Seismic Attribute Analysis and Petrophysical Interpretation of Balkassar Area, Chakwal District, Punjab, Pakistan (T-1536) (MFN 5876)

Abstract

In this research work,2-D seismic interpretation and petrophysical analysis of the Balkassar Oil field was done which is situated in the Chakwal District of Punjab, Pakistan. Balkassar is an exclusive D & P Lease of Pakistan Oilfields Limited (POL) and it was discovered in 1945 by Attock Oil Company Pakistan. Balkassar area lies in the Central part of the Potwar Sub-Basin which is a part of the Himalayan Foreland Fold and Thrust Belt. The purpose of this study is to understand the geological and tectonic setting of the area using seismic data andutilizing petrophysics to get the information about the saturation of hydrocarbons in the reservoir zones. To improve understanding and mapping reservoir and to resolve structural and stratigraphical complexities, three seismic attributes were analyzed; Instantaneous Phase, Instantaneous Amplitude and Instantaneous Frequency. Using this information, five horizons were marked on the seismic sections which are Chorgali, Sakesar, Lockhart, Tobra and Khewra and the faults passing through these horizons were identified. After marking the faults the values of time and interval velocity from the velocity windows of seismic sections were used to generate the two way time and depth maps. The faults marked on the seismic sections and the contour maps generated confirm the presence of “Anticlinal pop-up” structure in the area which undergoes compartmentalization shaped by both compressional and shear stress regimes. In the petrophysical analysis of the Balkassar area two wells were used namely OXY01 and POL01. The well OXY-01 showed four favourable zones of potential hydrocarbon reservoirs. Two of these zones were found in Sakesar Formation whereas one each was found in the Chorgali and Lockhart formations. On the other hand the well POL-01 also showed four favorable zones of potential hydrocarbon reservoirs. One of these zones was found in Chorgali Formation whereas three of them were marked in Sakesar Formation. The petrophysical analysis of the Oxy-01 and POL-01 wells confirm the presence of potential hydrocarbons in the subsurface horizons of Chorgali, Sakesar and Lockhart limetones.