Sake Near Field Exploration: An Exploration Strategy to De-Risk Subsurface Uncertainty

Abstract Sake Prospect is a near field exploration (NFE) opportunity in a fault assisted footwall closure adjacent to the Saku Main Producing Field. The Saku Field was discovered in 1957 and production started in 1971. The Southwestern, Eastern and Northern parts of the OML are under-explored. Sake Prospect is located in the Southwestern part of the Saku Main Field. The Sake NFE aims to unlock undiscovered gas volumes to mitigate Nigerian Liquified Natural Gas (NLNG) Trains 1-6 (T1-T6) gas supply shortfall and build resilience to sustain the Saku gas plant. The prospect consists of four amplitude supported reservoir-seal pairs (RSP) that are situated within the normally pressured depth window. The opportunity is assessed with a 76% probability of success (POS) and a potential to unlock commercial volume of gas resource which upon exploration success would be hooked up immediately to the Saku gas plant located less than 6km from Sake Prospect. Considering that the Saku Main Field has discovered commercial quantities of both gas and oil volumes, the major uncertainty therefore for the prospect is hydrocarbon type and presence of developable oil rim. While the business goal is premised on gas development, finding a developable oil rim could delay the production of the much-needed gas, therefore eroding value. Conventionally, exploration wells are typically drilled at the crest of the structure to prove the presence of hydrocarbon. However, in view of the risk of an oil rim the exploration strategy for the Sake prospect is to first drill a pilot hole down flank of the structure to test the seismically predicted fluid contacts – gas-oil contact (GOC) and oil-water contact (OWC) hence determine the oil rim thickness and prove commerciality of the gas volume. Success of this strategy would then trigger the drilling of a development well at the crest of the structure.