Aqueous storable cement spacer system

Abstract

A storable cement system comprises a suspending agent, a cement spacer and water. The composition may further optional contain a surfactant and/or an organic solvent and/or a weighting material. The suspending agent is preferably a carrageenan or scleroglucan. The cement system may be stored for an extended period of time prior to being interposed between a cement slurry and a drilling fluid. As such, the aqueous cement system may be made off-site and used when desired for preventing contact between non-compatible hydrocarbonaceous and aqueous fluids.

1 . An aqueous storable cement spacer system comprising: 
 a cement spacer;    a suspending agent selected from a carrageenan or scleroglucan; and    an aqueous fluid.    
   
   
       2 . The aqueous storable cement spacer system of  claim 1 , wherein the suspending agent is iota carrageenan.  
   
   
       3 . The aqueous storable cement spacer system of  claim 2 , wherein the iota carrageenan has a molecular weight of between about 150,000 and about 250,000.  
   
   
       4 . The aqueous storable cement spacer system of  claim 1 , wherein the cement spacer comprises at least one member selected from the group consisting of, xanthan gum, attapulgite, bentonite, sodium montmorillionite, hydroxyethyl cellulose, guar gum and derivatives thereof.  
   
   
       5 . The aqueous storable cement spacer system of  claim 1 , wherein the cement spacer comprises a polysaccharide.  
   
   
       6 . The aqueous storable cement spacer system of  claim 1 , wherein the cement spacer comprises welan gum.  
   
   
       7 . The aqueous storable cement spacer system of  claim 10 , wherein the surfactant comprises an ethoxylated alcohol.  
   
   
       8 . The aqueous storable cement spacer system of  claim 1 , further comprising a weighting agent.  
   
   
       9 . The aqueous storable cement spacer system of  claim 8 , wherein the weighting agent is selected from the group consisting of barite, calcium carbonate, hematite, sand, illmanite, trimanganese tetraoxide, iron oxide, and fly ash.  
   
   
       10 . The aqueous storable cement spacer system of  claim 1 , further comprising a dispersant or surfactant.  
   
   
       11 .- 29 . (canceled)  
   
   
       30 . The aqueous storable cement spacer system of  claim 10 , wherein the surfactant is anionic or non-ionic.  
   
   
       31 . The aqueous storable cement spacer system of  claim 1 , wherein the amount of suspending agent in the cement spacer system is between from about 0.05 to about 1 weight percent of the fluid base of the cement spacer system.  
   
   
       32 . The aqueous storable cement spacer system of  claim 31 , wherein the amount of suspending agent in the cement spacer system is between from about 0.05 to about 0.5 weight percent of the fluid base of the cement spacer system.  
   
   
       33 . The aqueous storable cement spacer system of  claim 32 , wherein the amount of suspending agent in the cement spacer system is between from about 0.05 to about 1 weight percent of the fluid base of the cement spacer system.  
   
   
       34 . The aqueous storable cement spacer system of  claim 33 , wherein the amount of suspending agent in the cement spacer system is about 0.3 weight percent of the fluid base of the cement spacer system.  
   
   
       35 . The aqueous storable cement spacer system of  claim 1 , wherein the cement system is prepared by (i.) mixing the fresh water and suspending agent for a time sufficient to hydrate the suspending agent; (ii.) introducing the cement spacer to the mixture containing the hydrated suspending agent; and (iii.) stirring for a time sufficient to render a homogeneous cement system.  
   
   
       36 . The aqueous storable cement spacer system of  claim 1  which has a viscosity of 20-200 cps at 25° C.  
   
   
       37 . The aqueous storable cement spacer system of  claim 1 , wherein the iota carrageenan has a molecular weight of between about 150,000 and about 250,000.  
   
   
       38 . An aqueous storable cement spacer system comprising: 
 a cement spacer;    a hydrated suspending agent selected from a carrageenan or scleroglucan; and    an aqueous fluid base or mix water.    
   
   
       39 . The aqueous storable cement spacer system of  claim 1 , wherein the cement spacer is selected from the group consisting of polybasic inorganic phosphate salts, mixed metal hydroxides, clays, polyanionic cellulose derivatives, carboxyalkylcellulose derivatives, nonylphenol ethoxylated with ethylene oxide, polyacrylamide and derivatives thereof.