Waterflooding Heavy Oil Reservoirs with Horizontal Wells: Field Examples from Canada

摘要

Very few papers describe waterflood projects in heavy oil reservoirs,and even less that involve the use of horizontal injectors and producers. A few years ago,Beliveau presented a review of waterfloods in viscous oil in several pools mostly in Canada and demonstrated that excellent results can be obtained in most cases,but he mostly focused on pools with vertical wells. The purpose of this paper is to present results of several heavy oil waterfloods in Canada that use horizontal producers and injectors. The production performances of eight heavy oil pools where waterflood has been implemented using horizontal wells have been studied. The pools are thin and bottom water is present in some of them;oil viscosity ranges from a few hundred to a few thousand centipoises. The overall performances of each flood will be discussed and compared to other heavy oil pools where waterflood is implemented with vertical wells. In addition,more detailed analyses will be performed in some patterns to better evaluate the impact of bottom water,well length,spacing and other factors on the flood performances. As could be expected,water breakthrough is generally fast,within a few months from the beginning of injection;but more surprisingly,Water Oil Ratio can often remain stable for long periods of time. Ultimate recovery is expected to vary from a few percents OOIP to over 20%OOIP. Similarly,to waterfloods with vertical wells,a large portion of the reserves can be recovered while producing at high Water Oil Ratio. This paper will present results of several waterfloods in heavy oil reservoirs in Canada which use horizontal wells. There are very few such field cases in the literature thus the information provided will be of interest to engineers who are considering waterflood as a follow-up to primary production in heavy oil reservoirs developed with horizontal wells.