Evolution of hysteresis relative permeability of wetting brine phase using contact angle hysteresis in a partially saturated CO2-brine system

Abstract

ABSTRACT In sequestration of CO2 in deep saline aquifers, the relative permeability of the immiscible fluids plays a crucial role in governing dissolution and capillary trapping mechanisms. Relative permeability is solely dependent on capillary pressure and saturation at that instant of time, whereas the capillary pressure dynamically changes during flow reversal resulting in the hysteresis behavior of the relative permeability curves. However, the conventionally used models equate relative permeability as an explicit function of saturation, neglecting the inherent physics that govern the immiscible displacement of fluids. On the other hand, upscaling the pore scale mechanisms, such as contact angle hysteresis and wettability characteristics, to Darcy scale remains complicated. In the present investigation, an attempt has been made in formulating a methodology to compute relative permeability of the phase fluids based on contact angle hysteresis. The relative permeability curves calculated using the present model have been compared with that computed using existing methodology present in the literature. It has been observed that the present relative permeability model effectively calculates the drainage and imbibition relative permeability of both the wetting and non-wetting phases in the porous system.