in the Llanos Basin, and (2) evaluate the influence of exhumation of the Eastern Cordillera in the development of petroleum kitchens in the adjacent foreland basin. The new data are instrumental in confirming the evolutionary models of the giant heavy oil accumulations of the South Llanos Basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"178 ","pages":"Article 107401"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820273","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":"Qualitative characterization of sandbody connectivity for meandering river composite channel sandbody at seismic scale with large well spacing","authors":"Liangtao Ma ,&nbsp;Weisheng He ,&nbsp;Xianwen Zhang ,&nbsp;Yunfeng Gao ,&nbsp;Zongjun Wang ,&nbsp;Rongsheng He ,&nbsp;Linjie Yin","doi":"10.1016/j.marpetgeo.2025.107397","DOIUrl":"10.1016/j.marpetgeo.2025.107397","url":null,"abstract":"<div><div>Studying the static connectivity of reservoir is essential to predict the lateral connectivity of sandbodies and devise field development strategies. Critical elements of static connectivity include geometry, <em>stacking pattern</em>, and the distribution of sandstone bodies. The meandering river reservoir in the lower member of the Minghuazhen (Nm) Formation is intersected and superimposed by multi-stage channel sandbody, resulting in a complex sandbody architecture. However, in the early phase of oilfield development with limited well data and sparse well spacing, there is a lack of comprehensive characterization of the strongly heterogeneous distribution pattern of channel sandbody and an incomplete understanding of sandbody connectivity, which complicates the optimization of well placement. We conducts a precise analysis of sandbody connectivity at different levels in seismic scale for Lm733 sandbody of the V oil group in the lower section of the Nm Formation, based on a comprehensive utilization of geological data in oilfield and guided by sequence stratigraphy and seismic sedimentology applying stratigraphic proportional slicing and sandbody edge detection technique. The results indicate that Lm733 sandbody can be classified into two composite channel sandbodies, respectively distributed in the early sequence (SQ1) and late sequence (SQ2). Based on the diverse seismic reflection characteristics, varying thicknesses, and plane distribution features of the interbed, the connectivity between two composite channel sandbodies for SQ1 and SQ2 could be classified into three categories (Type-Ⅰ, Ⅱ, and Ⅲ). According to the seismic attribute variation, including amplitude, waveform, and frequency at the internal boundaries of composite sandbodies, the internal connectivity of composite sandbody in SQ2 can be classified into three categories (Type-1,2, and 3), in conjunction with the existing injection-production well pattern. In this manner, predicting the characterization of sandbody connectivity at various levels in composite channel sandbody at seismic scale can aid in adjusting oilfield development plans.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107397"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791664","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":"Fault interactions and role of preexisting structures on the geometry of conjugate transfer zones: Structural insights from Cairo-Suez District, Egypt","authors":"Ahmed Henaish ,&nbsp;Sherif Kharbish ,&nbsp;Moustafa Abdelhady ,&nbsp;Fares Khedr","doi":"10.1016/j.marpetgeo.2025.107402","DOIUrl":"10.1016/j.marpetgeo.2025.107402","url":null,"abstract":"<div><div>The Cairo-Suez District (CSD), located in the northwestern sector of the Gulf of Suez rift, is characterized by significant structural complexity, including an intricate network of extensional faults and transfer zones. This study focuses on the Gebel El-Himeira and northern Gebel Ataqa areas, situated at the eastern part of the CSD. This research aims to clarify the internal architecture of these areas through detailed geological field mapping, structural data collection, and satellite imagery analysis. The primary objectives are to establish the geometry of the transfer zones, decipher their deformation history, and understand the influence of their evolution on syn-tectonic sedimentation. The structural analysis of the mapped areas reveals that the Gebel El-Himeira and northern Gebel Ataqa regions represent two prominent conjugate divergent transfer zones which formed between adjacent bounding faults that dip away from each other. The results indicate that the development of both transfer zones began during the Late Eocene and led to dissimilar geometries. This difference in geometry is attributed to the role of reactivated preexisting faults. The growth and propagation of these transfer zones exert significant control on syn-sedimentation processes. These findings provide valuable analogues for subsurface mapping and enhance the understanding of structural controls on hydrocarbon accumulation and migration pathways in similar rift-related basins.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107402"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769092","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":"Linking diagenesis to sequence stratigraphy: An integrated approach for understanding and predicting the reservoir quality distribution of the Ilam Formation (Santonian) in Abadan Plain, southwest of Iran","authors":"Yousef Abedi ,&nbsp;Hossein Mosaddegh ,&nbsp;Mohammad Ali Kavoosi","doi":"10.1016/j.marpetgeo.2025.107399","DOIUrl":"10.1016/j.marpetgeo.2025.107399","url":null,"abstract":"<div><div>The Santonian Ilam Formation, is one of the most important hydrocarbon reservoirs in the Abadan Plain, southwestern Iran. The aim of this study is to evaluate the diagenetic processes and products in a sequence stratigraphic framework by combining the results of core description, the study of microscopic thin sections and petrophysical diagrams from the perspective of facies, diagenetic features, and reconstruction of the depositional environments. Petrographic studies were performed on 235 thin sections from drill cuttings from four wells and about 124 m of core samples from two key wells across four oil fields in the study area. Facies analysis identified seven carbonate microfacies belonging to lagoon, shoal, and open marine facies belts. The findings indicate that the Ilam Formation was deposited in a homoclinal carbonate ramp platform. Sequence stratigraphic investigations led to the identification of two third-order depositional sequences. Diagenetic processes affecting include dissolution, recrystallization and dolomitization, mainly observed dominant in the late highstand systems tract of the lower Santonian depostional sequence. In the early TST and late HST stages, due to increased accommodation space, marine diagenetic processes such as micritization and cementation are more extensive. Due to the development of grain-supported microfacies, dissolution processes and the development of vuggy and moldic porosity are more prevalent. In the late TST stages, favorable conditions for low-energy environment microfacies and in the early HST stages, with the decline in relative sea level rise rate and reduced accommodation space, have expanded.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107399"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785880","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":"Quantification of free and adsorbed fluid content in shale oil reservoirs: Insights from preserved cores and different methods","authors":"Hongrui Zhang ,&nbsp;Jinbu Li ,&nbsp;Wanglu Jia ,&nbsp;Min Wang ,&nbsp;Ping'an Peng","doi":"10.1016/j.marpetgeo.2025.107400","DOIUrl":"10.1016/j.marpetgeo.2025.107400","url":null,"abstract":"<div><div>Developing an accurate assessment of the content of in-situ fluid in different states (adsorbed and free) within complex shale reservoirs is crucial for reserve evaluation and shale oil mobility. While various methods based on nuclear magnetic resonance (NMR) technology, such as the two-dimensional (2D) NMR Chart method, Heating method, and Centrifugal method, have been proposed and tested by researchers for evaluating the content of free and adsorbed oil/water in shale reservoirs, a comprehensive comparative analysis of these methods is lacking. Moreover, previous investigations have predominantly focused on NMR analysis of shale samples saturated with single-phase fluids (either oil or water), neglecting the significant impact of oil-water two-phase in-situ fluids on experimental outcomes. Therefore, this study employed 23 preserved initial shale core samples from the Paleogene Shahejie Formation in Bohai Bay Basin, eastern China, and conducted a series of NMR experiments for shale samples under initial, centrifugal, and heating conditions. The content of in-situ oil and water in different states was systematically evaluated using the three aforementioned methods. Key findings include: a. The free oil content evaluated using the Chart method and the Heating method were very similar, both significantly exceeding that obtained via the Centrifugal method, likely due to the ladder-like manner of fluid expulsion from the shale during the centrifugal process and the influence of oil-water two-phase interactions on the Centrifugal method. b. Direct evaluation of free and adsorbed water using the Chart method proved challenging for preserved samples, necessitating auxiliary pretreatment steps such as sample heating to determine appropriate T₂ cutoff values. c. The Heating method demonstrated limitations, including incomplete release of free fluid at the threshold temperature and premature expulsion of some adsorbed fluid prior to reaching the threshold, resulting in a slight underestimation of free fluid and an overestimation of adsorbed fluid. Given these observations, it is recommended that a combined approach incorporating the Chart method with the Heating method be employed for a comprehensive evaluation of fluid content in tight shale reservoirs saturated with multiphase fluids. These findings contribute valuable insights for quantifying the content of in-situ free and adsorbed fluids in unconventional reservoirs.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"177 ","pages":"Article 107400"},"PeriodicalIF":3.7,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747145","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}