Secondary recovery methods typically recover about 50% of the original oil in place. To recover the remaining oil, enhanced oil recovery (EOR) methods that reduce capillary effects and/or improve mobility ratio are implemented. In this work, several chemical EOR experiments were conducted and recovery mechanisms in carbonate and sandstone-like pore structures were visualized using micromodels. The objective of these experiments was to enhance our understanding of fluid flow and oil recovery mechanisms through utilization of surfactant solution as the main injectant.
Surfactants were used to minimize capillary effects at the pore level by reducing interfacial tension (IFT) between oil and water. Alkali was also added to the injectant to reduce adsorption of surfactant to solid surfaces. In some cases, the injectant was augmented by the addition of polymers to increase the viscosity and consequently decrease the injected phase mobility.
Micromodels are two dimensional representations of a pore network that provide a means of visualizing fluid-flow experiments under a microscope. To achieve a better understanding of the key parameters that impact ultimate recovery, various elements require investigations using time-consuming experiments; some are not even practical. An alternative is to run a few experiments to validate a fluid-flow simulator. The simulator is then utilized to run numerous cases in a relatively shorter time compared to physical experiments.
This paper discusses the micromodel experiments and the simulation runs performed to validate the numerical model. Initially, experiments were history matched utilizing a commercial numerical simulator. The simulation model was capable of reproducing similar results demonstrated in the micromodel experiments. Consequently, these results will be used to assist in designing chemical-flood experiments to acquire a broader understanding of fluid flow and ultimately achieve better oil recovery.