Foam
application in enhanced oil recovery (EOR) processes has been
promoted primarily to address the mobility control issue during gas
flooding which leads to poor sweep efficiency. Some critical factors
such as foam stability and strength in porous media need to be addressed
to ensure the effectiveness of foam flooding. In this research, a
relatively new additive for foam stabilization composed of ionic liquid
(IL) has been introduced. Systematic foam experiments in static condition
and porous media were performed to investigate the potential of IL-based
additives to enhance surfactant foam stability for gas mobility control.
Screening of the mixtures of surfactant and different types of IL
was initially conducted based on bulk foam stability measurement at
high temperature. Core flooding experiments were then executed to
evaluate the foam characteristic using the best formulation in the
absence of oil under reservoir conditions. Results from bulk foam
experiments indicated that the presence of IL as additive was able
to increase foam stability up to a certain extent depending on the
type of IL used and its formulation with surfactant. In comparison
with the base case, the foam stability increment achieved by the best
formulation was 136%. The ability of selected IL to lower the surface
tension of surfactant solution was found to be in good accordance
with its improvement on foam stability. In core flooding experiments,
the acceleration of foam generation was noticed in the presence of
IL indicated by an immediate increase in mobility reduction factor
(MRF) upon early nitrogen injection with 30% increment at the maximum
point. A small slug surfactant alternating gas (SAG) injection was
able to optimize the performance of the surfactant/IL mixture used
in reducing gas mobility by effectively producing stronger foam. This
research has provided a strong indication of the capability of IL
to perform as additive for foam stabilization, hence improving foam
performance in reducing the gas mobility during EOR processes.
