Investigation and Optimization of Deep Eutectic Solvent in Enhanced Oil Recovery Using Numerical Simulation

Abstract

Abstract In recent years, chemical enhanced oil recovery (EOR) application for heavy oil fields has been limited by low oil prices. The use of chemicals, though proven to be effective, can be toxic, expensive, and/or non-biodegradable. Deep Eutectic Solvents (DES) are potentially a much cheaper, greener alternative to conventional surfactants. However, there are very limited studies on the DES application. This study focused on numerical modeling of the effectiveness of a specific DES (Choline Chloride: Glycerol), in improving oil recovery and evaluating the parameters affecting the DES behavior. Data was gathered based on a literature review of the various but limited studies available and used to construct a black oil numerical model representing a heavy core-flooding experiment. The model was calibrated to some of the available published data. The study then used this model to examine different scenarios by comparing the performance of conventional water flooding using formation brine, with the performance of DES injection (after an initial period of brine flooding). The simulations were repeated at multiple temperatures and concentrations. Simulation results tally with the hypothesis and published data which is in favor of oil recovery enhancement with DES injection. In brine flooding cases, the oil recovery factor was in the range of 36-39%, with the high end occurring at a higher temperature. Increasing the DES concentration reduces the interfacial tension (IFT) which further improves oil recovery with the assistance of wettability alteration. Injected DES alters the rock wettability from oil-wet to water-wet thus improving the oil mobility. It was also observed that the oil recovery factor increases significantly with the increase of temperature as this reduces the oil viscosity and in turn, the mobility ratio, given the same formation properties. The highest recovery factor (60-62%) was achieved at the maximum injected concentration although this may not be practical in field application. Based on this, DES performance can be successfully applied as a substitute for current surfactant flooding methods in light of its low-cost, ‘greener’ nature as well as performance as a chemical EOR agent.