Experimental investigation of nonlinear flow for single rock fractures

8th International Conference on Environment Science and Engineering

生态环境科学

Zhang, S.J.^1 ; Dong, X.Z.^1 ; Wu, B.H.^1 ; Wang, C.L.^2,3

Zhejiang Institute of Hydrogeology and Engineering Geology, Zhengjiang Ningbo, China^1

School of Civil Engineering, Chongqing University, Chongqing, China^2

Key Laboratory of Geotechnical Engineering Stability Control and Health Monitoring of Hunan Province, Hunan University of Science and Technology, Xiangtan, Hunan, China^3

关键词: Confining pressures;    Differential pressures;    Empirical relationships;    Experimental investigations;    Forchheimer equation;    Fracture geometries;    Rock mechanics tests;    Transient pulse test;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/167/1/012003/pdf
DOI  :  10.1088/1755-1315/167/1/012003

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

The hydraulic behavior of rocks is significantly controlled by fracture geometries, such as aperture, contact areas, roughness, interconnections, and so on. However, these characteristics are strongly influenced by the confining pressure conditions. This paper experimentally investigated the nonlinear flow behaviors through single rock fractures subjected to a wide range confining pressures. A series of transient pulse tests were conducted on three fractured limestone samples by MTS815 Rock Mechanics Test System. The experimental results show that the pulse decay curves diverge from the classical exponential model due to nonlinearity, thus an empirical relationship between differential pressure and time is developed with consideration of nonlinearity. Subsequently, the nonlinear flow coefficient and permeability were calculated based on the Forchheimer equation. The calculated results show that nonlinear flow coefficient increases with confining pressure, and rougher fracture surface helps to stronger nonlinearity. As the confining pressure increases, the permeability first experiences a dramatic decrease and then behaviors a much slow-down drop. The critical confining pressure for climb-rush shifts increases with the fracture rouhghness.