Geochemical Characteristics of the Crude Oil of Melut Basin and Its Implications for Hydrocarbon Migration and Accumulat

The Melut basin is a Meso-Cenozoic rift basin accompanied by formation and development of Central African Shear Zone. Previous studies of the Melut Basin mainly related to the basin formation, evolution, structure and reservoir forming patterns, but there are still no systematic studies on the organic geochemical characteristics of oil samples. In this submission, based on the geochemical analyses of 20 oil samples from NMSB, the geochemical characteristics of oil samples were studied, and their organic matter type, depositional environment, maturity and the implication for hydrocarbon migration and accumulation were discussed. The analysis results indicated that the oil samples from NMSB have the similar organic matter source type which are typically derived from lacustrine source rock. The organic matter is predominately Type II-III, and the depositional environment is weak reducing-weak oxidizing environment. The maturity parameter showed that the oil from different area of NMSB all have matured. The lower maturity of the oil samples from the shallow buried Hammal Sub-depression reveals a relatively low degree of evolution and the relatively higher maturity of Cretaceous oil than that of Paleogene oil indicates that the oil generated in the early stage accumulated in the Paleogene reservoir preferentially through the fault.