Treatment fluids viscosifield with modified xanthan and associated methods for well completion and stimulation

Abstract

The present invention relates to viscosified treatment fluids used in well completion and stimulation operations for oil and gas production, and more particularly, to viscosified treatment fluids comprising xanthan gelling agents. In one embodiment, the present invention provides a method of treating a portion of a subterranean formation comprising the steps of: providing a viscosified treatment fluid that comprises water and a gelling agent that comprises a modified xanthan; and treating the portion of the subterranean formation. The present invention also provides methods of fracturing, gravel packing, acidizing with the viscosified treatments fluids. Also provided are viscosified treatment fluid compositions and gelling agent compositions.

1 . A method of treating a portion of a subterranean formation comprising the steps of: providing a viscosified treatment fluid that comprises water, a gelling agent that comprises a modified xanthan and a crosslinker to crosslink the modified xanthan; and treating the portion of the subterranean formation. 
     
     
         2 . The method of  claim 1 , wherein at least a portion of the xanthan is nonacetylated. 
     
     
         3 . The method of  claim 1 , wherein at least a portion of the xanthan is depyruvylated. 
     
     
         4 . The method of  claim 1 , wherein at least a portion of the xanthan is nonacetylated and depyruvylated. 
     
     
         5 . The method of  claim 1 , wherein the liquid portion of the viscosified treatment fluid has a density of about 8.3 pounds per gallon to about 19.3 pounds per gallon. 
     
     
         6 . The method of  claim 1 , wherein the portion of the subterranean formation has a temperature of from about 30° F. to about 400° F. 
     
     
         7 . The method of  claim 1 , wherein the gelling agent is included in the viscosified treatment fluid is an amount from about 5 lbs to about 200 lbs per 1000 gallons of the liquid viscosified treatment fluid. 
     
     
         8 . The method of  claim 1 , wherein the water contains calcium bromide brine, zinc bromide brine, calcium chloride brine, sodium chloride brine, sodium bromide brine, potassium bromide brine, potassium chloride brine, sodium nitrate brine, potassium formate brine, sodium formate, cesium formate, mixtures thereof or a mixture thereof. 
     
     
         9 . The method of  claim 1 , wherein the viscosified treatment fluid further comprises a salt, a pH control additive, a surfactant, a breaker, a bactericide, a crosslinker, a fluid loss control agent, a stabilizer, a chelant, a scale inhibitor, gases, mutual solvents, fibers, proppant, corrosion inhibitors, acids, bases, oxidizers, reducers, or a combination thereof. 
     
     
         10 . The method of  claim 1 , wherein the viscosified treatment fluid further comprises tackifying agent or resin. 
     
     
         11 . The method of  claim 1 , further comprising a salt selected from the group consisting of: calcium bromide, zinc bromide, calcium chloride, sodium chloride, sodium bromide, potassium bromide, potassium chloride, sodium nitrate, potassium formate, or any mixture thereof in any proportion. 
     
     
         12 . The method of  claim 1 , further comprising a pH control additive selected from the group consisting of: a base, a chelating agent, an acid, a combination of a base and a chelating agent, or a combination of an acid and a chelating agent. 
     
     
         13 . The method of  claim 1 , wherein the crosslinker is selected from the group consisting of:
 a peroxy compound, a ferric iron derivative, or a magnesium derivative.   
     
     
         14 . The method of  claim 1 , further comprising a breaker, wherein the breaker is selected from the group consisting of:
 an acid,   an acid generating material, a peroxide, an oxidizing agent, or an enzyme.   
     
     
         15 . The method of  claim 14 , wherein the breaker is encapsulated and comprises a coating. 
     
     
         16 . The method of  claim 15 , wherein the coating comprises a degradable material. 
     
     
         17 . The method of  claim 16 , wherein the degradable material is selected from the group consisting of:
 a polysaccharide, a chitin, a chitosan, a protein, an aliphatic poly(ester), a poly(lactide), a poly(glycolide), a poly(.epsilon.-caprolactone), a poly(hydroxybutyrate), a poly(anhydride), an aliphatic polycarbonate, an orthoester, a poly(orthoester), a poly(amino acid), a poly(ethylene oxide), a poly(phosphazene), a derivative thereof, or any combination thereof in any proportion.   
     
     
         18 . The method of  claim 6 , further comprising a fluid loss control agent included in an amount of from about 5 lbs to about 50 lbs per 1000 gals of the viscosified treatment fluid. 
     
     
         19 . The method of  claim 18 , wherein the fluid loss control agent comprises silica flour, a starch, diesel, or a degradable material. 
     
     
         20 . The method of  claim 1 , wherein the viscosified treatment fluid further comprises a breaker and an activator or a retarder. 
     
     
         21 . A method of placing a gravel pack in a portion of a subterranean formation comprising:
 providing a viscosified gravel pack fluid that comprises gravel, a brine, a gelling agent that comprises a modified xanthan, and a crosslinker to crosslink the modified xanthan; and   contacting the portion of the subterranean formation with the viscosified gravel pack fluid so as to place a gravel pack in or near a portion of the subterranean formation.   
     
     
         22 - 24 . (canceled) 
     
     
         25 . A method of treating a portion of a subterranean formation comprising the steps of:
 providing a viscosified treatment fluid that comprises water,   a gelling agent that comprises a modified xanthan, and a fluid loss control agent included in an amount of from about 5 lbs to about 50 lbs per 1000 gals of the viscosified treatment fluid; and   treating the portion of the subterranean formation, wherein the portion of the subterranean formation has a temperature of from about 30° F. to about 400° F.   
     
     
         26 . The method of  claim 25 , wherein the fluid loss control agent comprises silica flour, a starch, diesel, or a degradable material.