Prediction of single-well-constrained recoverable reserves in beach bar sand reservoir using different fracturing methods

Single-well-constrained recoverable reserve is an important index to evaluate whether the development of beach bar sand reservoir is economically feasible. Due to the characteristics of pressure sensitive effect, start-up pressure gradient and different fracturing methods, it is difficult to apply the conventional prediction method to single-well-constrained recoverable reserve in undeveloped ultra-low permeability beach bar sand reservoirs. In this paper, based on the static and dynamic data of typical blocks, a numerical simulation model of vertical well stratified fracturing was established. The coefficients in the characterization formula of start-up pressure gradient and pressure-sensitive effect were determined by history fitting, and the influences of pressure-sensitive effect and start-up pressure gradient on production performance were analyzed. On this basis, the influence of different reservoir parameters and development parameters on the single-well-constrained recoverable reserves of elastic development with vertical-well stratified fracturing was analyzed. The main factors of single-well-constrained recoverable reserves were determined as follows: pressure coefficient, permeability, oil saturation, effective thickness, porosity, fracture length, concentration and viscosity. A vertical-well stratified fracturing model was established by multiple regression. Compared with the data from actual production wells, the relative error was 4.58%, which showed that the formula had a high accuracy and could meet the requirements of mines. Furthermore, some prediction formulas between the single-well-constrained recoverable reserves and the reservoir parameters corresponding to the volume fracturing of vertical wells, the multi-stage fracturing of horizontal wells and the volume fracturing of horizontal wells were established. The results provided a basis for evaluating the production potential of beach bar sand reservoirs.