A novel approach to the calculation of the distance of a sealing fault from a well in a gas condensate reservoir

This paper introduces a novel approach using two-phase pseudo-pressures for the calculation of some important parameters in faulted reservoirs in the context of gas condensate well test analysis. The diffusivity equation for condensate and gas is linearised using defined pseudo-pressures. It is shown that knowledge of the relationship between condensate saturation and pressure is necessary for the integration of pseudo-pressures in all regions of the porous media. In the region of the porous media where immobile condensate saturations develop, an unsteady-state equation that relates condensate saturation to pressure is used. In the region where condensate is considered to be mobile, an equation has been developed based on the steady-state method. The method is tested using a data set that has been produced using a commercially available compositional simulator. Two sets of PVT data, one lean gas and one rich gas, have been used in three cases. The first case involves a well near a fault, the second case involves a well at an intermediate distance from the well, and the third case involves a fault far from the well. Using this approach, it is possible to calculate total skin, mechanical skin, effective permeability, and distance to a fault. The results obtained from the new method are extremely close to those of the simulator.