Marine and Petroleum Geology最新文献

{"title":"The Guajira contourite depositional system along the northern Colombian Caribbean convergent margin","authors":"J. Naranjo-Vesga ,&nbsp;O. Mantilla ,&nbsp;D. Rincón-Martínez ,&nbsp;E. Rodriguez-Rubio ,&nbsp;A. Ortiz-Karpf ,&nbsp;C. Winter ,&nbsp;Y. Rojas-Agramonte","doi":"10.1016/j.marpetgeo.2025.107556","DOIUrl":"10.1016/j.marpetgeo.2025.107556","url":null,"abstract":"<div><div>Bottom currents have a significant role in the transport, erosion and deposition of sediments. They also have the power to modify the seabed morphology. Contourite depositional systems have been reported worldwide, mainly in passive margins; with few examples reported at convergent margins. This study uses regional multibeam bathymetry and seismic data, to document for the first time a∼20,000 km² slope contourite depositional system along the upper continental slope of the northern Colombian Caribbean convergent margin. We compare the characteristics of the slope geomorphology with hydrodynamic modeling of the bottom currents. We identified on the upper slope, close to the shelf edge, the presence of erosional terraces and moats over an area of∼2,700 km². Near this sector, the modelled ocean currents can reach speeds of up to∼10 cm/s. However, the bottom currents have a high degree of variability, and low values of∼1 cm/s are also identified over the terraces; this may suggest that erosion can occur when the currents reach their highest speeds of circulation. Therefore, the erosion is neither homogeneous nor continuous along the slope. On the other hand, the plastered drift and sediment wave fields related to sediment accumulation have low current velocities between∼1 - 5 cm/s, and they cover a large area of the upper slope (∼17,600 km²), suggesting that sediment accumulation may occur in areas where bottom currents have low velocities. The plastered drift thickness also shows high variability in the study area. The major thicknesses of∼785 ms (or ± 800 m) are related to a gentle slope topography (&lt;2°). In contrast, the lowest thicknesses of∼300 ms (or ± 300 m) are identified in areas with steep slope topography (&gt;2–5°), indicating that in gently slope topography (&lt;2°) plastered drift deposits have a greater thickness. This work allows us to characterize for the first time a regional slope contourite depositional system along the northern Colombian Caribbean margin and highlights the influence of bottom current strength and slope gradient topography in controlling the erosion and preferential accumulation of sediments in an active margin with low sediment supply. This mode of occurrence may be characteristic of contourite depositional system development on convergent margins with low fluvial sediment discharge worldwide.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107556"},"PeriodicalIF":3.7,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144654850","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":"The sedimentary provenance of Upper Miocene Dongfang submarine fan, Yinggehai Basin: source-to-sink system unravelled through new detrital zircon U-Pb ages and heavy mineral analysis","authors":"Xingzong Yao ,&nbsp;Congjun Feng ,&nbsp;Wei Zhou ,&nbsp;Pengfei Wu ,&nbsp;Hongjun Qu ,&nbsp;Jiahao Lei ,&nbsp;Zhiqiang Chen ,&nbsp;Yanlong Ge ,&nbsp;Mengsi Sun","doi":"10.1016/j.marpetgeo.2025.107557","DOIUrl":"10.1016/j.marpetgeo.2025.107557","url":null,"abstract":"<div><div>The Upper Miocene Dongfang submarine fan, developed in the Yinggehai Basin, is considered one of the most valuable reservoirs in the northern South China Sea. However, the provenance of the fan remains a controversy between the Red River drainage area and Central Vietnam, hindering hydrocarbon exploration in the basin. In this study, heavy mineral analysis and detrital zircon geochronology of samples from the Upper Miocene intervals in four boreholes were conducted for provenance analysis of the fan. The occurrence of Cr-spinel and high leucoxene contents (34.3 %–85.9 %) in heavy mineral assemblages from these wells suggest sediment contributions from the Red River drainage area and Central Vietnam. Detrital zircon grains from the fan exhibit a wide U-Pb age range, including Luliangian, Jinningian, Caledonian, Indosinian, Yanshanian, and Himalayan populations. Multidimensional scaling (MDS) robustly supports a dual-provenance model consisting of the Red River drainage area and Central Vietnam. Furthermore, we propose that the Red, Ma, Lam, Gianh, and Ben Hai rivers served as sediment pathways owing to the similarities in zircon age distributions between the fan and modern drainage systems. Unmixing models employing the Kolmogorov-Smirnov (K-S) test D statistic quantify the relative source contributions, indicating a potential internal evolution of the fan. Among these, the Red River drainage area dominated the samples D132h and D1310h, accounting for 94.3 % and 86 % of detritus, respectively. Central Vietnam predominantly contributed 99.5 % of sediments to the sample D134h. For the sample D136h, 45.7 % of sediments were derived from the Red River drainage area and 54.3 % from Central Vietnam. The reconstruction of the source-to-sink system reveals that the global forcings (the uplift of the Tibetan Plateau, the expansion of Antarctic ice sheets) and regional adjustments (the intensification of East Asian monsoon, the reversal of Red River Shear Zone) collectively controlled the formation and development of Dongfang submarine fan. Specifically, the activity on the Red River Shear Zone destabilized the deltaic sediments along the western margin of Yinggehai Basin, generating sediment gravity flows that accumulated in the depocenter and formed the Dongfang submarine fan. The source-to-sink system model may provide valuable insights into the prediction of Upper Miocene reservoirs and guides the future hydrocarbon exploration in the basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107557"},"PeriodicalIF":3.7,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633923","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":"Isotopic equilibrium constraints on CO2 dissolution and carbon isotopic reversal in a thermogenic coalbed gas system associated with the Zhuzang syncline, Guizhou, China","authors":"Xiangrui Chen ,&nbsp;Yunpeng Wang ,&nbsp;Mingxin Tao ,&nbsp;Zheng Zhou ,&nbsp;Meng Wei","doi":"10.1016/j.marpetgeo.2025.107554","DOIUrl":"10.1016/j.marpetgeo.2025.107554","url":null,"abstract":"<div><div>Natural gas is a vital energy resource. The isotopic composition of natural gas plays a critical role in understanding its origin, thermal maturity, and secondary alteration. Both kinetic and equilibrium isotopic fractionations have been observed in various natural gas systems. However, the dominant mechanism (either equilibrium or kinetic) that controls the isotopic compositions of the primary natural gas is still unclear. Coalbed gas (CBG), formed and stored in situ coalbeds, is an ideal natural gas for studying this key issue. We collected CBG and coproduced water samples from the Zhuzang syncline in China. This study shows that the CBG is an over-mature thermogenic gas formed during the Yanshanian orogeny. The CH₄-C₂H₆-CO₂ system was likely near carbon isotope equilibrium during the CBG formation. However, later alterations, such as meteoric water recharge, CO₂ dissolution, and CBG recovery led to obvious isotopic disequilibrium of the CH₄-C₂H₆-CO₂-DIC (dissolved inorganic carbon) system. Carbon isotope reversals (δ¹³C_CH4 &gt; δ¹³C_C2H6) were observed in the CBG samples, resulting from decreasing δ¹³C_C2H6 values after CBG formation. Based on isotopic equilibrium, the δ¹³C values of the primary ethane were estimated. Some hypotheses often used to explain isotope reversals in natural gas cannot explain the isotope reversals of the CBG samples. We propose that the CBG recovery process led to more negative δ¹³C_C2H6 and thus δ¹³C_CH4 &gt; δ¹³C_C2H6. Model-estimated 53–99 % CO₂ generated during thermogenic or microbial CBG formation has dissolved into coalbed water to become DIC. Hence, dissolution trapping is an important mechanism for CO₂ storage in coalbeds over geological timescales. This study implies that isotopic equilibrium fractionation plays a vital role in understanding the primary geochemical composition and secondary alteration of CBG.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107554"},"PeriodicalIF":3.7,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144614855","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":"Sequence stratigraphic and reservoir modeling of KOC Field onshore Niger Delta Basin: implication for mature oilfield revitalization","authors":"Amoke Aniebonam Ignatius ,&nbsp;Ayonma Wilfred Mode ,&nbsp;Ikechukwu Onyema Njoku ,&nbsp;Eze Martins Okoro","doi":"10.1016/j.marpetgeo.2025.107553","DOIUrl":"10.1016/j.marpetgeo.2025.107553","url":null,"abstract":"<div><div>Recently, the exploration focus in the onshore areas of the Niger Delta Basin has been targeted towards extending the economic viability of “shallow hanging” producing reservoir units whilst searching wider and deeper for new oil and gas pools beyond known depths. The need therefore arises to deploy improved technologies for accurate mapping of prospect opportunities located at intermediate and deeper intervals within the basin. In this study, integrated sequence stratigraphic and reservoir modeling of the KOC Field onshore Niger Delta Basin was carried out using well logs, 3D seismic, and biostratigraphic data to assess the hydrocarbon potentials and also uncover the reservoir geometry, stratigraphic configuration, and structural framework of the study area. Logging and biofacies information from seven (7) wells, as well as key stratal surfaces including three (3) sequence boundaries (SB) and three (3) maximum flooding surfaces (MFS) provided in Well 001 and Well 039, formed the basis for chronostratigraphic correlation across the field. Two genetic sequences bounded at the top and base by maximum flooding surfaces were mapped and designated as Genetic Sequence 1 (G_SEQ1) and Genetic Sequence 2 (G_SEQ2). Three main stacking patterns (progradational, retrogradational and aggradational) interpreted as Lowstand Systems Tract (LST), Highstand Systems Tract (HST) and Transgressive Systems Tract (TST) were delineated from each of the identified genetic sequences. Lithological correlation of the wells revealed two hydrocarbon-bearing sand units with good reservoir quality characteristics. These reservoirs designated as R12 Sand and R15 Sand belonged to the LST and TST of G_SEQ2, and were interpreted to be basin floor fans and channel fill complexes, deposited within the neritic to bathyal environments. 3D geological modelling of the reservoirs showed good structural closures with thick sedimentary packages, suggesting that they are good locations for hydrocarbon accumulation. The major faults constitute good reservoir seals due to stratigraphic juxtapositions that may have prevailed in the cause of the dip slip movement.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107553"},"PeriodicalIF":3.7,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662041","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":"Genesis and developmental pattern of Middle Permian dolomite in Northwestern Sichuan, China","authors":"Zhidian Xi ,&nbsp;Fei Huo ,&nbsp;Huachuan Jiang ,&nbsp;Xingzhi Wang ,&nbsp;Huiwen Huang ,&nbsp;Yuhan Huang ,&nbsp;Yi Hu ,&nbsp;Xueyan Wu ,&nbsp;Yang Li ,&nbsp;Wenli Xu ,&nbsp;Anqing Chen","doi":"10.1016/j.marpetgeo.2025.107555","DOIUrl":"10.1016/j.marpetgeo.2025.107555","url":null,"abstract":"<div><div>The formation of large-scale dolomite reservoirs in the Middle Permian of Northwest Sichuan shares a good temporal correlation with the occurrence of major events in the Emeishan Large Igneous Province (ELIP). However, because the dolomitized fluids, the timing of dolomitization and the genesis mechanism of the dolomites are not comprehensively understood, its developmental pattern requires further analysis. This paper identified the diagenetic fluids of different types of dolomites via petrological characteristics of dolomites, carbon and oxygen isotopes, strontium isotopes, and other geochemical data, as well as fluid inclusions and laser U-Pb isotope dating. The dolomite genesis model related to the dynamical formation mechanism of the ELIP was also reconstructed. The Middle Permian dolomites in Northwest Sichuan are divided into matrix dolomite (Md) and cement dolomites (Cd). Importantly, the matrix dolomites include very finely to finely crystalline matrix dolomite (Md1), finely to medium crystalline matrix dolomite (Md2), and medium to coarsely crystalline matrix dolomite (Md3). The dolomites were primarily modified by three phases of dolomitizing fluids. The Md1 phase yields a U-Pb age of 262 ± 9.2 Ma, consistent with the host stratigraphic age, and exhibits ⁸⁷Sr/⁸⁶Sr ratios matching Permian seawater values. These features indicate Md1 formed dominantly through penecontemporaneous seawater reflux dolomitization. In contrast, the Md2 phase shows a U-Pb age of 261.3 ± 7.4 Ma—also stratigraphically consistent—but contains later-stage subsurface cements with a distinct U-Pb age of 245.7 ± 1.9 Ma. This significant age offset demonstrates that Md2 resulted from overprinting by multiple dolomitizing fluid phases. These fluids were mainly formed owing to the temperature difference between the warming stratigraphic water and the cold seawater in the ELIP under the geothermal warming effect. The cold seawater on the slope creates a fluid potential energy difference, generating lateral open circulation and causing thermal convection. Furthermore, Md3 and Cd have negatively skewed δ¹⁸O values, along with higher Th and Eu/Eu∗ values, suggesting that the diagenetic fluids were substantially shallow buried strata water, which resembled Permian seawater. They were mostly produced under the higher geothermal temperatures during the ELIP active period, which generated a substantial fluid potential energy difference, and were driven by a more rapid thermal convection cycle. This study quantitatively constrains the timing of dolomitization using laser U-Pb isotope dating, aiming to give a reliable and valuable reference for the impact of tectonic activities on dolomite genesis caused by the Large Igneous Province.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107555"},"PeriodicalIF":3.7,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633914","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 organosulfur compounds during natural and artificial maturation","authors":"Poorna Srinivasan ,&nbsp;Constantin Sandu ,&nbsp;Estefania M. Endara Arguello ,&nbsp;Ibrahim Atwah","doi":"10.1016/j.marpetgeo.2025.107541","DOIUrl":"10.1016/j.marpetgeo.2025.107541","url":null,"abstract":"<div><div>Hydrous pyrolysis techniques are valuable for understanding and quantifying petroleum yield, thermal maturity, compositional variations, and kinetics across different kerogen types. Such data is essential for basin modeling and well planning. Previous studies have shown that sulfur-rich Type II-S kerogen generates hydrocarbons at lower temperatures due to its lower activation energy, resulting in early cracking. Consequently, organosulfur presents a challenge in numerous basins worldwide, as sulfur-rich source rocks from various regions must be examined closely to accurately predict hydrocarbon generation in each basin. Additional factors, such as total organic carbon content and mineralogy, also influence the timing and yield of oil generation. Methyldibenzothiophene isomers have proven to be reliable maturity indicators in sulfur-rich source rocks, often providing more accurate maturity predictions than biomarkers at higher maturity levels. However, few studies have closely examined the compositional and isomeric changes of alkylated methyldibenzothiophene compounds under hydrous pyrolysis conditions. In this study, hydrous pyrolysis experiments were conducted on three sulfur-rich source rocks and one sulfur-rich crude oil at temperatures between 275 and 360 °C to monitor and quantify changes in alkylated MDBT compounds as well as other aromatic hydrocarbons. The results were compared to four naturally matured Type II-S source rocks, spanning the immature to condensate windows, to evaluate the effects of hydrous pyrolysis on aromatic compounds. Significant differences in thermal maturity parameters were observed in the kerogen, bitumen, and expelled oil. While the increase in the 4-MDBT/1-MDBT ('MDR') ratio provided consistent thermal maturity estimates in natural samples, the hydrous pyrolysis experiments revealed that these geochemical markers are inconsistent under artificial thermal conditions, potentially due to additional sulfur species forming in the reactor, buffering reactions in the closed system reactor, the limited temperature range of the experiments, or other matrix-controlled interactions that are found in nature but are not occurring in the reactor. In contrast, aromatic biomarkers such as triaromatic steroids showed a positive increase in their isomer ratios relative to the experimental run temperature. The chemical differences between these organosulfur-rich samples (e.g., TOC, hydrogen index, mineralogy) suggest that the original source material—not solely the sulfur content—plays a critical role in the kinetics of alkylated dibenzothiophene compounds.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107541"},"PeriodicalIF":3.7,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144654697","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":"Cenomanian channel system evolution of Mundaú Sub-basin deepwater, Brazilian Equatorial Margin: Reservoir characterization using machine learning techniques","authors":"Ian de Oliveira Souza Cerdeira ,&nbsp;Karen Maria Leopoldino Oliveira ,&nbsp;Jorge de Jesus Picanço Figueiredo ,&nbsp;Heather Bedle ,&nbsp;Narelle Maia de Almeida ,&nbsp;Ana Clara Braga Souza","doi":"10.1016/j.marpetgeo.2025.107540","DOIUrl":"10.1016/j.marpetgeo.2025.107540","url":null,"abstract":"<div><div>Submarine channel systems have garnered significant attention in recent years due to their importance in petroleum exploration and favorable reservoir characteristics. Specifically, the Brazilian Equatorial Margin basins have attracted considerable interest from various sectors because of substantial hydrocarbon discoveries in adjacent basins. In the Mundaú Sub-basin (Ceará Basin, NE Brazil), recent studies have identified a series of sand-rich structures associated with a Cenomanian submarine channel system. However, despite these advancements, the depositional elements, sedimentary architecture, and stratigraphic sequences remain poorly understood. This paper aims to integrate robust quantitative geophysical techniques, including unsupervised machine learning methods, multi-attribute analysis, and RGB blending, to clarify the main evolutionary stages of the Cenomanian submarine channel-lobo system in the central portion of the aforementioned Sub-basin and their controlling factors. We utilized data from four exploration wells drilled in the deep waters of the Mundaú Sub-basin, along with a 2200 km² seismic volume covering the study area. Our integrated approach identified three main evolutionary stages. The first stage is characterized by straight to low-sinuosity confined channels on the upper to middle slope, alongside poorly confined channels and splays on the lower slope to basin floor, primarily comprising sand-prone layers developed during a Falling Stage System Tract. The second stage exhibits low to moderate sinuosity confined channels in the upper to middle slope, with significantly poorly confined channels and splays on the lower slope to basin floor, also dominated by sand-prone layers developed in a Lowstand Tract System. The final stage features a high-sinuosity confined channel with dominant sand-prone and sand/mud-prone layers developed in a Transgressive System Tract. all stages and across almost the whole region, sand-prone and sand/mud-prone facies were identified and associated with various depositional elements at different scales. the presence of sand-prone layers in all stages is thought to result from high-density turbidity currents driven by a narrow shelf and stepped slope. The mapped features and predicted facies indicate an unexplored area with sand-rich layers likely possessing good lateral and vertical connectivity. Important structures that may facilitate oil migration were identified, highlighting the high exploration potential of the Cenomanian submarine channel system in the Mundaú Sub-basin.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107540"},"PeriodicalIF":3.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604136","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":"Reconstructing hydrocarbon accumulation and burial history of Permian reservoirs in northwest Sichuan Basin, China: Integrated fluid inclusion thermometry and U-Pb dating","authors":"Rui Ni ,&nbsp;Yong Chen ,&nbsp;Yifan Song ,&nbsp;Hui Zhang ,&nbsp;Yanwei Feng ,&nbsp;Fang Hao ,&nbsp;Xuesong Lu ,&nbsp;Xingzhi Ma","doi":"10.1016/j.marpetgeo.2025.107539","DOIUrl":"10.1016/j.marpetgeo.2025.107539","url":null,"abstract":"<div><div>The western Sichuan basin is a typical foreland basin, and great discovery of oil and gas exploration has been done here, but the history of hydrocarbon accumulation and burial history evolution is still uncertain. Fluid inclusion thermometry and isotopic dating are employed in this study to reconstruct the burial history and hydrocarbon accumulation of the Western Sichuan Foreland Basin. Furthermore, research was conducted research on the diagenesis, reservoir-forming stages and differences of the Qixia Formation reservoirs at different tectonic locations in the northwest of Sichuan. The results show that in the Shuangyushi area (concealed front-edge belt), the upper reservoirs of the Qixia Formation are mainly composed of sparry dolomitic limestone, with a diagenesis mineral sequence of: (1) the early microcrystalline calcite, (2) recrystallized calcite, (3) quartz, albite, pore bitumen in the surrounding rock, and (4) dolomite and calcite in fractures. In the Longmen Mountain piedmont area (thrust nappe belt), the outcrop rock of the Qixia Formation is mainly dolomitic limestone, with a diagenesis mineral sequence: (1) microcrystalline calcite, (2) recrystallized calcite, (3) quartz and bitumen, and (4) calcite filled in both pores and fractures. In the Shuangyushi area, the reservoirs of the Qixia Formation underwent crude oil charging from the Middle Triassic to Middle Jurassic, subsequent natural gas charging in the Late Cretaceous, and final natural gas reservoir destruction and adjustment at Late Cretaceous (81.2 ± 8.4 Ma). While, the outcrop of the Qixia Formation in the Longmen Mountain piedmont area recorded oil charging from the Lower Cambrian source rocks at Late Triassic (217.1 ± 0.9 Ma) and the destruction of oil reservoirs during the Miocene to Pleistocene (i.e., Himalayan orogeny). By comparing the petrological characteristics, fluid inclusion development and reservoir-forming periods of the two areas, it is considered that these disparities arise from the areas’ distinct tectonic positions within the foreland basin, leading to divergent responses to the Indosinian and Himalayan orogeny, as well as the resulting hydrocarbon accumulation processes.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107539"},"PeriodicalIF":3.7,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604137","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":"Porosity estimation using deep learning and ImageJ: Implications for reservoir characterization in Central Luconia Miocene carbonates","authors":"Abdulrahman Danlami Isa ,&nbsp;Haylay Tsegab Gebretsadik ,&nbsp;Abdulrahman Muhammad ,&nbsp;Hassan Salisu Mohammed ,&nbsp;Ibrahim Muhammad Kurah ,&nbsp;Adamu Kamaliddeen Salisu","doi":"10.1016/j.marpetgeo.2025.107538","DOIUrl":"10.1016/j.marpetgeo.2025.107538","url":null,"abstract":"<div><div>Accurate porosity prediction is essential for effective reservoir characterisation, particularly in heterogeneous carbonate systems. This study investigates applying deep learning techniques to predict porosity from petrographic thin-section images of Miocene carbonate reservoirs in Central Luconia, offshore Malaysia. Four semantic segmentation models—UNet, SegNet, PSPNet, and Fully Convolutional Network (FCN)—were trained and evaluated, with UNet achieving the highest performance across all metrics: accuracy (0.990), precision (0.849), recall (0.940), F1 score (0.892), and Intersection over Union (IoU) (0.805). These results were benchmarked against traditional image analysis using ImageJ, where UNet predictions showed strong alignment, highlighting its reliability. SegNet also performed robustly, while PSPNet and FCN demonstrated lower predictive accuracy. The study further explored the impact of data augmentation, revealing performance degradation in SegNet and PSPNet due to distortion of micropore structures. A classification scheme based on UNet output identified porosity ranges, with 71.90 % of samples exhibiting &lt;5 % porosity, reflecting a low-porosity-dominated system. A spatial porosity distribution map was also generated using UNet to visualise heterogeneity across thin-section samples. It is important to note that this map is a conceptual representation and does not reflect the actual porosity distribution of the broader reservoir. Instead, it serves as a hypothetical visualisation to enhance understanding of porosity characteristics and heterogeneity within the analysed thin-section images. This work demonstrates the advantages of deep learning over conventional techniques for pore-scale analysis. It offers a scalable framework for integrating artificial intelligence in quantitative reservoir quality assessment.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"182 ","pages":"Article 107538"},"PeriodicalIF":3.7,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144571261","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":"Differential diagenetic controls on petrophysical heterogeneity of lacustrine beach-bar tight sandstones: Insights from the Boxing Sag, eastern China","authors":"Cunfei Ma ,&nbsp;Haowen Song ,&nbsp;Yuqi Wu ,&nbsp;Xiaopeng Cao ,&nbsp;Haicheng Liu ,&nbsp;Huafeng Zhang ,&nbsp;Yong Fu ,&nbsp;Wei Wang ,&nbsp;Chao Huang ,&nbsp;Xianxu Fang","doi":"10.1016/j.marpetgeo.2025.107537","DOIUrl":"10.1016/j.marpetgeo.2025.107537","url":null,"abstract":"<div><div>The Bohai Bay Basin is rich in petroleum resources, and the lacustrine beach-bar tight sandstone facies in the upper part of the fourth Member of the Paleogene Shahejie Formation (Es4s) of the Boxing Sag is a key exploration target. However, the heterogeneity in petrophysical properties caused by differential diagenesis during burial impacts its development. In this study, an integrated approach is used that includes core and thin section descriptions, scanning electron microscopy (SEM), carbon and oxygen isotope analysis, fluid inclusion analysis, rock physical properties, and high-pressure mercury injection analyses to investigate the differential diagenesis of the beach-bar tight sandstone reservoirs and its effects on petrophysical heterogeneity. Key findings include: (1) The sequence of diagenetic evolution of the reservoirs is: mechanical compaction and spherical pyrite cementation → calcite and dolomite cementation → feldspar dissolution, authigenic kaolinite precipitation, and quartz overgrowth → ferro-calcite and ankerite cementation → secondary dissolution and quartz overgrowth → late agglomerate pyrite cementation, reflecting alternating alkaline and acidic diagenetic environments. (2) Mechanical compaction and cementation are the dominant factors responsible for the reduction in reservoir quality. (3) Four distinct diagenetic facies are identified: an intense compaction with intergranular dissolution diagenetic facies (DF-I), an intense compaction with residual intergranular porosity diagenetic facies (DF-II), a weak-moderate compaction with intergranular cementation diagenetic facies (DF-Ⅲ), an intense compaction with matrix occlusion diagenetic facies (DF-Ⅳ). DF-I and DF-II exhibit superior reservoir quality (porosity &gt;10 %, permeability &gt;0.1 mD), making them effective reservoirs. (4) The genesis and spatial distributions of these facies are controlled by the petrological structure, petrographic composition, sand-mud interface, mudstone thickness, and distance from oil-source faults. By integrating multiple factors, this study elucidates the genetic mechanisms of the four diagenetic facies and establishes their vertical distribution patterns. This provides a basis for predicting favorable reservoir distribution and guiding future exploration.</div></div>","PeriodicalId":18189,"journal":{"name":"Marine and Petroleum Geology","volume":"181 ","pages":"Article 107537"},"PeriodicalIF":3.7,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144572714","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}