Modified cement composition, preparation and application thereof

Abstract

Light to ultra-light cement compositions with modified rheological properties. The cement composition includes cement, hydrophobic nano-silica, at least one additive and a sufficient amount of water to make a cement slurry with high compressive strength, low porosity, low free water, and low fluid loss with a quick thickening time.

What is claimed is: 
     
         1 . A method of making a modified cement composition comprising:
 (a) mixing cement with hydrophobic nano-silica particles; and   (b) adding at least one additive to the mixture in step (a);   wherein (i) if the at least one additive is a plurality of microspheres, the plurality of microspheres are first added directly to the cement and the hydrophobic nano-silica particles, and then water is added to the mixture of the cement, the hydrophobic nano-silica particles, and the plurality of microspheres and (ii) if the at least one additive is not a plurality of microspheres, then the additive is first add to water to make a water-additive mixture and then the water-additive mixture is mixed with the mixture in step (a).   
     
     
         2 . The method of  claim 1 , wherein the hydrophobic nano-silica includes a surface area of from about 110 m 2 /g to about 260 m 2 /g. 
     
     
         3 . The method of  claim 1 , wherein the hydrophobic nano-silica includes a surface area of from about 240 m 2 /g to about 260 m 2 /g. 
     
     
         4 . The method of  claim 1 , wherein water is present in an amount of from about 30% by weight of blend cement to about 170% by weight of blend cement. 
     
     
         5 . The method of  claim 1 , wherein water is present in an amount of from about 30% by weight of blend cement to about 80% by weight of blend cement. 
     
     
         6 . The method of  claim 1 , wherein the hydrophobic nano-silica includes a particle size of from about 1 nm to about 100 nm. 
     
     
         7 . The method of  claim 1 , wherein the hydrophobic nano-silica includes a particle size of from about 1 nm to about 60 nm. 
     
     
         8 . The method of  claim 1 , wherein the hydrophobic nano-silica includes a particle size of from about 1 nm to about 6 nm. 
     
     
         9 . The method of  claim 1 , wherein the hydrophobic nano-silica is present in an amount of from about 1% BWOC to about 15% BWOC. 
     
     
         10 . The method of  claim 1 , wherein the hydrophobic nano-silica is present in an amount of from about 1% BWOC to about 9% BWOC. 
     
     
         11 . The method of  claim 1 , wherein the at least one additive comprises at least one of a light weight additive, an anti-foaming agent, a retardant, an accelerator, a dispersant, a fluid loss controlling agent, a surfactant, and a gas migration controlling agent. 
     
     
         12 . The method of  claim 11 , wherein the gas migration controlling agent comprises at least one of (i) a composition including at least about 90% SiO 2 , from about 0.5% to about 2.0% Al 2 O 3 , from about 0.2% to about 1.5% Fe 2 O 3 , from about 0.1% to about 0.5% CaO, from about 0.1% to about 1.5% Na 2 O, from about 0.5% to about 2.0% K 2 O, from about 0.5% to about 2.0% MgO, from about 0.1% to about 0.4% SO 3 , and from about 0.5% to about 2.5% C and (ii) a composition including at least latex particles. 
     
     
         13 . The method of  claim 1 , wherein the cement, hydrophobic nano-silica, and the at least one additive include a particle size to maximize a packing volume fraction. 
     
     
         14 . The method of  claim 1 , wherein the cement includes a particle size of from about 10 μm to about 50 μm and the at least one additive includes a particle size of from about 51 μm to about 370 μm. 
     
     
         15 . The method of  claim 1 , wherein the additive is present in an amount of from about 0.1% BWOC to about 150% BWOC. 
     
     
         16 . The method of  claim 1 , wherein the cement, the hydrophobic nano-silica, the at least one additive and water are mixed in a ratio to make a cement slurry having a 24-hour compressive strength of about 4450 psi. 
     
     
         17 . The method of  claim 16 , wherein water is added in an amount of about 127% or less by weight of blend cement. 
     
     
         18 . The method of  claim 1 , wherein the cement includes a particle size of from about 10 μm to about 50 μm, the hydrophobic nano-silica includes a surface area of from about 110 m 2 /g to about 260 m 2 /g, the at least one additive includes a particle size of from about 51 μm to about 370 μm, and water is in an amount sufficient to make a cement slurry. 
     
     
         19 . A method of making a modified cement composition comprising:
 (a) mixing cement, hydrophobic nano-silica particles, and microspheres; and   (b) adding sufficient water to create a modified cement composition.   
     
     
         20 . A method for making a well structure resistant to damaging and corrosive fluids and securement of a well casing to a well borehole wall comprising:
 mixing cement, hydrophobic nano-silica particles, at least one additive, and a sufficient amount of water to make a cement slurry; and   applying the cement slurry to at least a portion of the well structure.