SEISMIC INVERSION AND PETROPHYSICAL ANALYSIS OF MUBARAK AREA,CENTRAL INDUS BASIN,PAKISTAN

Abstract

Mubarak block is present in Ghotki area Sindh,Central Indus basin.Due to extensional tectonic regime normal faults are present in this area.Jurrasic to most recent rocks are present in its stratigraphic sequence.The most promising formation in this area is Lower Goru as it contains thin interbedded sandstone and shale. This study has been carried out in Rehmat gas field (Mubarak block).The provided data was seismic 3D data and well data of Rehmat-02.The purpose of study is to know the potential of Lower Goru formation.Structural and stratigraphic interpretation of 3d seismic data, fault geometry mapping and time and depth contour maps are main methods used to complete task. Three horizons are marked Sui Main Limestone, Upper Goru and Lower Goru Formation. Due to extension normal faults are developed which divide the area into horst and graben structures which play an important role in reservoir compartmentization.For estimation of fluid potential petrophysical logs are applied. Only one reservoiz zone of significant thickness and hydrocarbon saturation was marked.The estimated volume of shale varies between 20%-30%, effective porosity between 10-11% and saturation of water from 20-30%. Estimation of sand channels and detailed reservoir characterization is done by post stack inversion. Model based inversion technique play an important role in understanding lithology and porosity of B-interval reservoir. Model based inversion gives appropriate estimation of acoustic impedance and lithology. North to South impedance value increases and from East to West it decreases.At the encounter of Lower Goru formation, there is sharp increase in acoustic impedance showing low porosity value above and below well location and at well location low impedance value suggest high porosity which show presence of hydrocarbons. Hence, the study shows Lower Goru formation of Cretaceous has potential to produce hydrocarbon at commercial scale.