Marine and Petroleum Geology最新文献

{"title":"Seismic geomorphology of the karstified Upper Jurassic-Lower Cretaceous carbonate succession in the Carpathian Foredeep area, Poland","authors":"Jerzy Samojluk ,&nbsp;Jan Tveranger ,&nbsp;Jan Barmuta","doi":"10.1016/j.marpetgeo.2025.107331","DOIUrl":"10.1016/j.marpetgeo.2025.107331","url":null,"abstract":"<div><div>Characterization of subsurface reservoirs composed of soluble rock formations is commonly challenged by the presence of structures forming irregularly distributed, multi-scale inhomogeneities originating from karstification and karst degradation. Although the majority of paleokarst features occur at sub-seismic scales, seismic data interpretation can provide information on type and spatial distribution of meso-scale karst features. Integrating these with other data sources and a genetic understanding of karst formation provides a means to decipher former karst systems and their extent and potential impact on subsurface reservoirs. In turn this offers the potential for improved reservoir characterization and reducing exploration- and production-risks. The present work investigates the Upper Jurassic–Lower Cretaceous carbonate succession located in the Polish sector of the Carpathian Foredeep. From the Early Cretaceous to Middle Miocene, the stratigraphic record reveals that the region experienced two prolonged episodes of subaerial exposure, highlighting the potential for extensive overprinting of these formations by karst during these events. Using conventional 3D seismic data, supplemented by wireline logs, numerous karst-related features can be identified and mapped. Detailed structural, stratigraphic, and geomorphological analysis suggest that karst development was controlled by lithological and tectonic factors, as well as relative sea level change. The results are synthesized into a conceptual model for regional karst evolution and its impact on the Upper Jurassic–Lower Cretaceous carbonate succession in the Carpathian Foredeep. Our study demonstrates the utility of applying an integrated workflow when characterizing paleokarst systems in geologically complex, carbonate successions.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107331"},"PeriodicalIF":3.7,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143394244","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 controls on sweet spots pore types and reservoir quality of Permian tight sandstones in the Ordos Basin, China","authors":"Yaxin Shang ,&nbsp;Keyu Liu ,&nbsp;Ziyi Wang ,&nbsp;Bo Zhang","doi":"10.1016/j.marpetgeo.2025.107324","DOIUrl":"10.1016/j.marpetgeo.2025.107324","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Identification of sweet spots in tight sandstone reservoirs is crucial to the effective economic development of tight oil and gas. The pore types and porosity-permeability relationships in the sweet spots of tight sandstones are primarily controlled by sedimentary and diagenetic processes. All of the Permian tight sandstone sequences in the northeastern Ordos Basin were deposited under similar depositional environment with sediments supplied from the same source. Understanding the variations of the petrophysical properties of the Permian tight sandstones would thus provide insight into the control of reservoir quality by the diagenetic process. Petrographic and petrophysical analyses were conducted on the Permian tight sandstone sweet spot reservoir interval, revealing the distribution and characteristics of pore types that control reservoir quality. Pore types change from a mix pore type of primary intergranular, secondary dissolution porosity and undifferentiated microporosity in the shallower upper Permian reservoir interval to a secondary dissolution porosity- and microporosity-dominated one in the deeper lower Permian reservoir interval. Porosities decrease from 15.18% in the upper Permian to 10.43% in the lower Permian, while permeabilities decrease from 15.29 mD to 0.85 mD. The primary intergranular porosity decreases from 7.94% to 0%, while the secondary dissolution porosity increases from 4.75% to 6.22%. In contrast, microporosity increases from 3.60% to 4.52%. With increasing burial depth, the intergranular porosity decreases significantly due to mechanical compaction or occlusion by quartz cementation. The precipitation of authigenic clay minerals and ferrous carbonate cementation also contributes to the reduction of primary intergranular porosity. Although the dissolution of feldspars produced more secondary dissolution porosity with increasing burial depth, quartz cementation and authigenic clay minerals resulting from feldspar dissolution limit the porosity increase from mineral dissolution. Changes in pore type proportions and the reduction in total porosity with increasing burial depth alter porosity–permeability relationships. In the shallower upper and middle Permian reservoir intervals, primary intergranular porosity are well developed, typically exhibiting large pore throat sizes. The average medium pore throat radius in the upper and middle Permian reservoirs reaches 0.88 μm and 0.42 μm, respectively, resulting in high permeability. In contrast, the deeper lower Permian reservoir intervals lack primary intergranular porosity and primarily develop secondary dissolution porosity and microporosity, which connect to small pore throats. As a result, the lower Permian reservoir has an average medium pore throat radius of only 0.32 μm, resulting in low permeability. Because the lower Permian reservoirs are dominated by secondary dissolution porosity and microporosity, their porosity–permeability relationships have gentler ","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107324"},"PeriodicalIF":3.7,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378910","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":"Origin of reedmergnerite in sodium carbonate successions and environmental implications in a Late Paleozoic alkaline saline lake, NW Junggar Basin, China","authors":"Kuanhong Yu ,&nbsp;Xinyu Duan ,&nbsp;Yingchang Cao ,&nbsp;Shuo Du","doi":"10.1016/j.marpetgeo.2025.107323","DOIUrl":"10.1016/j.marpetgeo.2025.107323","url":null,"abstract":"<div><div>The Fengcheng Formation originated from a Late Paleozoic alkaline saline lake, characterized by abundant evaporites and serving as the primary source rocks within this evaporitic basin. Boron accumulation in this set of evaporitic deposits is primarily in the form of reedmergnerite (NaBSi₃O₈). Although reedmergnerite can be found in each sub-environment of this alkaline saline lake, it may dominate in evaporite successions near the evapocenter. However, its distribution pattern and origins within the evaporite succession remain unclear. Through comprehensive analyses of a reedmergnerite-rich evaporite core section, we propose the following: (1) boron originates from volcanic ash and hot spring; (2) diagenetic processes within a hydrothermal environment involve replacement of sodium carbonates by loughlinite (Na₂Mg₃Si₆O₁₆▪8H₂O) fibers followed by crystallization of reedmernerite within loughlinite during contemporaneous diagenesis; (3) vertical distributions of reedmergnerite within evaporitic successions are controlled by episodic volcanic eruptions, hot spring ejections, and climatic cycles; and finally, (4) significant volumes of reedmergnerite occur within sodium carbonate successions due to multiple stages of volcanic eruptions and hot spring ejections. Therefore, the boron accumulations within the sodium carbonate successions in the Fengcheng Formation provide compelling evidence of deep sources contributing to the formation of chemical deposits in an alkaline saline lake environment. The accumulation of reedmergnerite can be regarded as a boron resource that formed specifically within this type of alkaline saline lake setting. Furthermore, the presence of laminated reedmergnerite and louglinite can serve as indicators for identifying episodic volcanic activities and hot spring occurrences, thereby providing a basis for assessing the environmental conditions during source rock formation in an evaporitic basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107323"},"PeriodicalIF":3.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386831","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":"Sabkha deposition on an epicontinental-foredeep: The petroleum-bearing Cane Creek interval of the Pennsylvanian Paradox Formation, in the Paradox Basin, Utah, U.S.A.","authors":"Elliot A. Jagniecki ,&nbsp;Michael D. Vanden Berg ,&nbsp;Lauren P. Birgenheier ,&nbsp;Scott M. Ritter ,&nbsp;Gregor Maxwell ,&nbsp;Dave List","doi":"10.1016/j.marpetgeo.2025.107320","DOIUrl":"10.1016/j.marpetgeo.2025.107320","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Pennsylvanian Paradox Formation in the northern fold and fault belt of the foreland Paradox Basin, southeastern Utah, contains 4th and 5th order cyclothems of closed basin halite salt packages (60–92 m thick) interbedded with intervals of evaporitic-carbonate-siliciclastic (n = ∼30 cycles, each &lt;36 m thick). The cyclothems record rhythmic high-stand and low-stand deposition in an epicontinental foredeep marine basin influenced by subsidence, arid subtropical climate, and sea level changes that created continental inlets on the edge of the Panthalassic Ocean. Here, we document evaporitic-carbonate-siliciclastic facies of the unconventional hydrocarbon Cane Creek interval, clastic cycle 21, from eight cored drillholes spanning a northwest to southeast transect that represent sabkha-type deposition of an ancient interior seaway. This interpretation is collective from several past studies, however, a comparative sedimentological approach for the origin of depositional textures provides a finer scale description of parasequences that internally contain meter-scale shallowing upward successions. The successions are both allocyclic and autocyclic related to marine transgressions and regressions within a restricted, tidally influenced, marine basin and associated with subtidal, intertidal, and supratidal paleoenvironments. The Cane Creek is informally divided into three distinct stratigraphic zones: from top to bottom A, B, and C zones. The A and C zones are composed of fabric-destructive and laminated anhydrite laths, dolomitic mudstone, and algal-laminated source rock mudstones (15–20 wt % total organic carbon), interpreted as prograded supratidal flats during marine regressions. Anhydrite textures vary from finely laminated needles with dolomitic mud drape couplets, upward directed syntaxial crystalline fabric draped by silty dolomitic mud, and nodular laths. Volumetrically, smaller proportions of anhydrite occur in the C zone in the northwest part of the basin attributed to tidal inlet dilution. Intraclastic mudstone lag deposits composed of compacted mudrock clasts overlay anhydrite beds and are interpreted as diachronous storm or subaqueous debris flow deposits. The middle B zone is primarily low-permeable muddy sandstone to siltstone (0.009–0.202 mD; porosity 6%–17%) that contains bidirectional lenticular ripples, slack water mud drapes, trace fossil burrows, diagenetic anhydrite-dolomite-quartz-halite cements, and interbeds of organic-rich mudstone, and stratigraphically thickens to the northwest. Siliciclastic supply is interpreted as being sourced by fluvial drainage from the Uncompahgre Ancestral Rocky Mountains uplift and eolian processes that later were reworked by tidal and storm processes. Source rock analysis of interbedded organic-rich mudstones within all zones are mixed type I and II (lacustrine and marine) with more fluvial detrital type III in the southern part of the basin. Thin interbedded organic-rich mudstones (c","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107320"},"PeriodicalIF":3.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143394243","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":"Development model of fracture-filling gas hydrates at the top of gas chimneys, the Songnan Low Uplift in Qiongdongnan Basin of the northern South China Sea","authors":"Tingwei Li ,&nbsp;Jinfeng Ren ,&nbsp;Zenggui Kuang ,&nbsp;Xiaoxue Wang ,&nbsp;Mengjie Xu ,&nbsp;Chenlu Xu ,&nbsp;Zhejun Pan","doi":"10.1016/j.marpetgeo.2025.107326","DOIUrl":"10.1016/j.marpetgeo.2025.107326","url":null,"abstract":"<div><div>Fracture-filling gas hydrates are consistently associated with gas chimneys; however, the causal mechanism remains unclear. The W07 orebody in the Songnan Low Uplift, located in the Qiongdongnan Basin of the northern South China Sea, was examined as a case study. By employing a combination of logging while drilling and seismic surveys, we aimed to elucidate the developmental model of fracture-filling gas hydrates within the structural context of gas chimneys and quantitatively assess the roles of the overlying strata and faults in the formation of leakage pathways. Gas of various origins migrates to the bottom of the gas hydrate stability zone through the gas chimney and subsequently flows laterally within the permeable sand strata. Pore-filling gas hydrates develop in the peripheral areas surrounding the gas chimney. The continuous accumulation of free gas in the central area leads to an increase in fluid pressure. Once the fluid pressure reaches the horizontal minimum principal stress, the overlying strata will undergo hydraulic fracturing, leading to the formation of a network of vertical hydraulic fractures that provide a pathway for the further upward migration of gas-bearing fluids. Fracture-filling gas hydrates form in high-angle cracks under appropriate temperature and pressure conditions. In terms of leakage, the overlying strata, with a minimum hydraulic pressure of 1.08 MPa, take precedence over the F07 fault, which has a minimum increment in fluid pressure of 1.12 MPa. Thus, the overlying strata, rather than the F07 fault, play a decisive role in the formation of leakage pathways.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107326"},"PeriodicalIF":3.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386840","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":"Improved representation of sub-wireline scale lithological heterogeneity in geological models","authors":"Achyut Mishra ,&nbsp;Seyed Ahmad Mortazavi ,&nbsp;Julie Dickinson ,&nbsp;Ralf R. Haese","doi":"10.1016/j.marpetgeo.2025.107322","DOIUrl":"10.1016/j.marpetgeo.2025.107322","url":null,"abstract":"<div><div>Siliciclastic reservoirs often comprise lithological heterogeneity at mm-to cm-scales in the form of fine laminations of intraformational baffles. Such heterogeneities enhance capillarity and are often enriched in clay minerals such as chlorites. These properties could significantly influence subsurface fluid flow and fluid rock reactions. However, these heterogeneities are difficult to represent in geological models primarily because they exist at a scale which is below the resolution of conventional wireline logs. This paper presents an approach for deducing such heterogeneities using a combination of core plug and wireline log data to derive rock types capturing variations in intraformational baffles. The rock types were further populated in geological models to honour a nested representation of heterogeneity ranging from seismic to core plug scale. We also present a new upscaling method to ensure that cm-scale discrete rock properties are not lost to averaging. The study shows that property models derived using the conventional geo-modelling approach could overestimate porosity by about 20–30% for the sections with cm-scale laminations. Additionally, wireline log derived permeability values were found to be inconsistent with heterogeneity in fine laminations as observed in core plugs. The proposed approach attempts to overcome this issue by upscaling permeability in a way that honours variations in intraformational baffles.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107322"},"PeriodicalIF":3.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378907","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":"Tight origin and hydrocarbon potential of shell interlayers in shale: A case of Lower Jurassic Dongyuemiao member, Sichuan Basin, China","authors":"Zhiyun Yu ,&nbsp;Benzhong Xian ,&nbsp;Zhenkui Jin ,&nbsp;Qianran Wu ,&nbsp;Yi Shu ,&nbsp;Haocheng Shi ,&nbsp;Junyang Geng ,&nbsp;Lin Zhao ,&nbsp;Yichen Liu","doi":"10.1016/j.marpetgeo.2025.107325","DOIUrl":"10.1016/j.marpetgeo.2025.107325","url":null,"abstract":"<div><div>Tight shell interlayers are widely distributed in global marine and lacustrine organic-rich shale successions, serving as key targets for reservoir prediction. However, the limited understanding of these interlayers presents challenges in characterising reservoirs and optimising hydrocarbon recovery in shell-rich shale formations. This study investigates the Lower Jurassic Dongyuemiao Member in the Sichuan Basin, Southwest China, using petrological, geochemical, and pore structure characterization techniques to differentiate shale from shell interlayers, and investigate the mechanisms underlying the tight properties of shell-rich interlayers. Results suggest that two shale lithofacies (e.g., laminated argillaceous shale and massive mixed mudstone) and two shell interlayer lithofacies (e.g., bedded-to-laminated shelly-bearing argillaceous mudstone and massive shell limestone) were identified. Porosity, permeability, and total organic carbon content of shale lithofacies are significantly higher than those of interlayer lithofacies. Special attention was therefore given to the analysis of sedimentary processes and diagenesis occurring in the two interlayer lithofacies. Shell interlayers were deposited by sediment gravity flows triggered by storm events. The two shell interlayers were considered the products of low-density turbidity currents and cohesive debris flows. Among the two shell interlayers, massive shell limestones exhibited the worst reservoir quality due to their fine mud-grade matrix compositions and non-lamellar textures. Differential compaction had a significant impact on the heterogeneous distribution of cements in interlayer lithofacies. Additionally, massive shell limestones experienced three distinct stages of cementation, including eogenetic calcareous cement and pyrite, and mesodiagenetic microquartz, which filled intergranular pores in the massive shell limestones and reduced reservoir quality. By contrast, the bedded-to-laminated shelly-bearing argillaceous mudstone also underwent three stages of cementation, comprising eogenetic pyrite, mesodiagenetic microquartz and ferroan calcite cement. However, close contact with black shales facilitated the development of dissolved pores within the lithofacies. Finally, based on sedimentary and diagenetic processes, tight models were established for different shell interlayers, making them applicable to other shell-rich shale successions for shale gas and oil exploration and production worldwide.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107325"},"PeriodicalIF":3.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403081","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 of the Cretaceous-Paleogene carbonate breccia, Cantarell, Mexico: Evidence from geochemical proxies","authors":"Juan Manuel León-Francisco ,&nbsp;Karem Azmy ,&nbsp;José Manuel Grajales-Nishimura ,&nbsp;Joel Rosales-Rodríguez","doi":"10.1016/j.marpetgeo.2025.107301","DOIUrl":"10.1016/j.marpetgeo.2025.107301","url":null,"abstract":"<div><div>The Cretaceous-Paleogene (K-Pg) carbonate breccia in the Cantarell Field, Gulf of Mexico, consists of a fining-upward succession of breccias capped by an ejecta-rich seal layer. Petrographic analyses (cathodoluminescence, SEM, fluid inclusion microthermometry) and geochemical data (stable isotopes, elemental, trace elements) reveal a complex sequence of diagenetic processes that significantly impacted reservoir quality.</div><div>The breccia shows the highest porosity (∼9.4%) at the base of succession, decreasing upward. Six carbonate phases were identified including lime mudstone (C1), late blocky calcite (C2, 350 μm‒15 mm, concentric CL zoning), early replacement dolomite (D1, &lt;50 μm, bright to dull CL), medium to coarse replacement dolomite (D2, 50–155 μm, cloudy cores with bright CL and clear rims with dull CL), planar-e dolomite cement (D3a, 80–180 μm), and saddle dolomite (D3b, 450–950 μm) with undulose extinction and CL zoning.</div><div>Trace element data provide clues about the fluid chemistry evolution. The low Sr content of D1 (94 ± 18 ppm), combined with its near-micritic grain size and the estimated δ¹⁸O values of the parent dolomitizing fluid (−4.9‰ to 0.3‰ SMOW), suggest an early-stage dolomitization at low temperatures of near-surface conditions that was driven by a mixture of meteoric and seawater. The Sr contents decrease from D1 to D2 (78 ± 19 ppm), suggesting progressive burial, which is supported by the relative decrease in δ¹⁸O values (D1 = −0.3 ± 1.8‰ VPDB; D2 = −4.3 ± 2.7‰ VPDB). The increase of [Sr] in D3a (265 ± 238 ppm) followed by a decrease in D3b (108 ± 40 ppm) correlates with tectonic uplift and subsequent burial. The δ¹³C values of D3b and δ¹⁸O values reflect higher fluid-rock interaction during deeper burial, supported by high T_<em>h</em> values (105.7 ± 7.7 °C).</div><div>The shale-normalized REE patterns show that those of D1 and D2 mimic that of modern seawater and almost coincide with the C1 pattern, which suggests that C1 was likely the precursor. In contrast, the later phases (C2, D3a, D3b) show very low HREE concentrations, attributed to high fluid-rock interaction during tectonic uplift. This study of the K-Pg carbonate breccia provides a better understanding of its dynamic diagenetic history, shaped by fluid flow and tectonics, which critically influenced porosity and reservoir quality.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107301"},"PeriodicalIF":3.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143373009","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":"A general model for the compression of mudrocks","authors":"C. Emre Uyeturk,&nbsp;John T. Germaine","doi":"10.1016/j.marpetgeo.2025.107327","DOIUrl":"10.1016/j.marpetgeo.2025.107327","url":null,"abstract":"<div><div>Axial effective stress dependency of void ratio (or porosity) of a mudrock is described by the compression curve. Traditionally, this relationship has been linearized in the field of soil mechanics by plotting void ratio against the logarithm of axial effective stress. Various empirical compression models have been developed to describe this relationship, each linearizing the behavior in different spaces and fitting mathematical equations to the data. The relative accuracy and applicability of these models vary based on the mineralogy and texture of the mudrock, and no single model is suitable for all mudrocks. In this study, we propose a new empirical model that can describe the stress dependency of void ratio irrespective of mudrock lithology. The model is smooth, continuous, and differentiable; hence, it can be used to capture the stress dependency of the compression index (i.e., the slope of the curve). We validate the model using three distinctly different mudrocks covering the main types of compression behavior observed in decades of laboratory testing. We then compare the performance of the proposed model with existing models. Our findings demonstrate that the proposed model is able to capture the full spectrum of compression behaviors exhibited by mudrocks and provides statistically superior fits compared to existing models in the literature.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107327"},"PeriodicalIF":3.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143394245","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":"Laminae in multiple lithofacies and impact on pore structures in lacustrine shale: The cretaceous qingshankou formation, Songliao Basin","authors":"Jialin Wan ,&nbsp;Zhichao Yu ,&nbsp;Yujie Yuan ,&nbsp;Mengdi Sun ,&nbsp;Wenhui Huang ,&nbsp;Reza Rezaee","doi":"10.1016/j.marpetgeo.2025.107321","DOIUrl":"10.1016/j.marpetgeo.2025.107321","url":null,"abstract":"<div><div>Unconventional lacustrine shale oil reservoirs are characterized by strong heterogeneity of pore structures and intensive lithofacies variations in the vertical direction. This study systematically investigated the pore systems and factors influencing pore structures for the first member of the Cretaceous Qingshankou Formation (Qing 1 member) in southern Songliao Basin, employing geochemical, mineralogical, petrological, and petrophysical methods. Nine lithofacies types were identified based on total organic carbon <em>(TOC)</em> content-laminae structure-mineral composition. Organic-medium mixed lithofacies with silt-laminated structures were the most favorable in the Qing 1 shale, exhibiting dominant pore volume, exceptional connectivity, and significant movable oil content. Shale reservoirs were primarily controlled by interparticle pores and microfractures, with mesopores as the dominant reservoir space. Thick argillaceous laminae followed a \"primary source and reservoir rock\" model at the microscale, whereas \"oil generation-migration-accumulation\" in silt-laminated shale played a key role in pore system development. In the Qing 1 shale at the medium maturity stage, <em>TOC</em> content negatively impacted storage space due to asphalt blocking pores. Due to the in situ deposition of authigenic minerals and dissolved components, felsic minerals also negatively effected pore volume. Moreover, shales developed a significant number of pores associated with clay minerals to enhance reservoir space. Furthermore, an optimal balance of felsic minerals in the argillaceous laminae alleviated compaction. These findings enhance our understanding of pore formation mechanisms for lacustrine shale reservoir, which is crucial for accurately assessing shale oil resources.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"174 ","pages":"Article 107321"},"PeriodicalIF":3.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143386842","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}