Unlocking gas reserves in bypassed stratigraphic traps in a deepwater brownfield using prestack seismic inversion: A case study from offshore Nile Delta, Egypt

Abstract

In deepwater depositional systems such as the slope canyon-turbidite channel system encountered on the continental slope of the offshore West Nile Delta Basin, deterministic prestack seismic inversion followed by facies classification using formation microimager facies logs delineated thick-bedded and thin-bedded gas-sand reservoirs encased in bypassed stratigraphic traps. Prestack seismic inversion was applied over the Scarab Field in the West Delta Deep Marine concession to evaluate the hydrocarbon potential of newly identified stratigraphic traps. Three angle stacks were inverted using a simultaneous inversion approach to estimate the elastic properties (P-impedance and VP/VS ratio). Using the elastic volumes produced from the inversion, Bayesian facies classification was applied to separate thin- and thick-bedded gas-sand facies from shale. Facies classification was focused on two prospective bypassed stratigraphic traps: the Upper Scarab Channel remnant levees (remnant middle levee [RML] and southern remnant levee) and the Lower Scarab Channel lateral accretion packages (LAPs). A development well location is proposed to validate the interpreted gas-sand reservoirs in the shallower RML and the deeper LAPs stratigraphic traps. The results suggest that application of the prestack seismic inversion and facies classification led to reliable inferences likely to have a positive impact on field development, potential reserves growth, and consequently boosting gas production.