Subsurface Flow & Transport (SFT)

The Subsurface Flow and Transport (SFT) Team is a diverse group of people with extensive experience in developing and applying subsurface flow and transport computer codes to a wide range of programs involving  water and energy development, environmental cleanup and waste-storage over the last 3 decades.   The SFT team prides itself on applying state-of-the-art numerical tools that bridge the gap between theory and data to solve real-world problems of national importance.  It excels at integrating field and laboratory data with modeling and uncertainty analysis to develop a quantitative basis for decisions affecting the environment and water or energy development.  Recently, it has emerged as a national leader in developing risk-assessment tools such as CO2-PENS for evaluating candidate sites as possible subsurface carbon storage reservoirs. The SFT Team works closely with geologists, geophysicists, geochemists in other groups within EES-16 and the Earth Science Division as a whole to bring observational and simulation science together to maximize their benefits.

Building on the subsurface computational tools it developed during its decades-long involvement in nuclear waste repository program at Yucca Mountain, the SFT Team continues to investigate innovative concepts for the disposal of nuclear waste through its involvement in the Spent Fuel Disposition Program, where it is exploring waste disposal concepts in a variety of geologic media.  It has also applied its extensive experience in simulating radionuclide transport in groundwater to former nuclear weapons testing areas at the Nevada Test Site, where it plays a major role in helping the DOE assess the likely extent of groundwater contamination in the foreseeable future and the risk it poses to the off-site public.   The SFT Team also plays an important role in the environmental cleanup at Los Alamos National Laboratory itself, where defense-related activities have resulted in local groundwater contamination.

In energy, the SFT team is involved in the development of unconventional sources of fossil fuels, including oil shale and tar sands. It has recently expanded the capabilities of its workhorse multi-phase, multi-component flow and transport code FEHM to include coupled thermal-hydrologic-chemical-mechanical (THCM) processes. These capabilities have been deployed in industrial partnerships to extract oil in situ from oil shales, thereby reducing environmental impacts relative to the open-pit methods used in the past.  Building on its experience with the Hot Dry Rock project, the SFT team has applied FEHM’s coupled THCM capability to enhanced geothermal systems (EGS) where hot but relatively impermeable rock is hydro-fractured to produce the permeability necessary for the economic extraction of heat. Implementation of a coupled THCM capability has also led to new insights regarding the possible risks of CO2 storage in saline aquifers and depleted oil fields, where high injection pressures could damage overlying caprocks and create CO2 leaks into overlying freshwater aquifers.  Field and modeling studies are currently underway by SFT staff of a natural CO2 seep in northern New Mexico to better constrain the possible consequences of a CO2 leak on the quality of shallow groundwater.  Other key projects in carbon management and storage include partnerships with the State of Wyoming to capture and inject CO2 from the Jim Bridger power plant into the Weber Sandstone in the Rock Springs Uplift and partnerships with leading Chinese research institutions to develop subsurface strategies to store CO2 as part of the US-China Clean Coal Initiative.

The SFT team’s modeling capabilities include pore-scale Lattice-Boltzmann models that have been used to simulate processes such as the evolution of pore geometry due to mineral dissolution and precipitation following CO2 injection into a brine-filled reservoir. These pore-scale models are also being applied to fuel-cell and lithium battery design.

In high-performance computing, SFT staff have developed the PFLOTRAN code, a parallelized multi-phase, multi-component, flow and heat- and mass-transport simulator that has been used to solve problems with more than 2 billion degrees of freedom using more than 130,000 cores.  SFT staff are also in leadership roles on the new ASCEM (Advanced Simulations Capability for Environmental Management) Project, a multi-laboratory effort to develop a code that takes advantage of advances in high-performance computing within the DOE complex in order to address DOE legacy-waste issues.