Experimentally Informed Simulation of Creep Behavior in Shale Rocks Induced by Chemo-mechanical Loading
Experimentally Informed Simulation of Creep Behavior in Shale Rocks Induced by Chemo-mechanical Loading
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DOI：
10.1007/s00603-023-03413-0
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发表时间：
2023-06-19
影响因子：
6.2
通讯作者：
Abedi，Sara
中科院分区：
文献类型：
--
作者：
Prakash，Ravi;Abedi，Sara
页岩蠕变在地质构造的可持续性、井筒稳定性、地面沉降评估、CO2储存、有毒废物控制和水力压裂等许多应用中是一个重要因素。在恒定载荷下导致这种时间依赖性变形的一种机制是溶解/形成过程，伴随着与反应环境的化学-机械相互作用。当溶解/形成过程发生在材料相内时，材料微观结构内的应力和应变分布发生变化。在溶解过程的情况下，由溶解相携带的应力被分布到相邻的体素中，这导致材料的进一步变形。本研究的目的是探讨岩石在化学-机械载荷作用下的微结构演化与随时间变化的蠕变行为之间的关系。这项工作使用实验表征的微观结构和力学演化的页岩岩石引起的反应性盐水（富CO2的盐水）和非反应性盐水（富N2的盐水）在高压和高温条件下的相互作用，计算产生的时间依赖性变形使用时间步进有限元为基础的建模方法。使用反应前后岩石样品的分段显微CT图像获得样品显微结构快照。耦合纳米压痕/EDS提供了空间改变的各个材料相的机械性能，由于溶解和沉淀过程作为结果的化学机械加载的样品。时间依赖性的机械通知的微观结构，然后被纳入到一个机械模型，以计算蠕变行为所造成的溶解/沉淀过程中的矿物相的固有的粘性特性无关。结果表明，溶解/沉淀过程中的粘性行为的岩石反应环境中的实质性作用。
Creep deformation in shale rocks is an important factor in many applications, such as the sustainability of geostructures, wellbore stability, evaluation of land subsidence, CO2storage, toxic waste containment, and hydraulic fracturing. One mechanism leading to this time-dependent deformation under a constant load is the dissolution/formation processes accompanied by chemo-mechanical interactions with a reactive environment. When dissolution/formation processes occur within the material phases, the distribution of stress and strain within the material microstructure changes. In the case of the dissolution process, the stress carried by the dissolving phase is distributed into neighboring voxels, which leads to further deformation of the material. The aim of this study was to explore the relationship between the microstructural evolution and time-dependent creep behavior of rocks subjected to chemo-mechanical loading. This work uses the experimentally characterized microstructural and mechanical evolution of a shale rock induced by interactions with a reactive brine (CO2-rich brine) and a non-reactive brine (N2-rich brine) under high-pressure and high-temperature conditions to compute the resulting time-dependent deformation using a time-stepping finite-element-based modeling approach. Sample microstructure snapshots were obtained using segmented micro-CT images of the rock samples before and after the reactions. Coupled nanoindentation/EDS provided spatial alteration of the mechanical properties of individual material phases due to the dissolution and precipitation processes as a result of chemo-mechanical loading of the samples. The time-dependent mechanically informed microstructures were then incorporated into a mechanical model to calculate the creep behavior caused by the dissolution/precipitation processes independent of the inherent viscous properties of the mineral phases. The results indicate the substantial role of the dissolution/precipitation processes on the viscous behavior of rocks subjected to reactive environments.