CO2 Injection in an Oil Reservoir with Gas Cap (Compositional Simulation Case at Heidrun Field Norway)

Abstract

A potential problem with CO2 Injection in oil reservoirs with gas caps is that gas cap may be contaminated by CO2. This could be an issue on the Heidrun Field where down dip using CO2-WAG is considered. Compositional reservoir simulations should be performed to investigate if the injected CO2 will form a stable CO2 layer below the hydrocarbon gas cap or if the CO2 will be mixed with the hydrocarbon gas before or during the production of the gas cap.

The project thesis will be started with an existing black oil sector model (from Upper Tilje Formation in Segment H and I form Heidrun field). The sector model (or a part of it) should first be converted to a compositional model (Eclipse 300) using an existing equation of state. A number of predictions should be performed, starting with down dip WAG at constant reservoir pressure followed by depletion of the gas cap. The project thesis will discuss also how to optimize the amount of gas that can be produced before CO2 breakthrough by considering different alternatives for gas production wells. Other sensitivities like gas production rate, well location, changing perforation interval and diffusion should be evaluated.