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Title: Long-term thermal effects on injectivity evolution during CO 2 storage

Carbon dioxide (CO 2 ) is likely to reach the bottom of injection wells at a colder temperature than that of the storage formation, causing cooling of the rock. This cooling, together with overpressure, tends to open up fractures, which may enhance injectivity. Here, we investigate cooling effects on injectivity enhancement by modeling the In Salah CO 2 storage site and a theoretical, long-term injection case. We use stress-dependent permeability functions that predict an increase in permeability as the effective stress acting normal to fractures decreases. Normal effective stress can decrease either due to overpressure or cooling. We calibrate our In Salah model, which includes a fracture zone perpendicular to the well, obtaining a good fitting with the injection pressure measured at KB-502 and the rapid CO 2 breakthrough that occurred at the observation well KB-5 located 2 km away from the injection well. CO 2 preferentially advances through the fracture zone, which becomes two orders of magnitude more permeable than the rest of the reservoir. Nevertheless, the effect of cooling on the long-term injectivity enhancement is limited in pressure dominated storage sites, like at In Salah, because most of the permeability enhancement is due to overpressure. But, thermal effectsmore » enhance injectivity in cooling dominated storage sites, which may decrease the injection pressure by 20%, saving a significant amount of compression energy all over the duration of storage projects. Overall, our simulation results show that cooling has the potential to enhance injectivity in fractured reservoirs.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth and Environmental Sciences Area; Spanish National Research Council (CSIC), Barcelona (Spain). Inst. of Environmental Assessment and Water Research; Associated Unit Hydrogeology Group (UPC-CSIC), Barcelona (Spain)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth and Environmental Sciences Area; Swiss Federal Inst. of Technology, Zurich (Switzerland). Swiss Seismological Service
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth and Environmental Sciences Area
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
International Journal of Greenhouse Gas Control
Additional Journal Information:
Journal Volume: 64; Journal Issue: C; Journal ID: ISSN 1750-5836
Publisher:
Elsevier
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:
58 GEOSCIENCES; cooling; fracture aperture; permeability increase; thermo-hydro-mechanical coupling
OSTI Identifier:
1379923