Earth Sciences at DUSEL: Ideas and Progress to Date

Eric Sonnenthal & Brian McPherson

Earth Science Working Groups

• Coupled Processes (Hydrology, Geochemistry, Petrology)

• Rock Mechanics and Geophysics

Note: Engineering is an integral of Earth Sciences

Progress and Continuing Discussion

• Participants have generally agreed on the unique attributes of DUSEL for Earth Sciences:

Unprecedented experiments covering a wide range of spatial and temporal scales

Transparent Earth: Visualization, probing the Earth in 3-DLife in “extreme environments, ancient life”

• Participants have not agreed on:“Societal benefits” (resources, waste management, industry

needs) vs “Fundamental science and engineering”“Hard rock” vs “Soft rock”

• Participants need to define still:Why go deep - Specific criteria for experiments unique to

DUSEL (depth - fluid pressure, temperature, stress, rock characteristics)Infrastructure needs for experiments, compatibilities, etc.

Question: What’s the major benefit to Earth Science of “going underground”?

One Typical Approach to Subsurface Investigations: Use drill-hole data with computer model simulations

Data collectedat bottom of borehole.

-4000

-2000

SL

2000

Ele

vatio

n (m

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Vertical Exaggeration x 16

Salt Creek Anticline

Black Hills

Powder River Basin, Wyoming

Oil or Gas Well

Courtesy: URL at Atomic Energy of Canada Ltd

Proposed New Approach:

Develop a US laboratory and observatory underground,inside the earth.

Much like surgery permits a physician to examine internal bones and organs recognized on X-rays or CAT scans, NUSL will be a fully instrumented, dedicated laboratory and observatory for scientists and engineers to examine Earth’s interior.

Surface laboratories for core, water, gas, and microbial analyses, experiments, and archives

From NSF EarthLab Report

Deep Flow and Paleoclimate Laboratory and Observatory

From NSF EarthLab Report

Induced Fracture and Deformation Processes Laboratory

From NSF EarthLab Report

Ultradeep Life and Biogeochemistry Observatory

From NSF EarthLab Report

Deep Coupled Processes Laboratory: study coupling among thermal, mechanical, hydrological, chemical, and biological processes in the subsurface (injection

and transport experiments at several different depths along highly instrumented and well-characterized fracture/matrix zones)

From NSF EarthLab Report

Priority Attributes of DUSEL for Earth Science and Engineering

1. Long-term access to large (~20+ km3) volume of subsurface in which

geological features are well characterized in three dimensions, including appropriately placed sensing equipment.

2. Ability to access this environment through selective/ choice placement of drill holes, underground workings, laboratories, or observatories. Accessed host rock should reach temperatures of 120°C and waterfilled fracture systems.

3. Ability to modify geochemical characteristics of this environment by introduction of materials into holes or workings. At least one fracture zone should be accessed by multiple holes that are instrumented with an array of samplers for transport studies.

4. If an existing mine is chosen as the DUSEL site, complete access to entire archive of existing data and samples.

EARTH SCIENCE AND ENGINEERING CRITERIA FOR DUSEL SITE

Diverse chemical and physical environments, including:

• Variety of hydrologic environments, such as highly permeable, near-surface soils and alluvium vs. deeper, low-permeability crystalline rocks.

• Variety in groundwater compositions, such as high vs. low salinity, pH, and dissolved gas concentrations.

• Variety of structural environments, especially density and orientation of faults and fractures.

• Variety of geochemical environments, especially in concentration of reduced minerals (e.g., sulfides) vs. oxidized minerals (e.g., hematite).

Progress Made During Berkeley and Blacksburg Workshops

Starting from previous studies and workshops, the scientific community is actively working on:

Identification of Major Themes • Identify syntheses that make sense for the specialists, but also resonate with other scientists and fascinate the non-scientists

• Working groups have formed for this task: Coupled processes, rock mechanics and tectonics, geo-microbiology and applications

Prioritization• What are the most pressing questions to answer deep underground?

“Ever Changing

Earth”Dynamic, Coupled

processes

Conditions for Life

Progress Made During Berkeley and Blacksburg Workshops

Some Major Themes:Conditions for Life

• Limits• Metabolism/ Energy source• Evolution

The “Ever Changing Earth”Behavior of rock and fluids at depth.

Coupled processes in inhomogeneous media: mass, momentum,energy flow Spatial and temporal scaling “laws”

The structure and the evolution of the earth

Observing from inside out: Core/mantle/crust/mountainDynamics: earthquakesThe concentration of ore deposits

Climate changePaleo-climate ? Ancient sequestered waterClouds

“Transparent Earth” :Resources

Origin & Discovery

Progress Made During Berkeley and Blacksburg Workshops

One Approach: Evaluate DUSEL in different contexts

(1) An “Observatory”(2) An “Active Processes Laboratory”

1. What are the limits of conditions for microbial life?

2. Can we increase our fundamental knowledge of the earth and its dynamic processes? Observe Earth from the inside…

3. Can we improve resolution, using observations at multiple-scales and at ranges of depths, of the couplings among thermal, hydrologic, chemical and mechanical (deformation) processes? (natural observatory context)

As an “observatory,” some major science questions include:

Progress Made During Berkeley and Blacksburg Workshops

Progress Made During Berkeley and Blacksburg Workshops

1. How do Mass, Momentum, and Energy transfer and transform in fractured media? (carry out THMCB Experiments)

2. How may we image and scale in fractured media?

3. How may we engineer ultra-deep and large excavations?

4. How may we better understand cloud processes to improve climate prediction?

As an “active laboratory,” some major science questions include:

Examples–Ore formation, characterization and recovery–Heat extraction (geothermal reservoirs)–Fracture and fault deformation and flow–Mineral precipitation and dissolution

Progress Made During Berkeley and Blacksburg Workshops

FRACTURED WATER CHEM MINE-BACK AIR QUALITY PRISTINE HETEROGENEOUS COMPATIBILITY TIME FRAME (YRS)EITHER OLDER Y/BH NA Y Y ALL - 2 5 TO 10 EITHER NA N Y NA NA ? 10+

Y ANY LIMITED NA EITHER Y ALL - 2 10+

Y ANY Y NA Y Y 1,3,4 10++Y ANY Y NA EITHER EITHER ALL - 2 10++

EITHER ANY Y NA Y EITHER ALL - 2 10++Y ANY Y NA Y Y ALL - 2 10++

EITHER DILUTE Y NA EITHER EITHER 1,6,4 10EITHER ANY Y NA EITHER EITHER ALL - 2 10+

Y ANY Y NA EITHER Y ALL-2,6 10++

DEDICATED EARTH SCIENCE FACILITY

EXPERIMENT OPEN/CLOSED DEPTH SIZE REMOTE BC WET TEMPERATURE LITHOLOGYBIO-STIMULATION C ANY 20M Y CONTROLLED Y AMBIENT + ANYCLOUD PHYSICS O ANY .5 - 1 KM N CLOSED/ Y AMBIENT - ANYMICROGRAVITY CONTROLLED

AQUIFER DYNAMICS C DIFFERING M-KM VARIED CONTROLLED Y AMBIENT + ANYAND TRANSPORTHYDROCARBON C DEEP KM Y CONTROLLED Y AMBIENT + SED PREF.

ROCK MASS O/C ALL 100M N MIXED Y/N AMBIENT + ANYMECHANICS CHAMBER

ORE DEPOSIT C DEPENDS KM Y CONTROLLED Y CONTROLLED ANYTHERMAL TEST C DEEP 100M+ Y CONTROLLED Y CONTROLLED ANY

MINING EXTRACTION TECHNOLOGY C ANY KM Y CONTROLLED Y AMBIENT ANYFRACTURE PROPAGATION C DIFFERING 10-100M N CONTROLLED Y/N AMBIENT ANYCARBON MANAGEMENT C DEEP KM Y CONTROLLED Y AMBIENT ANY

ADD EXPT HERE……

Experiment Requirements and Infrastructure Matrix

Example: Drift Scale Test at Yucca Mountain• Purpose of the test is to evaluate

coupled thermal, hydrological, mechanical and chemical processes surrounding the potential repository

• Dimensions: ~ 50 meters long by 5 meters in diameter

• Electric heaters activated Dec. 1997, turned off Jan. 2002

• Maximum drift wall temperature reached ~ 200°C

• Water, gas, and rock samples collected from boreholes for geochemical and isotopic studies

• Reaction-transport modeling performed prior to and during test (examples on following slides)

ObservationDrift

ConnectingDrift

HeatedDrift

Wing HeatersThermalMechanicalHydrologicalChemical

Water-Gas-Rock and Fracture-Matrix Interaction of Heat and Mass

Water-Gas-Rock Interaction:• Mineral dissolution and precipitation• Changes in fluid chemistry as a result of transport/mixing, boiling/evaporation, mineral-water-gas reactions• Reaction rates in fractures related to wetted surface area

Fracture-Matrix Interaction:• Advection and diffusion across fracture-matrix interface• Also related to wetted surface area

Measured and Modeled CO2 Over Time

Calcite Precipitation-Dissolutionand 14C Evolution

Calcite precipitation in fractures above heaters owing to boiling of water draining in fractures (reflux zone)

• Calcite dissolution occurs in drainage and condensation zones• 14C strongly lowered in CO2 due to calcite dissolution and addition of “dead

carbon”

Considerations for Boulder Workshop

• De• Define rationale and requirements for depth - Pressure, temperature, stress, chemistry

Plot showing depth-property ranges for experiments comparable to plots shown for physics experiments

• Define rationale and requirements for rocktype and characteristics

• Infrastructure needs for experiments