Sealant Composition

Abstract

A sealant composition for use in subterranean wells comprising an alkali metal silicate and a calcium containing inorganic compound wherein the particles of the calcium containing compound have a mean particle size that is submicron.

1 . A sealant composition for use in subterranean wells comprising an alkali metal silicate and an inorganic calcium-containing-compound having particles with a mean particle size less than 1 micrometer. 
   
   
       2 . The sealant composition according to  claim 1 , wherein the solubility of the calcium containing compound in water is less than 2 g/L at 20° C. 
   
   
       3 . The sealant composition according to  claim 1 , wherein the calcium containing compound is calcium carbonate. 
   
   
       4 - 17 . (canceled) 
   
   
       18 . The sealant composition according to  claim 3 , wherein the particles have a hydrophobic coating. 
   
   
       19 . The sealant according to  claim 1 , wherein the calcium-containing-compound is calcium hydroxide. 
   
   
       20 . The sealant composition according to  claim 1 , wherein the alkali metal silicate is sodium metasilicate. 
   
   
       21 . The sealant composition according to  claim 1 , wherein the mean particle size of the particles is less than 500 nm. 
   
   
       22 . The sealant composition according to  claim 1 , wherein the mean particle size of the particles is between 200 and 350 nm. 
   
   
       23 . The sealant composition according to  claim 1 , wherein the mean particle size of the particles is less than 100 nm. 
   
   
       24 . The sealant composition according to  claim 1 , wherein the composition further comprises a surfactant. 
   
   
       25 . The sealant composition according to  claim 1 , wherein the composition further comprises an antifoam agent. 
   
   
       26 . A method of sealing voids in a subterranean well, comprising:
 (i) preparing a sealant composition comprising an alkali metal silicate and an inorganic calcium-containing-compound having particles with a mean particle size less than 1 micrometer;   (ii) injecting the sealant composition into a void; and   (iii) allowing the sealant composition to set.   
   
   
       27 . The method according to  claim 26 , wherein the sealant composition is mixed at the surface and pumped from the surface down a wellbore before injection into the void. 
   
   
       28 . The method according to  claim 26 , wherein:
 (i) the alkali metal silicate compound and the calcium-containing-compound are pumped separately down the wellbore; and   (ii) the alkali metal silicate and calcium containing compound mix together downhole and form the sealant composition before injection into the void.   
   
   
       29 . The method according to  claim 26 , wherein the subterranean well is in a low-temperature environment. 
   
   
       30 . The method according to  claim 26 , wherein the sealant composition further comprises a surfactant. 
   
   
       31 . The method according to  claim 26 , wherein the sealant composition further comprises an antifoam agent. 
   
   
       32 . A method of sealing voids in a subterranean well, comprising:
 (i) preparing a sealant composition comprising an alkali metal silicate and an inorganic calcium-containing-compound having particles with a mean particle size less than 1 micrometer, the particles having a hydrophobic coating;   (ii) injecting the sealant composition into a void; and   (iii) allowing the sealant composition to set.   
   
   
       33 . The method according to  claim 32 , wherein the alkali metal silicate is sodium metasilicate. 
   
   
       34 . The method according to  claim 32 , wherein the solubility of the calcium-containing-compound in water is less than 2 g/L at 20° C.