CHARACTERIZING THERMAL MATURITY AND HYDROCARBON POTENTIAL OF SOURCE ROCK USING ROCK-EVAL 6 PYROLYSIS TECHNIQUE: A CASE STUDY OF POLOGBENE-1 WELL, NORTHERN DELTA DEPOBELT, NIGER DELTA BASIN
Authors: Lucas F.A, Aduomahor B.O, *Omodolor H.E, Egbule F.I
Organic geochemical evaluation of source rock within a petroleum system is important considering its role as the source of hydrocarbon. Subsurface samples at depth of 2361 m (outer shelf) and 2613 m (lower slope) from Pologbene-1 Well located within the northern delta depobelt were analysed using Rock-Eval pyrolysis analytical technique. This technique involves the temperature programmed heating of samples in an inert environment. Inference was drawn from Rock-Eval geochemical parameters, which include the already generated oil in the rock (S1), the amount of hydrocarbon generated through thermal cracking of nonvolatile organic matter (kerogen) (S2), Total Organic Carbon (TOC), and Maximum Temperature (Tmax). Others are Hydrogen Index (HI), Oxygen Index (OI) and Production Index (PI). The results were compared with the inner shelf (1716 m) and the upper slope (2595m) of the same well. Two geochemical models were established; Hydrogen Index/Oxygen Index (HI/OI) and Hydrogen Index/Maximum Temperature (HI/Tmax), for the outer shelf and upper slope source rock of Pologbene-1 Well. The two models were derived from Hydrogen Index (HI) values of 502 and 548, Oxygen Index (OI) value of 14 and 15 and Maximum Temperature (Tmax) value of 429oC and 419oC (outer and upper slope respectively). The model indicate that the samples are oil and gas prone, are Type II source rock containing Type II kerogen. S1, S2 and Total Organic Carbon (TOC) values of 7.96 mg/g, 328mg/g and 65.36 wt. percentage for outer shelf and 7.51mg/g, 325mg/g, 59.37 percent for upper slope respectively indicate good to source capacity and high petroleum potential for Pologbene-1 Well.
Affiliations: Department of Geology, Faculty of Physical Sciences, University of Benin, PMB 1154, Benin City, Nigeria
Keywords: Organic Geochemical Evaluation, Source Rock, Depositional Environment, Kerogen Type, Niger Delta Basin
Published date: 2018/06/30