An Integrated Approach Towards Better Understanding The Distribution Of Reservoir Properties Through Petrophysical Analysis And Well Correlation Of Kohat And Potwar Sub-Basins, Pakistan

Abstract

In this study, efforts are made to relate formations related to depth in 3 wells, petrophysical analysis, Electrofacies analysis, behavior of seismic velocities with the different rock types, source rock identification and behavior of logs with the input of fluids. This thesis consists of two parts, one is related to geology and the other is based on geophysics. In first part we discussed about the correlation of different lithologies variation with depth. Correlation is done between three wells Chanda_deep_01, Chanda 02 and Esa Khel-01. Two wells have many formations in common to each other this include Chanda-deep-01 and Chanda 02 because of their location. While Isa-khel-01 have not similarity in formation as compare to other two wells. Electrofacies plays an important role for the discrimination of different facies related to mineralogy. The prediction of Electrofacies is done on the basis of log behavior. Five facies are identified and marked in the reservoir. Results of Electrofacies reveal Limestone as the reservoir rock. In the second part, geophysical aspects of the well data are taken into account. This includes observation of seismic velocities variation through different lithologies. Sudden decrease in velocity is observed at Samanasuk limestone level (4499-4579m) which is main reservoir. Estimation of TOC helps in delineation of source rock. Lockhart Limestone is marked as a source rock which shows very good TOC of 12%. At the end, Gassmann’s Fluid Substitution is carried out. Curves of velocity and density are generated at different saturations level. This is a 4-D analysis which incorporate time lapse in characterization of reservoir which helps in estimation of hydrocarbon reserves.