裂缝性油藏非结构四边形网格数值模拟研究

在裂缝性油藏数值模拟中，引入非结构四边形网格系统是目前高精度数值模拟研究的热点，它能对复杂油藏边界、交叉裂缝、多条裂缝、多方向分布裂缝、复杂分支结构井等条件下任意连通区域进行网格剖分，相对其他非结构网格，它需要的网格数量少，且精度更高。建立连续介质模型和离散裂缝模型相结合的混合渗流模型并数值离散求解发现，非结构四边形网格的引入导致数值模拟计算效率严重下降。针对此问题，提出了3种解决方案：改进Paving算法的裂缝末端形态变形法、二维和三维网格编号重新排序方法和MPI并行计算方法，计算效率平均提高70%。

Study of Quadrilateral Unstructured Grids in a Numerical Simulation of Fractured Reservoirs

The introduction of unstructured quadrilateral meshes in the numerical simulation of fractured reservoirs is a popular area of research in the field of high-precision numerical simulation. These meshes can be used to create a grid with an unfixed number of connected components under the conditions of complex reservoir boundaries, cross fractures, multiple fractures, multi-directional fractures, complex multilateral wells, etc. Compared to other unstructured meshes, these meshes require fewer grids and have a higher precision. In this study, a mixed percolation model was established by combining the continuous medium model and the discrete fracture model. The numerical solution showed that the introduction of quadrilateral unstructured grids resulted in a significant decrease in the computational efficiency of the numerical simulation. Therefore, three solutions were proposed:morphing of the fracture endpoints with an improved paving algorithm, reordering of two-dimensional and threedimensional mesh numbers, and MPI parallel computing. The computational efficiency was then increased by an average of 70%.