Rock-Eval Pyrolysis Analysis of Agbada and Akata Shale from Niger Delta Basin, Nigeria

Abstract

Thirty (30) shale core samples from the Agbada and Akata formations in the Niger Delta, Nigeria were evaluated using a Rock-Eval pyrolysis to determine their richness, type, thermal maturity and hydrocarbon potential. Agbada and Akata formation samples show fair to Excellent content of total organic carbon (TOC > 0.5 wt.%) for oil generation. The S2 yield values for Agbada and Akata samples ranging between 0.1 and 10 mgHC/g rock and genetic potential (0.1 mgHC/grock<PG<20 mgHC/grock), indicating that organic matter generated fair to very good significant hydrocarbon. The results acquired from Rock-Eval analysis of Agbada and Akata Formation show low to medium hydrogen index (IH) values (32 to 216 mgHC/g TOC) which indicate gas prone kerogen Type III to minor mixed kerogen Type II/III. The Tmax values for the most of studied samples range from 410°C to 444°C. In Agbada formation, Tmax values varie between 414°C and 438°C, indicating an Immature to early mature organic matter. Tmax values for Akata formation range from 410°C to 444°C, suggesting immature to mature source rocks. This study concluded that Agbada formation has organic matter for world class oil generation but the limitation of the thickness of the formation gives Akata formation a better stand, with a fair generation capacity but an ocean of thick source rock, the thickness compensates for the fair generation capacity.