Methods, Systems, and Compositions for the Controlled Crosslinking of Well Servicing Fluids

Abstract

Treating fluid compositions for use in hydrocarbon recovery operations from subterranean formations are described, as well as methods for their preparation and use. In particular, treating fluid compositions are described which comprise a liquid, a crosslinkable organic polymer material that is at least partially soluble in the liquid, a crosslinking agent that is capable of increasing the viscosity of the treating fluid by crosslinking the organic polymer material in the liquid, and a crosslinking modifier additive which can delay or accelerate the crosslinking of the treating fluid composition. Such compositions may be used in a variety of hydrocarbon recovery operations including fracturing operations, drilling operations, gravel packing operations, water control operations, and the like.

What is claimed is: 
     
         1 . A composition for controllably crosslinking, aqueous crosslinkable organic polymer solutions, the composition comprising:
 a crosslinkable viscosifying organic polymer;   a sparingly-soluble borate crosslinking agent; and   a crosslink modifier composition capable of controlling the rate at which the crosslinking agent promotes the gelation of the crosslinkable organic polymer   wherein the crosslink modifier is a salt, an alkaline or acidic chemical, or a combination thereof.   
     
     
         2 . The composition of  claim 1 , wherein the crosslinkable viscosifying organic polymer is a polysaccharide. 
     
     
         3 . The composition of  claim 2 , wherein the polysaccharide is guar, cellulose, starch, galactomannan gum, xanthan, succinoglycan or scleroglucan or a derivative thereof. 
     
     
         4 . The composition of  claim 3 , wherein the polysaccharide is selected from the group consisting of guar, hydroxypropyl guar (HPG), carboxymethylhydroxypropyl guar (CMHPG), methyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxybutyl cellulose, hydroxyethylmethyl cellulose, hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, methylhydroxyethyl cellulose, methylhydroxypropyl cellulose, ethylhydroxyethyl cellulose, carboxyethylcellulose, carboxymethylcellulose or carboxymethylhydroxyethyl cellulose (CMHC). 
     
     
         5 . The composition of  claim 1  wherein the sparingly-soluble borate is an alkaline earth metal borate, an alkali metal-alkaline earth metal borate, or an alkali metal borate containing at least two boron atoms per molecule. 
     
     
         6 . The composition of  claim 5  wherein the sparingly-soluble borate is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof. 
     
     
         7 . The composition of  claim 1 , wherein the concentration of sparingly-soluble borate is in the range from about from about 0.1 kg/m 3  to about 5 kg/m 3 . 
     
     
         8 . The composition of  claim 7 , wherein the concentration of sparingly-soluble borate is in the range from about 0.25 kg/m 3  to about 2.5 kg/m 3 . 
     
     
         9 . The composition of  claim 1 , wherein the crosslink modifier is a compound of lithium, sodium, potassium, and/or cesium in a +1 valence state, or a mixture thereof. 
     
     
         10 . The composition of  claim 9 , wherein the crosslink modifier in a +1 valence state is a salt, an acidic agent, or basic agent. 
     
     
         11 . The composition of  claim 1 , wherein the crosslink modifier is a compound of calcium and/or magnesium in a +2 valence state, or a mixture thereof. 
     
     
         12 . The composition of  claim 11 , wherein the crosslink modifier in a +2 valence state is a salt, an acidic agent, or basic agent. 
     
     
         13 . The composition of  claim 1 , wherein the crosslink modifier is selected from the group consisting of KCO 2 H, KC 2 H 3 O 2 , CH 3 CO 2 H, HCO 2 H, KCO 2 H, NaCO 2 H, NaC 2 H 3 O 2 , NaCO 2 H, and combinations thereof. 
     
     
         14 . The aqueous suspension of  claim 1 , wherein the crosslink modifier is a freeze point depressant. 
     
     
         15 . The aqueous suspension of  claim 1 , further comprising a suspension agent in an amount ranging from about 1 pound per 42 gallon barrel to about 10 pounds per 42 gallon barrel. 
     
     
         16 . The aqueous suspension of  claim 15 , wherein the suspension agent is a palygorskite clay selected from the group consisting of attapulgite, sepiolite, and mixtures thereof. 
     
     
         17 . The composition of  claim 1 , wherein the fluid further contains an additive selected from the group consisting of buffers, permeability modifiers, fluid loss additives, biocides and corrosion inhibitors. 
     
     
         18 . A fracturing fluid composition, comprising:
 an aqueous liquid;   a crosslinkable viscosifying organic polymer;   a sparingly-soluble borate crosslinking agent; and   a crosslinking modifier composition,   wherein the crosslink modifier is capable of controlling the rate at which the boron-containing crosslinking composition promotes the gellation of the organic polymer at pH values greater than about 7.   
     
     
         19 . The fracturing fluid composition of  claim 18 , further comprising a proppant. 
     
     
         20 . A system for controllably crosslinking aqueous crosslinkable organic polymer solutions in a well treating fluid, the system comprising:
 a crosslinkable viscosifying organic polymer;   a sparingly-soluble borate crosslinking agent; and   a crosslink modifier agent having a +1 or +2 valence state and being capable of controlling the rate at which the crosslinking agent promotes the gelation of the crosslinkable organic polymer,   wherein the crosslink modifier is a salt, an acidic agent, or basic agent.   
     
     
         21 . A method of treating a subterranean formation, the method comprising:
 generating a treating fluid comprising a blend of an aqueous fluid and a a crosslinkable viscosifying organic polymer that is at least partially soluble in the aqueous fluid;   hydrating the treating fluid;   generating a borate crosslinking composition comprising a sparingly-soluble borate crosslinking agent and a crosslink modifier;   adding the borate crosslinking composition to the hydrated treating fluid so as to crosslinking the treating fluid in a controlled manner; and   delivering the treating fluid into a subterranean formation.   
     
     
         22 . The method of  claim 21 , wherein the sparingly-soluble borate crosslinking agent is an alkaline earth metal borate, an alkali metal-alkaline earth metal borate, or an alkali metal borate containing at least 2 boron atoms per molecule. 
     
     
         23 . The method of  claim 22  wherein the sparingly-soluble borate is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof. 
     
     
         24 . The method of  claim 21 , wherein the crosslink modifier is a compound of lithium, sodium, potassium, and/or cesium in a +1 valence state, or a mixture thereof. 
     
     
         25 . The method of  claim 24 , wherein the crosslink modifier in a +1 valence state is a salt, an acidic agent, or basic agent. 
     
     
         26 . The method of  claim 21 , wherein the crosslink modifier is a compound of calcium and/or magnesium in a +2 valence state, or a mixture thereof. 
     
     
         27 . The method of  claim 26 , wherein the crosslink modifier in a +2 valence state is a salt, an acidic agent, or basic agent. 
     
     
         28 . The method of  claim 21 , wherein the crosslink modifier is selected from the group consisting of KCO 2 H, KC 2 H 3 O 2 , CH 3 CO 2 H, HCO 2 H, KCO 2 H, NaCO 2 H, NaC 2 H 3 O 2 , NaCO 2 H, and combinations thereof. 
     
     
         29 . The method of  claim 21 , further comprising delivering an inorganic or organic peroxide breaker into the subterranean formation. 
     
     
         30 . The method of  claim 29 , wherein the inorganic or organic peroxide breaker is slightly soluble in water.