CAREER: Solute Transport Coupled to Geomechanics and Convective Mixing

裂隙含水层中流体的运动和稀释很重要，因为它影响安全处置和有效遏制渗入地下的工业废物。用计算机模拟来预测流动的流体羽流的位置和形状是具有挑战性的，因为裂缝内的流体比外部的流体移动得更快。控制这一行为的裂隙性质随含水层中流体压力和机械应力的变化而变化。在地下水系统中，受污染的流体的粘度和密度往往与饱和含水层的水的粘度和密度不同，这导致流体以手指的形式流经含水层。虽然这些指进过程是已知的，但它们的相互作用对裂隙含水层中污染物羽流的扩散和混合的影响是未知的。该项目将使用实验室实验和计算机模拟模型来研究流体流动、岩石变形和破裂过程之间的相互作用，这些过程影响用于放射性废物处理和碳汇应用的含水层羽流的扩散和稀释。增加我们的知识将有助于更好地选择废物处置地点，并将选定地点的羽流位置和羽流大小的预测误差降至最低，并有助于减少含水层修复的成本和时间。该项目将生成公开可用的数据集和建模工具，并将通过产业界与学术界的伙伴关系与地下水工程师、水文地质学家和环境工程师共享。由于流体流动、溶质运移和地质力学过程的耦合，地下水溶质在裂隙岩石中的扩散和混合是水文地质学中的多个物理问题。该项目将增进我们对指进和对流混合情况下应力敏感型含水层中溶质运移和地质力学过程之间双向耦合所产生的物理机制的理解。耦合如何激活某些裂缝和指进方向，同时抑制其他方向，以及流体力学性质如何影响扩散和混合度量，这些问题将通过高分辨率数值模拟、断裂力学和流体动力失稳理论以及溶质在岩石中的运移实验来解决。将开发一种新的结合分布式应变传感的荧光示踪剂定量方法。实验和模拟结果将综合起来，根据含水层的流体力学性质和溶液的物理性质来定义运输-地质力学耦合强度参数。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The movement and dilution of fluids in a fractured aquifer is important because it affects the safe disposal and effective containment of industrial wastes leaching into the ground. Computer simulations to predict the position and shape of the moving plume of fluid are challenging because the fluid inside the fractures moves faster than the fluid outside. The fracture properties that control this behavior change with the fluid pressure and mechanical stress in the aquifer. In groundwater systems, the viscosity and density of the contaminant fluid often differ from that of the water saturating the aquifer, which causes the fluid to channel through the aquifer in the form of fingers. Although these fingering processes are known, the effects of their interaction on the spreading and mixing of a contaminant plume in a fractured aquifer are unknown. This project will use laboratory experiments and computer simulation modeling to study the interaction between fluid flow, rock deformation, and fracture processes that affect the spreading and dilution of aquifer plumes for radioactive waste disposal and carbon sequestration applications. Increasing our knowledge will lead to better selection of the waste disposal site, and minimize errors in the forecast of plume position and plume size at a selected site, and help decrease the aquifer remediation cost and time. The project will generate publicly available datasets and modeling tools which will be shared with groundwater engineers, hydrogeologists, and environmental engineers through an industry-academia partnership. A Masters-to-PhD Bridge program with summer research experience will be created for students from under-represented groups.The spreading and mixing of groundwater solutes in fractured rocks are multiphysics problems in hydrogeology due to the coupling between fluid flow, solute transport, and geomechanical processes. This project will improve our understanding of the physical mechanisms stemming from the two-way coupling between solute transport and geomechanical processes in stress-sensitive aquifers in the presence of fingering and convective mixing. How the coupling activates certain fracture and fingering directions while suppressing others and how the hydromechanical properties affect the spreading and mixing metrics are questions that will be addressed through high-resolution numerical simulations, fracture mechanics and hydrodynamic instability theory, and experiments of solute transport in rocks. A novel spectrofluorimetric tracer quantification method coupled with distributed strain sensing will be developed. Experimental and simulation results will be synthesized to define a transport-geomechanics coupling strength parameter based on the hydromechanical properties of the aquifer and the physical properties of the solute.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.