Model of groundwater flow, gas migration, and reactive transport in the Virgin River Basin, SW Utah

To better understand the possible risks posed to shallow groundwater resources by geologic carbon sequestration (GCS), a multi-scale numerical modeling approach was invoked using the TOUGHREACT code from Lawrence Berkeley National Laboratory. The code solves coupled equations representing conservation of mass and energy on a finite difference grid to simulate multiphase, multicomponent, non-isothermal heat and mass transport in porous media. Two different two-dimensional cross-section modeling domains were constructed to improve understanding of groundwater flow and contaminant transport processes at a field site in soutwestern Utah. The site represents a natural analogue for leakage from a GCS site because water with elevated concentrations of salt and CO2 are migrating upward into a shallow aquifer system. The first modeling domain was designed to improve understanding of long-term hydrological leakage and conservative transport processes at the regional scale, while the second was designed to investigate site-scale reactive transport processes that could occur if the leaking fluids, or those with higher carbon dioxide (CO2) concentrations, were to interact with a potential source of contamination along their flow path toward the ground surface. Lead (Pb+2) was used as an example heavy metal contaminant and was incorporated into a region of iron oxide representing concretion zones that are common in the geographic area. Results indicate that the initial state of potential heavy metal contaminant (i.e., sorbed onto the surface of the iron oxide or in an oxide mineral assemblage as PbO, litharge), exerts strong control on the amount of contamination that may occur, and that precipitation readily sequesters mobilized Pb+2. This USGS data release contains all of the input and output files for the simulations described in the associated journal article. Descriptions of the data in each subdirectory are given to facilitate understanding of this model archive. File descriptions are provided for select files to provide additional information that may be of use for understanding this model archive. Support is provided for correcting errors in the data release and clarification of the modeling conducted by the U.S. Geological Survey. Users are encouraged to review the complete journal article (See 'Related External Resources' section below) to understand the purpose, report construction, and limitations of this model.

为深入探究地质碳封存（geologic carbon sequestration, GCS）对浅层地下水资源可能带来的风险，本研究采用美国劳伦斯伯克利国家实验室开发的TOUGHREACT代码，构建多尺度数值模拟方法。该代码基于有限差分网格求解耦合的质量与能量守恒方程，用以模拟多孔介质内多相、多组分、非等温的热量与质量运移过程。研究构建了两个二维剖面模拟域，以加深对犹他州西南部某野外场地地下水流与污染物运移过程的认知。该场地可作为GCS场地泄漏的天然类比场景：当地地下水中盐类与二氧化碳（CO₂）浓度升高，并向上运移进入浅层含水层系统。第一个模拟域旨在深化对区域尺度下长期水文泄漏与保守性污染物运移过程的理解，而第二个模拟域则用于探究当泄漏流体或高浓度二氧化碳流体在向地表运移的路径中与潜在污染源发生相互作用时，场地尺度下的反应性运移过程。研究选取铅（Pb²⁺）作为典型重金属污染物，并将其设置在代表该区域常见结核带的氧化铁区域内。模拟结果表明，潜在重金属污染物的初始赋存状态（即吸附于氧化铁表面，或以PbO、密陀僧（litharge）形式赋存于氧化物矿物集合体中）对可能发生的污染程度具有显著控制作用；且沉淀作用可有效固定活化的Pb²⁺。本次美国地质调查局（United States Geological Survey, USGS）发布的数据包含了相关期刊论文中提及的所有模拟输入与输出文件。本数据集对每个子目录内的数据均提供说明，以帮助用户理解本模型存档文件。同时针对部分选定文件提供详细说明，以补充有助于理解本模型存档的额外信息。美国地质调查局可为本次数据发布中的错误修正以及模拟工作的相关疑问提供技术支持。建议用户查阅完整的期刊论文（详见下文「相关外部资源」部分），以全面了解该模型的设计目的、报告结构与局限性。