Professional Review of Subsurface Data Integration Practices for Field Development Plan Optimisation in the Offshore Ijaw Complex, Bayelsa State

Field development plan optimisation for multi-reservoir offshore developments requires the systematic integration of subsurface data from seismic interpretation, petrophysical evaluation, fluid characterisation, and dynamic modelling into a coherent decision-support framework. This study professionally reviews subsurface data integration practices for field development plan optimisation in the Offshore Ijaw Complex, Bayelsa State, South South Nigeria. The review examines the technical workflows and decision management processes applied during the development planning phase of a mid-sized offshore development, where seven producing reservoir intervals require co-development under shared surface facilities constraints. Data integration challenges reviewed include the incorporation of four-dimensional seismic time-lapse data into dynamic history matching workflows, reconciliation of material balance and simulation model estimates of hydrocarbon pore volume, and the management of petrophysical uncertainty in net pay determination. Decision support framework evaluation draws on the SPEI integrated subsurface evaluation guideline and the uncertainty quantification methodology from the Norwegian Petroleum Directorate Petec standard. Specific workflow improvements identified include reducing volumetric uncertainty from plus or minus 35 percent to plus or minus 21 percent through constrained stochastic inversion in the primary reservoir, and improving recovery factor predictions by incorporating geomechanical compaction effects into the dynamic model. Recommended data acquisition strategies for the field development appraisal phase are outlined. Keywords: subsurface data integration, field development plan, Offshore Ijaw Complex, Bayelsa State, reservoir uncertainty.