High temperature, low residue well treating fluids and methods

An improved high temperature, low residue viscous well treating fluid comprising:

• water;
• hydrated carboxymethylhydroxypropylguar present in said treating fluid in an amount of about 0.24% to about 0.30% by weight of water in said treating fluid;
• a retarded cross-linking composition for buffering said treating fluid and cross-linking said hydrated carboxymethylhydroxypropylguar comprised of an aqueous liquid solvent comprising a mixture of water, triethanolamine, a polyhydroxyl compound and isopropyl alcohol, a titanium triethanolamine chelate and a borate ion containing compound, said retarded cross-linking composition being present in said treating fluid in an amount in the range of from about 0.1% to about 0.2% by weight of water in said treating fluid;
• and
• a delayed gel breaker for causing said viscous treating fluid to revert to a thin fluid comprised of a mixture of sodium chlorite and a copper ion producing compound present in said treating fluid in an amount in the range of from about 0.025% to about 1.2% by weight of water in said treating fluid.

An improved method of treating a subterranean zone penetrated by a well bore comprising the steps of:

• (a) preparing a viscous, low residue well treating fluid comprised of water, a hydrated galactomannan gelling agent, a retarded cross-linking composition comprised of a liquid solvent comprising a mixture of water, triethanolamine, a polyhydroxyl compound and isopropyl alcohol, an organotitanate chelate, a borate ion producing compound, and a delayed gel breaker;
• (b) pumping said well treating fluid into said zone by way of said well bore at a rate and pressure sufficient to treat said zone during which said hydrated gelling agent in said treating fluid is cross-linked by said retarded cross-linking composition;
• and
• (c) allowing said viscous treating fluid to break into a thin fluid.