There have been numerous laboratory tests conducted in recent years, studying the potential for heavy oil recovery through chemical addition (polymers and surfactants). In these tests, recovery is often understood in terms of pre-water breakthrough and post-water breakthrough improved oil recovery. Pre-breakthrough tests focus on viscous fingering and sweep efficiency from water vs. polymer additives. Post breakthrough tests study the potential for oil recovery after a waterflood has already been run: in these systems surfactants and polymers are added and there is conclusive evidence that chemical additives can be very effective at improving heavy oil recovery at the scale of these core flood systems.
The observation made in laboratory core floods is that chemical recovery of oil is achieved under very high pressure gradients. The mechanism proposed in these tests is that chemicals plug water pathways and lead to improved sweep within the core. In reservoir applications of this technology, these same conditions may not be met and it is unclear whether these chemicals will still be as effective in non-linear systems. This study shows tests run in a 2D Hele-Shaw cell, which displaces oil with no pore scale trapping and with many open flow pathways like what is expected in the field. The objective of running tests in this system is to understand the mechanisms of heavy oil recovery and to observe whether chemical additives can still be successful for producing heavy oil in non-linear core systems with no capillary trapping.