HYDROFRAME : Hydromechanical and Biogeochemical Processes in Fractured Rock Masses in the Vicinity of a Geological

Disposal Facility for Radioactive Waste

PI: Robert W. Zimmerman Imperial College London

Overview of Project

The project will consist of six complementary work packages, which are linked to each other in most cases through shared data and overlapping supervision of PhD students.

Overall, the project addresses two scientific areas that were prioritised in the RATE call:

Technological innovation for rock mass characterisation at a range of spatial scales,

Biogeochemical coupling, including deep multiphase transport processes,

along with Capacity Building

The project will involve three UK universities (Imperial College, University of Birmingham, University of Leeds), as well as collaborators from several academic and research institutions in the US and Europe.

Participating Institutions

Lead Institution: Imperial College London

Co-Investigating institutions: University of Birmingham University of Leeds

Partner Institutions/Organisations: MCM International NAGRA (Swiss Nuclear Waste Management Organisation) Natural History Museum Stanford University Lawrence Berkeley National Laboratory

Investigators and Collaborators

Principal Investigator: Prof. Robert Zimmerman (ICL)

Work-Package Leaders: Dr Doug Angus (Leeds) Dr Alan Herbert (Birmingham) Dr Mark Hildyard (Leeds) Dr John-Paul Latham (ICL) Dr Dominik Weiss (ICL) Prof. Robert Zimmerman (ICL)

Other investigators: Prof. Martin Blunt (ICL) Prof. John Cosgrove (ICL) Prof. Chris Pain (ICL) Prof. Graham Stuart (Leeds)

Collaborators: Prof. Kate Maher (Stanford) Dr Chin-Fu Tsang (LBNL) Dr Javier Cuadros (NHM) Prof. Alan Hooper (AH Consulting)

Work Package 1: Hydraulic transmissivity of geologically realistic fracture networks

Predicted (x-axis) vs. numerical (y-axis) transmissivities (m2) of 2D fracture networks; from C.T.O. Leung and R.W. Zimmerman, “Estimating the hydraulic conductivity of two-dimensional fracture networks”, Transport in Porous Media, 2012.

Methodology developed in EPSRC/NDA Case studentship (2009-2102) will be extended to apply to geologically realistic, three-dimensional networks. Above: fracture pavement, Bristol Channel coast; from J.W. Cosgrove, “Structural geology understanding of rock fractures for improved rock mechanics characterization”, Proc. Int. Cong. Rock Mech., Lisbon, 2009.

Work Package 2: Integrated seismic and thermo-hydro-mechanics for time-lapse monitoring of repository sites Specific objectives: •  Explore suitable seismic monitoring

strategies •  Assess monitoring techniques key

for observing deformation and stress changes

•  Develop calibration methodology to link models with observation

•  Develop data processing methodologies •  Enhance measurement of induced

seismic anisotropy •  Quantify stress evolution and

deformation

Expected outcomes: •  Develop integrated seismic and

geomechanical workflow for nuclear repository applications

•  Advance 4D and microseismic monitoring strategies for risk reduction

AECL URL underground access tunnel

Geomechanical stress predictions

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vp (km/s)

4.3

4.32

4.34

4.36

4.38

4.4

4.42

4.44

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vs (km/s)

2.4

2.42

2.44

2.46

2.48

2.5

2.52

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vp (km/s)

4.3

4.32

4.34

4.36

4.38

4.4

4.42

4.44

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vs (km/s)

2.4

2.42

2.44

2.46

2.48

2.5

2.52

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vp (km/s)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

7.06 7.08 7.1 7.12 7.14 7.16 7.18x 105

6.048

6.05

6.052

6.054

6.056

6.058

6.06

6.062

6.064

6.066

6.068x 106 vs (km/s)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Vp

Vs

Start DifferenceFinish

Time-lapse velocity predictions

Observed induced microseismicity

Microseismic predictions

Angus (1998)

Angus et al. (2010)

Specific objectives:

•  Use models of discrete fracture networks to explore seismic attributes diagnostic of fracture properties

•  Use fracture models to design acquisition strategies that enhance observations of fracture systems

Expected outcomes: •  New understanding that isolates responses of

specific fracture properties

•  New understanding for decoupling fracture properties from measurable seismic attributes

•  Acquisition strategies optimised for nuclear repository applications

•  Quantified performance of inversions through application to known fracture sets

Influence of stress on waves through fractures

Work Package 3: Seismic forward modelling of fracture response to inform survey design for repositories

Work Package 4: Hydro-thermo-mechanical and fracturing processes in fractured rocks around a repository

•  Develop a highly accuracy discrete fracture and matrix flow model that incorporates mesh refinement within realistic 3D fracture networks, and includes fracture-matrix coupling

•  At the <1 m scale, apply 3D modelling to study fracture tip behaviour and fracture coalescence

•  At the 1-10 m scale, apply 3D fracture modelling and alternative network creation methods to generate fully 3D fracture and matrix models to study geomechanically driven 3D flow behaviour

•  Develop thermal modelling so that the effects of radioactive decay heating, in both near-field and far-field of the repository, can be determined

Work Package 5: Modelling of transport in fractures from tests performed at Grimsel

http://www.grimsel.com/gts-phase-v/crr/crr-introduction

Need to develop an understanding of radionuclide migration processes Flow geometry

•  non-Fickian dispersive processes Fracture modification

•  mechanical coupling •  chemical alteration

Matrix diffusion Sorption and chemical processes Colloid migration (and biological coupling)

•  fast migration paths •  filtration and flow restriction •  kinetics

Work Package 6: Do microbes and natural organic matter lead to increased actinide mobility in fractured rocks?

Key deliverables •  Detailed quantitative and qualitative understanding of sorption processes and extent of retention and effect of organic matter •  Tested reactive transport model adjusted for potential nuclear sites in the UK

Adsorption and redox state are key parameters controlling mobility of actinides in fractured rocks. Both of these parameters are strongly affected by the presence of microbes and natural organic matter