Abstract
Condensate banking is a much studied phenomenon in gas condensate reservoirs. An excessive drop in flow rate occurs when the bottom hole flowing pressure of a producing well falls below the dew-point pressure. Condensate dropped around the well bore increasingly reduces relative permeability to gas until a critical liquid saturation is reached. As liquid saturation increases above the critical value, two phase flow of both liquid and gas creates the equilibrium necessary to maintain the reduced, but steady state flow. The reduced gas permeability is described as a positive skin reducing the well rate PI used in the forecasts. In more severe cases, the PI may be reduced to cause sub-commercial rates. Even though several equations are available in the literature to estimate skin damage due to condensate banking, it is well recognized that localized reservoir characteristics, especially in naturally fractured carbonates must be applied to obtain an accurate value.
In this paper, numerical inverstigations of the impact of condensate banking on well productivity in the North Kuwait Jurassic Complex (NKJC) gas-codensate reservoirs are performed. A representative reservoir from Sabriyah field in the Najmah Sargelu formation was selected for the purpose. A general equation thus developed for rich condensate gas in naturally fractured carbonates was applied to the complex of reservoirs existing in the NKJC to study the impact condensate banking of full field performance.
