FACIES CHARACTERIZATION AND ASSOCIATED DIAGENETIC MODIFICATION USING CORE STUDIES AND WELL LOG DATA OF THE EOCENE CHORGALI FORMATION, POTWAR SUB-BASIN, PAKISTAN

Abstract

The Balkassar Oilfield is located in the eastern Potwar sub-basin, and lies on the Soan Syncline southern flank of the Himalayan collisional regime. Present study is conducted to understand the depositional environment, diagenetic modification and electrofacies of Eocene Chorgali Formation. The study based on core studies, petrography and well logs analysis. The Formation consist of light to dark gray color limestone with shale intercalations. Five microfacies have been classified on the basis of core studies and petrography which are as follows: Non-laminated mudstone, mud-wackstone, larger foraminifera wack-packstone, Mixed bioclastic wack packstone and shale lithofacie. Based on depositional texture and fossils assemblages suggest that the Chorgali Formation is deposited in supra tidal to middle shelf depositional settings. Further analysis shows that the Formation underwent different diagenetic changes mainly showing micritization, compaction, cementation, neomorphims, dissolution and stylolitization. These features are passing through different diagenetic environments. Three electrofacies are developed by K mean clustering method which is limestone, shaly limestone and calcareous shale.