Coupled Processes and Stochastic Hydrology

Scope:

The transport of heat and fluids in soils and rocks can be affected by significant coupling between thermal, hydrological, mechanical, and chemical (THMC) processes.  These include, but are not limited to conductive, convective and radiative transport of heat, flow of liquids and gases under viscous, capillary and gravitational forces, stress-induced deformation and degradation, reactive transport, mineral precipitation/dissolution, and colloid transport.  Understanding of such processes is important for various applications, such as environmental remediation, nuclear waste disposal, and oil/gas as well as geothermal reservoir recovery.  Coupled processes are particularly sensitive to the effect of subsurface heterogeneity on various scales.  Understanding heterogeneity and scaling effects often requires application of stochastic methods, aiming at evaluating the aleatory and epistemic uncertainties related to modeling results.

In summary, this research area covers coupled processes as investigated by integrated experimental and modeling approaches, and includes consideration of new conceptualizations and models for handling heterogeneity at all relevant scales.

ESD Activities:

We address the complex field of coupled processes analysis through an integrated experimental and modeling effort, combining laboratory experiments and in situ tests using advanced monitoring methods with sophisticated modeling analysis.  Powerful numerical simulators have been developed for flow and transport of multi-phase, multicomponent fluids, capable of modeling TH processes (TOUGH2), THC processes (TOUGHREACT), and THM processes (TOUGH2-FLAC).  Using these tools, ESD scientists are heavily involved in the performance assessment of underground repositories for nuclear waste, where the future subsurface flow and transport mechanisms will be strongly perturbed by thermal processes (e.g., boiling of groundwater as a result of decay heat), mechanical processes (e.g., porosity and permeability changes as a result of thermal expansion), and chemical processes (e.g., porosity and permeability changes from mineral alterations caused by thermally-induced flow).  Other ESD projects with particular focus on understanding coupled processes include, for example, CO2 disposal in deep aquifers or chemical alterations in hydrothermal reservoirs. 

ESD scientists have been active in the field of stochastic hydrology for more than two decades.  Current work in this area includes characterization of subsurface heterogeneity with a variety of stochastic approaches, upscaling of hydrologic properties for both saturated and unsaturated zones, development of multiple-scale and multiple-continua modeling approaches for flow and transport, application of fractal concepts to developing advanced theories for liquid flow in the unsaturated zone, and integration of measurements from different sources to reduce uncertainties in parameter estimations.

Contact:

Jens Birkholzer
ph: 510.486.7134
email: jtbirkholzer@lbl.gov