3D effects in two-phase steady-state tests

Abstract

This study analyses three-dimensional (3D) effects during steady-state tests in short cores, primarily used to determine relative permeability (Kr) and capillary pressure (Pc). Here we concentrate on steady-state transition tests (SSTTs), which allows simultaneous determination of Kr and Pc from the steady-state data and the transition data measured between the steady states. Comparison between three- and one-dimensional (1D) modelling in short cores shows a significant difference in measured water-cut and pressure-drop data. This difference has been observed for cores with different inlet distributor geometries, aspect ratios, and anisotropy. Despite the influence of 3D flow effects on measurement data, the agreement between Kr and Pc as obtained from the 3D and 1D models is close. This phenomenon of conservative inverse-solution results has been demonstrated for different inlet distributor geometries. The Spiral distributor exhibits lower 3D flow effects and more accurate determination of relative permeability and capillary pressure from SSTT tests.