HYDROCARBON GENERATIVE POTENTIAL OF CRETACEOUS SEDIMENTS OF KANADI-1 WELL, BORNU BASIN, NIGERIA

ABSTRACT

The hydrocarbon potential and paleodepositional environment of Cretaceous sediments from the Borno Basin, Nigeria, were assessed by Rock-eval pyrolysis and biomarker geochemistry. The Total Organic Carbon (TOC), soluble organic matter (SOM) and genetic potential (GP) values ranged from 0.52 – 0.82wt%, 455.64 – 1003.04 ppm and 0.23 – 0.63 mg/g, respectively. These values suggested that the sediments were moderately rich in organic matter. The Hydrogen Index (HI) values (19 – 85 mgHC/gTOC) and cross plots of Hydrogen Index (HI) versus Oxygen Index (OI), classified the sediments as types 111 and IV organic matter which had potential o to generate mainly gas. The T and Production Index (PI) values ranged from 339 – 436 C and 0.08 – 0.32 max while the Production Index (PI) ranged from 0.08 – 0.32, respectively, suggesting low maturity. Biomarker data revealed the presence of C to C steranes and oleanane which indicated organic matter from mixed sources with 27 29 more terrigenous contribution. The dominance of C over C and C also supported higher terrigenous input. 29 28 27, Various thermal maturity parameters computed from the terpanes and steranes distributions in the sediments indicated low thermal maturity. The C /C – C Homohopane index and Pr/Ph values ranged from 0.06-0.24 35 31 35 and 0.23 – 2.52 respectively. These values suggested organic matter deposited under anoxic to suboxic conditions. The results of this study showed that the sediments had potential to generate mainly gas at appropriate thermal maturity.