induced deformation and transport

DUSEL Experiment Development and Coordination (DEDC)Internal Design Review

July 16-18, 2008Steve Elliott, Derek Elsworth, Daniela Leitner, Larry Murdoch, Tullis C. Onstott and Hank Sobel

Homestake DUSEL Initial Suite of ExperimentsDUSEL Experiment Development and Coordination

Induced Deformation and Transport

• Leonid Germanovich and Eric Sonnenthal – group leaders

• Steve Martel• Steve Glaser• Dmitry Garagash• Rob Jeffrey• Bob Lowell• Derek Elsworth• Ze’ev Reches• T. C. Onstott• Charles Fairhurst• Eric Westman• Chris Marone• Maochen Ge• Eliza Marone• Joe Labuz• Larry Murdoch


Science

• Objective - to evaluate how – fractures propagate and deform during fluid flow and changes in stress in rock– faults initiate, heal, seal, and reactivate– fractures interact to create networks – scaling laws can apply to rock fracture processes – heat, mass, and microbes are transported through fractures and the adjacent rock matrix– chemical and microbially-mediated reactions are controlled by heat and mass transport– new technologies can improve the imaging of fractures and faults

• Why is DUSEL the best or only place this experiment can be done?Objectives can only be achieved by manipulating in situ conditions at large scales and depths, and then

directly observing results. Such experiments require– Substantial and specialized sub-surface infrastructure over many years– excavating host rock in the vicinity of created faults and fractures

• Expected results and their significance– Improved understanding of seismicity– Advanced understanding of fractures and fracture networks

• Why is it important to do these experiments in the near future?– public safety – water supply– hydrocarbon production and geothermal energy recovery– waste remediation and disposal– CO2

sequestration and climate change

Homestake DUSEL Initial Suite of ExperimentsDUSEL Experiment Development and Coordination4

SUITE OF EXPERIMENTS Big picture

• Fracture propagation • Fluid flow in networks• Deformation of fractures• Faulting• Scaling of fracture energy• Transport and geochemical reactions in fractures• Pressure solution at fracture asperities• Hydrothermal convection - permeability changes

from mechanical and chemical processes• Microbiological processes during fracturing


FRACTURE PROCESSES LAB

Create fractures in highly instrumented setting to characterize deformation processes, then use for transport experiments


APPROACH

Create idealized fractures for basic processes, then move to natural fractures

a.) Hydraulic fracturing to evaluate Mode I propagation b.) Change stresses using thermal technique ”designer fractures”

– Small stress change a. stress and permeability (up to critical stress) b. create cross-cutting hfrx development of percolating networks

– Large stress change a. slip on existing fractures, b. gouge development, c. fault growth

c.) Use well understood/designed fractures and fracture networks to: – Characterize scaling of fracture energy – Displacement during pressure change

d.) Change stresses enough to create faults, slip on existing surfaces

e.) Use highly instrumented fractures and thermal instrumentation to evaluate transport and reactions in hydrothermal conditions.


Example: FAULT EXPERIMENT

Approach

Utilize large, natural in-situ stresses – currently, the only option

Create failure by reducing existing load


Concept

1. Create a pair of parallel lines of boreholes or slots normal to 3

2. Cooling by T reduces 3 and allows controlled modification of stress state between lines

3. Reduce 3 between boreholes until failure occurs


1 bta T

Will it be fast enough to be practical?

Will the stress change enough to cause failure?

3

2 T at

L

b

w

L

Could it work?

Scaling


EXAMPLEASSUME

Depth ~ 1 km in generic rock

E ~ 1011 Pa

~ 10 C

a ~ 10 m2/s

~ 2600 kg/m3

1 ~ 25 MPa

3 ~ 23 MPa

T ~ 102 C

11 dayst

1 bta T

Will it be fast enough to be practical?

Will the stress change enough?

3

2 T at

L

3 22MPa

Stress change to cause failure Mohr-Coulomb,

3@ 17MPafailure

b~1m3m

10 m


FEASIBILITY

• Scaling is promising

• Preliminary numerical resultsconfirm scaling results, demonstrateversatility

• Looks good, but need additional work for planning DUSEL

3-D modelingDesign analysesLab experimentsSmall-scale field experiments


Fault experiments at 300 ft level

4/21/2008 DUSEL Meeting, Lead, SD, April 21, 2008

12

Cooling


Fracture surface

Heating

Fault experiments at 300 ft level


Facility Needs

300 Level

Space: 100 m of drift through pristine (undrilled) rock extending 100 m from drift

4850 Level


8000 Level


All Levels:

Access: Walking, drill rig, wheeled equipment

Power: 110 Single Phase, 240 3-phase

Communications: Internet to the ground surface

Special Materials: Liquid nitrogen

Services: Excavation

3 Levels to leverage access, space and stress magnitude


Coupled Thermal-Hydrolocal-Mechanical-Chemical-Biological (THMCB) Experiments

• Multiphase flow• Thermal deformation• Advection- and diffusion-limited

reactions between the rock matrix and fractures

• Mineral dissolution, nucleation, growth

• Fracture sealing, slippage under shear stress, strengthening

• Effects on local microbiological populations

Processes

Example Lab Experiment of Amorphous Silica Precipitation and Fracture Sealing During Boiling

(Kneafsey et at., 2001, HLRWMC; Dobson et al., 2003, JCH, Vol. 62-63)

Create a well-controlled field experiment that can provide the basis for understanding and quantitatively modeling coupled THMCB processes


• A long term coupled process THMCB experiment can be used to test many problems of scientific interest and societal benefit

• Ideal opportunity for student projects and theses of various durations• Will involve testing of new geochemical and geophysical monitoring methodologies,

computer modeling tools, and data acquisition• Basic Science:

– Reactive transport processes in fractured heated rock under stress– Microbiological activity at elevated temperatures– Development/validation of next generation THCMB numerical models

• Applications:– Evolution of hydrothermal flow in fractured rocks– CO2 transport and sequestration– Contaminant migration and remediation under heated conditions– Mobilization of metals and ore deposit formation– Permeability evolution in geothermal reservoirs– Efficiency of heat recovery in enhanced geothermal systems

Justification/Opportunities

Modeling


THMCB Experiment Science Goals

• Fundamental: How do rock and fluids evolve in the Earth’s crust under elevated temperatures, stress, and flow (water, gases)?

• Reaction rates in fractured rock under stress govern many aspects of the evolution of reservoirs, faults, alteration, ore deposits, etc …

• Biological Gradient Test (Population changes over a temperature gradient with a range similar to the deep drilling)

• Biological repopulation during cooldown - transport mechanisms • Processes are complex and cannot be duplicated in small laboratory experiments nor analyzed

in enough detail in natural systems to develop a quantitative model• Quantitative understanding of these processes is essential for long-term prediction of CO2

sequestration, nuclear waste isolation, water resources, resource recovery• The objective of this THMCB experiment will be:

– Allow scientists to perturb rock at depth under in-situ conditions– Test and develop new models for the coupling between fluid flow, heat transport,

chemical and isotopic transport and reaction, mechanical deformation, and biological processes

– Test in-situ measurement techniques under “extreme” conditions


THMCB Experiment Conceptual Design

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Based on Proposed Thermal Test

Tunnel

Attributes

• Block Size: ~ 50x40x40m +

• Planar heat source (vertical plane would set up rapid upward convective flow)

• Scalable: Nominally heaters are 10 x 10 m

• Heated rock dimensions ~ 104 m3

• Temperature Max (~ 150-200C)

• Sample collection and observation boreholes (geochemistry, thermal, mechanics, biological)

• Geophysical/thermal measurements


In-Situ Measurements

• DTPS consists of a borehole length electrical resistance heater and fiber-optic DTS

• Apply constant heating along wellbore

• Temperature transient is recorded • Estimate

– formation thermal properties– fluid advection– saturation

From Barry Freifeld, LBNL

The Distributed Thermal Perturbation Sensor


Isotopic measurements can be used to quantify flow and reaction rates in natural systems

Gradient and length of isotope profile depend on the ratio:

reaction rate/ flow rate

Isotopic measurements can be used to quantify flow and reaction rates in natural systems

From Kate Maher, Stanford, Univ.


Sr and U isotopes used to quantify flow and reaction rates

Coupling of different isotopes can uniquely constrain both transport

and reaction rates.

(Maher et al, 2003, 2006)


Coupled Mechanical-Chemical Deformation in Fractures

Premise: Long-term rock behavior is governed by chemical-mechanical interactions (e.g., pressure solution, mineral alteration, dissolution/precipitation creep, etc.)

Polak et al., 2003

Possible Grain Contact Evolution (Koehn et al., 2006)


(Phased) Approach

1. Selection of candidate rock mass and tunnel complexes to perform experiments. (2008-2010) Volcan use at SDSMT

2. Assemble/acquire physical and chemical data on candidate rock blocks3. Choose samples for preliminary batch or plug flow expts to estimate rates of reaction and

time-scale of expt needed4. Preliminary hydrological, thermal, ad chemical models for evaluating possible

experimental designs5. Assemble data or and/or measure microbiological populations6. Preliminary design of experiments, refined through steps of characterization/modeling:7. Rock mass characterization (2009 -->)8. Laboratory experiments on fundamental kinetic dissolution rates, rock physical, hydrological,

and thermal properties. Experiments on fracture closure/pressure solution (2009 -->)9. Refine/finalize experimental design (2010-2011)10. Installation of first phase of heater experiment – Single borehole heater with array of

measurement/collection boreholes. Systematic spatial/temporal measurements (2012-2014)11. Selected monitoring/collection of high fluid flow features rock (2012 -->12. Expansion of heater array, monitoring/collection boreholes. Long-term expts (2014 -->)

Phased Approach


(Phased) ApproachInfrastructure Requirements and Impacts

• Size: Nominally, a 50x40x40 m block relatively isolated from other labs

• Power: On the order of 100 kW for heaters, plus other equipment

• Timescale: Heating for ~10+ years

• Test block could be used for 20+ years (post-test analyses and re-use of the test block for related experiments

• Potential Impacts:– Power usage

– Increased humidity and temperature would require area to be insulated/sealed

– Radon increases (?)

– Water mobilization in the rock, and potentially some seepage locally

– Increased fracturing by heat and fluid pressure (microseismicity)


Risk identification and management

Effectiveness of Experimental Methods

Risk:Various aspects of experimental program won’t work

Management: Baseline exploration data is needed to evaluate the state of stress, pre-existing fractures, rock layering and other factors affecting fracturing and flow. Experimental development program to evaluate, refine, and prove methods prior to deployment/

Excavation

Risk: Infeasible to adequately reveal the fractures by excavation.

Management: Create small fractures in advance of excavation to create physics cavities to develop techniques. Use mine-back efforts at Nevada Test Site as starting point for methods.

Seismicity

Risk: Seismicity causes safety concerns or interferes with physics experiments.

Management: Development program required to evaluate seismic risk. Locate facilities away from sensitive experiments

Liquid Nitrogen

Risk: Nitrogen gas could escape and create a suffocation hazard.

Management: Use closed-loop heat exchanger, monitor mass balance in system, maintain minimal nitrogen reserves on location to limit potential size of release.


Development Needs and S-4 Activities

Development NeedsLaboratory experiments where small faults are created using thermal techniques

Scaling analyses intended to bound the basic operational conditions

Numerical design calculations intended to evaluate geometries

Equipment design and testing to evaluate and refine field implementation

S-4 ActivitiesWorkshops

Planning: Initial planning, idea formulation, task assignment, interaction with design engineer

Review and discuss preliminary draft of proposal. Identify tasks that need to be resolved

Writing meeting to prepare final draft of proposal.

Teleconferences

Initial Design Overview

Design Propagation Experiment

Design Stress Control Experiment

Design Faulting Experiment

Design Fault Scaling Experiment

Design Transport Experiment

Integrate Facility Design


Schedule

S-4 Schedule Months after start

Task 1 2 3 4 5 6 7 8 9Initial Program Design Design Propagation ExperimentDesign Stress Control ExperimentDesign Faulting ExperimentDesign Fault Scaling ExperimentDesign Transport ExperimentIntegrate Facility DesignWorkshops

Overall Schedule 2008 2009 2010 2011 2012 2013 2014 2015 2016

Preliminary designShakedown experimentsFinal designConstructionPropagation experimentStress control experimentFaulting experimentFault scaling experimentTransport experiment

induced deformation and transport

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