The Effect of Capillary Number on a Condensate Blockage in Gas Condensate Reservoirs

Abstract

In the petroleum industry, gas condensate reservoirs are becoming more common as exploration targets. However, there is a lack of knowledge of the reservoir behaviour mainly due to its complexity in the near wellbore region, where two phases, i.e. reservoir gas and condensate coexist when the wellbore pressure drops below the dew point pressure. The condensation process causes a reduction of the gas productivity (1). It has been reported in the literature that there is an increasing gas mobility zone due to a capillary number effect in the immediate vicinity of the wellbore in gas condensate reservoirs (2). This zone, called “velocitystripping zone”, compensates the well productivity loss due to the condensate drop-out. However, existence of this zone has just been recently found in an actual well test data (3,4). There is no conclusive study of this velocity-stripping zone in this type of reservoir. The objective of this study was to gain a better understanding of near wellbore effects in gas condensate reservoirs under production and well testing.