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Title: Thermal and capillary effects on the caprock mechanical stability at In Salah, Algeria

Thermo-mechanical effects are important in geologic carbon storage because CO 2 will generally reach the storage formation colder than the rock, inducing thermal stresses. Capillary functions, i.e., retention and relative permeability curves, control the CO 2 plume shape, which may affect overpressure and thus, caprock stability. To analyze these thermal and capillary effects, we numerically solve non-isothermal injection of CO 2 in deformable porous media considering the In Salah, Algeria, CO 2 storage site. Here, we find that changes in the capillary functions have a negligible effect on overpressure and thus, caprock stability is not affected by capillary effects. But, we show that for the strike slip stress regime prevalent at In Salah, stability decreases in the lowest parts of the caprock during injection due to cooling-induced thermal stresses. Simulations show that shear slip along pre-existing fractures may take place in the cooled region, whereas tensile failure is less likely to occur. Indeed, only the injection zone and the lowest tens of meters of the 900-m-thick caprock at In Salah might be affected by cooling effects, which would thus not jeopardize the overall sealing capacity of the caprock. Furthermore, faults are likely to remain stable far away from the injectionmore » well because outside the cooled region the injection-induced stress changes are not sufficient to exceed the anticipated shear strength of minor faults. Nonetheless, we recommend that thermal effects should be considered in the site characterization and injection design of future CO 2 injection sites to assess caprock stability and guarantee a permanent CO 2 storage.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Swiss Federal Inst. of Technology, Lausanne (Switzerland)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Swiss Federal Inst. of Technology, Zurich (Switzerland)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Greenhouse Gases: Science and Technology
Additional Journal Information:
Journal Volume: 5; Journal Issue: 4; Journal ID: ISSN 2152-3878
Publisher:
Society of Chemical Industry, Wiley
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; thermal stresses; induced seismicity; geological carbon storage; geomechanical stability
OSTI Identifier:
1407269
Alternate Identifier(s):
OSTI ID: 1400513