Numerical study of water coning control with downhole water sink (DWS) well completions in vertical and horizontal wells.

摘要

Approximately 2.5 billion dollars is spent annually to solve the problem of produced water in oil and gas wells. Downhole Water Sink (DWS) technology is one industry solution to control water coning in oil wells. DWS technology involves the segregated production of oil and water through separate completions with zonal isolation packer. However, several problems have been experienced in the application of the technology in watered-out oil wells.; This study identified two factors that could aid in a better modeling of the technology in old vertical wells—inclusion of capillary transition pressures and relative permeability hysteresis. It also identified a pressure enhanced capillary transition zone enlargement around the wellbore as responsible for the concurrent production of contaminated fluid from both completions.; Another widely recommended industry solution to the problem of produced water is horizontal well technology. However, field reports indicates that water breakthrough into horizontal wells could be quite dramatic and tend to erode the merit of high deliverability.; This study analyzed the problem of water cresting in horizontal wells and developed a “generalized compound friction pressure loss relation” for horizontal wells and pipes. The new relation includes factors such as perforations, oil-water emulsions, and radial influx of fluid into the wellbore as well as phase inversion. It also shows the results of the application of this relation in the modeling of water cresting in horizontal wells subject to bottom water drive. These results reveal an asymmetrical distribution of water influx skewed toward the heel in line with field observations.; Finally, the study presents two innovative dual-completion concepts for controlling water cresting in horizontal wells adapting the principles of the Downhole Water Sink technology. The results of the initial studies shows that oil recovery could be improved by as much as 7 percent over conventional horizontal wells.