RESERVOIR POTENTIAL OF EOCENE LIMESTONE IN UPPER INDUS BASIN, PAKISTAN.

Abstract

Two dimensional seismic interpretation has been carried out in Missa Kaswal area (study area) located near Gujar Khan in the district of Rawalpindi, Pakistan to reveal the subsurface geology. The data used for this study was provided by DGPC. Seismic data given for well Qazian-01X includes navigation of well and segy data whereas well data include well tops and well headers. Geologically, study area is located in Potwar sub-basin, Upper Indus basin bounded by Soan syncline in the north, Salt Ranges in the south, Jhelum fault in east and Kalabagh fault in west. Prospect evaluation (including gridding, time and depth contouring and identification of structures) has been carried out using Kingdom suit of Software. Structural interpretation has identified anticlinal structure bounded by two reverse faults and is marked on seismic sections. These structures have been marked at Chorgali of Eocene and Patala Formation of paleocene. The horizons are identified and named on the basis of well and generalized stratigraphic data. Seismic Attributes analysis shows that the Chorgali Formation is marked on high acoustic impedence and consolidated material exists. Different petrophysical parameters like volume of shale, water saturation, porosity and hydrocarbon saturation are taken into consideration for reservoir characterization. By performing petrophysical analysis on Chorgali Formation, it is found that the value of volume of shale in Chorgali is 40%, effective porosity is 7%, hydrocarbon saturation is 15% and water saturation is 85%. Facies analysis is performed on the Chorgali Formation, which indicates the presence of shale, limestone and shaly limestone in the formation. Coloured inversion shows the inverted seismic section of the control line, confirming the picking of reflectors marked and Chorgali Formation at high acoustic impedence