Petroleum Science最新文献

{"title":"Carbon dioxide storage and cumulative oil production predictions in unconventional reservoirs applying optimized machine-learning models","authors":"Shadfar Davoodi ,&nbsp;Hung Vo Thanh ,&nbsp;David A. Wood ,&nbsp;Mohammad Mehrad ,&nbsp;Sergey V. Muravyov ,&nbsp;Valeriy S. Rukavishnikov","doi":"10.1016/j.petsci.2024.09.015","DOIUrl":"10.1016/j.petsci.2024.09.015","url":null,"abstract":"<div><div>To achieve carbon dioxide (CO₂) storage through enhanced oil recovery, accurate forecasting of CO₂ subsurface storage and cumulative oil production is essential. This study develops hybrid predictive models for the determination of CO₂ storage mass and cumulative oil production in unconventional reservoirs. It does so with two multi-layer perceptron neural networks (MLPNN) and a least-squares support vector machine (LSSVM), hybridized with grey wolf optimization (GWO) and/or particle swarm optimization (PSO). Large, simulated datasets were divided into training (70%) and testing (30%) groups, with normalization applied to both groups. Mahalanobis distance identifies/eliminates outliers in the training subset only. A non-dominated sorting genetic algorithm (NSGA-II) combined with LSSVM selected seven influential features from the nine available input parameters: reservoir depth, porosity, permeability, thickness, bottom-hole pressure, area, CO₂ injection rate, residual oil saturation to gas flooding, and residual oil saturation to water flooding. Predictive models were developed and tested, with performance evaluated with an overfitting index (OFI), scoring analysis, and partial dependence plots (PDP), during training and independent testing to enhance model focus and effectiveness. The LSSVM-GWO model generated the lowest root mean square error (RMSE) values (0.4052 MMT for CO₂ storage and 9.7392 MMbbl for cumulative oil production) in the training group. That trained model also exhibited excellent generalization and minimal overfitting when applied to the testing group (RMSE of 0.6224 MMT for CO₂ storage and 12.5143 MMbbl for cumulative oil production). PDP analysis revealed that the input features “area” and “porosity” had the most influence on the LSSVM-GWO model's prediction performance. This paper presents a new hybrid modeling approach that achieves accurate forecasting of CO₂ subsurface storage and cumulative oil production. It also establishes a new standard for such forecasting, which can lead to the development of more effective and sustainable solutions for oil recovery.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 296-323"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional internal multiple elimination in complex structures using Marchenko autofocusing theory","authors":"Pei-Nan Bao ,&nbsp;Ying Shi ,&nbsp;Xin-Min Shang ,&nbsp;Hong-Xian Liang ,&nbsp;Wei-Hong Wang","doi":"10.1016/j.petsci.2024.07.023","DOIUrl":"10.1016/j.petsci.2024.07.023","url":null,"abstract":"<div><div>Internal multiples are commonly present in seismic data due to variations in velocity or density of subsurface media. They can reduce the signal-to-noise ratio of seismic data and degrade the quality of the image. With the development of seismic exploration into deep and ultradeep events, especially those from complex targets in the western region of China, the internal multiple eliminations become increasingly challenging. Currently, three-dimensional (3D) seismic data are primarily used for oil and gas target recognition and drilling. Effectively eliminating internal multiples in 3D seismic data of complex structures and mitigating their adverse effects is crucial for enhancing the success rate of drilling. In this study, we propose an internal multiple prediction algorithm for 3D seismic data in complex structures using the Marchenko autofocusing theory. This method can predict the accurate internal multiples of time difference without an accurate velocity model and the implementation process mainly consists of several steps. Firstly, simulating direct waves with a 3D macroscopic velocity model. Secondly, using direct waves and 3D full seismic acquisition records to obtain the upgoing and downgoing Green's functions between the virtual source point and surface. Thirdly, constructing internal multiples of the relevant layers by upgoing and downgoing Green's functions. Finally, utilizing the adaptive matching subtraction method to remove predicted internal multiples from the original data to obtain seismic records without multiples. Compared with the two-dimensional (2D) Marchenko algorithm, the performance of the 3D Marchenko algorithm for internal multiple prediction has been significantly enhanced, resulting in higher computational accuracy. Numerical simulation test results indicate that our proposed method can effectively eliminate internal multiples in 3D seismic data, thereby exhibiting important theoretical and industrial application value.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 222-233"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141850484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of preprocessing on performances of machine learning-based mineral composition analysis on gas hydrate sediments, Ulleung Basin, East Sea","authors":"Hongkeun Jin ,&nbsp;Ju Young Park ,&nbsp;Sun Young Park ,&nbsp;Byeong-Kook Son ,&nbsp;Baehyun Min ,&nbsp;Kyungbook Lee","doi":"10.1016/j.petsci.2024.11.012","DOIUrl":"10.1016/j.petsci.2024.11.012","url":null,"abstract":"<div><div>Gas hydrate (GH) is an unconventional resource estimated at 1000–120,000 trillion m³ worldwide. Research on GH is ongoing to determine its geological and flow characteristics for commercial production. After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin, the mineral composition of 488 sediment samples was analyzed using X-ray diffraction (XRD). Because the analysis is costly and dependent on experts, a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data. However, the model’s performance was limited because of improper preprocessing of the intensity profile. Because preprocessing was applied to each feature, the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition. In this study, the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis. For 49 test data among the 488 data, the convolutional neural network (CNN) model improved the average absolute error and coefficient of determination by 41% and 46%, respectively, than those of CNN model with feature-based preprocessing. This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data. The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau. In addition, the overall procedure can be applied to any XRD data of sediments worldwide.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 151-162"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of interaction behavior between hydraulic fractures and gravels in heterogeneous glutenite using a grain-based discrete element method","authors":"Zhao-Peng Zhang ,&nbsp;Yu-Shi Zou ,&nbsp;Hai-Yan Zhu ,&nbsp;Shi-Cheng Zhang","doi":"10.1016/j.petsci.2024.08.004","DOIUrl":"10.1016/j.petsci.2024.08.004","url":null,"abstract":"<div><div>The glutenite reservoir is strongly heterogeneous due to the random distribution of gravels, making it challenging to perform hydraulic fracturing effectively. To solve this issue, it is essential to study interaction behavior between hydraulic fractures (HFs) and gravels. A coupled hydro-mechanical model is proposed for HF propagation in glutenite using a grain-based discrete element method. This paper first investigates the dynamic evolution of HFs in glutenite, then analyzes the influences of various factors such as horizontal stress difference (Δ<em>σ</em>), minimum horizontal stress (<em>σ</em>_h), gravel content (<em>V</em>_g), gravel size (<em>d</em>_g), and stiffness ratio of gravel to matrix (<em>R</em>_s) on HF propagation geometries. Results show that penetrating the gravel is the primary HF-gravel interaction behavior, which follows sequential and staggered initiation modes. Bypassing the gravel is the secondary behavior, which obeys the sequential initiation mode and occurs when the orientation of the gravel boundary is inclined to the maximum horizontal stress (<em>σ</em>_H). An offset along the gravel boundary is usually formed while penetrating gravels, and the offsets may cause fracture widths to decrease by 37.8%–84.4%. Even if stress dominates the direction of HF propagation, HFs still tend to deflect within gravels. The deviation angle from <em>σ</em>_H decreases with rising Δ<em>σ</em> and increases with the increase of <em>d</em>_g and <em>R</em>_s. Additionally, intra-gravel shear HFs (IGS-HFs) are prone to be generated in coarse-grained glutenite under high Δ<em>σ</em>, while more gravel-bypassing shear HFs (GBS-HFs) tend to be created in argillaceous glutenite with high <em>R</em>_s than in sandy glutenite with low <em>R</em>_s. The findings above prompt the emergence of a novel HF propagation pattern in glutenite, which helps to understand the real HF geometries and to provide theoretical guidance for treatments in the field.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 348-369"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning-based grayscale analyses for lithofacies identification of the Shahejie formation, Bohai Bay Basin, China","authors":"Yu-Fan Wang ,&nbsp;Shang Xu ,&nbsp;Fang Hao ,&nbsp;Hui-Min Liu ,&nbsp;Qin-Hong Hu ,&nbsp;Ke-Lai Xi ,&nbsp;Dong Yang","doi":"10.1016/j.petsci.2024.07.021","DOIUrl":"10.1016/j.petsci.2024.07.021","url":null,"abstract":"<div><div>It is of great significance to accurately and rapidly identify shale lithofacies in relation to the evaluation and prediction of sweet spots for shale oil and gas reservoirs. To address the problem of low resolution in logging curves, this study establishes a grayscale-phase model based on high-resolution grayscale curves using clustering analysis algorithms for shale lithofacies identification, working with the Shahejie Formation, Bohai Bay Basin, China. The grayscale phase is defined as the sum of absolute grayscale and relative amplitude as well as their features. The absolute grayscale is the absolute magnitude of the gray values and is utilized for evaluating the material composition (mineral composition + total organic carbon) of shale, while the relative amplitude is the difference between adjacent gray values and is used to identify the shale structure type. The research results show that the grayscale phase model can identify shale lithofacies well, and the accuracy and applicability of this model were verified by the fitting relationship between absolute grayscale and shale mineral composition, as well as corresponding relationships between relative amplitudes and laminae development in shales. Four lithofacies are identified in the target layer of the study area: massive mixed shale, laminated mixed shale, massive calcareous shale and laminated calcareous shale. This method can not only effectively characterize the material composition of shale, but also numerically characterize the development degree of shale laminae, and solve the problem that difficult to identify millimeter-scale laminae based on logging curves, which can provide technical support for shale lithofacies identification, sweet spot evaluation and prediction of complex continental lacustrine basins.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 42-54"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141838547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of petrophysical and seismic properties for CO2 storage with sensitivity analysis","authors":"Yan-Jiao Dong ,&nbsp;Yi Shen ,&nbsp;Kai Guo ,&nbsp;Xiao-Qin Wu ,&nbsp;Qiang Mao ,&nbsp;Wen-Yue Sun ,&nbsp;Zhi-Qiang Wang","doi":"10.1016/j.petsci.2024.07.011","DOIUrl":"10.1016/j.petsci.2024.07.011","url":null,"abstract":"<div><div>Saline aquifers are considered as highly favored reservoirs for CO₂ sequestration due to their favorable properties. Understanding the impact of saline aquifer properties on the migration and distribution of CO₂ plume is crucial. This study focuses on four key parameters—permeability, porosity, formation pressure, and temperature—to characterize the reservoir and analyse the petrophysical and elastic response of CO₂. First, we performed reservoir simulations to simulate CO₂ saturation, using multiple sets of these four parameters to examine their significance on CO₂ saturation and the plume migration speed. Subsequently, the effect of these parameters on the elastic properties is tested using rock physics theory. We established a relationship of compressional wave velocity (<span><math><mrow><msub><mi>V</mi><mi>p</mi></msub></mrow></math></span>) and quality factor (<span><math><mrow><msub><mi>Q</mi><mi>p</mi></msub></mrow></math></span>) with the four key parameters, and conducted a sensitivity analysis to test their sensitivity to <span><math><mrow><msub><mi>V</mi><mi>p</mi></msub></mrow></math></span> and <span><math><mrow><msub><mi>Q</mi><mi>p</mi></msub></mrow></math></span>. Finally, we utilized visco-acoustic wave equation simulated time-lapse seismic data based on the computed <span><math><mrow><msub><mi>V</mi><mi>p</mi></msub></mrow></math></span> and <span><math><mrow><msub><mi>Q</mi><mi>p</mi></msub></mrow></math></span> models, and analysed the impact of CO₂ saturation changes on seismic data. As for the above numerical simulations and analysis, we conducted sensitivity analysis using both homogeneous and heterogeneous models. Consistent results are found between homogeneous and heterogeneous models. The permeability is the most sensitive parameter to the CO₂ saturation, while porosity emerges as the primary factor affecting both <span><math><mrow><msub><mi>Q</mi><mi>p</mi></msub></mrow></math></span> and <span><math><mrow><msub><mi>V</mi><mi>p</mi></msub></mrow></math></span>. Both <span><math><mrow><msub><mi>Q</mi><mi>p</mi></msub></mrow></math></span> and <span><math><mrow><msub><mi>V</mi><mi>p</mi></msub></mrow></math></span> increase with the porosity, which contradicts the observations in gas reservoirs. The seismic simulations highlight significant variations in the seismic response to different parameters. We provided analysis for these observations, which serves as a valuable reference for comprehensive CO₂ integrity analysis, time-lapse monitoring, injection planning and site selection.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 193-209"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141695765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TOC","authors":"","doi":"10.1016/S1995-8226(25)00009-3","DOIUrl":"10.1016/S1995-8226(25)00009-3","url":null,"abstract":"","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages i-ii"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sub-lacustrine debrite system: Facies architecture and sediment distribution pattern","authors":"Jian-Ping Liu ,&nbsp;Ben-Zhong Xian ,&nbsp;Xian-Feng Tan ,&nbsp;Zhen Wang ,&nbsp;Jun-Hui Wang ,&nbsp;Long Luo ,&nbsp;Peng Chen ,&nbsp;Yan-Xin He ,&nbsp;Rong-Heng Tian ,&nbsp;Qian-Ran Wu ,&nbsp;Jia Wang ,&nbsp;Jin Li ,&nbsp;Long Chen ,&nbsp;Wen-Yi Peng ,&nbsp;Yi-Man Zhou ,&nbsp;Quan-Feng Jiang","doi":"10.1016/j.petsci.2024.11.007","DOIUrl":"10.1016/j.petsci.2024.11.007","url":null,"abstract":"<div><div>The deep-water systems in different types of sedimentary basins exhibit significant variability. Current knowledge of deep-water deposition is mainly derived from deep-marine turbidite systems. However, the characteristics and differences of sub-lacustrine gravity flow deposition systems have been a research focus in the fields of sedimentology and petroleum geology. This study investigates the facies architecture, depositional processes, and sediment distribution patterns of a sub-lacustrine debrite system in the Eocene Dongying Rift of the Bohai Bay Basin, China, through the analysis of integrated core data, 3-D seismic data, and well-log data. Nine facies have been identified within the debrite system, representing various depositional processes such as sandy debris flow, muddy debris flow, turbidity currents, sandy slide, sandy slide/slump, and mud flow. Our research indicates that the sub-lacustrine system is primarily influenced by debris flow rather than turbidity currents, as supported by facies quantification, interpretation, and flow rheology analysis. Additionally, we have identified five basic facies building blocks in debrite systems, including slide masses, slump masses, debrite channels, debrite lobes, and turbidite sheets. We have also elucidated and proposed detailed sedimentary processes, flow transport, and transformation within the sub-lacustrine system through analysis of flow origins, facies sequences, and distribution characteristics. Our findings highlight the evolutionary progression from delta-front collapse to sandy slide/slump, sandy debris flow, and finally muddy debris flow. The efficient generation of turbidity currents from parental landslides on sand-prone slopes is deemed unlikely due to rift-basin morphology and transport distances. The formation of the five basic facies building blocks is closely linked to depositional processes and dominant flow types. Consequently, we present a deep-water depositional model for sub-lacustrine debrite systems, focusing on flow dynamics, sediment distribution patterns, and basin morphology within deep lacustrine rifts. This model offers valuable insights into the variability of deep-water deposition in diverse basin settings and aids in predicting lithologic reservoirs during deep-water hydrocarbon exploration.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 110-129"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Internal-multiple-elimination with application to migration using two-way wave equation depth-extrapolation scheme","authors":"Jia-Chun You ,&nbsp;Gu-Lan Zhang ,&nbsp;Xing-Guo Huang ,&nbsp;Xiang-Wen Li ,&nbsp;Jun-Xing Cao","doi":"10.1016/j.petsci.2024.06.021","DOIUrl":"10.1016/j.petsci.2024.06.021","url":null,"abstract":"<div><div>Internal multiple interference, affecting both seismic data processing and interpretation, has been observed for long time. Although great progress has been achieved in developing a variety of internal-multiple-elimination (IME) methods, how to increase accuracy and reduce cost of IME still poses a significant challenge. A new method is proposed to effectively and efficiently eliminate internal multiples, along with its application in internal-multiple-eliminated-migration (IMEM), addressing this issue. This method stems from two-way wave equation depth-extrapolation scheme and associated up/down wavefield separation, which can accomplish depth-extrapolation of both up-going and down-going wavefields simultaneously, and complete internal-multiple-elimination processing, adaptively and efficiently. The proposed method has several features: (1) input data is same as that for conventional migration: source signature (used for migration only), macro velocity model, and receiver data, without additional requirements for source/receiver sampling; (2) method is efficient, without need of iterative calculations (which are typically needed for most of IME algorithms); and (3) method is cost effective: IME is completed in the same depth-extrapolation scheme of IMEM, without need of a separate processing and additional cost. Several synthesized data models are used to test the proposed method: one-dimensional model, horizontal layered model, multi-layer model with one curved layer, and SEG/EAGE Salt model. Additionally, we perform a sensitivity analysis of velocity using smoothed models. This analysis reveals that although the accuracy of velocity measurements impacts our proposed method, it significantly reduces internal multiple false imaging compared to traditional RTM techniques. When applied to actual seismic data from a carbonate reservoir zone, our method demonstrates superior clarity in imaging results, even in the presence of high-velocity carbonate formations, outperforming conventional migration methods in deep strata.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 178-192"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for active generation and seepage of sub-salt natural gas/condensate blend in the east offshore Nile Delta, Egypt: Integrated geochemical, petrophysical and seismic attribute approaches","authors":"Mahmoud Leila ,&nbsp;Ahmed A. Radwan ,&nbsp;Amir Ismail ,&nbsp;Emad A. Eysa","doi":"10.1016/j.petsci.2024.11.008","DOIUrl":"10.1016/j.petsci.2024.11.008","url":null,"abstract":"<div><div>Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet “TCF”. Most of these occur in the post-salt hydrocarbon plays where biogenic gases are dominant. This study integrates organic geochemistry, seismic geomorphology and petrophysics in order to decipher the origin, and accumulation conditions of the wet gas/condensate blend in the Upper Miocene sub-salt Wakar Formation sandstones in Port Fouad Marine “PFM” Field, offshore Nile Delta. Hydrocarbon pay zones are scattered thin (&lt;10 m) sandstones deposited in as turbiditic channel/levee complex facies. Spatial distribution of vertical gas chimneys (∼2 km wide) rooting-down to the Messinian Rosetta salt is associated with the lateral pinching-out of the turbiditic sandstones. Organically-rich (total organic carbon “<em>TOC</em>” &gt; 1 w.t.%, hydrogen index “<em>HI</em>” &gt; 200 mgHC/g<em>TOC</em>) and mature (<em>T</em>_max &gt; 430 °C, vitrinite reflectance “<em>VR</em>” &gt; 0.6 %<em>R</em>_o), source rocks are restricted to Upper Miocene Wakar and Oligo-Miocene Tineh formations. The latter contains more mature organofacies (up to 1.2 %<em>R</em>_o) and type II/III kerogen, thereby demonstrating a good capability to generate wet gases. The studied gas is wet and has thermogenic origin with signs of secondary microbial alteration, whereas the condensate contains a mixture of marine and terrestrial input. Molecular biomarkers of the condensate, isotopic and molecular composition of the gas reveals a generation of condensate prior to gas expulsion from the source. The Wakar sandstones have a heterogeneous pore system where three reservoir rock types (RRTI, RRTII and RRTIII). RRTI rocks present the bulk composition of the Wakar pay zones. Spatial distribution of RRTI facies likely control the accumulation of the sub-salt hydrocarbons. Our results provide a new evidence on an active petroleum system in the sub-salt Paleogene successions in the offshore Nile Delta where concomitant generation of gas/condensate blend has been outlined.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 1","pages":"Pages 130-150"},"PeriodicalIF":6.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}