Time-Lapse Seismic Monitoring of Onshore Reservoirs in Niger Delta, Field ‘K’ as a Case Study

Abstract

Field ‘K’ is a mature field in the coastal swamp onshore Niger delta, which has been producing since 1960. As a huge producing field with some potential for further sustainable production, field monitoring is therefore important in the identification of areas of unproduced hydrocarbon. This can be achieved by comparing production data with the corresponding changes in acoustic impedance observed in the maps generated from base survey (initial 3D seismic) and monitor seismic survey (4D seismic) across the field. This will enable the 4D seismic data set to be used for mapping reservoir details such as advancing water front and un-swept zones. The availability of good quality onshore time-lapse seismic data for Field ‘K’ acquired in 1987 and 2002 provided the opportunity to evaluate the effect of changes in reservoir fluid saturations on time-lapse amplitudes. Rock physics modelling and fluid substitution studies on well logs were carried out, and acoustic impedance change in the reservoir was estimated to be in the range of 0.25% to about 8%. Changes in reservoir fluid saturations were confirmed with time-lapse amplitudes within the crest area of the reservoir structure where reservoir porosity is 0.25%. In this paper, we demonstrated the use of repeat Seismic to delineate swept zones and areas hit with water override in a producing onshore reservoir.

Reservoir Prediction and Prospectivity of Omos Field Onshore Niger Delta Basin, Nigeria

“…In this case, structural maps and amplitude maps of the three reservoir levels were analyzed to identify potential prospect in both the exploited and undrilled areas of the field. Hydrocarbon reservoir is considered to be a potential prospect if they are trapped within structural traps such as fault blocks or stratigraphic traps (Ogbamikhumi et al, 2017a). The D2 reservoir structural map in figure 4 have six interpreted faults; one major fault to the north and five intra reservoir faults which is typical of the structural configuration of the field.…”

Rock physics attribute analysis for hydrocarbon prospectivity in the Eva field onshore Niger Delta Basin

“…The observed amplitudes on seismic data are as a result of contrast or variation in these rock properties at the boundary between two geological or geophysical interfaces, i.e., changes in lithology or fluid in the subsurface (Brown 1987). Analysis of these amplitudes provide valuable information across field between and away from well control points, providing greater understanding of the subsurface geology heterogeneity related to lithology and fluid effect (Ogbamikhumi et al 2017).…”