Journal of Petroleum Geology最新文献

{"title":"Palynofacies Analysis Illustrates the Source Rock Potential of the Menilite Beds, Polish Outer Carpathians","authors":"Filipek Anna,&nbsp;Barski Marcin,&nbsp;Wysocka Anna,&nbsp;Jankowski Leszek","doi":"10.1111/jpg.70005","DOIUrl":"https://doi.org/10.1111/jpg.70005","url":null,"abstract":"<div>\u0000 \u0000 <p>The deposition of the Menilite Beds began during the reorganization of the sea ways and the extensional stage of the Carpathian Basin evolution in the early Oligocene. The beginning of their sedimentation is considered to be isochronous throughout the entire marine basin, which formed a part of the Paratethys and was likely isolated from the global ocean due to tectonic movements. However, the changes in the Carpathian region were likely also influenced by processes associated with the Eocene–Oligocene Transition. The present study focuses on the investigation of the Menilite Beds from two Outer Carpathians (OC) main tectonic units: the Skole (Krościenko section) and Silesian (Korzenna section), using a coupled palynofacies, Rock-Eval pyrolysis, and sedimentological framework. This approach permitted the observation of lateral variations in lithology, sedimentary structures, and palynofacies, recording the changes that took place in the early Oligocene, during the deposition of the Menilite Beds, in regions that are currently separated by great distances. In both sections, the palynofacies of the Menilite Beds are predominantly composed of amorphous organic matter (AOM), suggesting that the Menilite Beds were deposited under strongly oxygen-depleted conditions. The presence of spherical bacteria and AOM with alveolar structures in the Korzenna section indicates that microbial mats were probably locally present at the sediment–water interface during the deposition of the Menilite Beds. Analyses of microplankton with organic walls indicate that brackish conditions were present during the deposition of the lower Menilite Beds. Identified microplankton notably included <i>Botryococcus</i> sp. (Krościenko, Korzenna), <i>Campenia</i> sp. (Krościenko, Korzenna), <i>Leiosphaeridia</i> sp. (Krościenko, Korzenna), <i>Pterospermella</i> sp. (Krościenko, Korzenna), and <i>Cymatiosphaera</i> sp. (Korzenna). These results indicate that some lower Menilite Beds, which are located directly above the Eocene deposits (Krościenko—Complex II, III, and IV; Korzenna—Complex I, II, IV, VI), contain horizons with palynological compositions favorable to hydrocarbon generation, including <i>Botryococcus</i> sp. and <i>Leiosphaeridia</i> sp., which are characterized by a high ability to synthesize and accumulate hydrocarbon. We demonstrate that the integration of sedimentological, palynofacies, and organic matter analyses under UV light supported by Rock-Eval pyrolysis can facilitate the identification of potential hydrocarbon horizons—characterized by elevated algal abundances—within the differentiated lithostratigraphic profile of the Menilite Beds. The formation of these deposits was influenced by a complex interplay of paleogeographical, paleoclimatic, and tectonic factors.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 4","pages":"352-391"},"PeriodicalIF":1.7,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013123","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":"A Conceptual Model of Hydrocarbon Migration Conduits in the Outer Carpathian Fold-and-Thrust Belt in Poland: An Interplay Among Fractures, Faults and Rock Properties","authors":"Barbara Rybak-Ostrowska,&nbsp;Małgorzata Kozłowska,&nbsp;Michał Wyglądała,&nbsp;Anna Haluch,&nbsp;Joanna Uroda,&nbsp;Mirosław Ludwiniak,&nbsp;Sara Wróblewska-Janc,&nbsp;Marcin Barski,&nbsp;Andrzej Konon","doi":"10.1111/jpg.70006","DOIUrl":"https://doi.org/10.1111/jpg.70006","url":null,"abstract":"<div>\u0000 \u0000 <p>The hydrocarbon migration conduits in the Outer Carpathian fold-and-thrust belt (OCFTB) are related to the dynamic development of the structural framework combined with changes of rock properties during the deformation process. Application of an integrated methodology, including fieldwork coupled with analysis of cores and thin sections as well as geophysical and petrophysical data from eight wells, made it possible to describe the relationships between the structural framework and the porous sandy rocks of the Cretaceous-to-Oligocene succession during the evolution of the OCFTB. The results indicate that the folding and thrusting, along with the associated rock fracturing during sustained horizontal contraction, resulted in the complex structure of the Silesian Nappe (part of the OCFTB). Structural deformation of lithified rocks created a system of conduits for hydrocarbon migration. The presence of bitumen in the thrust fault zones, normal faults and longitudinal joints (L), parallel to the anticline axes, transversal joints (T) and shear joints (D₁ and D₂) indicates permanent hydrocarbon migration through complex conduits formed by the subsequent structural deformation of the Silesian Nappe. The assembled evidence points to the existence of an interconnected system of a structural framework combined with porous carrier beds contributing to the formation of conduits for hydrocarbon migration during the progressive deformation of the OCFTB.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 4","pages":"325-351"},"PeriodicalIF":1.7,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013240","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":"New Insights Into the Geochemical Characteristics of Petroleum Source Rocks and Oils From Southern Nigerian Sedimentary Basins","authors":"Abdulkareem Toyin,&nbsp;Falilat Omotolani Idris,&nbsp;N'Guessan Francois De Sales Konan,&nbsp;Olabisi Adekeye","doi":"10.1111/jpg.70007","DOIUrl":"https://doi.org/10.1111/jpg.70007","url":null,"abstract":"<div>\u0000 \u0000 <p>The Anambra and the Niger Delta Basins are well-known hydrocarbon-producing sedimentary basins in Southern Nigeria. In the present research, bulk geochemical analysis, which includes total organic carbon (TOC) and rock pyrolysis, molecular markers, and bulk and compound-specific carbon isotopes (CSIAs), in addition to organic petrological analysis was carried out on source rocks of Cretaceous age from the Anambra Basin and oils (both Anambra and Niger Delta Basins) in order to provide information on why there was a sudden seizure in liquid hydrocarbon production in the ANAR oilfield of the Anambra Basin and also to shed more light on the unending debate on the source of Cretaceous Niger Delta oils. From the results, bulk geochemical data and maceral abundances revealed that Nkporo shales from well-x and outcrop Mamu shales are dominantly of Types II and III organic matters and are capable of producing oil and gas upon attaining appropriate thermal maturity, whereas outcrop Mamu coals are of Types II and II/III organic matter, with good potential for oil generation but with minor gas, especially in the deeper section of the basin. Organic matter richness as deduced from TOC revealed that the Mamu coals are the richest (average TOC: 50.74 wt%), whereas Mamu shales are richer (average TOC: 2.89 wt%) than Nkporo shales (average TOC: 1.66 wt%). The hydrocarbon generative potentials of the analyzed source rocks as obtained through the hydrogen index are highest in the Mamu coals (average: 329.25 mg HC/g TOC), and are followed by Mamu shales (average: 130.89 mg HC/g TOC), whereas the least was obtained in Nkporo shales (average: 69.73 mg HC/g TOC). The maximum temperature (<i>T</i>_max) and the vitrinite/huminite reflectance values of the source rocks are 396–443°C, 417–430°C, and 417–421°C, and 0.38%–1.51%, 0.23%–0.42%, and 0.22%–0.46% in Nkporo shales, Mamu shales, and coals, respectively. The values revealed that Nkporo shales are in immature to early–late hydrocarbon generation stages, whereas Mamu shales and coals are dominantly thermally immature. Further, the analyzed source rocks were deposited under sub-oxic-to-oxic conditions based on molecular indices and petrographic evidence. In the Nkporo shales, there was dominant input from lacustrine organic matter, as evident from the high abundance of C₂₈R sterane, higher C₂₁TT, and <i>n</i>-alkane maxima at <i>n</i>-C₂₀ and <i>n</i>-C₂₃. In contrast, the Mamu shales and coals and crude oil from the Anambra Basin received major input from terrigenous organic matter (high C₂₉ R sterane, C₂₉/C₂₇ ratios, wax index, terrigenous/aquatic ratio (TAR), C₁₉ + ₂₀TT, and <i>n</i>-alkane maxima at <i>n</i>-C₂₇–<i>n</i>-C₂₉). The oils (crude oils and condensates) from the Niger Delta are dominated by C₂₉ R steranes, whereas C₂₇ and C<su","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 4","pages":"280-306"},"PeriodicalIF":1.7,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145012789","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":"A Paleotectonic Atlas of the African Plate: Permian to Recent","authors":"Duncan S. Macgregor,&nbsp;Colin V. Reeves","doi":"10.1111/jpg.70000","DOIUrl":"https://doi.org/10.1111/jpg.70000","url":null,"abstract":"<p>The fragmentary release of petroleum data defining the deep structure and stratigraphy of African basins has been integrated with existing literature to compile 19 tectonic maps over key geological intervals from Permian to Recent times. African plate margins range in their age of opening from Late Triassic (off Lebanon), through Early/Middle Jurassic (Eastern Mediterranean, Central Atlantic, Somali Basin) and Cretaceous (West Africa) to ongoing (northern Red Sea). Their opening follows propagational trends, for example, from the eastern Mediterranean to Guinea and from the Somali Basin in a “smile” shape around southern Africa, eventually to Guinea. Just under half of African margins are rifted margins. North Africa margins are controlled initially by transforms, while volcanic rifted margins dominate in southern Africa. The most debated ocean, the eastern Mediterranean, is demonstrated through well and seismic interpretations to have commenced spreading in late Early to early Middle Jurassic times. Much of West African Cretaceous tectonics, including the generation of strike–slip fault systems, is related to the counter-rotation of Africa versus South America initiated through South Atlantic opening, partly driven by the Bouvet and Tristan Plumes. From the Aptian onward, Africa receives a series of transpressional shocks, largely derived from the Tethyan margin. The most pronounced such event occurs in the Santonian, which is a global-scale event, with? Turonian events in the Indian Ocean also affecting East Africa. Africa is segmented by many interior rifts, with these developed on all mapped intervals, though with peaks of activity in the Permian (South Africa), Late Triassic (North Africa), Early Cretaceous (Central Africa), and Neogene (East Africa). In the Early Cretaceous, a tensional regime is imposed which creates a series of NW-SE trending rifts across the plate: this switches gradually to a N-S rift trend in the Cenozoic. Passive rifts show a high degree of inheritance and can be orientated both perpendicular and parallel to associated strike–slip faults. This type of rift dominates in the Mesozoic, with active plume-related rifts becoming the principal type as mantle activity becomes a more dominant control in the Cenozoic. The Early Cretaceous Sirt Basin is viewed as an isolated plume-related rift, later evolving into a strike–slip associated rift. Analogue-driven hypotheses are proposed for the origin of the more poorly controlled African rifts, such as the Western Desert of Egypt. The formation of the various elements of petroleum systems are responses to these tectonics. For example, geographical trends in basin restriction and potential anoxia are observed to follow the propagational trends of continental breakup.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 4","pages":"231-279"},"PeriodicalIF":1.7,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpg.70000","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013047","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":"Magnetic Properties of Sandstones Within the Zone of Hydrocarbon Migration Near the Boundary of Dukla and Silesian Units (Western Carpathians, Poland)","authors":"Maciej Łoziński,&nbsp;Kamil Kobyliński,&nbsp;Radosław Staniszewski,&nbsp;Anna Wysocka,&nbsp;Anna Filipek","doi":"10.1111/jpg.70004","DOIUrl":"https://doi.org/10.1111/jpg.70004","url":null,"abstract":"<div>\u0000 \u0000 <p>This study represents the application of magnetic techniques in hydrocarbon prospection within the Outer Western Carpathian petroleum play, specifically focusing on the Eocene–Oligocene rocks of southeastern Poland. Magnetic minerals serve as a sensitive proxy for diagenetic processes, particularly concerning hydrocarbon generation, migration, and biodegradation. We investigated the magnetic characteristics of surface rock samples from Dukla and Silesian Units, which have been altered by hydrocarbons migrating through pore spaces and tectonic fissures. The magnetic mineralogy of 29 specimens was analyzed through thermal demagnetization (Lowrie's test), complemented by hysteresis loop and anhysteretic remanence susceptibility measurements to assess domain states and ultrafine grain size ranges. Scanning electron microscope analysis of mineral composition revealed that traces of bitumen and abundant pyrite were common in almost all samples. Ultrafine maghemite emerged as the predominant magnetic mineral within the host rock, with some samples exhibiting varying amounts of ultrafine magnetite, often associated with iron sulfides. Areas adjacent to calcite veins stained with hydrocarbons displayed enhanced magnetic properties, primarily due to increased magnetite content. Additionally, aggregates of barite were identified as accessory minerals within these veins. Our study indicates that detrital iron oxides underwent partial dissolution, leading to the formation of new authigenic minerals such as paramagnetic pyrite and, likely, ultrafine magnetite. These constituents were subsequently transformed partially or completely into maghemite during the oxidation stage of diagenesis. Importantly, the presence of hydrocarbon appears to facilitate the formation of ultrafine (&lt;100 nm) magnetic particles, with magnetite being particularly characteristic of tectonic migration pathways.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 4","pages":"307-324"},"PeriodicalIF":1.7,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013034","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":"Evolution of Microporosity in Mature Mudstones of the Outer Carpathians, Poland","authors":"Olga Odrzygóźdź,&nbsp;Grzegorz Machowski,&nbsp;Mario Borrelli,&nbsp;Marta Waliczek,&nbsp;Edoardo Perri,&nbsp;Marek Szczerba,&nbsp;Mirosław Słowakiewicz","doi":"10.1111/jpg.70003","DOIUrl":"https://doi.org/10.1111/jpg.70003","url":null,"abstract":"<div>\u0000 \u0000 <p>The Polish Carpathian region has over 170 years of conventional hydrocarbon exploration history, with numerous discovered oil and gas fields. In recent years, increasing attention has been given to the potential for new, alternative hydrocarbon deposits. This study evaluates three types of mature mudstones from the Oligocene Menilite Beds, Krosno Beds and Grybów Beds, collected from boreholes in the Polish part of the Outer Carpathians, as potential unconventional source and reservoir rocks. X-ray diffraction (XRD), optical and scanning electron microscopy (SEM), N₂ adsorption and mercury injection capillary pressure (MICP) techniques were used to evaluate the pore system, organic matter and mineral composition in each lithofacies. The findings reveal that the Menilite Beds mudstone is thermally mature, with Type II/III kerogen. In contrast, the mudstones of the Grybów and Krosno beds are highly thermally mature, corresponding to the dry gas window stage, with kerogen Types IV and mixed III/IV, respectively. All three formations display a fair total organic carbon (TOC) value (0.7%–1.1%) but have low hydrocarbon generation potential (hydrogen index [HI] &lt; 85 mg HC/g TOC). Microscopic observations confirm the presence of both mineral and organic matter pores in all three mature mudstones. Samples are dominated by nanoporosity (average pore size &lt;14 nm), with low effective porosity values across all samples, ranging from 1.51% to 3.59%. Permeability is very low (0.029–0.081 mD). Nitrogen adsorption isotherms are type IV for all mudstones, with H3/H4 hysteresis loops, indicating slit- and wedge-shaped pores. The <i>S</i>_BET N₂ values range from 1.352 to 7.277 m²/g, with the highest values for Krosno Beds samples. The mudstones and claystones of the Menilite, Krosno and Grybów beds are primarily affected by compaction, with only a minor influence from cementation and dissolution. The evaluated mudstones do not qualify as effective shale oil/gas source rock; despite good thermal maturity, their hydrocarbon generation potential at the analysed depths is very low. It could be hypothesised that, given the overall volume of nanopores and their interconnectivity, such a potential unconventional hydrocarbon system may occur at greater depths or in regions where hydrocarbon generation potential has been documented, even at shallower depths.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 3","pages":"205-226"},"PeriodicalIF":1.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144891659","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":"A New Saturated and Aromatic Hydrocarbon-Based Scheme to Decipher the Origin of Extracted Organic Matter in the Outer Carpathians: From the Jurassic to the Miocene","authors":"Mirosław Słowakiewicz","doi":"10.1111/jpg.70001","DOIUrl":"https://doi.org/10.1111/jpg.70001","url":null,"abstract":"<div>\u0000 \u0000 <p>In this review, published and new geochemical data characterising 17 potential source rocks for hydrocarbons in the Polish part of the Outer Carpathians have been used to establish a new scheme that can be useful for oil–source rock correlations. Rock and drill core samples, ranging in age from Jurassic to Miocene, were analysed using Rock-Eval pyrolysis. The results confirmed that the best source rock is shale from the Oligocene Menilite Beds, particularly the so-called deep shale, occurring at depths greater than 4000 m. The Palaeocene/Eocene mudstone interbeds in the Istebna Beds can serve as a source rock for natural gas, although only locally, due to their highly irregular geochemical parameters. Lower Cretaceous strata, specifically the fine-grained sediments of the Spas Shales, Lgota Beds and Veřovice Beds, appear to be significant for microbial generation of methane. Molecular analysis of extractable organic matter, combined with pyrolytic data, revealed a wide range of organic matter maturation stages, from immature to overmature. These analyses also identified rare zones of high maturity at shallow depths in source rocks, confirming the upwards displacement of once deeply buried strata in the Outer Carpathians. Additionally, the saturated and aromatic hydrocarbon-based compounds and their ratios revealed characteristic biomarkers and polycyclic aromatic hydrocarbons (PAHs) that differentiate various shale- (mudstone, claystone) or marl-rich formations within specific lithostratigraphic units. These chemical compounds serve as strong tools for deciphering the origin of oils in the Outer Carpathians, regardless of the organic matter's maturity level. This age-based molecular characterisation highlights the particular importance of higher plant-derived compounds, such as oleanane isomers, which are most abundant in the Oligocene samples but also present in Kimmeridgian shale. Aromatised terpenoid precursors, in turn, are abundant in shale from the Menilite Beds as well as in the Krosno and Istebna beds. Terrigenous organic matter is also accompanied by algal-derived components (e.g., dinosteroids) and bacterial contributions (e.g., hopanes). Finally, the analysed organic matter was deposited in sedimentary basins under varied redox conditions. Anoxic environments were confirmed by high bisnorhopane/C₃₀ hopane ratios, whereas oxic to suboxic conditions were indicated by high pristane/phytane ratios, suggesting a mixed oxic–anoxic water column.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 3","pages":"188-204"},"PeriodicalIF":1.7,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144891641","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":"Characteristics of Tight Gas Accumulation and Main Controlling Factors of Differential Enrichment in the Shaximiao Formation, Yanjinggou Area, Southwest of the Western Sichuan Depression","authors":"Fengzan Zheng,&nbsp;Jianhui Zeng,&nbsp;Zaiquan Yang,&nbsp;Zhe Feng","doi":"10.1111/jpg.70002","DOIUrl":"https://doi.org/10.1111/jpg.70002","url":null,"abstract":"<div>\u0000 \u0000 <p>The Jurassic Shaximiao Formation in the southwest of the Western Sichuan Depression is an important tight gas reservoir. However, due to the strong heterogeneity of its reservoir properties and gas saturation, the factors influencing the differential enrichment of tight gas remain unclear. Based on logging, seismic, experimental, and drilling data, we have systematically studied the gas-bearing property characteristics, source rock characteristics, reservoir physical properties, fault characteristics, accumulation Period, and the factors controlling differential enrichment using the tight gas reservoir in the Yanjinggou area as a case. The study shows that the Shaximiao Formation is underlain by high-quality source rocks of the Xujiahe Formation (Upper Triassic) and capped by a regional seal of the Suining Formation (Jurassic). In the Yanjinggou area, anticline structures are well-developed, with sandbodies widely distributed and vertically stacked, and the overall reservoir is tight. The thickness and petrophysical properties of the reservoir display significant heterogeneity, which is controlled by the coupling of depositional and diagenetic processes. Gas layers are mainly found in channel sands trending NE-SW that exhibit superior reservoir properties. The fault–sand transport system is a crucial pathway for gas charging, migration, and accumulation, with structural highs and “V” shaped fault–sand configurations controlling the preferential enrichment zones. A tight gas accumulation model of “reservoir controlled enrichment, fault–sand controlled migration, and structural adjustment” was established. This model emphasizes that under the control of the fault–sand transport system, hydrocarbons initially migrate upward along faults into reservoirs that are separated from the source rocks, then laterally through the sandbodies. Favorable enrichment occurs in reservoir characterized by structural highs, good petrophysical properties, and greater thickness. The differential enrichment of tight gas in the Shaximiao Formation is controlled by a combination of factors, including the petrophysical properties and distribution of sandbodies and reservoirs, fault distribution, tectonic movement, and tectonically high positions. Comprehensive analysis indicates that the tight gas accumulation conditions in the Shaximiao Formation of the Yanjinggou area are favorable, providing a theoretical basis for predicting tight gas sweet spots in similar regions of the southwest of the Western Sichuan Depression.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 3","pages":"163-187"},"PeriodicalIF":1.7,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144891794","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":"The Effect of Orogenesis on the Petroleum System in the Outer Carpathians","authors":"Piotr Such","doi":"10.1111/jpg.12884","DOIUrl":"https://doi.org/10.1111/jpg.12884","url":null,"abstract":"","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 3","pages":"159-162"},"PeriodicalIF":1.7,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144891667","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":"Thermal History and Source Rock Maturity Modeling of the Akri-Bijeel Area, NW Zagros Fold Belt, Kurdistan Region, Northern Iraq","authors":"Ayad N. F. Edilbi,&nbsp;Stephen A. Bowden,&nbsp;Abdalla Y. Mohamed,&nbsp;David Muirhead","doi":"10.1111/jpg.12883","DOIUrl":"https://doi.org/10.1111/jpg.12883","url":null,"abstract":"<div>\u0000 \u0000 <p>The Akri-Bijeel area in the NW Zagros fold-and-thrust belt (Kurdistan region of northern Iraq) has been the focus of petroleum exploration, and its subsurface has been drilled extensively. This makes it possible to combine outcrop studies of this mountainous region with subsurface data. The region has five potential or regionally proven source rock units: the Ora Formation (Devonian–Carboniferous), the Baluti Formation (Upper Triassic), the Sargelu and Naokelekan Formations (Middle–Upper Jurassic), and the Chia Gara Formation (Upper Jurassic–Early Cretaceous). The area has a complex tectonic history, and it is therefore not necessarily clear when source rocks may have been active or inactive and therefore their generative potential. This makes basin modeling particularly useful as a tool to evaluate source rock thermal maturity and the timing of hydrocarbon generation and the amounts expelled. PetroMod version 2017 was used to reconstruct 1D burial and thermal history for four wells. The reconstructed burial and thermal history models were then calibrated against porosity, pressure, temperature, and vitrinite reflectance data. The results of constrained models show significant variations in heat flow through time, with high heat flows during Mesozoic rifting followed by low values, with sharp decreases in heat flow since the end of the Miocene. The present-day average geothermal gradient at Akri-Bijeel is low (18°C/km), with an average heat flow of 32 mW/m². The low heat flow can best be explained by the rapid deposition of a thick, cold Cenozoic sedimentary section, Zagros thrusting and accompanying uplift and exhumation, and the ongoing circulation of cold meteoric waters under hydrodynamic conditions. Thermal maturity modeling reveals that the present-day oil window extends from a depth of 860 m in well Bakrman-1 down to 5090 m in well Bijeel-1. The generation of hydrocarbons in the modeled source rocks (except for the Ora Formation) continued until it was halted by Zagros folding and thrusting in the Miocene, after which generation ceased or became negligible. Models predict that the majority of the oil discovered at Akri-Bijeel was generated by the Sargelu, Naokelekan, and Chia Gara Formations. On the basis of 1D basin modeling, the Paleozoic Ora Formation generated oil during the Early Triassic and is now in the gas window, and Jurassic source rocks generated oil during the Cretaceous. Volumetric calculations for the five source rock formations modeled in the area suggest that around 4.94 billion tons (or 36 billion barrels [bbl]) of petroleum have been expelled and charged to the reservoirs, indicating significant remaining potential for undiscovered resources.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"48 2","pages":"134-155"},"PeriodicalIF":1.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809482","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}