Cement compositions containing flexible, compressible beads and methods of cementing in subterranean formations

Abstract

Cement compositions comprising flexible, compressible beads, processes for preparing such cement compositions, and methods of cementing in subterranean formations using such cement compositions. One or more flexible, compressible beads are mixed with the cement before pumping the cement into a well bore. The flexible, compressible beads are preferably composed of an elastomeric material such as a copolymer of methylmethacrylate and acrylonitrile; a terpolymer of methylmethacrylate, acrylonitrile, and dichloroethane; a styrene-divinylbenzene copolymer; and polystyrene. The flexible, compressible beads may be heated to expand the beads before mixing with the cement such that the ensuing cement composition will have a desired density. Non-flexible beads such as spherulites may also be added to the cement compositions.

1 . A cement composition comprising: 
 hydraulic cement; and    one or more flexible beads.    
     
     
         2 . The composition of  claim 1  wherein the beads are capable of expanding up to about 8 times their original diameters.  
     
     
         3 . The composition of  claim 1  wherein the beads are capable of expanding up to about 40 times or greater their original volumes.  
     
     
         4 . The composition of  claim 1  wherein the beads are capable of contracting.  
     
     
         5 . The composition of  claim 1  wherein the beads comprise an elastomeric material selected from the group consisting of a copolymer of methylmethacrylate and acrylonitrile; a terpolymer of methylmethacrylate, acrylonitrile, and dichloroethane; a styrene-divinylbenzene copolymer; phenolic resins; and polystyrene.  
     
     
         6 . The composition of  claim 1  wherein the beads are hollow.  
     
     
         7 . The composition of  claim 6  wherein the beads contain a liquid.  
     
     
         8 . The composition of  claim 6  wherein the beads contain a gas.  
     
     
         9 . The composition of  claim 8  wherein the gas is selected from the group consisting of air, carbon dioxide, nitrogen, n-butane, isobutane, pentane, and combinations thereof.  
     
     
         10 . The composition of  claim 1  wherein the beads have a diameter ranging from about 6 to about 150 micrometers at a temperature of 25° C. and at atmospheric pressure.  
     
     
         11 . The composition of  claim 1  wherein the beads are introduced to the cement composition in an amount in the range of from about 1% to about 200% by weight of cement therein.  
     
     
         12 . The composition of  claim 1  wherein the beads are introduced to the cement composition in an amount in the range of from about 2% to about 100% by weight of cement therein.  
     
     
         13 . The composition of  claim 1  wherein the beads are introduced to the cement composition in an amount in the range of from about 5% to about 50% by weight of cement therein.  
     
     
         14 . The composition of  claim 1  wherein the cement composition further comprises at least one of water, non-flexible beads, a surfactant, silica fume, bentonite, a fluid loss agent, a retarding agent, sodium chloride, and a defoamer.  
     
     
         15 . The composition of  claim 1  further comprising a surfactant or mixture of surfactants having an hydrophile-lipophile balance (HLP) of from about 7 to about 20.  
     
     
         16 . The composition of  claim 1  wherein the cement composition further comprises at least one of ceramic spheres, glass spheres, and cenospheres.  
     
     
         17 . The composition of  claim 1  further comprising water in an amount sufficient to form a pumpable slurry.  
     
     
         18 . The composition of  claim 17  wherein the slurry has a density of from about 6 to about 23 lb/gal.  
     
     
         19 . The composition of  claim 18  wherein the slurry comprises expanded hollow beads that contract upon curing of the slurry.  
     
     
         20 . The composition of  claim 19  wherein the density of the cured slurry is greater than the density of the uncured slurry.