Assessment of foam generation and stabilization in the presence of crude oil using a microfluidics system

Abstract

The use of foams is a promising technique to overcome gas mobility challenges in petroleum reservoirs. Foam reduces the gas mobility by increasing the gas apparent viscosity and reducing its relative permeability. A major challenge facing foam application in reservoirs is its long-term stability. Foam effectiveness and stability depends on several factors and will typically diminish over time due to degradation as well as the foam-rock-oil interactions. In this study, the effect of crude oil on CO2-foam stability and mobility will be investigated using in-house build microfluidics system developed for rapid prescreening of chemical formulations. Two-phase flow emulsification test (oil-surfactant solutions) and dynamic foam tests (in the absence and presence of crude oil) were conducted to perform a comparative assessment for different surfactant solutions. A microfluidics device was used to evaluate the foam strength in the presence and absence of crude oil. The assessment was conducted using five surfactant formulations and different oil fractions. The role of foam quality (volume of gas/total volume) on foam stability was also addressed in this study. The mobility reduction factor (MRF) for CO2-foam was measured in the absence and presence of crude oil using high salinity water and at elevated temperatures. The results indicated that foam stability has an inverse relationship with the amount of crude oil. Crude oil has a detrimental effect on foams, and foam stability decreased as the amount of crude oil was increased. Depending on the surfactant type, the existence of crude oil in porous media, even at very low concentrations of 5% can significantly impact the foam stability and strength. The oil can act as an antifoaming agent. It enters the thin aqueous film and destabilizes it. This resulted in a lower foam viscosity and less stable foams. Thus, the CO2 MRF dropped significantly in the presence of higher oil fractions. This study also demonstrated that in-house assembled microfluidics system allows for a rapid and cost-efficient screening of formulations.