A Study of Fracture-Induced Coupling Phenomena in Rocks

亚利桑那大学Kemeny：耦合现象在岩石中是极其重要的，包括机械、水力、热和化学过程。在这项研究中，将通过实验和模型研究来研究裂纹诱导的耦合机制。重点将放在研究裂隙中的机械载荷、热载荷和流体环境的化学如何影响岩石的流动特性。实验重点将放在一系列机械/流动耦合三轴试验上，在这些试验中，当样品受到三轴应力达到或超过峰值应力时，测量轴向和横向渗透率。实验室测试还将包括热载荷(均匀和井眼加热)和研究不同流体化学条件下裂纹扩展的测试。建模的重点将是建立有限元损伤模型。将在耦合机制之间建立基于断裂力学的关系，并将包括裂纹相互作用效应。这些关系将被应用到有限元模型中，以预测复杂边界条件下的耦合行为。此外，还将建立一个离散的裂纹边界元模型，以研究热载荷和不同流体化学条件下的裂纹扩展能力(通过亚临界裂纹扩展)，并增加通过生成的裂纹群计算渗透率的能力。

ABSTRACT CMS9523072 PI: Kemeny, University of Arizona Coupling phenomena are extremely important in rocks and include mechanical, hydraulic, thermal, and chemical processes. In this study, crack-induced coupling mechanisms will be investigated with both experimental and modeling studies. The focus will be on investigation of how mechanical loading, thermal loading, and the chemistry of the fluid environment in the cracks influences the flow properties of the rock. Experimental emphasis will be placed on a series of coupled mechanical/flow triaxial tests in which both axial and lateral permeabilities are measured while samples are subjected to triaxial stresses up to and past peak stress. Laboratory tests will also involve thermal loading (both uniform and borehole heating) and tests to study crack growth under different fluid chemistries. Modeling will be focused on development of a finite element damage model. Fracture mechanics-based relationships will be developed between the coupling mechanisms, and will include crack interaction effects. These relationships will be implemented into a finite element model to predict coupled behavior under complex boundary conditions. In addition, a discrete crack boundary element model will be developed to study the capability of crack growth due to thermal loading and under different fluid chemistries (via subcritical crack extension), and the capability of calculating the permeability through a generated crack population will be added.