This paper presents a study of the micromechanics of the coupled hydro-mechanical (H-M) behavior of brittle rock during hydraulic fracturing. The study is conducted using the discrete element method (DEM), which spatially discretizes a rock mass into discrete disc particles, coupled with a solver for modeling fluid flow through a network of connected pores. In the coupled H-M DEM modeling, fluid flows through newly formed hydraulic fractures due to pore pressure increase from fluid injection in a wellbore and is coupled with rock mechanical response across a wide range of flow rates. The micromechanical insights from the DEM modeling provide better understanding of coupled H-M processes which precede rock breakdown during hydraulic fracturing, and the transition in deformation in brittle rock from a single hydraulic fracture to branched hydraulic fractures and a diffused damage zone. The effects of the properties of the fracturing fluid and the rock matrix as well as the effects of loading flow rate on the development of pressure-induced deformation and fracturing in crystalline brittle rocks fracturing are investigated. The DEM models used properties that were obtained by calibrating flow-rate-dependent stress–strain response against previously published experimental data on brittle rocks (granite in particular). DEM results are compared with experimental results from a true-triaxial scale model testing on hydraulic fracturing in an analogue rock. The presented results are expected to enable better understanding of conditions which lead to successful fracture propagation versus damage and fracture arrest in geo-reservoirs.

中文翻译：

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基于DEM的岩石水力压裂损伤微观力学。

本文介绍了脆性岩石水力压裂过程中的耦合水力（HM）行为的微力学研究。这项研究是使用离散元方法（DEM）进行的，该方法在空间上将岩体离散为离散的盘状颗粒，并结合了求解器，用于对通过连通孔网络的流体流动进行建模。在耦合HM DEM模型中，由于井眼中流体注入引起的孔隙压力增加，流体流经新形成的水力压裂，并在很宽的流量范围内与岩石力学响应耦合。来自DEM建模的微观力学见解可更好地理解水力压裂过程中岩石破裂之前的耦合HM过程，脆性岩石的变形从单一的水力压裂过渡到分支的水力压裂并扩散到破坏带。研究了压裂液和岩石基质的性质以及装料流速对晶体脆性岩石压裂中压力诱导变形和压裂发展的影响。DEM模型使用的特性是通过根据与流速有关的应力-应变响应针对先前发表的有关脆性岩石（特别是花岗岩）的实验数据进行校准而获得的。将DEM结果与模拟岩石中水力压裂的真三轴比例模型测试的实验结果进行比较。