Thin-Compartmented Reservoir Simulation and Quantitative Interpretation Using Seismic Attributes: A Case Study in ‘Jude Field’, Offshore Niger Delta

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Thinly bedded hydrocarbon reservoirs are often by-passed during most exploration activities. Unfortunately, fewer research activities have been done within these unobvious by-passed zones. In recent times as technology advances, reservoir characterization within thin beds has improved. Notable high resolution and optimal strategies were established in Agbada formation, Niger Delta for exploring thin compartmentalized reservoirs, predict the viability and reservoir effects, and generate relevant models conditioned by seismic. This was achieved using the results obtained from well logs and seismic data through a complete evaluation involving integrating geological, petrophysical, and seismic interpretation combined with advanced rock physics modelling of thin bedded reservoirs in the study area. Reservoir architecture, thicknesses, seismic properties which control the reservoir quality, and the rock properties that control the seismic signal were also determined. Three reservoirs (AJ2, BJ2 and CJ2) were identified and correlated across the wells using gamma ray, resistivity and neutron-density logs. The results of the petrophysical analysis showed that there are variations in the evaluated parameters within the correlated reservoirs. The porosity value ranged from 25% - 35%, hydrocarbon saturation ranged from 0.49-0.79 and the volume of shale varied from 0.04 to 0.22. The outcome of the rock physics models affirmed the proven relationship existing within the elastic and reservoir properties. This further confirmed that by-passed zones (thin reservoirs, pinch-out, off-laps, etc.) could contain reasonable amounts of unexplored hydrocarbons. A new model, Power Law equation was generated from the cross plot of velocity ratio (Vp/Vs) against acoustic impedance (AI) which was used in obtaining reservoir data inter-wells especially where there are no wells in the study area. This is in contrast to the linear equation earlier generated for conventional (thick) reservoirs. The modelled properties revealed good storage capabilities, favourable description of reservoir distribution and significant interconnectivity.