High temperature lightweight foamed cements
AssigneeAssociated Universities, Inc.
InventorToshifumi Sugama
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Abstract
Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed.
Claims4
A lightweight foamed cement slurry composition having, when exposed to temperatures up to 350.degree. C., a slurry density of between 1.1 g/cc and 2.0 g/cc and, upon curing, a compressive strength of greater than 1,000 psi which consists essentially of:
- (a) a cementitious matrix comprising a cement and silica flour wherein the cement to silica flour ratio is approximately 1.0;
- (b) a retarder to retard the setting of the cement;
- (c) a foam generator comprising a foaming agent and a foam stabilizer wherein the addition of said foam generator to said cementitious matrix results in a foamed cement containing a uniform distribution of fine foam bubbles in the size range of from approximately 5 .mu.m to 20 .mu.m;
- (d) a reinforcement material;
- and
- (e) water.
A cement slurry composition consisting essentially of
- (a) a cementitious matrix comprising Portland cement and silica flour in which the amount of the Portland cement used is 20 to 40% by weight of the total cement slurry, the amount of the silica flour used is 20 to 40% by weight of the total cement slurry, and the Portland cement to silica flour ratio is approximately 1.0;
- (b) water, wherein the amount of water used is 20 to 60% by weight of the total cement slurry;
- (c) sodium tetraborate decahydrate, wherein the amount of the sodium tetraboratedecahydrate used is about 1 to 5% by weight of the Portland cement component of the cementitious matrix;
- (d) sodium alpha olefin sulfate, wherein the amount of the sodium alpha olefin sulfate used is about 0.1 to 0.5% by weight of the water component of the slurry;
- (e) coconut diethanolamide, wherein the amount of the coconut diethanolamide used is about 0.02 to 0.11% by weight of the water component of the slurry;
- and
- (f) graphite fiber, wherein the amount of the graphite fiber used is about 0.1 to 0.5% by weight of the total weight of the Portland cement and silica flour and water components of the cement slurry.
Dependencies are inferred from the claim text.