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，因为它影响到工业废物的安全处置和有效控制。计算机模拟来预测移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。控制这种行为的断裂特性随着含水层中的流体压力和机械应力而变化。在地下水系统中，污染物流体的粘度和密度往往不同于含水层中饱和的水的粘度和密度，这导致流体以指状物的形式通过含水层。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。该项目将利用实验室实验和计算机模拟建模，研究流体流动、岩石变形和断裂过程之间的相互作用，这些过程影响放射性废物处置和碳封存应用中含水层羽流的扩散和稀释。增加我们的知识将导致更好地选择废物处置场地，并尽量减少在选定的网站羽流位置和羽流大小的预测误差，并有助于减少含水层修复成本和时间。该项目将生成公开可用的数据集和建模工具，并通过行业-学术界合作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。将为来自代表性不足的群体的学生创建一个具有夏季研究经验的硕士到博士桥梁课程。地下水溶质在裂隙岩体中的扩散和混合是水文地质学中的多物理问题，由于流体流动，溶质运移和地质力学过程之间的耦合。该项目将提高我们对指进和对流混合存在下应力敏感含水层中溶质运移和地质力学过程之间双向耦合的物理机制的理解。耦合如何激活某些断裂和指进方向，同时抑制其他人，以及流体力学性质如何影响扩散和混合指标的问题，将通过高分辨率数值模拟，断裂力学和流体动力学不稳定性理论，以及溶质在岩石中的传输实验。将发展一种新的荧光示踪定量方法与分布式应变传感相结合。实验和模拟结果将被合成，以定义基于含水层的水力力学性质和溶质的物理性质的运输-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知识价值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.