T. Lynch 1,2 , Q.J. Fisher 2 , D. Angus 2 , P. Lorinczi 2

1. Coupled Geomechanical-Fluid Flow Modelling for Carbon Capture and Storage CO2 Injection Scenarios T. Lynch1,2, Q.J. Fisher2, D. Angus2, P. Lorinczi2 1 Low Carbon Technologies Doctoral Training Centre, University of Leeds 2 Centre for Integrated Petroleum Engineering and Geoscience, University of Leeds

2. Overview Summary Background – PhD Project and research group Context of research – Aims of research and wider research goals Modelling approach – Coupled geomechanical-fluid flow modelling Modelling capabilities – Current and future capabilities Current work – “Two fault” generic model Current work – Full field modelling

3. Background PhD Project and Research group Doctoral Training Centre in Low Carbon Technologies – Wide ranging centre for low carbon energy technologies - collaboration between Engineering and Earth Sciences Mainly work with CiPEG – Quentin Fisher and Doug Angus Interdisciplinary PhD – Geological Storage of CO2 in the UK: Risks and Opportunities – mainly technical but also focuses on risk and risk based regulation

4. Context of research Aims of research and wider research goals • Developed ‘risk register’ of storage risks - as part of lit. review similar to work of others e.g. Quintessa database • Used to identify risks where further research beneficial • Numerical approach applied to: • Stress path hysteresis • Temperature effects in reservoirs

5. Coupled Modelling Approach How do we model flow and geomechanics? Industry standard – fluid flow model – pressure & saturation

6. Coupled Modelling Approach How do we model flow and geomechanics? Surface No account of interaction with rock above reservoir

7. Coupled Modelling Approach How do we model flow and geomechanics? Stresses in material in and around reservoir affect flow

8. Modelling Capabilities Couple methodology TEMPEST - Initial grid - Initial porosity - Pressures • Modified pore volume ELFENRS ELFEN Couple industry standard software – improve solution

9. Coupled Modelling Approach Coupled modelling TEMPEST Universities of Leeds and Bristol and Rockfield Software Ltd. developed coupled methodology ELFEN (geomechanics) – Tempest (flow) - Initial grid - Initial porosity - Pressures • Modified pore volume ELFENRS ELFEN

10. Modelling Capabilities Current capabilities and future developments • SR3 – calibrate with triaxial – large strains, wide range initial stress • Geometry - complex • Uplift and surface deformation • Seismics and Microseismics TEMPEST - Initial grid - Initial porosity - Pressures • Modified pore volume ELFENRS ELFEN • Future: • Temperature – through manual pass through from Tempest, hope to automate

11. Coupled Modelling Approach Fluid flow modelling Tempest black oil flow simulation – simplification - cut down run times Using experimentally derived relative permeabilities – available for fault and host rock Restart runs allow multiple phases – depletion/injection Message passing interface – allows efficient coupling w/out write files

12. Current work Generic “Two fault” model • 3km and 2km depth versions • Sandstone reservoir, shale over/sideburden • Fault transmissiblity – sealing and non-sealing • Fault movement also controlled with friction parameter

13. Current work Stress path hysteresis • Stress path hysteresis • Reduction of fracture pressure on injection • Santarelli, Tronvoll et al 1998 and Santarelli, Havmoller et al 2008 • Need to investigate more parameters • Investigate realistic scenarios • Use realistic well/lab data • Investigate in realistic field

14. Mohr Circles and Stress Stress path hysteresis a) Classic textbook pore pressure response

15. Mohr Circles and Stress Stress path hysteresis b)/c) Reservoir scale pore pressure/stress coupling

16. Mohr Circles and Stress Stress path hysteresis d) Stress path hysteresis e.g Field data from: Santarelli, Tronvoll et al 1998 and Santarelli, Havmoller et al 2008

17. Current work Stress path hysteresis • Stress path hysteresis • Reduction of fracture pressure on injection • Santarelli, Tronvoll et al 1998 and Santarelli, Havmoller et al 2008 • Need to investigate more parameters • Investigate realistic scenarios • Use realistic well/lab data • Investigate in realistic field

18. Current work Generic “Two fault” model - Results • Run several cases exploring: • Uncoupled/coupled • Different injection scenarios • Different fault properties • Temperature • Working with DA exploring: • Implemented seismic code to produce synthetic seismic from models

19. Current Work Full field model • Obtained full field dataset of offshore oil field • History match data • North Sea abandoned field - potential target for EOR/CO2 storage • Currently: • Building geomechanical model – FE mesh • In order to: • Use workflow from two fault model • Investigate stress path hysteresis incl. temp effects

20. Current Work Full field model • Progress • Constructed horizons for over/side/underburden • Initial work on deriving parameters for geomechanical model • Remaining • Build realistic representation of faults in model – preserve geometry + create watertight intersections • Intersecting mesh with good equilateralarity

21. Current Work Full field model Fault offset - Discontinuity

22. Current Work Full field model Intersection of fault/horizon – must be node sharing + watertight

23. Current Work Full field model To mesh in goCAD must also remove ‘free extremities’

24. Current Work Full field model To mesh in goCAD must also remove ‘free extremities’

25. Current Work Full field model

26. Summary • Developing complex models to investigate CO2 injection scenarios • Potential for investigating multiple aspects of a problem • Including geomechanics, seismics, microseismics • Developing capability to assess some risks that have received little attention in literature so far • Have field data for a specific site in the UK • Ongoing development of workflow to produce realistic field geometries with incorporation of faults – still a difficult and time consuming process

27. Thank You