Overpressure Identification and Petrophysical Evaluation of DIAG Field, Offshore Niger Delta, Nigeria in Nigeria

Abstract

An accurate prediction of the sub-surface pore pressures is a necessary requirement for safety, economics and efficiency in the drilling of wells for exploration and production of oil and gas. The study therefore is aimed at determining overpressured zone(s) and the lateral extent from seismic and well log data and to evaluate petrophysical parameters of diverse sand units within DIAG Field. Qualitative evaluation of four sand bodies within three wells was determined. The identified sand horizons were correlated across the studied wells and tied to the seismic section. The depth structural maps and the isochore maps of the sand horizons were generated. The results show five over-pressured zones within the study wells which occurred at depth range from 1793.88 m (5919.68 ft) to 2119.62 m (6994.76 ft) and were tied to seismic section.The depth structured map of the overpressured zones were generated. The identified reservoir Sand 1, Sand 2 and Sand 4 can produce both oil and gas with Sand 3 producing only oil. From the petrophysical parameters, it was evident that all the reservoirs are highly prolific. The Movable Hydrocarbon Index for the entire hydrocarbon reservoir is lower than 0.7 indicating a high mobility of the hydrocarbon within the reservoir.