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Present study deals with reservoir characterization of Kot-Sarang-2 well, located in central part of Potwar plateau of Upper Indus Basin, District Chakwal. The geological structure of the Potwar Basin is the product of the Tertiary Himalayan orogeny, which resulted in the formation of complex fold and thrust belt in this region. In the present work, an attempt has been made to delineate zones having fair shows of hydrocarbons accumulation. In addition to this, estimation of reservoir properties and formation evaluation using wireline logs is also the foremost objective of this study. Based on the wireline logging results, three zones have been marked. Paleocene Lockhart Limestone (3967m to 4045m), Permian Wargal Limestone (4160m to 4245m) and Permian Amb Formation (4246m to 4285m) are possible reservoirs encountered. Physical properties i.e. total porosity (Øt), effective porosity (ØE), resistivity of water (Rw), saturation of water (Sw) and saturation of hydrocarbons (Sh) are calculated. For the calculation of saturation of water (Sw) both Archie’s equation (Swa) and Indonesian equation (Swi) are applied. Results show that Amb and Wargal formations are showing fair to good saturation of Hydrocarbons (Sh) i.e.73% and 88% respectively, but this is due to high resistivity values of these formations and porosity log also giving very low values. Effective porosity for zones Lockhart, Wargal and Amb are 2.56%, 3.5% and 1.32% respectively. Based on these results it is inferred that these formations have low potential for an economically feasible production of hydrocarbons.

The present study investigates the microfacies and source rock potential of the Eocene Nammal Formation in the Nammal Gorge Section, western Salt Range, Pakistan. The Nammal Formation consists of light grey to creamy color limestones, olive green to grey shales and light grey marls. Twelve rock samples of limestone were collected for microfacies analysis and nine samples of limestone and shale were analyzed for determination of Total Organic Carbon (TOC) content and source rock potential of the Nammal Formation. Thin section studies of rock samples revealed four microfacies, i.e., mudstones, wackestones, wackestones to packstones and packstones. Microfacies analysis showed that intraclast, planktons and some small benthic foraminifera, pelecypods and opperculina are present in the Nammal Formation. The type of microfacies and abundance of planktons suggest deposition on a carbonate ramp platform within outer neritic to distal shelf environment in the study area. The Nammal Formation presents a coarsening upwards trend and rise in sea level during its deposition. The average TOC value of nine samples of shale is 0.0812 which shows very little organic matter and poor source rock potential of the Nammal Formation.