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Presentation_Budapest_EAGE_Sep_2008

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Todd Flach

The document summarizes simulations conducted to analyze the potential for reducing peak reservoir pressures during CO2 storage by utilizing secondary storage formations. The simulations showed that dispersing CO2 into a deep reservoir and overlying shallow aquifer through a migration pathway can help reduce lateral extent of the pressure front compared to injection only into the deep reservoir. Producing and reinjecting saline brine from the deep reservoir into the shallow aquifer further realigned the CO2 plume with little effect on overall dissolution rates over 1000 years.

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Managing over-pressure in deep saline aquifer storage of CO2 Mike Carpenter, Todd Flach, Semere Solomon (DNV) Terje Aurdal (Aker Kværner Geo) EAGE, September 2008 We gratefully acknowledge support for this work from: - NFR CLIMIT - DNV Corporate - Aker Kværner Geo
© Det Norske Veritas AS. All rights reserved ݺߣ 201 December 2008 Fracturing of caprock Capillary entry pressure of caprock exceeded Migration along/across faults Abandoned wells compromised Wide pressure pulse and area of impact Motivation Many potential storage formations will have their capacity constrained by the increase in reservoir pressure caused by injection In addition a number of risk factors will become more likely with higher formation pressures:
© Det Norske Veritas AS. All rights reserved ݺߣ 301 December 2008 Motivation EU Commission, January 2008: “storage complex means the storage site and surrounding geological domains which can have an effect on overall storage integrity and security (i.e., secondary containment formations)” Environment Protection Agency, July 2008: “The confining system should be of sufficient regional thickness and lateral extent to contain the entire CO2 plume and associated pressure front under the confining system following the plume’s maximum lateral expansion” Simulate reduction in peak reservoir pressure by utilising secondary containment formations
© Det Norske Veritas AS. All rights reserved ݺߣ 401 December 2008 Injection well flow rate = 500,000 Sm3/day (for 40yrs = 14.5 Mt total) Choice of model Reservoir Caprock Reservoir Injection point R = 3500 m, h = 10 m Top of model = 750 m depth Kv = 100 mD, Kh = 200 mD Porosity = 0.15 Cell size = 175 x 175 x 10 m
© Det Norske Veritas AS. All rights reserved ݺߣ 501 December 2008 Model permeability Depth 750 m 850 m 900 m 1000 m Reservoir (100 mD) Caprock (0.0005 mD) Reservoir (100 mD) Migration pathway (0.05 mD) Injection point Colour scheme indicates permeability
© Det Norske Veritas AS. All rights reserved ݺߣ 601 December 2008 100yrs 250yrs 500yrs 1000yrs Top of structure @ 750 m depth CO2 molality - injection only Mol/kg
© Det Norske Veritas AS. All rights reserved ݺߣ 701 December 2008 CO2 molality - with brine production 100yrs 250yrs 500yrs 1000yrs Top of structure @ 750 m depth Mol/kg
© Det Norske Veritas AS. All rights reserved ݺߣ 801 December 2008 Top of structure @ 750 m depth CO2 molality - with brine re-injection 250yrs 500yrs 1000yrs 100yrs Mol/kg
© Det Norske Veritas AS. All rights reserved ݺߣ 901 December 2008 Pressure(kPa) Initial pressure Pressure vs. time - single cell at top of deep aquifer Deep + shallow aquifers - and re-injection - with brine production Time (yr)
© Det Norske Veritas AS. All rights reserved ݺߣ 1001 December 2008 Global CO2 dissolution rates Deep + shallow aquifers - with brine production - and re-injection Pressure effects from brine production and re-injection re-align the CO2 plume, but little net change in dissolution Supercritical CO2 Dissolved CO2
© Det Norske Veritas AS. All rights reserved ݺߣ 1101 December 2008 What happens to produced brine? Will depend on salinity and chemical composition Offshore - released into the sea Onshore - re-circulation to shallower formations may be an option - source of potable water if de-salination possible - potential source of coolant to powerstations in water stressed areas - low salinity brackish waters suitable for some agriculture purposes (Dwarf glasswort grows well at 70 g/l of dissolved solids, and may be useful as a crop. Plants such as barley and the date palm can tolerate about 5 g/l)
© Det Norske Veritas AS. All rights reserved ݺߣ 1201 December 2008 Conclusions CO2 storage performance is a geosphere issue and can benefit from using more than just one aquifer and caprock Proposed EU legislation permits definition of a “storage complex” with more than one storage formation Dispersion of the pressure pulse in more than one storage formation will limit the lateral extent of the pressure front and decrease risk exposure
© Det Norske Veritas AS. All rights reserved ݺߣ 1301 December 2008 Questions?
© Det Norske Veritas AS. All rights reserved ݺߣ 1401 December 2008 Grid cell permeability in the caprock is reduced in order to simulate a generalised CO2 migration pathway (leaky well, fault zone) General migration pathway 1 m wide pathway @ 10mD 175m 10m Caprock (0.0005 mD) 1m Caprock (0.0005 mD) Cell size = 175 x 175 x 10 m Fracture size = 1x 175 x 10 m Simple averaging gives: ((0.0005*174)+(10*1))/175 = 0.06 mD Rounded down to 0.05 mD in model CO2
© Det Norske Veritas AS. All rights reserved ݺߣ 1501 December 2008 Sensitivity tests for grid cell size CO2 molality after 500 yrs 300x300x60 m 200x200x20 m 100x100x5m 300x300x15 m Plot global rate of disolution to see effects of numerical dispersion…
© Det Norske Veritas AS. All rights reserved ݺߣ 1601 December 2008 Medium (i,j = 200m) Fine (i,j = 100m) Coarse (i,j = 300m) h/v ratio = 20:1 h/v ratio = 10:1 h/v ratio = 5:1 Sensitivity tests for grid cell size 1200 x 1200 x 300m (0.432km3) Top of model depth = 900 m Kv = 100mD, Kh = 200 mD, Porosity = 0.15 Injection rate = 12,500 m3/day for 40yrs (0.36Mt total) Inventory plot for global SC CO2 vs. time (yrs) 200 x 200 x 10 m Reduced to 175 x 175 x 10 m In model

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Presentation_Budapest_EAGE_Sep_2008

  • 1. Managing over-pressure in deep saline aquifer storage of CO2 Mike Carpenter, Todd Flach, Semere Solomon (DNV) Terje Aurdal (Aker Kværner Geo) EAGE, September 2008 We gratefully acknowledge support for this work from: - NFR CLIMIT - DNV Corporate - Aker Kværner Geo
  • 2. © Det Norske Veritas AS. All rights reserved ݺߣ 201 December 2008 Fracturing of caprock Capillary entry pressure of caprock exceeded Migration along/across faults Abandoned wells compromised Wide pressure pulse and area of impact Motivation Many potential storage formations will have their capacity constrained by the increase in reservoir pressure caused by injection In addition a number of risk factors will become more likely with higher formation pressures:
  • 3. © Det Norske Veritas AS. All rights reserved ݺߣ 301 December 2008 Motivation EU Commission, January 2008: “storage complex means the storage site and surrounding geological domains which can have an effect on overall storage integrity and security (i.e., secondary containment formations)” Environment Protection Agency, July 2008: “The confining system should be of sufficient regional thickness and lateral extent to contain the entire CO2 plume and associated pressure front under the confining system following the plume’s maximum lateral expansion” Simulate reduction in peak reservoir pressure by utilising secondary containment formations
  • 4. © Det Norske Veritas AS. All rights reserved ݺߣ 401 December 2008 Injection well flow rate = 500,000 Sm3/day (for 40yrs = 14.5 Mt total) Choice of model Reservoir Caprock Reservoir Injection point R = 3500 m, h = 10 m Top of model = 750 m depth Kv = 100 mD, Kh = 200 mD Porosity = 0.15 Cell size = 175 x 175 x 10 m
  • 5. © Det Norske Veritas AS. All rights reserved ݺߣ 501 December 2008 Model permeability Depth 750 m 850 m 900 m 1000 m Reservoir (100 mD) Caprock (0.0005 mD) Reservoir (100 mD) Migration pathway (0.05 mD) Injection point Colour scheme indicates permeability
  • 6. © Det Norske Veritas AS. All rights reserved ݺߣ 601 December 2008 100yrs 250yrs 500yrs 1000yrs Top of structure @ 750 m depth CO2 molality - injection only Mol/kg
  • 7. © Det Norske Veritas AS. All rights reserved ݺߣ 701 December 2008 CO2 molality - with brine production 100yrs 250yrs 500yrs 1000yrs Top of structure @ 750 m depth Mol/kg
  • 8. © Det Norske Veritas AS. All rights reserved ݺߣ 801 December 2008 Top of structure @ 750 m depth CO2 molality - with brine re-injection 250yrs 500yrs 1000yrs 100yrs Mol/kg
  • 9. © Det Norske Veritas AS. All rights reserved ݺߣ 901 December 2008 Pressure(kPa) Initial pressure Pressure vs. time - single cell at top of deep aquifer Deep + shallow aquifers - and re-injection - with brine production Time (yr)
  • 10. © Det Norske Veritas AS. All rights reserved ݺߣ 1001 December 2008 Global CO2 dissolution rates Deep + shallow aquifers - with brine production - and re-injection Pressure effects from brine production and re-injection re-align the CO2 plume, but little net change in dissolution Supercritical CO2 Dissolved CO2
  • 11. © Det Norske Veritas AS. All rights reserved ݺߣ 1101 December 2008 What happens to produced brine? Will depend on salinity and chemical composition Offshore - released into the sea Onshore - re-circulation to shallower formations may be an option - source of potable water if de-salination possible - potential source of coolant to powerstations in water stressed areas - low salinity brackish waters suitable for some agriculture purposes (Dwarf glasswort grows well at 70 g/l of dissolved solids, and may be useful as a crop. Plants such as barley and the date palm can tolerate about 5 g/l)
  • 12. © Det Norske Veritas AS. All rights reserved ݺߣ 1201 December 2008 Conclusions CO2 storage performance is a geosphere issue and can benefit from using more than just one aquifer and caprock Proposed EU legislation permits definition of a “storage complex” with more than one storage formation Dispersion of the pressure pulse in more than one storage formation will limit the lateral extent of the pressure front and decrease risk exposure
  • 13. © Det Norske Veritas AS. All rights reserved ݺߣ 1301 December 2008 Questions?
  • 14. © Det Norske Veritas AS. All rights reserved ݺߣ 1401 December 2008 Grid cell permeability in the caprock is reduced in order to simulate a generalised CO2 migration pathway (leaky well, fault zone) General migration pathway 1 m wide pathway @ 10mD 175m 10m Caprock (0.0005 mD) 1m Caprock (0.0005 mD) Cell size = 175 x 175 x 10 m Fracture size = 1x 175 x 10 m Simple averaging gives: ((0.0005*174)+(10*1))/175 = 0.06 mD Rounded down to 0.05 mD in model CO2
  • 15. © Det Norske Veritas AS. All rights reserved ݺߣ 1501 December 2008 Sensitivity tests for grid cell size CO2 molality after 500 yrs 300x300x60 m 200x200x20 m 100x100x5m 300x300x15 m Plot global rate of disolution to see effects of numerical dispersion…
  • 16. © Det Norske Veritas AS. All rights reserved ݺߣ 1601 December 2008 Medium (i,j = 200m) Fine (i,j = 100m) Coarse (i,j = 300m) h/v ratio = 20:1 h/v ratio = 10:1 h/v ratio = 5:1 Sensitivity tests for grid cell size 1200 x 1200 x 300m (0.432km3) Top of model depth = 900 m Kv = 100mD, Kh = 200 mD, Porosity = 0.15 Injection rate = 12,500 m3/day for 40yrs (0.36Mt total) Inventory plot for global SC CO2 vs. time (yrs) 200 x 200 x 10 m Reduced to 175 x 175 x 10 m In model