滩坝砂油藏不同压裂方式下单井控制可采储量预测方法

单井控制可采储量是评价滩坝砂油藏开发是否经济可行的重要指标。由于未动用特低渗透滩坝砂油藏存在压敏效应、启动压力梯度、不同压裂方式等特征，难以应用常规的单井控制可采储量预测方法进行预测。基于典型区块静、动态数据，建立直井分层压裂油藏数值模拟模型，通过历史拟合确定启动压力梯度及压敏效应表征公式中的系数，并分析压敏效应和启动压力梯度对生产动态的影响。在此基础上，分析不同油藏参数和开发参数对直井分层压裂弹性开发单井控制可采储量的影响，确定单井控制可采储量的主控因素依次为:压力系数、渗透率、含油饱和度、有效厚度、孔隙度、压裂缝长、集中度和黏度；通过多元回归方式建立直井分层压裂弹性开发下单井控制可采储量与主控因素之间的计算公式，经与实际生产井数据对比，相对误差为4.58%，说明公式具有较高的精度，能够满足矿场要求。进一步建立直井体积压裂、水平井多段压裂和水平井体积压裂弹性开发单井控制可采储量与油藏参数之间的预测公式，研究结果为评价滩坝砂油藏动用潜力提供基础。 

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.