PETROPHYSICAL ANALYSIS OF RESERVOIR ROCKS OF SELECTED WELLS IN THE PUNJAB PLATFORM, CENTRAL INDUS BASIN, PAKISTAN

Abstract

The Punjab Platform is tectonically stable area in the Central Indus Basin. It is an evident monoclinal structure on the geological map due to envisaged salt-related dynamics that affect the Paleozoic strata. About 60,000 km2 area is covered with sedimentary rocks but only a few hydrocarbon explorations projects have been carried out since then. Literature reveals that only nineteen wells have been drilled to date, containing three gas discoveries from Lumshiwal Formation of Cretaceous age and Samanasuk Formation of Jurassic age which explain hopeful oil and gas prospects in this area. The petrophysical analysis of Datta and Khewra Sandstone was carried out on Bijnot-1, Fort Abbas-1, and Ahmadpur-1 wells which are situated in the Punjab Platform area. The purpose of this analysis was to find out the reservoir potential of both the formations. On the basis of petrophysical analysis zones of interest were found at different depths in the Datta Formation of the Punjab Platform. The effective porosity values range between 12-16%. The thickness of zones of the Datta Formation ranges from 9-18 m and the saturation of water ranges from 62-88%. The GR log trend shows coarsening to finning upward sequence which represents the deltaic environment of deposition. Zone of interest in the Khewra Sandstone of the Punjab Platform has effective porosity of 8- 12%. The average porosity of the Khewra Sandstone ranges from 10-20% in the Punjab Platform. The average water saturation is 89%. Low resistivity values along with high water saturation shows that formations are hydrocarbon depleted water-wet reservoir.