El-Sayed Ali S, Mabrouk Walid M, Metwally Ahmed M
Geophysics Department, FacultyofScience, Cairo University, Giza, 12613, Egypt.
Sci Rep. 2025 Jan 7;15(1):1180. doi: 10.1038/s41598-024-75015-x.
The Nile Delta, North Africa's leading gas-producing region, was the focus of this study aimed at delineating gas-bearing sandstone reservoirs from the Pleistocene to Pliocene formations using a combination of pre-stack inversion and rock physics analysis. This research employed seismic inversion techniques, including full-angle stack seismic volumes, well logs, and 3-D with rock physics modeling to refine volumes of P-wave velocity (Vp), S-wave velocity (Vs), and density. Traditional seismic attributes, such as far amplitude, proved insufficient for confirming gas presence, highlighting partial angle stacks, integrated the need for advanced methods. Extended Elastic Impedance (EEI) analysis was used to predict fluids and identify lithology in clastic reservoir environments. The EEI approach facilitated the determination of optimal projection angles for key petrophysical properties such as porosity, shale volume, and water saturation. This method was applied to the middle Pliocene (Kafr El Sheikh Formation) and the Pleistocene (El Wastani Formation), revealing promising drilling sites. In the Kafr El Sheikh Formation, porosity ranged from 16 to 29%, shale volume from 21 to 40%, and hydrocarbon saturation from 25 to 90%. The study concludes that integrating pre-stack seismic inversion with EEI significantly enhances the likelihood of identifying gas-bearing sands while reducing exploration risks. The improved POS for the Pleistocene anomaly gas bearing sand (from 49 to 69%) and the middle Pliocene anomaly (from 46 to 66%) underscores the effectiveness of this approach in the Baltim Field, Offshore Nile Delta, and supports further drilling and development wells.
尼罗河三角洲是北非主要的天然气产区，是本研究的重点，该研究旨在通过叠前反演和岩石物理分析相结合的方法，从更新世到上新世地层中圈定含气砂岩储层。本研究采用了地震反演技术，包括全角叠加地震体、测井数据以及三维岩石物理建模，以优化纵波速度（Vp）、横波速度（Vs）和密度体。传统的地震属性，如远偏移距振幅，已证明不足以确认天然气的存在，突出了部分角度叠加，这表明需要先进的方法。扩展弹性阻抗（EEI）分析用于预测碎屑岩储层环境中的流体并识别岩性。EEI方法有助于确定关键岩石物理性质（如孔隙度、页岩体积和含水饱和度）的最佳投影角度。该方法应用于上新世中期（卡夫尔谢赫组）和更新世（瓦斯塔尼组），发现了有前景的钻探地点。在卡夫尔谢赫组中，孔隙度范围为16%至29%，页岩体积为21%至40%，烃类饱和度为25%至90%。研究得出结论，将叠前地震反演与EEI相结合可显著提高识别含气砂岩的可能性，同时降低勘探风险。更新世异常含气砂岩的改进概率（从49%提高到69%）和上新世中期异常的概率（从46%提高到66%）突出了该方法在尼罗河三角洲近海巴尔蒂姆油田的有效性，并支持进一步钻探和开发井。
