Structural Distribution and Evaluation of Siliciclastic Reserviors of X-onshore Oil Field of Niger Delta, Nigeria

The mapping and evaluation of the structural distribution of siliciclastic reservoirs in the X-onshore oil field, Niger Delta, using well logs and seismic data sets has been established. This is aimed at mitigating the challenges of reservoir facies faced during development, delineation, and drilling of hydrocarbons from such reservoirs. The petrophysical results show that the identified reservoirs are made up of the intercalation of sand and shale lithofacies with varying sensitivity within the reservoir intervals. The reservoirs in the oil field are found to be free siliciclastic reservoirs, as their porosity and permeability values exceed 12% and 1000mD respectively. Three different faults, corresponding to the three correlated and adopted reservoirs, were mapped and interpreted on the seismic sections. The result of study's structural pattern suggests that growing faults, a frequent trapping mechanism noticed in the Niger Delta region, are trapping the hydrocarbons. From well-13 to well-30, the amount of hydrocarbon saturation increased (in the direction of the northeastern part of the covered seismic area). This was substantiated by the results of the time surface contour maps. This is because the concentration of hydrocarbon saturation increased as the oil field moved toward the Northeast. Hence, the fault, which is a rollover anticline, encloses the hydrocarbon prospect region in this study. This fault growth conforms to the area of possible hydrocarbon accumulation.