Prospects For Oil Supplies From Enhanced Oil Recovery Projects
Authors: Griffith J.D. 
Published: March 2010

Abstract
Enhanced oil recovery (EOR) processes have the potential of adding several billion barrels of oil to Canada's supplies. This source has the advantage of being readily accessible, originating within existing areas of production, and the capability of development over a short to medium time range. Thus, EOR could provide valuable assistance in maintaining production levels prior to the mega projects in the oil sands and the frontiers being brought on-stream.
The realization of this potential is complicated by numerous technical and economic problems and uncertainties. However, the present indications are that these problems are being resolved and that conditions will be ready for significant action to develop these reserves.

Introduction
A number of enhanced oil recovery processes have been developed to improve upon the water flood process, which has been the basic recovery method in Canada for many years for conventional oil reserves. These processes have been researched extensively and field-tested, but they have not received widespread utilization, basically because of the much higher costs associated with them.
The much-publicized energy crisis and the accompanying sharp rise in oil prices together with the advancing stage of depletion of most of the major oil fields has changed this situation so that these enhanced oil recovery processes are currently receiving a great deal of attention. In the following, the status of the development of enhanced oil recovery processes is reviewed briefly and an assessment of their role in future energy supply is made.

Technology Status
Water flooding, which is a relatively simple and inexpensive way to increase oil recovery, unfortunately has some basic limits on recovery due to the retentive effects of the capillary forces in the reservoir rock which result in an unrecoverable oil saturation. This recovery limit varies with different reservoirs and different rock types, but an average value is in the range of 55% of the oil-in-place. In practice, even this recovery limit is never reached because the water volume that must be handled becomes sufficiently, large, and the oil volume produced sufficiently small, that an economic limit to recovery is reached before complete sweep out is accomplished., This commonly occurs at a recovery level in the range of 25 to 45% of the oil in- place. Thus, it can be seen that there is ample room for improvement.
For an improved recovery process, there are but two technical requirements: an agent capable of increased displacement efficiency; and a means of applying it to the reservoir. To these conditions, a third must be added if the processes are to meet the requirement of practical utilization: it must be economically feasible.
The improved processes, commonly termed "enhanced oil recovery", "EOR" or "tertiary oil recovery" methods, are based, in most cases, on the principle of miscible displacement. In place of water, which is immiscible with reservoir oil, as the displacing agent, a miscible fluid is used which does not establish an interface on contact with the oil. As a result, the limitations on recovery efficiency resulting from capillary forces are eliminated.