基于物质平衡原理解释致密油藏体积压裂有效改造体积的新方法

致密油藏需要经过大规模体积压裂改造才能获得工业油流。本文在物质平衡原理的基础上综合考虑了体积压裂施工过程中大量压裂液注入导致油藏压力升高,压后流体产出导致油藏压力降低以及裂缝与基质孔隙体积随压力非线性变化等致密油藏实际情况,进行合理假设,建立了模型方程,并推导计算了体积压裂有效改造体积和裂缝与基质的有效接触面积等参数。该方法解释出的三个新参数：能够提供有效渗流的裂缝总体积、油藏有效渗流体积、裂缝有效渗流面积,其物理意义更明确,对致密储层的开发设计及增产改造指导意义更强。将该方法应用到油田现场,并评价了3口已实施体积压裂油井的应用效果。现场应用表明该方法具有评价解释快捷、获取数据方便、成本低、准确度高的优点,适合于油田现场多井次大规模推广应用。

A new method using Material Balance Equations to interpret the effective stimulation volume of Fracture network fracturing in tight reservoirs

For tight reservoirs it is required to conduct the large scale of fracture network fracturing in order to obtain industrial oil flow rate. On the basis of the material balance equations, the model was built to consider the actual situations of fracturing in tight reservoirs: fracturing fluids injection leading to the increasing of reservoir pressure, oil and water production leading to reservoir pressure decreasing, and fracture and matrix porosity volume nonlinear change with reservoir pressure. Using this model and oil well production dynamic data, the three key parameters were interpreted: the total effective fracture seepage volume, the effective reservoirs seepage volume, and the effective fracture seepage area. With the help of these parameters, the petroleum engineers are able to make a better development and stimulation design for tight reservoirs. The method was applied to evaluate the effect of three fracture network fracturing wells in a tight oil reservoir of China. The interpretation result was compared with that of micro seismic. It is showed that the method provides a quick and easy way with low cost and high accuracy to evaluate and interpret the effect of fracture network fracturing. It is suitable for large-scale multi-well oil field application.