Parametric investigation of well testing analysis in low permeability gas condensate reservoirs

Abstract

Most of gas condensate reservoirs (GCRs) are detected in deep and tight formations. In these reservoirs, formation of near wellbore gas condensate is a significant factor influencing the production even in low fluid richness situation. The formation of condensate jots while the pressure dropping below the dew point and low well deliverability in low permeability GCRs complicate analyzing the well test and characterizing the reservoir. In this work, the pseudo-pressure functions were applied to linearize a two-phase flow including gas and gas condensate through the porous media. In analyzing the well test, various techniques such as a single-phase function and a two-phase pseudo-pressure function were used. In addition, a two-zone steady-state and a three-zone method were examined to calculate a two-phase pseudo-pressure function. Also, the role of different parameters e.g. fluid richness, relative permeability curves, mechanical skin factor, initial pressure difference with the dew point and flow rate were precisely determined. The effects of various causes on the condensate formation and pseudo-pressure function were studied and the accuracy of permeability and skin factor estimations of mentioned various methods in different near wellbore regions were determined.