This publication presents how 4D seismic and reservoir simulation techniques were used to optimise the trajectory of an infill production well in a producing oil field. The A6 infill well target in Field X offshore Nigeria was planned as a 12000 feet horizontal drill well with a 4900 feet gravel pack completion in the reservoir formation. The initial well trajectory delivered early water breakthrough and low oil recovery. The well planning team resolved the issue by reconciling the well trajectory and completion data in the geologic and reservoir simulation models, and used 4D seismic difference maps to validate the infill drilling target. Alternative well trajectories were then simulated to improve reservoir penetration and to place the well up-structure and away from the current oil water contact.

The optimised well trajectory increased the incremental oil recovery from 1.8 MMSTB to 3.0 MMSTB, and significantly boosted the project economics. The well came online in 2016, and delivered higher oil rates than the forecast. 4D seismic and reservoir simulation techniques optimised the infill well trajectory, delayed water breakthrough, and maximised oil recovery. Nearby wells can be shut in during drilling operations to minimise the risk of drilling losses and well integrity failures. Oil asset net present value can also be preserved and boosted with water injection performance monitoring, zonal testing, short circuit diagnosis and remediation, and water shut off work-overs. This paper presents a case study of an infill production well placement optimised with 4D seismic and reservoir simulation tools, and simplifies the infill well placement value creation process.

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