Enhanced carbon sequestration via foam cementing

A hardened foamed cement comprising from about 40 to 60 vol % of supercritical CO2 per m3, wherein the hardened foamed cement is produced by:

• entraining carbon dioxide (CO2) in a cement slurry composition and subjecting the cement slurry composition to conditions under which the entrained CO2 achieves and maintains a supercritical state;
• introducing the cement slurry composition comprising the entrained CO2 in the supercritical state downhole at a wellsite;
• and
• allowing the cement slurry composition to harden to form the hardened foamed cement having the entrained CO2 sequestered in the supercritical state therein,
• wherein the cement slurry composition in which the CO2 is entrained comprises a cementitious material and water, and wherein the cementitious material consists of a Portland cement, a pozzolana cement, a gypsum cement, an alumina based cement, or a combination thereof.