Advances in Geological CO{sub 2} Sequestration and Co-Sequestration with O{sub 2}

• Main Authors: Verba, Circe A, O'Connor, William K., Ideker, J.H.
• Language: unknown
• Published: 2016
• Subjects: 54 ENVIRONMENTAL SCIENCES; Psi; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/1061298; https://www.osti.gov/biblio/1061298

The injection of CO{sub 2} for Enhanced Oil Recovery (EOR) and sequestration in brine-bearing formations for long term storage has been in practice or under investigation in many locations globally. This study focused on the assessment of cement wellbore seal integrity in CO{sub 2}- and CO{sub 2}-O{sub 2}-saturated brine and supercritical CO{sub 2} environments. Brine chemistries (NaCl, MgCl{sub 2}, CaCl{sub 2}) at various saline concentrations were investigated at a pressure of 28.9 MPa (4200 psi) at both 50{degree}C and 85{degree}C. These parameters were selected to simulate downhole conditions at several potential CO{sub 2} injection sites in the United States. Class H portland cement is not thermodynamically stable under these conditions and the formation of carbonic acid degrades the cement. Dissociation occurs and leaches cations, forming a CaCO{sub 3} buffered zone, amorphous silica, and other secondary minerals. Increased temperature affected the structure of C-S-H and the hydration of the cement leading to higher degradation rates.