Abstract
The aim of this work is to study the effect of the capillary trapping of phases in gas-condensate formations on the pattern of fluid filtration and, consequently, the productivity of gas condensate wells. The article proposes a method for increasing the accuracy of filtration modeling in gas condensate wells by including the effect of the capillary trapping in the filtration model.
In this paper, the Forchheimer's equation was used as the filtration law, which is most often used in the modeling of gas and gas condensate reservoir, since it describes the filtration with high-pressure gradients and high velocities quite accurately. The cases were simulated with various nonlinearity coefficients in the form of empirical functions of porosity and permeability described in the literature. Additionally, the work took into account the effects of capillary trapping of phases, the effects of compressibility of the reservoir and the effects of mudding of the wellbore zone. The residual saturation of each phase was calculated by the empirical function of the capillary number.
A solver for open-source software OpenFOAM, which is an integrated platform for computational fluid dynamics problems, was written and verified. The numerical model of this solver allows taking into account such effects as, for example, capillary trapping of phases, mudding of the near wellbore zone and other effects that impair the productivity of gas condensate wells. As a result of numerical calculations, a significant influence of the capillary trapping effect on the performance of gas condensate wells was revealed. The non-additivity of the discussed effect and other effects affecting filtration in the gas-condensate reservoir was shown. Accounting for one-side open pores in numerical simulation also made a significant contribution to the performance of gas condensate wells. The possibility of improving the accuracy of filtration modeling for industrial numerical calculations conducted via special software on supercomputers was shown.
A method for significantly improving the accuracy of fluid filtration modeling in gas-condensate reservoirs by including the effects of capillary trapping and one-side open pores into the numerical model is proposed. Such corrections of the numerical model does not lead to its significant complication and the speed of the computation increases slightly. Thus, the proposed method can be widely used for numerical calculations in the oil and gas industry.
