Episodes 2023; 46(1): 1-18
Published online March 1, 2023
Copyright © International Union of Geological Sciences.
Aamir Ali1, Asam Farid2*, Taimoor Hassan1
1 Department of Earth Sciences, Quaid-i-Azam University, 45320, Islamabad, Pakistan
2 Department of Geophysics, Arab Company for Laboratories and Soil, 70156, Al Khobar branch, Kingdom of Saudi Arabia
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
This study is aimed at building a 3D static model of the C-Interval horizon within the Lower Goru Formation of the Sawan gas field, Pakistan. The C-Interval horizon is a proven gas reservoir with considerable potential for further development. Sequence stratigraphic interpretation reveals that C-Interval horizon was deposited under transgressive-regressive conditions, with forced regression resulting in deposition of sand bodies in a deltaic environment. Well logs and core analysis reveal different lithological facies. Thin interbedded shales induced extreme heterogeneity in C-Interval reservoir properties. Sequential Indicator Simulation (SIS) and Sequential Gaussian Simulation (SGS) have been applied to spatially map the heterogeneities of the reservoir properties such as water saturation (Sw), porosity (ϕ), facies, etc. The models indicate thick reservoir quality sand facies are present in the northeastern half with high effective porosity (ϕe) being consistent with the high sand content near the paleo-coast line. However, the shale content (Vsh) increases towards the southwestern half consistent with more basinward settings. The lithologies in the southwestern half exhibit low ϕe with an increase in Sw. The techniques utilized in this study have implications for other producing hydrocarbon fields with complex reservoir properties and similar geological settings.