Identifying Non-Darcian Flow and Non-Fickian Pressure Propagation in Field-Scale Discrete Fracture Networks

Bingqing Lu,Chunmiao Zheng,Hongguang Sun,Dongbao Zhou,Yong Zhang,Yuan Xia,Donald M Reeves

doi:10.4236/gep.2018.65005

Abstract

Non-Darcian flow has been well documented for fractured media, while the potential non-Darcian flow and its driven factors in field-scale discrete fracture networks (DFNs) remain obscure. This study conducts Monte Carlo simulations of water flow through DFNs to identify non-Darcian flow and non-Fickian pressure propagation in field-scale DFNs, by adjusting fracture density, matrix hydraulic conductivity, and the general hydraulic gradient. Numerical simulations and analyses show that interactions of the fracture architecture with the hydraulic gradient affect non-Darcian flow in DFNs, by generating and adjusting complex pathways for water. The fracture density affects significantly the propagation of hydraulic head/pressure in the DFN, likely due to fracture connectivity and flow channeling. The non-Darcian flow pattern may not be directly correlated to the non-Fickian pressure propagation process in the regional-scale DFNs, because they refer to different states of water flow and their controlling factors may not be the same. Findings of this study improve our understanding of the nature of flow in DFNs.

Highlights

IntroductionThis fundamental law has been used to quantify various dynamics in natural media with different degrees of heterogeneity and scales for more than one century, such as disposal of radioactive waste, geothermal utilization by hot dry rock systems, oil and gas production from fractured reservoirs, and water production from fractured rock [2] [3]
The non-Darcian flow pattern may not be directly correlated to the non-Fickian pressure propagation process in the regional-scale discrete fracture networks (DFNs), because they refer to different states of water flow and their controlling factors may not be the same
This study aims at exploring the potential for non-Darcy flow in field-scale discrete fracture networks (DFNs)

Summary

Introduction

This fundamental law has been used to quantify various dynamics in natural media with different degrees of heterogeneity and scales for more than one century, such as disposal of radioactive waste, geothermal utilization by hot dry rock systems, oil and gas production from fractured reservoirs, and water production from fractured rock [2] [3]. Non-Darcian flow has been observed in a variety of situations, such as a single confined vertical fracture toward a well [6], catalytic packed-bed reactors [7], and fractured rock [2]

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Discussion

Conclusion