Application of Digital Rock Analysis for Evaluation of Gas-Condensate Transport

Abstract

The computational method for gas-condensate phase permeabilities is presented using digital rock analysis. The proposed method combines: a) construction of high-resolution tomographic images of the pore space; b) development of compositional model of a gas-condensate mixture at pore-scale including rheology, fluid-fluid and fluid-rock interfacial tension coefficients, and thermodynamic and kinetic properties of fluid phases; c) 3D pore-scale modeling of multiphase transport and interfacial chemical component exchange using the density functional hydrodynamics numerical simulator. This digital rock analysis workflow is applied to the gas-condensate transport at pore-scale. The numerical simulations are carried out using the 3D digital rock model constructed by X-ray microCT imaging of the rock pore structure. By specifying different gas and condensate fractions and injection rates it has been possible to obtain computationally 3D saturation distribution fields and the phase permeabilities. The results of 3D density functional hydrodynamic simulations provide the comprehensive description of gas-condensate mixture at pore-scale including hydrodynamic desaturation effects and phase transition kinetic phenomena. It is demonstrated that condensate distribution in pores, phase mobility thresholds and phase permeabilities are dependent on wettability properties and flow rates. It is shown that condensate composition in individual pores is also dynamically dependent on flow regimes. These results can be used in field development planning for the improved evaluation of condensate banking in the vicinity of production wells and condensate losses in the reservoir.