Gruy Federal has recently undertaken a three-par study of the Enhanced Oil Recovery (EOR) potential of West Virginia. Part one is the preparation of a list of reservoirs amenable to one or more EOR techniques. Part two is an evaluation of the EOR potential of selected candidate reservoirs. Part potential of selected candidate reservoirs. Part three is a detailed study of three ongoing CO injection projects partially funded by the Department of Energy (DOE) in West Virginia. Parts one and two are the subjects of this paper.
An examination of published screening criteria, as well as rock properties, fluid saturations, oil properties and reservoir conditions normally found properties and reservoir conditions normally found in West Virginia, suggests that CO displacement may be the most suitable EOR technique for this area. Other techniques may be applicable in specific fields, whose properties vary widely from the statewide averages of the critical parameters.
After a suitable EOR technique is selected for a reservoir, an evaluation can be made of the EOR potential for that technique in that reservoir. This potential depends largely upon existing fluid saturations, saturation distribution, volume of reservoir affected by the EOR process, and effiency of the process. This type of evaluation calls for certain basic reservoir information, much of which is unavailable for West Virginia oilfields. This paper describes the techniques we developed in paper describes the techniques we developed in using the available information to evaluate the EOR potential of West Virginia.
In general, oil recovery in West Virginia has been low despite the fact that many of the state's reservoirs have produced oil continuously since the early 1900's. Average total recovery is about 160 B/AF (Table 1). Low-pressure gas displacement has been the most widely used technique to maintain production from the major reservoirs. Waterflooding, although it has been successful in a few cases (notably Cabin Creek and Granny's Creek), has not been widely used. Consequently, significant amounts of oil (producible with existing technology and appropriate economics) still exist in West Virginia.
Gruy Federal has contracted to determine the potential of EOR technology in West Virginia potential of EOR technology in West Virginia concentrating on the CO displacement process. We have found that this is no easy task. Most West Virginia oil fields were drilled long before the development of modern logging techniques, and little quantitative reservoir information exists. Because of the limited availability of the necessary information, we have had to develop methods using what data we could obtain to perform the study. Fortunately, West Virginia oil fields are surprisingly uniform in many respects, which facilitates the use of such methods.
To accomplish the contract, we have applied published screening criteria and commonly used published screening criteria and commonly used reservoir parameters. Going one step farther, we have also considered the ranges of critical parameters over which each technique has been parameters over which each technique has been successfully applied. Since all EOR methods (except the chemical methods) are primarily constrained by oil gravity (viscosity) and depth, we used those characteristics of successful application of each technique to establish the range of applicability of the techniques.
This plot is shown in Figure 1. The accepted or theoretical limits of each technique are outlined by the patterned lines. The enclosed spaces represent the ranges that include all successful applications of the specified technique. Reservoir depth information is available for almost all fields in West Virginia. The average depth of production for 104 fields is plotted in Figure 2. production for 104 fields is plotted in Figure 2.
