Source Rock Evaluation of Shale in Parts of Ini Local Government Area, Akwa Ibom State, Southeastern Niger Delta Basin, Nigeria

Abstract

Total organic carbon and Rock – Eval pyrolysis studies were conducted on seven (7) shale samples outcropping in parts of Ini Local Government Area of Akwa Ibom State, Southeastern Niger Delta, Nigeria. The studies were done to determine the quantity and quality of organic matter in the shale source rock, and their hydrocarbon generation potential. Total organic carbon (TOC) values indicate poor to excellent organic richness with values ranging from 0.46 wt.% to 5.98 wt.%. The free oil content (S1) values range from 0.02-0.21 mg HC/g rock, (mean = 0.07 mg HC/g rock), while the source rock potential (S2) ranges from 0.08-1.09 mg HC/g rock with an average value of 0.45 mg HC/g rock both indicating poor source rock generative potential. The Hydrogen Index (HI) and the Oxygen Index (OI) range from 11 mg HC/g TOC to 59 mg HC/g TOC and 41 mg CO/g TOC to 74 mg CO/g TOC with an average value of 27.28 mg HC/g TOC and 55.71 mg CO/g TOC respectively. HI versus OI and S2 versus TOC cross plot results indicate that shale in parts of Ini Local Government Area contains organic matter capable of generating kerogen type III to type 1V which is gas prone.