A No-Drill Decision for Beige Deepwater Prospect: An Integrated Subsurface Perspective

Abstract The Beige prospect is an exploration opportunity in deepwater – offshore Gulf of Guinea. A key business driver was to drill 2 exploration wells to test the prospect for commercial hydrocarbon volumes and in a success case tie-back to a nearby Bassa Floating Production Storage and Offloading (FPSO) facility. Following the outcome of neighboring Bassa-X Near Field Exploration (NFE) well that drilled into a Class II/III AVO anomaly which turned out wet, the Beige prospectivity maturation was deferred for revalidation using the latest (2022) seismic (broadband), well data and incorporate the postmortem results from Bassa-X exploration well outcome. Preliminary 2023 assessment of the Beige opportunity showed significant change in the overall geology requiring a full revalidation. A suite of reliable technology was deployed in the subsurface evaluation leading to an improved understanding of the prospect. Artificial intelligence-backed applications were utilized to generate fault probability cubes using full-stack conditioned relative acoustic impedance and Wide Band Spectral Decomposition (WBSD) seismic volumes. While elevation decomposition and amplitudes from auto-tracked events provided a better understanding of stratigraphy & structural elements for each reservoir. Differentiating seismic quantitative interpretation (QI) methodologies – Rock Physics analysis, AVO inversion of LambdaRho/MuRho formed the basis for polarizing false positive anomalies from hydrocarbon bearing reservoirs while amplitude versus depth analysis was deployed for fluid contacts prediction. The revalidated results confirm that the Beige Deepwater opportunity is valid. Howbeit, in comparison with previous evaluation a ca.43% reduction in recoverable volume was observed. This was largely due to shorter predicted column height & higher water saturation with 3 of the 5 business case targets not meeting commercial volume threshold. Body-KA – the largest volume carrier was observed to be highly compartmentalized with significantly low volumes for each fault block. The recommendation from the subsurface team enabled an on-time business decision to suspend Beige exploration well from the drilling sequence until an optimally commercial development approach is realized and focus resources to mature recently high-graded Bassa NFE opportunities.