The precise characterization of reservoir parameters is vital for future development and prospect evaluation of oil and gas fields. C-sand and B-sand intervals of the Lower Goru Formation (LGF) within the Lower Indus Basin (LIB) are proven reservoirs. Conventional seismic amplitude interpretation fails to delineate the heterogeneity of the sand-shale facies distribution due to limited seismic resolution in the Sawan gas field (SGF). The high heterogeneity and low resolution make it challenging to characterize the reservoir thickness, reservoir porosity, and the factors controlling the heterogeneity. Constrained sparse spike inversion (CSSI) is employed using 3D seismic and well log data to characterize and discriminate the lithofacies, impedance, porosity, and thickness (sand-ratio) of the C- and B-sand intervals of the LGF. The achieved results disclose that the CSSI delineated the extent of lithofacies, heterogeneity, and precise characterization of reservoir parameters within the zone of interest (ZOI). The sand facies of C- and B-sand intervals are characterized by low acoustic impedance (AI) values (8 × 106 kg/m2s to 1 × 107 kg/m2s), maximum sand-ratio (0.6 to 0.9), and maximum porosity (10% to 24%). The primary reservoir (C-sand) has an excellent ability to produce the maximum yield of gas due to low AI (8 × 106 kg/m2s), maximum reservoir thickness (0.9), and porosity (24%). However, the secondary reservoir (B-sand) also has a good capacity for gas production due to low AI (1 × 107 kg/m2s), decent sand-ratio (0.6), and average porosity (14%), if properly evaluated. The time-slices of porosity and sand-ratio maps have revealed the location of low-impedance, maximum porosity, and maximum sand-ratio that can be exploited for future drillings. Rock physics analysis using AI through inverse and direct relationships successfully discriminated against the heterogeneity between the sand facies and shale facies. In the corollary, we proposed that pre-conditioning through comprehensive petrophysical, inversion, and rock physics analysis are imperative tools to calibrate the factors controlling the reservoir heterogeneity and for better reservoir quality measurement in the fluvial shallow-marine deltaic basins.

中文翻译：

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控制巴基斯坦东南部 Sawan 气田浅海油藏的油藏非均质性：使用声阻抗反演预测油藏质量的意义

储层参数的精确表征对于油气田未来的开发和前景评价至关重要。下印度河流域 (LIB) 内下沟组 (LGF) 的 C 砂层和 B 砂层是已探明的储层。由于 Sawan 气田 (SGF) 的地震分辨率有限，常规地震振幅解释无法描绘砂页岩相分布的非均质性。高非均质性和低分辨率使得表征储层厚度、储层孔隙度和控制非均质性的因素具有挑战性。约束稀疏尖峰反演 (CSSI) 使用 3D 地震和测井数据来表征和区分 LGF C 和 B 砂层段的岩相、阻抗、孔隙度和厚度（砂比）。取得的结果表明，CSSI 描绘了感兴趣区 (ZOI) 内的岩相范围、非均质性和储层参数的精确表征。C-、B-砂层段砂相特征为低声阻抗（AI）值（8×106 kg/m2s～1×107 kg/m2s）、最大砂比（0.6～0.9）、最大孔隙度（10% 到 24%）。由于低 AI（8 × 106 kg/m2s）、最大储层厚度（0.9）和孔隙度（24%），主储层（C-砂）具有出色的产气能力。然而，如果评估得当，由于低 AI（1 × 107 kg/m2s）、良好的砂比（0.6）和平均孔隙度（14%），二级储层（B 砂）也具有良好的产气能力. 孔隙度和砂比图的时间片揭示了低阻抗的位置，最大孔隙度和最大砂比，可用于未来钻探。通过反向和直接关系使用 AI 进行的岩石物理分析成功区分了砂相和页岩相之间的异质性。在推论中，我们提出通过综合岩石物理、反演和岩石物理分析进行预处理是校准控制储层非均质性因素和更好地测量河流浅海三角洲盆地储层质量的必要工具。