Since the accidental discovery in the late 1800s of the benefits of injecting water into oil reservoirs to improve recovery, water has been the injection fluid preferred by the oil industry for use in recovery processes. Traditionally, waterflooding is considered an effective secondary recovery method for light and medium oil reservoirs. However, as production rates in these conventional reservoirs continue their decline, waterflooding is being considered, and used, more and more for the exploitation of more challenging heavy oil resources. Despite the unfavorable mobility ratio between injected water and more viscous heavy oils, many waterflood projects have been undertaken in heavy oil reservoirs around the world. However, the literature on heavy oil waterflooding is sparse. Those papers that have been published present a wide range of recovery factors for projects, and offer conflicting information on the theory and mechanisms involved in heavy oil waterfloods. The good news is that there is a long history in western Canada with waterfloods in heavy oil reservoirs, spanning more than 50 years. A vast amount of data and anecdotal information has been generated from these waterfloods. This could provide a key to raising the limits, in terms of reservoir conditions, under which waterflooding would be viable.
In this paper we will discuss lessons learned after 50 years of waterflooding in heavy oil reservoirs, identify gaps in the application of the process, and speculate about what the future may hold as this technology evolves.