裂隙网络非达西渗流REV及非达西系数张量研究

裂隙网络渗流理论最初建立在裂隙渗流服从立方定律的基础上,而裂隙中非达西渗流更为广泛存在,因此,裂隙网络非达西渗流特性研究更具工程应用前景。本文首先对基于单裂隙立方定律的线素法模型进行改进,用以实现裂隙网络非达西渗流的计算,进而将其应用于实测裂隙数据生成的裂隙网络非达西渗流特性的研究。研究结果表明:根据改进线素法模型和Forchheimer定律计算得到的等效渗透系数张量与线素法模型和达西定律计算得到的具有一致性。对于同一裂隙网络而言,等效非达西系数张量确定的渗流REV要比等效渗透系数张量确定的大,且等效渗透系数张量与等效非达西系数张量的主轴方向一致,但两者之间的长轴互相垂直。

Non-Darcy seepage rev and non-Darcy coefficient tensor in fracture network

The theory of fracture network seepage is initially established on the basis of the cubic law obeyed by fracture seepage, while non-Darcy seepage in fractures exists more widely. Therefore, the research on non-Darcy seepage characteristics of fracture network has more engineering application prospect. In this paper,the linear element method based on the cubic law of single fracture is improved to calculate non-Darcy seepage in fracture network. Then it is applied to the study of non-Darcy seepage characteristics of fracture network generated by measured fracture data. The results show that the equivalent permeability coefficient tensor calculated by improved linear element method model and Forchheimer''s law is consistent with those calculated by linear element method model and Darcy''s law. For the same fracture network,the seepage REV determined by the equivalent non-Darcy coefficient tensor is larger than that by the equivalent permeability coefficient tensor. The principal axes of the equivalent permeability coefficient tensor and the equivalent non-Darcy coefficient tensor are the same,but the long axes between them are perpendicular to each other.