Enhancing Carbon Dioxide Flooding Sweep Efficiency in High Permeability Hydrocarbon Reservoirs Using Micro-Particle Gels

Abstract

Abstract Carbon dioxide (CO2) flooding is one of the most applied enhanced oil recovery processes nowadays. Conformance problems such as reservoir heterogeneity can diminish the amount of hydrocarbons produced using CO2 flooding, thus resulting in a lower than expected oil recovery. This research studies the ability of a chemical conformance control agent referred to as micro-sized particle gel (PPG) to improve CO2 sweep efficiency in hydrocarbon reservoirs thus increasing oil recovery. Several core flooding experiments were conducted using a high permeability sand pack model. The factors that were examined include gel strength, varied using PPG swollen in 0.05, 0.25, 1, and 10 wt% NaCl, gel concentration using 0.5, and 2 wt% gel, presence of residual oil, and CO2 injection flow rate using flow rates of 2, 4, 6, and 8 ml/min. The ability of PPG to improve CO2 conformance was quantified using the PPG's plugging efficiency improvement. PPG with low gel strength resulted in poor CO2 conformance, but when gel strength increased above approximately 1000 Pascal, a much better CO2 conformance was observed. Higher gel concentrations resulted in an improved plugging efficiency; however, the injection of the particles took a longer time. Increasing the CO2 injection flow rate resulted in a decreased plugging efficiency. Residual oil reduced the gel strength and thus the sweep efficiency was reduced. To the authors' knowledge, no detailed core flooding experiments have been conducted to study the PPG's ability to improve CO2 conformance thus making this a very important and insightful research on the utilization of PPG during CO2 flooding. By identifying, studying and analyzing the factors that impact PPG's ability to improve CO2 conformance, novel PPG technologies can be developed and utilized in the industry to improve CO2 flooding and increase oil recovery.