Rejuvenating an Aging Asset through a Comprehensive Reservoir Simulation Study

Abstract

With a peak production of ∼30,000 bopd, "Field_M" was one of the most prolific fields in Niger-delta. However, over a forty-year period, production has declined to less than 3% of the peak value. In order to unlock new potentials in this asset, a multi-disciplinary team embarked on an asset re-assessment using reservoir simulation studies while focusing on the top reservoirs in the field with the highest expected incremental recovery. The first group of studies were done on a genetically related stack of four (out of available eleven) reservoirs: two depleted reservoirs and two virgin reservoirs, using a single comprehensive structural and stratigraphic framework. For virgin reservoirs, probabilistic simulation studies were conducted with decoupled static and dynamic parameters. The most dominant parameters were identified and used to guide selection of P10/P50/P90 models. Sensitivities studies were conducted under different recovery mechanisms and different development scenarios using both idle wellbores and new wells. Erstwhile economically challenged opportunities due to small in-place volumes were improved by consolidating these opportunities. Integration of new opportunities were facilitated using the comprehensive model which allowed the testing of wellbores across all reservoirs simultaneously1. For depleted reservoirs deterministic history matches were done using available pressure and production. History match helped to characterize connectivity between faults and across multiple lobes in these reservoirs2, an important factor in planning infill drilling. Post history match sensitivities provided reactivation opportunities and infill developments under secondary recovery mechanism. The study outcomes will drive implementation of waterflood in these reservoirs in addition to non-rig intervention and infill drilling. The study identified a total of nine opportunities: two reactivations, two new injection strings and five new producing strings with an incremental recovery of 26 MMBO.