El-Sayed Ali S, Mabrouk Walid M, Metwally Ahmed M
Geophysics Department, Faculty of Science, Cairo University, Giza, 12613, Egypt.
Sci Rep. 2024 Nov 28;14(1):29596. doi: 10.1038/s41598-024-78186-9.
Given useful rock properties, gas sands generally appear as bright events on seismic data. Unfortunately, partially saturated gas sands tend to be of similar brightness to fully saturated gas sands so cannot be distinguished easily. Seismic inversion can sometimes help, given adequate seismic data and a robust understanding of rock physics. This study employs both post- and pre-stack seismic inversion techniques to estimate gas in place (OGIP) and evaluate reservoir properties within the Pleistocene gas sandstone reservoir of the Baltim Field, focusing specifically on the Kanaria prospect. The primary objectives are to estimate gas volumes, assess reservoir properties, and identify optimal well locations. Post-stack inversion is used to detect changes in acoustic impedance, which is essential for hydrocarbon identification, while pre-stack inversion provides insights into rock properties such as density. This approach helps to differentiate true gas sands from other geological features, like water layers or lithological anomalies, which can be misinterpreted as gas zones due to similar seismic responses or fluid variations. Although seismic indicators such as root mean square (RMS) amplitude and AVO analysis can suggest potential gas zones, they may also be affected by similar lithological effects, complicating accurate interpretation. The study confirms the presence of gas-bearing sands in the El Wastani and estimates an OGIP of approximately 0.4 Gm³ for well WB-1 and 6.6 Gm³ for well TERSA-1 ST. By providing detailed reservoir characterization and improving gas estimation accuracy, the findings support informed decision-making for drilling locations and enhance the potential for successful gas production in the Baltim Field.
考虑到有用的岩石特性，气砂在地震数据上通常表现为明亮的信号。不幸的是，部分饱和气砂的亮度往往与完全饱和气砂相似，因此不容易区分。在有足够的地震数据和对岩石物理学有深入理解的情况下，地震反演有时会有所帮助。本研究采用叠后和叠前地震反演技术来估算原地天然气储量（OGIP），并评估巴尔蒂姆油田更新世气砂岩储层的储层特性，特别关注卡纳里亚勘探区。主要目标是估算天然气储量、评估储层特性并确定最佳井位。叠后反演用于检测声阻抗的变化，这对烃类识别至关重要，而叠前反演则能深入了解岩石特性，如密度。这种方法有助于将真正的气砂与其他地质特征区分开来，如水层或岩性异常，这些特征可能由于相似的地震响应或流体变化而被误判为气层。尽管均方根（RMS）振幅和AVO分析等地震指标可以指示潜在的气层，但它们也可能受到相似岩性效应的影响，使准确解释变得复杂。该研究证实了埃尔瓦斯塔尼存在含气砂层，并估算出WB - 1井的原地天然气储量约为0.4 Gm³，TERSA - 1 ST井为6.6 Gm³。通过提供详细的储层特征描述并提高天然气估算精度，这些发现为钻井位置的明智决策提供了支持，并增强了巴尔蒂姆油田成功产气的潜力。
