Diagenetic Control on Porosity Development in Early Eocene Carbonate Reservoirs of Potwar Sub-Basin, Pakistan

Abstract

The Eocene carbonates of Sakesarand Chorgali rock units are the main oil and gas producing horizons in Potwar sub-basin of Pakistan. Petrographic analysis of core samples of wells from six different fields, demonstrates that diagenesis has played the major role in the development of porosities in the reservoirs of these two formations. Dolomitization and solution are the major diagenetic processes involved in the development of intercrystalline, moldic and vuggy porosities; whereas, structural deformation has resulted in joint and fracture porosities. Effective porosities, within the carbonates of the two rock units, are almost confined to the northwestern portion of the Potwar region; whereas, in the south-eastern part, open pore spaces are almost not existing.