|Publisher||American Rock Mechanics Association||Language||English|
|Content Type||Conference Paper|
|Title||A Study of Injection-Induced Mechanical Deformation At the In Salah CO2 Storage Project|
|Authors||J.P.Morris, Now at Schlumberger Doll Research Center, One Hampshire St, Cambridge; Y.Hao, W.Foxall, W.McNab, Lawrence Livermore National Laboratory, Livermore|
|Source||44th U.S. Rock Mechanics Symposium and 5th U.S.-Canada Rock Mechanics Symposium, June 27 - 30, 2010 , Salt Lake City, Utah|
|Copyright||2010. American Rock Mechanics Association|
Large-scale carbon capture and storage projects involve injecting CO2 into a porous, permeable formation that is overlain by an impermeable “caprock”. The In Salah Project (a joint venture of BP, Statoil and Sonatrach) includes a CO2 sequestration effort that has successfully injected millions of tons of CO2 into a deep saline formation close to a producing gas field in Algeria. We have performed detailed simulations of the hydromechanical response in the vicinity of the KB-502 CO2 injector specifically because the morphology of the observed surface deformation differed from that above the other injectors at the field. Associated with the injection, we have simulated the mm-scale uplift of the overburden and compared the results with observed deformation using InSAR data. Our results indicate that the best fit is obtained through a combination of reservoir and fault pressurization (rather than either alone). However, our analysis had to make assumptions regarding the mechanical properties of the faults and the overburden. These results demonstrate that InSAR provides a powerful tool for gaining insight into fluid fate in the subsurface, but also highlight the need for detailed, accurate static geomodels.
In order for geological carbon sequestration to achieve substantial reductions of greenhouse gas emissions, many large injection projects will be required. Each project is likely to require multiple wells, each injecting millions of tons of CO2 over many years. For storage in saline formations, this is likely to create a large and increasing pressure anomaly that will grow over the duration of the injection project. The In Salah Project (a joint venture of BP, Statoil and Sonatrach) includes a CO2 sequestration effort that has successfully injected millions of tons of CO2 into a deep saline formation close to a producing gas field in Algeria [1, 2]. Since 2004, CO2 has been separated from extracted natural gas at the Krechba gas field at In Salah, Algeria, and reinjected along the limbs of the trapping anticline as a supercritical fluid. Three injectoion wells have been used, targeting depths on the order of 1.8 km. We have been jointly funded by the Joint Industry Project (A consortium consisting of BP, Statoil and Sonatrach, hereafter referred to as the JIP) and the U.S. Department of Energy to investigate the role of injection-induced mechanical deformation and geochemical alteration at the In Salah CO2 storage project. In this paper we will focus upon the hydromechanical portion of this study. Surface deformation has been observed associated with the injection at the Krechba field at In Salah via interferometric synthetic-aperture radar (InSAR). In addition, CO2 breakthrough has been observed at a suspended appraisal well (see Ringrose et al.  for details). More recently, Rutqvuist et al.  used a sequentially coupled hydromechanical simulation to model injection into the Krechba reservoir using a model that consisted of homogeneous layers of rock with and without a vertically oriented fault zone and was able to match the magnitude, of surface displacement observed above the KB-501 CO2 injector.
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