Journal of Petroleum Geology最新文献

{"title":"Reservoir Characteristics and Main Controlling Factors of the Permian Maokou Formation Carbonates in the Southern Sichuan Basin","authors":"Xiaoyan Fu,&nbsp;Dongfan Yang,&nbsp;Wei Xu,&nbsp;Tao Li,&nbsp;Wenjun Luo,&nbsp;Tianjun Huang,&nbsp;Puwei He,&nbsp;Yun Liu","doi":"10.1111/jpg.70084","DOIUrl":"https://doi.org/10.1111/jpg.70084","url":null,"abstract":"<div>\u0000 \u0000 <p>The carbonate reservoir of the Permian Maokou Formation (MF) in the southern Sichuan Basin represents a key target for regional hydrocarbon exploration. However, current understanding of its reservoir characteristics and controlling factors remains insufficient. To address this knowledge gap, a systematic study was conducted using a suite of analytical techniques, including scanning electron microscopy, 3D computed tomography scanning, nuclear magnetic resonance, whole-core porosity and permeability measurements, carbon–oxygen isotope analysis, and rare-earth element analysis. Research findings indicate that the reservoir lithology of the MF in southern Sichuan is relatively uniform, dominated by sparry bioclastic-algal limestone with local development of micritic limestone. Microscopic analysis reveals that the reservoirs are dominated by dissolution pores, microfractures, and intercrystalline pores/fissures within the powder-crystal calcite. The pore system in the study area is predominantly composed of micropores and mesopores, accompanied by minor macropores and nanopores. It features relatively low effective porosity and generally poor pore-throat connectivity. Reservoir development is jointly controlled by Permian-aged faults and epigenetic karstification. High-quality reservoirs are mainly isolated fracture-cavity reservoirs, primarily developed in paleo-slopes and paleo-highlands. This study can provide exploration guidance for analogous isolated or poorly connected carbonate reservoirs globally, offer reliable technical approaches for hydrocarbon production and development, and improve overall exploration efficiency.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1255-1269"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unconventional Lower Middle Jurassic Source Rock Evaluation Prospects in the Indus Basin, Pakistan: An Integrated Petrographic, Geochemical, and Maturity Modeling Investigation","authors":"Fahad Ali,&nbsp;Nazan Yalcin Erik,&nbsp;Shiqi Zhang,&nbsp;Douaa Fathy,&nbsp;George Kontakiotis","doi":"10.1111/jpg.70073","DOIUrl":"https://doi.org/10.1111/jpg.70073","url":null,"abstract":"<div>\u0000 \u0000 <p>The fluvial-dominated deltaic to shallow marine depositional systems were studied by utilizing integrated approach of organic and inorganic geochemistry and petroleum system modeling (PSM). Employing an integrated approach encompassing through scanning electron microscopy (SEM), x-ray diffraction analysis (XRD), I D maturity modeling, vitrinite reflectance (VRr%), total organic contents (TOC%), and rock–eval analysis (RE), with techniques used for volumetric calculation in the current study, sheds light on the region's hydrocarbon generation potential. The TOC% in the Lower Jurassic rocks is 1.10%–7.45%, and in the Middle Jurassic, it is 1.06%–5.43%, having II and III kerogens from cross-plots, that is, RE temperature (<i>T</i>_max) versus productive index (PI) and <i>T</i>_max versus hydrogen index (HI). The VRr% is 0.97%–1.53%, demonstrating that the mature unconventional oil prospects and falls in oil-to-wet gas window. The PSM demonstrates that petroleum generation from the studied succession was started during the Late Cretaceous to Paleocene era for Jurassic and Cretaceous source rocks inferred from burial history, indicating the economic viability of unconventional prospect. Although the combined use of geochemistry and stratigraphy determined the values of the original old total organic contents (TOC_o, i.e., 2.39 and 1.69) and old HI (HI_o, i.e., 282 and 251) in the Upper Indus Basin (UIB) as well as TOC_o (3.07) with HI_o (625) in Lower Indus Basin (LIB) were used for the volumetric calculations. Besides the good values of TOC, TOC_o, kerogen subtypes, RE parameters, I D maturity modeling, and VRr%, the XRD and SEM analyses indicated good suitability for fracability under hydraulic stimulation. However, the oil shale potential of the studied strata shows a good correlation with the People's Republic of China, the United States (US), and Canada primarily based on criteria of depositional setting, TOC%, VRr%, and mineralogy. The key comparative indicators of oil shale potential in Indus Basin with international cases are TOC% &gt;1, VRr% &gt;0.6, and shale thickness &gt;30 m with characteristics of mineral composition supportive of brittle features.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1123-1141"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Blast Penetration Behavior and Blast-Induced Fracturing in Liquid Nitrogen–Modified Coal: Experimental Characterization and LS-DYNA Numerical Modeling","authors":"Zhongqiu Liang,&nbsp;Wei Guo,&nbsp;Tingrong Wang,&nbsp;Qiaojun Chen,&nbsp;Shipeng Xue,&nbsp;Jianhong Kang","doi":"10.1111/jpg.70067","DOIUrl":"https://doi.org/10.1111/jpg.70067","url":null,"abstract":"<div>\u0000 \u0000 <p>To address the limited fracturing range produced by liquid-nitrogen freezing and the insufficient permeability enhancement achieved by blasting in low-permeability soft coal seams, this study proposes a coupled liquid-nitrogen freezing and blast-induced permeability enhancement method. Uniaxial compression and Brazilian splitting tests were performed on coal samples with varying water contents and freezing durations to quantify the mechanical modifications induced by freezing. These parameters were incorporated into a Riedel–Hiermaier–Thoma (RHT) constitutive model to simulate dynamic damage evolution and fracture propagation during blasting. The results show that compressive strength and elastic modulus increase initially and then decline with either prolonged freezing or increasing water content. The most favorable mechanical state occurred at 12% water content and 60 min of freezing, where compressive strength and elastic modulus increased by 109.8% and 143.8%, respectively, whereas tensile strength decreased by 55.8% relative to unfrozen dry coal. This combined strengthening–weakening effect reshapes the coal's load-bearing structure and promotes tensile-dominated failure. Blasting simulations further reveal that, for dry coal, both the proportion of fissure zone volume in total damage and crack length first increase and then decline with freezing duration, reaching their maxima at 60 min, where they rise by 9.9% and 245.0%, respectively, compared with unfrozen coal. For samples with different water contents frozen for 60 min, both parameters display the same trend and peak at 12% water content, with fissure zone volume proportion and crack length increasing by 7.7% and 50.0%, respectively, relative to dry coal.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1108-1122"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source Rock Potential and Structural Traps Signature in Outcropping Imo Formation, Niger Delta Basin: Structural Geometry and Petroleum Migration Pathway","authors":"Okeke Kingsley Kachikwulu","doi":"10.1111/jpg.70080","DOIUrl":"https://doi.org/10.1111/jpg.70080","url":null,"abstract":"<div>\u0000 \u0000 <p>Detailed palynofacies source rock potential model, structural trap signatures intertwined with lateral facies changes in petroleum system synthesis of the outcropping Imo Formation of the Niger Delta Basin, unravelled the palynofacies origin and fracture networks of clastic sediments. The research exposé modelled the structural trap design, hydrocarbon potential in addition to the petroleum migration pathway in the petroleum reserves and hydrocarbon generation prospects estimation of the formation. Palynological acid maceration techniques of using hydrochloric and hydrofluoric acids for removal of calcite and silicates were perfected on the 33 sampled mudrock facies obtained from sedimentary rock outcrop studies. Palynofacies elements modelled kerogen hydrocarbon index essentially indicated thermally mature Type II–III kerogen, triggered by oil- and gas-prone particulate organic matter substances. The source rock and temperature mechanics in the oil and gas window interplay substantiate Kerogen Type III (gas-prone) and Kerogen Type II (oil-prone) as products of essential palynofacies elements. The structural hydrocarbon entrapment design of the outcropping Imo Formation consists of hangingwall closures, footwall closures, shale cracks, infilled and open joint key structural trapping style in faulted and unfaulted sandstone units. Primary and secondary petroleum migration pathways in sandstone pores and fracture arrays are the pivotal mechanisms within the formation of petroleum accumulations and the reservoir quality of the formation. The oil and gas reserves in the structural style of the regional fault array linked the petroleum system architecture interplay for hydrocarbon formation and structural traps within the Niger Delta Basin. The interaction of complex structural fault systems, lateral facies variations and source rock potential controls hydrocarbon yields and fluid migration pathways in the Niger Delta Basin for effective exploration and drilling campaign in the outcropping Imo Formation petroleum plays.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1241-1254"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seismostratigraphic Evaluation of Lower Cretaceous Unconventional Shelf-Edge Rifting Indus Delta: Instantaneous Lateral Thickness and Gas Saturation-Constrained Dynamical Simulations","authors":"Muhammad Tayyab Naseer","doi":"10.1111/jpg.70070","DOIUrl":"https://doi.org/10.1111/jpg.70070","url":null,"abstract":"<div>\u0000 \u0000 <p>With its distinctive extraction technology and substantial influence on energy markets, shale gas is a major, unconventional, and quickly developing area of the global energy sector. It is seen as an important but complicated energy source that fills the gap for future energy solutions. These unconventional energy systems are developed within the diversity of geological systems, for example, shelf-edge delta, and therefore, the shale gas-bearing shelf-edge delta (SDelta) forms excellent sedimentation configurations for the development of stratigraphic-based shale gas-bearing sedimentary systems. However, the band-limited impedance restricts the resolution of sub-seismic seismostratigraphic reflection configurations, for eample, parallel, divergent, and so on, gas saturation and pressure breakthroughs, stratigraphic pinch-outs, basin development zones, simulated density (SDensity), simulated velocity (SVelocity), simulated thickness (SThickness), and seismic-based gas saturation (SeisGas) (%), which facilitate seismostratigraphic assessments of sedimentary influxes for SDelta. This research applies the spectral wavelets and high-tech broadband spectrum decomposition-founded thickness besides gas saturation-controlled seismostratigraphic simulations (STGasSim) to quantify the Indus SDelta. Spectral wavelet 37 Hz resolves a 12 m thick channel complex and lateral impedance anomaly along the organically rich shale zone but failed to image the pressure breakthroughs. STGasSim-based 1400–1466 m/s SVelocity at 60%–68% SeisGas implicates the onset of permeability, moderate influxes and migration, and hence, progradational facies. STGasSim-based ∼1344, 1365, to 1395 m/s SVelocity at 76% to 80% SeisGas implicates pressure breakthrough, highest permeability, migration, and highest influxes, and hence, aggradational facies. STGasSim-based ∼3.34, 3.38, to 3.4 g/cm³ SDensity at 60%, 64%, and 68% SeisGas implicates the onset of tectonic subsidence, moderate fractures, and hence, aggradational stratigraphic pinch-out reservoir facies. STGasSim-based 3.38–3.41 g/cm³ SDensity at 76%–80% SeisGas implicates gas saturation breakthrough in dense fractures. The lateral impedance anomaly serves as the direct shale gas indicator (DSHI) for aggradational stratigraphic pinch-out facies of SDelta, and hence, it might assist equally an equivalent aimed at Onshore Indus SDelta as well as global SDelta.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1034-1053"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical Features and Depositional Environment of Lower Zhongjiangou Formation Mudstone in Wudun Sag, Northwestern China","authors":"Jiacheng Zeng,&nbsp;Taotao Cao,&nbsp;Hu Liu,&nbsp;Ye Chen,&nbsp;Gaofei Ning,&nbsp;Wenqing Yuan","doi":"10.1111/jpg.70071","DOIUrl":"https://doi.org/10.1111/jpg.70071","url":null,"abstract":"<div>\u0000 \u0000 <p>The depositional environment strongly influences the shale gas potential by affecting how organic matter is preserved. Lower Zhongjiangou Formation mudstones from the DY1 well in Wudun Sag, Dunhuang Basin, northwestern China, were subjected to a series of geochemical and petrological experiments. Analyses included total organic carbon (TOC) quantification, maceral composition identification, carbon isotope analysis, and measurements of major, trace, and rare earth element concentrations. These data were used to infer paleoproductivity, redox conditions, paleoclimate, salinity, and water depth and ultimately to reconstruct the depositional environment. The lower Zhongjiangou Formation consists of gray–black, carbon-rich silty mudstones interbedded with thin coal seams. TOC content ranges from 0.53% to 25.25% with a mean value of 8.2%, and vitrinite reflectance of 0.74%–1.27% indicates an immature to mature thermal maturity range. Productivity and redox proxies, Mo content, P/Ti, V/(V + Ni), Ce anomaly (Ce_anom), Th/U, and Mo–U covariance consistently indicate low primary productivity and predominantly oxygen-deficient bottom-water conditions. Organic matter was predominantly supplied by terrigenous higher plant debris rather than by in situ proliferation of algae. Paleoclimate indicators suggest a warm, semi-arid climate, whereas salinity proxies and sedimentological ratios indicate deposition in freshwater to slightly brackish, shallow to semi-deep lake conditions. Depositional cycles capture shifts between deltaic and semi-deep lake conditions. Organic matter enrichment peaked during the period of semi-deep water and anoxic conditions marked by slow sedimentation and abundant terrigenous input in Wudun Sag and thus enhanced the preservation of organic matter. These results highlight oxygen-deficient bottom-water conditions and reduced bottom-water ventilation as the main preservational controls on organic-matter enrichment in the lower Zhongjiangou Formation and provide a framework for understanding Jurassic shale gas accumulation and identifying favorable zones in the Dunhuang Basin.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1142-1163"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Super-Permeable Flow Zones in the Permo–Triassic Carbonates of the South Pars Gas Field: Genesis and Characteristics","authors":"Behrooz Esrafili-Dizaji","doi":"10.1111/jpg.70090","DOIUrl":"https://doi.org/10.1111/jpg.70090","url":null,"abstract":"<div>\u0000 \u0000 <p>Super-permeable flow zones (SPFZs) are thin yet hydraulically dominant intervals that exert a first-order control on fluid flow in carbonate reservoirs. This integrated study identifies and characterizes two stratigraphically discrete SPFZs within the Permo–Triassic carbonate reservoir of the South Pars gas field. Although these zones constitute less than 4% of the total reservoir thickness (17 m), flow-unit analysis using stratigraphic modified Lorenz plots (SMLPs) and normalized cumulative permeability plots (NCPP) demonstrates that they control nearly half of the cumulative flow capacity of the studied well. Integration of sedimentological, stratigraphic, petrographic, geochemical, and petrophysical datasets demonstrates that SPFZs are not anomalous or randomly distributed features, but stratigraphically predictable and genetically constrained. These zones preferentially occur within dolomitized shoal grainstones developed during late transgressive to early highstand conditions of specific fourth-order depositional sequences, although not all comparable intervals evolved into SPFZs. Their exceptional permeability is interpreted to reflect the combined effects of facies-selective reflux dolomitization, limited anhydrite cementation, and subsequent burial recrystallization that enhanced pore connectivity and imparted a characteristic geochemical signature marked by <i>δ</i>¹⁸O depletion and enrichment in Mn and Fe. This process-based understanding provides a robust geological framework for the deterministic incorporation of SPFZs into static and dynamic reservoir models, replacing purely stochastic permeability distributions with stratigraphically and diagenetically constrained predictions. Although SPFZs generate extreme internal heterogeneity, the results demonstrate that their occurrence and hydraulic impact can be anticipated and effectively managed, with direct implications for reservoir modeling, completion design, sweep efficiency, and long-term recovery optimization in heterogeneous carbonate reservoirs.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1357-1381"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148903715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shale Content Implementation on the Application of the Acoustic Impedance of the Upper Ordovician Mamuniyat Reservoir in Murzuq Basin, Libya","authors":"Bahia M. Ben Ghawar,&nbsp;Bassem S. Nabawy,&nbsp;Hesham A. Saad","doi":"10.1111/jpg.70075","DOIUrl":"https://doi.org/10.1111/jpg.70075","url":null,"abstract":"<div>\u0000 \u0000 <p>Understanding the reservoir characteristics by integrating the petrophysical and elastic properties is a valuable procedure for hydrocarbon fields. Therefore, this work concerns an integration of petrophysical and elastic rock properties with the acoustic impedance (AI) and rock physics diagnostics (RPDs) of the Upper Ordovician Mamuniyat reservoir that provides a significant illustration of shale content influence. These interpretations are based on the processing of well-logging data (spectral gamma ray [SGR], neutron, density, and photoelectrical factor (PEF), as well as shallow and deep resistivities), which are derived from four oil wells in the Murzuq Basin of Libya. Using spectral gamma-ray (GR) data indicated that the formation comprises upper clean and lower shaly sandstone (SS) units with a spiky behavior of the lower unit due to the alternation between the sand and shaly sand causing a spiky variation of the total and effective porosities. The relatively high concentration of potassium (K) and thorium (Th) within the lower unit of the Mamuniyat Formation indicates a granitic basement as the parent rock. Plotting the Th/K versus the potassium and PEF values is used to define the clay type of the studied reservoir. The neutron-density crossover is well presented in the upper clean sand unit and a few intercalations in the lower shaly sand unit. Increasing the deep resistivity values in the upper unit indicates its hydrocarbon content and its promising nature for oil extraction. Utilizing the RPDs revealed that plotting the AI versus the <i>V</i>_p/<i>V</i>_s ratio, the bulk density, and Poisson's ratio data points of the clean sand reservoir unit shows well-aligned points rather than scattered plotting of the shaly SS unit. Furthermore, plotting the <i>λρ</i> and <i>μρ</i> against the effective porosity helped to find out the rock type and its interstitial fluid type that has been trapped in the pore spaces. This study adds more understanding of the Mamuniyat reservoir properties based on the RPDs.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1270-1290"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"1D Basin Modelling of Upper Jurassic to Upper Cretaceous Source Rocks in the Southern Pletmos Sub-Basin, Outeniqua Basin, Offshore South Africa","authors":"Fritz Ako Agbor,&nbsp;Sanelisiwe Mhlambi,&nbsp;Nimuno Achu Teumahji,&nbsp;Wasiu Adedayo Sonibare,&nbsp;Jan van Bever Donker","doi":"10.1111/jpg.70091","DOIUrl":"https://doi.org/10.1111/jpg.70091","url":null,"abstract":"<p>The Pletmos sub-basin in the Outeniqua Basin, offshore South Africa, is divided by the Superior, Pletmos and Plettenberg faults into northern and southern depocentres. In this study, geological and organic geochemical data together with 1D basin modelling were used to investigate the burial, thermal and maturation histories, and the timing of hydrocarbon generation and expulsion of clay-rich source rocks in the southern depocentre. The modelled source rocks were of Kimmeridgian, Valanginian, Hauterivian, Aptian and Turonian ages. Source rock burial histories at the Ga-A4, Ga-E1, Ga-E2, Ga-H1, Ga-Q1 and Ga-Q2 wells in the Ga-A gas field were reconstructed with subsequent modelling of source rock thermal and maturation histories. The models were calibrated using vitrinite reflectance data from six offshore wells and constrained by palaeotemperature, heat flow and kinetic parameters. The modelling results indicate three principal phases of hydrocarbon generation (132–89, 89–45 and 45 Ma to present day), with a critical moment occurring at approximately 23 Ma during the Oligocene. The deepest syn-rift Kimmeridgian and Valanginian source rocks reached late-mature to over-mature conditions and are interpreted as the principal contributors to hydrocarbon charge in the basin. These results indicate that the petroleum system in the southern Pletmos sub-basin is predominantly gas-prone to gas-dominant, reflecting the advanced maturity of the deeper syn-rift source intervals and highlighting the continued exploration potential of deeply buried petroleum systems in the Outeniqua Basin.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1382-1411"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpg.70091","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine Learning Algorithms to Predict Source and Reservoir Zones of Abu Roash Formation Using Spectral Gamma-Ray Logs, Khalda Oil Field, Northern Western Desert, Egypt","authors":"Ahmed Bakry,&nbsp;Ashraf Ghoneimi,&nbsp;Qamar Yasin,&nbsp;Ibrahim M. Al-Alfy,&nbsp;Muhammad Nabih,&nbsp;Mohamed A. Kamel","doi":"10.1111/jpg.70079","DOIUrl":"https://doi.org/10.1111/jpg.70079","url":null,"abstract":"<div>\u0000 \u0000 <p>Accurate estimation of delineation of radioactive anomalies deviation (DRAD) is critical for characterizing subsurface radioactive element distributions commonly associated with hydrocarbon accumulations. However, DRAD estimation traditionally relies on natural gamma-ray spectrometry measurements, which are costly, operationally demanding, and not routinely acquired in many wells. This study proposes a physics-informed machine learning model that aims to predict DRAD using traditional well logs while embedding geological constraints to ensure physically consistent predictions. Conventional logs, including gamma ray, density, neutron porosity, resistivity, and photoelectric factor from the Khalda oil field (Shushan Basin, Western Desert, Egypt), are subjected to systematic preprocessing involving outlier removal and feature standardization. Two predictive models are implemented: random forest (RF) as a data-driven baseline and a physics-informed neural network (PINN) incorporating radioactive element relationships within the optimization process. Training of the models is carried out using well KH-24 with an 80–10–10 split for training, testing, and validation sets, whereas prediction stability is carried out using a three-point moving average smoothing technique after prediction. The PINN demonstrated superior predictive capability, yielding <i>R</i>² values of 0.90, 0.82, and 0.85 for training, testing, and validation datasets, respectively, improving to 0.92, 0.90, and 0.89 after smoothing. The generalization capability of the models is validated with blind wells KH-17 and KH-21, where predicted DRAD profiles successfully reproduced anomaly magnitudes and stratigraphic variability consistent with measured data. These results showed that the use of physics-based learning is more stable in terms of prediction performance and geological reliability in comparison with empirical-based models, providing a transferable and cost-effective alternative for estimating DRAD values in wells lacking spectrometric measurements and supporting more efficient hydrocarbon exploration workflows.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"49 4","pages":"1164-1178"},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148904246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}