Simulation Study of Enhanced Condensate Recovery

In gas condensate reservoirs, by reservoir depletion, pressure decreases below the dew point pressure of the fluid and condensate forms in the reservoir. This heavy part of the gas has found many applications in industry and also in daily life. When condensate drops out in the reservoir not only is this valuable liquid lost, but also its accumulation results in forming a condensate bank near the wellbore region. The created bank makes a considerable reduction in gas well productivity. These facts demonstrate that finding an economical way to increase the condensate recovery from condensate reservoirs is essential. In this study gas injection has been simulated in a gas condensate reservoir to increase the condensate recovery factor. In addition, capability of injection of different types of gas in condensate recovery has been compared through different injection schemes. The injection schemes that have been considered are: different injection rates, different reservoir pressures at which the injection is implemented and different injection durations. A compositional simulator was applied to simulate a simplified gas condensate reservoir model. The injection pattern was a one-eighth of a five-spot pattern with finer grids near the producer and injector. The simulation results showed an increase in condensate recovery from 5% to 30% in all injection cases. Many parameters can affect the decision of selecting the injection scheme, other than the gas and condensate recovery factor. Therefore, an economical evaluation and analysis is inevitable to take them all into account to determine the optimum scheme.