There has been a large number of laboratory tests run in the past, looking at recovery of heavy oil by chemical flooding (polymer, surfactant and SP or ASP systems). These tests have all shown a potential for significant incremental oil recovery from chemical injection compared to water alone. The higher oil recovery was generally achieved under high pressure gradients that were generated during chemical injection. As such, the mechanism proposed in all of these studies is that of water channel blockage and improved sweep from chemical injection. In actual reservoir applications of chemical flooding, the impact of these water pathway blockages may be much less important than what is observed in the linear laboratory scale tests, so the actual mechanisms of chemical flooding in real systems may not be properly represented.
In this project, an experimental investigation is performed using a 2D visual Hele-Shaw cell, to visualize production mechanisms during the chemical flooding process. The 2D nature of the system allows for an understanding of whether chemicals sweep incremental oil from along the same channels as the pre-formed water or if new displacement channels are formed. The flow of a fluid in such models also represents flow without any pore-scale trapping, so observations can be made regarding whether trapping and fluid re-diversion are the only ways that these chemicals can yield improved oil recovery, or if simple alteration of the mobility ratio without additional trapping will already lead to incremental oil.