A new evaluation method for determining reservoir parameters for the development of edge-water-driven oil reservoirs

Edge-water support is associated with many oil reservoirs. To develop this kind of reservoir, it is helpful to evaluate reservoir parameters such as well initial gas-in-place and aquifer energy. The evaluation of reservoir and aquifer parameters is an important prerequisite in making oil development plan. This paper focused a reservoir parameter evaluation method for use when reservoirs are driven by an edge-aquifer. This paper also proposed no-aquifer influx period-type curves and early aquifer-influx period-type curves that can be matched by well production data to determine reservoir and aquifer parameters. This method considers transient aquifer-influx models; curves are based on the Blasingame advanced production data analysis method and the simple-composite reservoir model. The purpose of the theory is to quantitatively evaluate the well initial gas-in-place, aquifer energy, and other reservoir parameters. This method first divides well history production data into three influx periods: no-aquifer, early aquifer, and middle-late aquifer. The no-aquifer influx period-type curves are matched with the corresponding no-aquifer influx period data, then the dimensionless drainage radius and positioning of the field well production data relative to type curves can be obtained, and next well initial gas-in-place and other reservoir parameters can be calculated by the relevant equations. In the case of the dimensionless drainage radius, the early aquifer-influx period-type curves can be drawn, and the aquifer energy can be determined by matching the early aquifer-influx period data with the corresponding type curves. The method in this paper uses well production data to match. It does not need the reservoir pressure that is measured through well shutting-in and must be used in the empirical aquifer-influx model, which is convenient and more reasonable. The results of a conceptual numerical simulation model indicate that this method is reliable and can help to evaluate oil reservoirs and provide useful guidance in developing oil reservoirs with transient edge-aquifer drives.