In-situ characterization of wettability and pore-scale displacements during two- and three-phase flow in natural porous media

摘要

We establish a unique approach to measure in-situ contact angle from micro-CT images acquired during two-and three-phase miniature core-flooding experiments in order to overcome the uncertainties associated with conventional contact angle measurement techniques. The measurements are used to quantify the wettability behavior of the rock and explain pore-level displacement events occurring in three-phase flow. Six two-phase experiments are performed on individual core samples with three pairs of fluids, i.e., oil-brine, gas-oil, and gas-brine, and under two thermodynamic conditions: (a) binary-equilibrated, when only the two respective phases are at equilibrium and (b) ternary-equilibrated, when all three phases are equilibrated and only the two desired fluids are injected into the core. A three-phase experiment set is also performed under ternary-equilibrated conditions, which includes gas injection, a waterflood, and an oilflood process. All experiments are performed on Berea miniature core samples using a nonspreading brine-oil-gas fluid system.