Methods and thermally stable aqueous borate-based cross-linking suspensions for treatment of subterranean formations
An aqueous cross-linking suspension composition having brine, water-soluble suspending agent and borate cross-linker in a single package and methods for using the package composition for increasing the efficiency of fracturing subterranean formations and effectively delivering borate cross-linkers.
1. A method for fracturing a subterranean formation having a downhole temperature ranging from about 65° F. to about 350° F. with a fracturing fluid containing a gellant comprising the steps of:
a) preparing an aqueous cross-linking suspension composition of 20-70 weight percent sodium thiosulfate, 0.1-5 weight percent boric acid, 0.1-5 weight percent of water soluble suspending agent and 20-70 weight percent ulexite;
b) treating a fracturing fluid containing said gellant with said aqueous cross-linking suspension composition to form a treated gellant-containing fracturing fluid, thereby enhancing thermal stability of said fracturing fluid containing gellant; and then
c) contacting the treated gellant-containing fracturing fluid and at least a portion of said subterranean formation at pressures sufficient to form fractures in said formation,
wherein said water-soluble suspending agent is a cellulose ether selected from the group consisting of: carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, methyl hydroxyethyl cellulose, hydroxypropyl cellulose and combinations thereof.
2. The method of claim 1 wherein said gellant is guar.
3. A method for efficiently delivering borate-based cross-linkers for fracturing a subterranean formation having a downhole temperature ranging from about 65° F. to about 350° F. with a fracturing fluid containing a gellant comprising the steps of:
a) preparing an aqueous cross-linking suspension package comprising 20-70 weight percent sodium thiosulfate, 0.1-5 weight percent boric acid, 0.1-5 weight percent of water-soluble suspending agent and 20-70 weight percent ulexite;
b) treating a fracturing fluid containing said gellant with said aqueous cross-linking suspension package to form a treated gellant-containing fracturing fluid; and then
c) contacting the treated gellant-containing fracturing fluid and at least a portion of said subterranean formation at pressures sufficient to form fractures in said formation,
wherein said water-soluble suspending agent is a cellulose ether selected from the group consisting of: carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, methyl hydroxyethyl cellulose, hydroxypropyl cellulose and combinations thereof.
4. The method of claim 3 wherein said gellant is guar.
5. A method for fracturing a subterranean formation having a downhole temperature ranging from about 65° F. to about 350° F. with a fracturing fluid containing a gellant comprising the steps of:
a) preparing an aqueous cross-linking suspension composition of 20-70 weight percent sodium thiosulfate, 0.1-5 weight percent boric acid, 0.1-5 weight percent of water soluble suspending agent and 20-70 weight percent ulexite;
b) treating a fracturing fluid containing said gellant with said aqueous cross-linking suspension composition to form a treated gellant-containing fracturing fluid, thereby enhancing thermal stability of said fracturing fluid containing gellant; and then
c) contacting the treated gellant-containing fracturing fluid and at least a portion of said subterranean formation at pressures sufficient to form fractures in said formation,
wherein said water-soluble suspending agent is polyvinyl alcohol.
6. The method of claim 5 wherein said gellant is guar.