Thermal Maturity and Hydrocarbon Generation Potential of Shales: A case study of Parts of Ini, Akwa Ibom State, Southeastern Niger Delta Basin, Nigeria

The thermal maturity and source rock potential of shale samples from outcrops in Ini, Akwa Ibom State, located within the Niger Delta Basin, Nigeria, were assessed through Total Organic Carbon (TOC), Rock-Eval pyrolysis, and vitrinite reflectance measurements. The TOC, Hydrogen Index (HI), and Genetic Potential (GP) exhibited a range of 0.46 to 5.98 wt %, with an average of 1.65 wt%. Additionally, HI values ranged from 11 to 59 mg HC/g TOC (mean = 27.28 mg HC/g TOC), while GP varied from 0.10 to 1.30 mg HC/g rock, averaging 0.53 mg HC/g rock. Classification based on Hydrogen Index (HI) versus Oxygen Index (OI) and S2 (represents the hydrocarbons generated from kerogen during pyrolysis) versus TOC plots identified the organic matter in the shales as Type III to Type IV kerogen. Furthermore, Tmax (oven temperature that corresponds with S2) values spanning 353 to 427 °C, along with measured vitrinite reflectance values (Ro) of 0.37 to 0.38 %, indicated that the shales are thermally immature concerning hydrocarbon generation. HI versus Tmax and production index (PI) versus Tmax plots further supported this assessment of thermal immaturity in the shale samples.