Under high temperature and stress reservoir conditions, proppant embedment induced by the time-dependent creep behavior of shale rocks has posed great challenges to the long-term maintenance of fracture conductivity in unconventional reservoirs. In this study, a numerical workflow combining a 3D continuum–discrete mechanical coupling approach with the lattice Boltzmann (LB) method is developed to simulate the coupled thermal–mechanical process in a rock/proppant system and to investigate the role of the time-dependent deformation of shale rocks on proppant embedment and fracture conductivity loss under varying temperature and stress conditions. The numerical workflow is first compared with an experiment under varying temperature and stress conditions to calibrate the elastic, plastic, viscoelastic, and thermal properties of the shale rock, as well as the proppant properties. Then, the effect of fracture axial and confining stress, numbers of proppant layers, proppant size, proppant spatial distribution, and proppant crushing is systematically investigated. The simulation results indicate that when the rock creep is significant, large size and a multilayer of proppant structure are suggested to maintain the fracture conductivity. The small percentage of particle breakage in a proppant assembly plays a less important role in the long-term maintenance of fracture conductivity. The findings of this study will shed light on the creep-induced proppant embedment mechanisms at reservoir conditions as well as their influence on the sustainability of fracture conductivity over long periods of time.

在高温高压储层条件下，页岩随时间蠕变引起的支撑剂嵌入对非常规储层裂缝导流能力的长期维持提出了巨大挑战。在这项研究中，开发了一种将 3D 连续体-离散机械耦合方法与格子玻尔兹曼 (LB) 方法相结合的数值工作流程，以模拟岩石/支撑剂系统中的热-机械耦合过程，并研究时间相关的作用。页岩在不同温度和应力条件下支撑剂嵌入的变形和裂缝导流能力损失。首先将数值工作流程与不同温度和应力条件下的实验进行比较，以校准页岩的弹性、塑性、粘弹性和热特性，以及支撑剂的特性。然后，系统地研究了裂缝轴向和围压、支撑剂层数、支撑剂尺寸、支撑剂空间分布和支撑剂破碎的影响。模拟结果表明，当岩石蠕变显着时，建议采用大尺寸和多层支撑剂结构来保持裂缝导流能力。支撑剂组合中的小比例颗粒破碎在长期维持裂缝导流能力方面的作用不太重要。这项研究的结果将阐明在储层条件下蠕变诱导的支撑剂嵌入机制及其对长时间裂缝导流能力的影响。系统地研究了支撑剂层数、支撑剂尺寸、支撑剂空间分布和支撑剂破碎。模拟结果表明，当岩石蠕变显着时，建议采用大尺寸和多层支撑剂结构来保持裂缝导流能力。支撑剂组合中的小比例颗粒破碎在长期维持裂缝导流能力方面的作用不太重要。这项研究的结果将阐明在储层条件下蠕变诱导的支撑剂嵌入机制及其对长时间裂缝导流能力的影响。系统地研究了支撑剂层数、支撑剂尺寸、支撑剂空间分布和支撑剂破碎。模拟结果表明，当岩石蠕变显着时，建议采用大尺寸和多层支撑剂结构来保持裂缝导流能力。支撑剂组合中的小比例颗粒破碎在长期维持裂缝导流能力方面的作用不太重要。这项研究的结果将阐明在储层条件下蠕变诱导的支撑剂嵌入机制及其对长时间裂缝导流能力的影响。建议采用大尺寸和多层支撑剂结构以保持裂缝导流能力。支撑剂组合中的小比例颗粒破碎在长期维持裂缝导流能力方面的作用不太重要。这项研究的结果将阐明在储层条件下蠕变诱导的支撑剂嵌入机制及其对长时间裂缝导流能力的影响。建议采用大尺寸和多层支撑剂结构以保持裂缝导流能力。支撑剂组合中的小比例颗粒破碎在长期维持裂缝导流能力方面的作用不太重要。这项研究的结果将阐明在储层条件下蠕变诱导的支撑剂嵌入机制及其对长时间裂缝导流能力的影响。