Cement compositions containing degradable materials and methods of cementing in subterranean formations

Abstract

The present invention provides cement compositions that include degradable materials, and methods of using such compositions in subterranean cementing operations. An example of a method of the present invention includes: providing a cement composition that includes a hydraulic cement, and a degradable material; placing the cement composition in a subterranean formation; allowing the cement composition to set therein; and allowing the degradable material to degrade. Another example of a method of the present invention is a method of enhancing the mechanical properties of a cement composition including adding a degradable material to the cement composition and allowing the degradable material to degrade.

1 . A cement composition comprising a hydraulic cement, water sufficient to form a pumpable slurry, and a degradable material, wherein the degradable material is selected from the group consisting of aliphatic polyesters, poly(lactides), poly(glycolides), poly(ε-caprolactones), poly(hydroxybutyrates), poly(anhydrides), aliphatic polycarbonate, ortho esters, poly(orthoesters), poly(vinylacetates), polyamides, proteins, polyaminoacids, nylons, poly(caprolactams), polylactic acid, cellulose acetate, and combinations thereof.  
   
   
       2 . The cement composition of  claim 1  wherein the hydraulic cement is selected from the group consisting of Portland cements, pozzolanic cements, gypsum cements, high alumina content cements, phosphate cements, silica cements, and high alkalinity cements.  
   
   
       3 . The cement composition of  claim 1  wherein the degradable material comprises a material that degrades at a desired time after contact with the cement composition.  
   
   
       4 . The cement composition of  claim 1  wherein the degradable material comprises a material that prevents fluid loss into the subterranean formation.  
   
   
       5 . The cement composition of  claim 1  wherein the degradable material, upon degradation, forms at least one gas, salt or combination thereof.  
   
   
       6 . The cement composition of  claim 1  wherein the cement composition further comprises an additive selected from the group consisting of fluid loss control additives, defoamers, dispersing agents, set accelerators, salts, formation conditioning agents, weighting agents, set retarders, ceramic beads, glass beads, elastomers, and combinations thereof.  
   
   
       7 . The cement composition of  claim 1  wherein the degradable material comprises particles in the form of a thin film, a flake, a substantially spherical particle, a bead, a fiber, or a combination thereof.  
   
   
       8 . The cement composition of  claim 1  wherein the degradable material is present in the cement composition in an amount sufficient to leave voids in the set cement that enhance the mechanical properties of the set cement.  
   
   
       9 . The cement composition of  claim 1  wherein the degradable material is present in the cement composition in an amount in the range of from about 1% to about 25% by weight of cement.  
   
   
       10 . The cement composition of  claim 1  wherein the cement composition further comprises a polymer emulsion, wherein the polymer emulsion is present in the cement composition in an amount in the range of from about 5% to about 100% by weight of an amount of water in the cement composition.  
   
   
       11 . The cement composition of  claim 10  wherein the polymer emulsion comprises a polar monomer selected from the group consisting of vinylamine, vinyl acetate, acrylonitrile, and the acid, ester, amide, and salt forms of acrylates, and at least one elasticity-enhancing monomer selected from the group consisting of ethylene, propylene, butadiene, 1,3-hexadiene, and isoprene.  
   
   
       12 . The cement composition of  claim 11  wherein the polar monomer is present in the polymer emulsion in an amount in the range of from about 1% to about 90% by weight of the polymer emulsion.  
   
   
       13 . The cement composition of  claim 11  wherein the at least one elasticity-enhancing monomer is present in the polymer emulsion in an amount in the range of from about 10% to about 99% by weight of the polymer emulsion.  
   
   
       14 . The cement composition of  claim 11  wherein the polymer emulsion further comprises a stiffness-enhancing monomer.  
   
   
       15 . The cement composition of  claim 14  wherein the stiffness-enhancing monomer is selected from the group consisting of styrene, t-butylstyrene, α-methylstyrene, and sulfonated styrene, and is present in the polymer emulsion in an amount in the range of from about 0.01% to about 70% by weight of the polymer emulsion.  
   
   
       16 . The cement composition of  claim 10  wherein the polymer emulsion is an aqueous styrene butadiene latex.  
   
   
       17 . The cement composition of  claim 10  wherein the cement composition further comprises a surfactant, wherein the surfactant is present in the cement composition in an amount in the range of from about 10% to about 20% by weight of the polymer emulsion.  
   
   
       18 . The cement composition of  claim 1  wherein the cement composition comprises a gas, wherein the gas is present in the cement composition in an amount sufficient to provide a gas concentration in the range of from about 0.5% to about 30% by volume of the cement composition, measured when the cement composition has been placed in a subterranean formation.  
   
   
       19 . The cement composition of  claim 1  wherein the cement composition comprises a gas-generating additive selected from the group consisting of an aluminum powder and azodicarbonamide, wherein the gas generating additive is present in the cement composition in an amount in the range of about 0.1% to about 5% by weight of the cement.  
   
   
       20 . The cement composition of  claim 1  wherein the cement is a Portland cement; wherein the degradable material is polylactic acid, wherein the polylactic acid is present in the cement composition in an amount in the range of about 1% to about 25% by weight of the cement; and wherein the water is present in the cement composition in an amount in the range of from about 25% to about 150% by weight of the cement.