致密油储层基质块渗流特征

Percolation characteristics of matrix block in tight oil reservoir

高效开发致密油藏需要分段多簇水平井体积压裂技术,以形成网络裂缝。压裂后的致密油藏为基质-裂缝双重孔隙介质,渗流过程复杂。由于缝网的复杂性及表述的困难性,导致产能模拟的不确定性。为此文中由易到难,先以一个基质块为研究对象,研究存在启动压力梯度的致密储层压裂后流体从基质块向裂缝的流动;再在一个基质块内建立考虑启动压力梯度的三维渗流模型,并给定不同的边界条件描述基质块衰竭开采的过程,利用有限差分方法建立隐式压力并求解模型。通过选取地质及流体参数进行实例计算,得到不同生产时间、不同启动压力梯度、不同基质块尺寸下的基质块压力分布、日产量、累计产量、可动用体积百分比、采收率等关系,定量地认识了一个基质块的渗流参数,为致密油储层渗流特征研究打下基础。

Efficient development of tight reservoir requires the technique of horizontal well volume fracturing to produce a network of cracks. The fractured reservoir is the matrix-fracture double porosity medium, and the flow process is complex. Due to the complexity of the network and the difficulty of expression, the production capacity simulation is not certain. In this article, a matrix block is studied, which is considered as a whole. To study the percolation from matrix block to crack in tight reservoir with threshold pressure gradient. On the basis of previous studies, a 3D percolation model considering threshold pressure gradient is established.And a new boundary condition is given to describe the process of matrix block failure development. A finite difference method is used to establish the implicit pressure to solve the model. Calculation through examples, the pressure distribution of the matrix is obtained. And the relationships between the size of the matrix block and the percentage of the available volume or the recovery ratio under different starting pressure gradient are obtained. Yield and cumulative yield can also be obtained. In this paper, the seepage parameters of a matrix block are quantitatively analyzed. This study provides a basis for the percolation characteristics of the tight oil reservoir.