CLASSIFICATION OF PETROLEUM COMPOUNDS AND THEIR IMPLICATION FOR HYDROCARBON GENERATION: A STUDY FROM HERWA-1 EXPLORATORY WELL, SW CHAD BASIN

Abstract

Herwa-1 is one of the exploratory wells drilled by the NNPC in SW Chad basin which is used for this study. Organic geochemical analysis was carried out using ten (10) selected shale samples from Fika Shale Formation. Petroleum compounds are classified into hydrocarbons which principally are the Saturated Hydrocarbon (SHC) and Aromatic Hydrocarbon (AHC) and the nonhydrocarbon compound containing Nitrogen, Sulphur and Oxygen (NSO) on the basis of their hydrogen and carbon contents. While soluble organic matter is used to determine the maturity of organic matter in the extract for possible oil/gas generation. The overall average soluble organic matter (SOM), saturated hydrocarbons (SHC) aromatic hydrocarbons (AHC) and the nonhydrocarbon i.e. Nitrogen, Sulphur and Oxygen (NSO) values are 280ppm, 33.5ppm, 65.3ppm and 156ppm. The concentration of the nonhydrocarbon compounds (NSO) is higher than the hydrocarbon compounds (SHC&AHC), and generally the petroleum compounds do not show consistency in terms of maturity with burial depth. But there is a progressive increase of saturated hydrocarbon from (1745- 2450) m with burial depth and the values are relatively within the limit of onset oil generation and therefore considered as the “oil window” within the studied strata. Additionally, the hydrocarbon compounds (SHC&AHC) show mediocre properties than the heteroatomic/nonhydrcarbon compounds (NSO). This is so because the anaerobes utilizes sulfate and nitrate instead of molecular oxygen and survived under anoxic- suboxic condition.