A method of cementing an annular space between a pipe string and a well bore, the method comprising the steps of (a) providing a cement composition including a calcium-deficient calcium silicate; (b) mixing the cement composition with water to form a cement slurry; (c) mixing the cement slurry composition with carbon dioxide form a foamed cement; and (d) placing the foamed cement in the annular space between the pipe string and the wellbore.

A method of cementing a geothermal wellbore includes pumping a first volume of cement slurry down a wellbore. The first volume of cement slurry has a first water to cement ratio. A second volume of cement slurry is pumped down the wellbore. The second volume of cement slurry has a second water to cement ratio that is less than the first water to cement ratio. The first volume of cement slurry hardens at a vertical portion of the wellbore, and the second volume of cement slurry hardens at a horizontal portion of the wellbore.

Apparatus, systems, and methods for preparing foam cement compositions in a laboratory are disclosed. The apparatus includes a blender body, a base connector, an inlet port, a test port, an outlet port, a blender blade apparatus, and a blender cap. Systems to prepare foam cement compositions in a laboratory, include the apparatus, a first tubing assembly threaded to the inlet port configured to receive a pressurized gas and provide the pressurized gas to the apparatus, a second tubing assembly threaded to the test port, and a motorized base. Methods for preparing a foam cement composition using the apparatus for preparing foam cement compositions in a laboratory include adding a cement composition to the apparatus, fitting a blender cap on the apparatus, mixing the cement composition, and providing a pressurized gas and surfactant to the cement composition to produce a foam cement composition.

Apparatus, systems, and methods for preparing foam cement compositions in a laboratory are disclosed. The apparatus includes a blender body, a base connector, an inlet port, a test port, an outlet port, a blender blade apparatus, and a blender cap. Systems to prepare foam cement compositions in a laboratory, include the apparatus, a first tubing assembly threaded to the inlet port configured to receive a pressurized gas and provide the pressurized gas to the apparatus, a second tubing assembly threaded to the test port, and a motorized base. Methods for preparing a foam cement composition using the apparatus for preparing foam cement compositions in a laboratory include adding a cement composition to the apparatus, fitting a blender cap on the apparatus, mixing the cement composition, and providing a pressurized gas and surfactant to the cement composition to produce a foam cement composition.

The present application belongs to the technical field of civil and architectural engineering materials, and in particular relates to an environmental and low-carbon foamed lightweight soil prepared by using CO.sub.2 and MgO as raw materials. Raw material compositions of the carbon sequestration foamed lightweight soil include, in parts by weight, 10 to 200 parts of MgO, 10 to 100 parts of a filler, 2 to 45 parts of a CO.sub.2 bubble cluster and 20 to 400 parts of water. The present application is made in view of the problems of large carbon emission and serious energy consumption caused by a cement solidification agent used in traditional foamed lightweight soil.

A method of cementing a geothermal wellbore includes pumping a first volume of cement slurry down a wellbore. The first volume of cement slurry has a first water to cement ratio. A second volume of cement slurry is pumped down the wellbore. The second volume of cement slurry has a second water to cement ratio that is less than the first water to cement ratio. The first volume of cement slurry hardens at a vertical portion of the wellbore, and the second volume of cement slurry hardens at a horizontal portion of the wellbore.

A method including entraining carbon dioxide (CO.sub.2) in a cement slurry composition and subjecting the cement slurry composition to conditions under which the CO.sub.2 achieves and maintains a supercritical state; and allowing the cement slurry composition to harden to form a hardened cement having CO.sub.2 sequestered therein.