Improved diagnosis of the Carbonate Reservoirs: A case study from the Potwar Basin, northwest Pakistan

Abstract The key obstacles to the development of the four wells in the Pariwali Block of the Potwar Basin in Pakistan continue to be an accurate age diagnosis of the reservoir intervals, facies variation, and locating the hydrocarbon target for future development wells. The purpose of this work is to offer integrated biostratigraphic, facies, and sequence stratigraphic information from well cuttings in order to more fully characterize the carbonate reservoirs. The diagnosis of exact stratigraphic units, their ages, and order of cyclicity were constrained by larger benthic foraminiferal biostratigraphy, and the facies integration has made it possible to identify the sequence stratigraphic architecture. The Paleogene Lockhart, Sakessar, and Chorgali Formation were diagnosed, which were deposited on a ramp carbonate platform in a range of environments, including tidal flats, the inner ramp, the proximal middle ramp, and the outer ramp. The Transgressive Systems Tract and the Regressive Systems Tract, which make up a third-order cycle, were validated by the Lockhart, Sakessar, and Chorgali Formation in the Potwar-5, 2, and 7 wells. The facies correlation of the Potwar-2, 4, 5, and 7 wells shows a distinct vertical and lateral change. The occurrence of LBF wackestone-packstone facies possesses excellent reservoir rock characteristics as seen in the Potwar 2, 4, and 5 wells. The poor reservoir intervals are indicated by the lime mudstone facies and their absence in the Potwar-2, which may have contributed to optimal hydrocarbon recovery. The repetition of lime mudstone facies has caused the reservoir compartmentalization in Potwar 4 &7 wells.