2D Seismic Interpretation of Compressional Regime of the Dohdak Concession and Source Rock Assessment of the Early Cretaceous Sembar Formation; a Case Study from Central Indus Basin, Pakistan

Abstract

Dhodak concession is a part of eastern margin of Sulaiman Fold and Thrust Belt formed as a result of complex transpressional interactions during the Indian-Eurasian collision. Study area reveals the compressional structures that provide suitable hydrocarbon traps of Cretaceous age. Different lithological boundaries and structural properties are identified from 2D seismic, amplitude, and frequency derived seismic attributes. Time and depth structural mapping of the Pab Sandstone (Late Cretaceous) demonstrated an ideal doubly plunging anticlinal structure that represents four way closure for hydrocarbons accumulation in the study area. Observed relatively low-frequency anomaly confirms the hydrocarbon-bearing reservoirs. Since hydrocarbon quantity in a reservoir also depends on the generation potential of source rock, so an attempt has been made to estimate the Total Organic Carbon (TOC) of the source i.e. Sembar Formation. The latter was divided divided into three parts based on the calculated TOC using the Δ log R technique. Upper and lower parts of the Sembar Formation chiefly comprise the lower TOC values (1.90 and 2.1 wt %), whereas the middle part comprises the higher TOC values averaging 3.01 wt %.