Polymer flooding: Current status and future directions

“Despite having been declared a “mature” technology, successful polymer flooding requires a notably different mindset than water flooding. For the reservoir engineer, standard flooding patterns (e.g., 5-spot) often make sense for water flooding. However, in polymer flooding, prior awareness of the naturally preferred fracture directions can and has made the difference between early polymer breakthrough and a field performance that closely mimics an idealized Buckley-Leverett displacement. Prior measurement of at least the endpoint relative permeability to water can and has made the difference between choosing the optimum polymer injection viscosity and either insufficient polymer viscosity (leading to viscous fingering and early polymer breakthrough) or overly viscous polymer (leading to unnecessary injectivity losses and excessive fracture extension). With a water flood, the facilities or production engineer may view poor water quality or air leakage into the system as nuisances not worth correcting. In contrast, in a polymer flood, modest viscosity losses due to oxidative or mechanical degradation can and have cost tens of millions of dollars per year. Undissolved polymer can and has unnecessarily clogged wells, reduced injectivity, over-extended fractures, and wasted valuable polymer. Awareness of the stability limits of polymers can and has made the difference between trouble-free production operations and wells and surface facilities that become clogged with gelled polymers after exposure to excessively hot pumps or heater-treaters. As was mentioned in the introduction, we encourage innovation, even if it deviates from the suggestions made in this paper. However, if you try a “new” idea, please be objective in reporting the results in the literature—i.e., resist the natural temptation to report a “success” if it really wasn’t. Everyone benefits from objective reporting of failures.”