The results of systematic compositional simulations of gas- condensate depletion in a radial and cross-sectional reservoir model are presented. The effects on productivity, recoveries and fluid distribution are analyzed and quantified when changing various parameters, such as the role of non-Darcy flow, the permeability, the relative permeabilities (kr) in relation with the interfacial tension (IFT), the nature of the fluid.
Below the dew point pressure, the drop in gas productivity is linked to the development of a condensate ring around the wellbore. Gas and condensate kr and their dependence on IFT control the time or pressure at which condensate buildup becomes significant and gas productivity drops. Tight reservoirs with lean gas-condensates may pose early and drastic productivity problems. Far from wellbore, condensate may segregate under the low-IFT conditions met during depletion, especially if the reservoir permeability is high ana the fluid is rich. In a depletion process, condensate recovery is all the lower as the condensate content of the fluid is higher.
The results of this study can be used as a guide during the development planning of a gas-condensate field (1) to estimate the quantitative role played by key rock-fluid parameters during future exploitation, (2) to define the most relevant corefluid measurements and simulation studies for reducing uncertainties on field performance predictions.