High thermal coefficient grout compositions and methods therefor

A method of producing a high thermal conductivity grout for placement in a wellbore, wherein a casing is located in the wellbore such that an annular space is formed therebetween, the method comprising:

• preparing or providing a pumpable slurry comprising a high-thermal conductivity grout composition in admixture with a quantity of water;
• wherein the high thermal conductivity grout composition comprises cementitious material, a retarder, and a high-thermal k material;
• pumping the pumpable slurry to a target location within the wellbore having a geostatic target temperature of at least 300° F.;
• allowing the pumpable slurry to harden in the annular space to thereby form the high-thermal conductivity grout in the wellbore, wherein the high-thermal conductivity grout is in thermal exchange with the casing and a formation surrounding the wellbore;
• wherein the time to set for the pumpable slurry is at least two hours at a formation temperature of at least 300° F.;
• and
• wherein the high-thermal conductivity grout has, upon hardening, a thermal conductivity of at least 1 W/mK.