Condensate Tracking and GOR Management in an Oil-Gas Reservoir

Abstract

An onshore reservoir in Abu Dhabi is a thin four-way anticline reservoir with an oil rim and extensive gas cap. The oil rim and gas cap have different ownership interests. The oil rim is under active development, while the gas cap is yet to be developed. The first part of this study was to verify the adequacy of tools for calculating historical and estimating future resource exchange between the gas cap and oil rim. This condensate tracking study involved QC (Quality Control) of the fluid characterization of the oil rim and gas cap, and validation of the tracking features in the t-Navigator reservoir using a dual-EOS model. The second part of this study was to investigate the optimal reservoir management strategy around the wells in the oil-rim closest to the gas cap, and the row of injectors (gas cap fence) surrounding the oil rim. The gas cap fence is intended to form a barrier between the gas cap and oil rim producers and prevent gas encroaching into the oil rim. The study showed that the fence is effective, however, due to heterogeneity, drilling timing and gaps in the fence a perfect seal is not achieved. Historical reservoir performance was analyzed to understand the fence behavior and simulation studies were also performed to give insight into the future reservoir management strategy. Alignment of the condensate tracking study with the reservoir management strategy update ensured that the benefits of the new strategy come primary from increase oil production and not condensate. The updated reservoir management strategy (injection strategy and production limits) is predicted to increase oil production rate by 20% in the short term and increase oil rim recovery factor by 2.4%, with little additional cost.