title: Degradation of well cement by CO2 under geologic sequestration conditions.
abstract: Experiments were conducted to assess the durability of cements in wells penetrating candidate formations for geologic sequestration of CO2. These experiments showed a significant variation in the initial degradation (9 days of exposure) based on the curing conditions. The high-temperature (50 degrees C) and high-pressure (30.3 MPa) curing environment increased the degree of hydration and caused a change in the microstructure and distribution of the Ca(OH)2(s) phase within the cement. Cement cured at 50 degrees C and 30.3 MPa (representing sequestration conditions) proved to be more resistant to carbonic acid attack than cement cured at 22 degrees C and 0.1 MPa. The cement cured at 50 degrees C and 30.3 MPa exhibited a shallower depth of degradation and displayed a well-defined carbonated zone as compared to cement cured under ambient conditions. This is likely due to smaller, more evenly distributed Ca(OH)2(s) crystals that provide a uniform and effective barrier to CO2 attack.
authors: United States Department of Energy, National Energy Technology Laboratory, Pittsburgh, Pennsylvania 15236, USA.
authors: Barbara G
authors: BG
authors: Kutchko
authors: Brian R
authors: BR
authors: Strazisar
authors: David A
authors: DA
authors: Dzombak
authors: Gregory V
authors: GV
authors: Lowry
authors: Niels
authors: N
authors: Thaulow
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D055593:Geological Phenomena; D005844:Geology; D008855:Microscopy, Electron, Scanning
chemical_list: D002245:Carbon Dioxide