SEISMIC RESERVOIR CHARACTERIZATION AND 3D MODELLING OF OY FIELD, OFFSHORE NIGER DELTA

Abstract

As exploration and production move further offshore, a better understanding of the Niger Delta reservoir system is necessary. In order to quantify reserves, eliminate uncertainty, and find the best strategy for optimum recovery of hydrocarbon, it is critical to model the reservoir as accurately as possible. 3D reservoir modelling and characterization was carried out on the OY Field, which is a shallow offshore hydrocarbon field situated in the north-western Niger Delta region of Nigeria. The dataset used for this study were 3D migrated seismic data, composite well logs and check shot. The Petrel E&P software was used for reservoir correlation, petrophysical analysis, 3D seismic interpretation and reservoir modelling. The methods adopted involved the well log analysis, generation of synthetic seismograms, surface attribute analysis and the 3D static modelling. In the well log analysis, five hydrocarbon bearing reservoir (Sand A, B, C, D and E) were delineated. The five horizons were mapped on the 3D seismic data and the time and depth maps generated, showed fault dependent closure, four assisted closure and four-way closure. Attributes analysis were carried out to enhance data interpretation and high anomalies were observed around the closure drilled on the field. The 3D petrophysical models of the reservoir have shown the prominence of good porosity distribution with porosity varying from 0.3 - 0.4, the net to gross model reveals good net to gross within the well area varying from 0.5 - 1.0 and the 3D water saturation model shows the hydrocarbon zone region with water saturation value varying from 0.1 - 0.5. The 3D petrophysical model have enhanced a better understanding of the distribution of the petrophysical properties and can guide an optimal field development plan (FDP), well planning and production of hydrocarbon on the field.