Abstract
The total apparent skin factor in a gas condensate system contains contributions from mechanical damage and perforation, liquid drop-out and non-Darcy flow. A comprehensive theory of the skin factor in two-phase flow based on pseudo-pressure is developed. Field data from three gas condensate reservoirs have been analysed using the pseudo-pressure function. The effect of compressibility variation was accounted for by the use of pseudotime extended to two-phase conditions. The method requires knowledge of relative permeability relations and a review of these for gas condensate system is given. The determination of relative permeability from well tests is shown to be nearly impossible in practice. Conditions where the reservoir pressure is above or below the dew-point are examined. In the former case the test can be analysed in a dry gas with a composite skin. In the latter a two-phase pseudo-pressure must be used. Permeability relation are utilised in the interpretation of gas condensate well tests.
