Numerical modelling of stable isotope ( H-2 and O-18) transport in a hydrogeothermal system: Model development and implementation to the Guide Basin, China
Numerical modelling of stable isotope ( H-2 and O-18) transport in a hydrogeothermal system: Model development and implementation to the Guide Basin, China
复制标题
水热系统中稳定同位素（H-2 和 O-18）输运的数值模拟：中国贵德盆地的模型开发和实施
DOI：
10.1016/j.jhydrol.2018.11.065
复制
发表时间：
2019
影响因子：
6.4
通讯作者：
Daniel D R Owen
中科院分区：
文献类型：
--
作者：
Zhenjiao Jiang;Tianfu Xu;Dirk Mallants;Hailong Tian;Daniel D R Owen
The groundwater tracers, deuterium ( H-2 or D) and oxygen-18 (O-18) are widely used to determine groundwater recharge origin, rate and temperature. Quantitative methods able to interpret delta D and delta O-1(8) mobility in the subsurface, especially under high pressure and temperature conditions, remain the focus of ongoing research. Here we developed an isotope transport module as an add-on to the TOUGH2 simulator, which is able to describe the evolution of delta D and delta O-1(8) in groundwater induced by advection, dispersion, water-rock interaction, and fractionation due to changes of water phase and density. The new model was tested by modelling the groundwater flow, temperature, fluid density and isotopic composition in a faulted, geothermal system in the Guide Basin, China. We found that the density-driven flow induced by temperature variations can lead to isotope fractionation between low- and high-density water. In addition, the density-driven flow creates multiple flow systems in the fault damage zone, increasing the complexity of the spatiotemporal isotope distribution. The results indicate that in scenarios where a density contrast occurs, such as in geothermal systems, the relationship between delta D and delta O-1(8) in recharge water and discharging groundwater can only be fully understood if the coupled processes of fluid flow, heat transport and isotope fractionation in the subsurface are accounted for.
