3D-Seismic Interpretation Integrated with Seismic Post Stack Inversion of Zamzama Area, Lower Indus Basin, Pakistan

Abstract

Zamzama gas field with in the Zamzama block, the research area lies in Dadu district, Sindh. The area of investigation lies in Kirthar foredeep of the lower Indus basin Pakistan. The stratigraphic sequence is composed of Jurassic to recent age. The Zamzama structure is large north-south oriented, eastward verging thrusting anticline. The seismic and well data is provided to interpret its structure and tectonic regime. General geology, Stratigraphy and tectonic of the area is extensively studied to understand the tectonic evolution since the existing of Pangea. Various faults and horizons of interest is marked and interpreted to delineate subsurface structure and its depth, extension and orientation. The petrophysical analysis is carried out to study reservoir formation studied to interpret rock type and fluid presence. Various cross overs is formed in different logs such as RHOB and NPHI which indicate the presence of fluid and porous and permeable rocks. Porosities, shale volume, saturation of water and saturation of hydrocarbon is calculated which show that the reservoir rock has sufficient conventional reservoir rock potential for producing oil and gas. Seismic post stack inversions of two types are applied on the seismic cube integrated with well data to understand the reservoir response at large scale. Both the inversion types; model-based inversion and band limited inversion show low impedance at the depth of reservoir which gives an indication of presence of porous and permeable rock unit within which substantial amount of fluids is present. Hence Zamzama is a potential gas producing field producing in lower Indus basin where Pab sandstone and Khadro formation are widely producing in economical quantity.