Evaluation of source, depositional environment, thermal maturity and biodegradation of organic matter from Kohat-Potwar Basin, Pakistan

Abstract

The study focusses on investigation of source rock generative characteristics and nature of crude oils from Upper Indus Basin (UIB), Pakistan. The source rock sediments and crude oil samples were geochemically analyzed. These samples belong to Lockhart, Patala, Datta and Kingriali formations from Kohat-Potwar region. The sediments samples were extracted using soxhlet extractor with organic solvents. Soluble organic matter (SOM) and crude oil were fractionated into saturates, aromatics, NSOs and asphaltenes. SOM and Total organic carbon (TOC) values reveal good generative potential of rocks. SOM and TOC values increase with depth which point out the increasing thermal maturity with depth. Bitumen to TOC ratio exhibits that samples are within the oil window. High API gravity, absence of unresolved complex mixture (UCM) and very low sulfur content indicate the non-biodegraded nature of the crude oils. The metals were present in a trace amount. This study provides scientific insight particularly for those involved in oil exploration in region under study.

Keywords:

• biodegradation
• depositional environment
• porphyrin
• source input
• thermal maturity
• Upper Indus Basin