From Field Trial to Full-Scale Deployment of Pulse Waterflooding on Mature Oil Fields. Incremental Oil at No Cost

Abstract

Abstract Pulse or cyclic waterflooding is a well-known technique to optimize water injection schematics, that requires virtually neither capital nor operational expenditures. Therefore, it is very attractive for marginally mature oil fields to stabilize and even boost oil production with the aim of improving economics. So, the paper demonstrates successful case studies from the South-Turgai Basin in Kazakhstan. Pulse waterflooding was implemented by increasing the injection volumes of one group of injectors and choking or shutting down another, thereby, sending periodic pulses in a sandstone formation. The pulses created translate into a fast pressure drop in high permeability and a slow pressure drop in low layers, causing a pressure differential and fluid crossflow. So, it was designed for stratified heterogeneous reservoirs, where we couldn't properly displace oil from poor zones. The theory was put into practice in the KK field trial area, and unexpectedly, we achieved profound improvements in production performance. Thus, the next step was to upscale the activity on other sites. As a result of the first trial, more than 150 Mbbl of oil increment was obtained. That was promising, and the second field went through the same procedure. Pulse waterflooding was applied to the north and south parts, divided by the extensive gas cap of the A field. Most producers in both parts exhibit a clear trend of not only stabilization but also gradual growth. That was mainly reached due to an increase in fluid rates and no changes or event reduction in watercut. Previously, the average oil rate in the south had steadily declined at a 26% annual rate, but after that, it increased for the first time in 10 years. A similar picture is observed in the north, where a 22% annual decline turned into a rate stabilization and then increase. Eventually, the total oil increment is 21 400 tons or 166 Mbbl. Pulse waterflooding proved to be an efficient EOR technique. If wisely applied, waterflooding optimization by playing with rates of injection patterns can lead to considerable sweep efficiency and, in turn, recovery factor. Finally, the most critical aspect of this story is that 166 Mbbl of oil increment costs zero for the operating company. That becomes the best option in terms of economics and the extension of fields’ lives.