Abstract: Alkaline earth metal or transition metal peroxides are used as a delayed breaker in alkaline aqueous fluids containing a water soluble hydrophilic polysaccharide polymer hydrated therein. The peroxide is activated by increasing the temperature of the fluid. The invention is particularly useful for the delayed break of hydraulic fracturing fluids containing hydroxypropyl guar polymer.

Abstract: Disclosed is a process of minimizing damage of the formation surrounding perforation channels in a subterranean formation during workover and completion operations when the need exists to temporarily seal the perforation channels and subsequently clean them before packing the channels with gravel. The process comprises filling the perforation channels with a water soluble particulate sized salt to form a highly permeable salt pack therein, sealing the salt pack with a low permeability film by treatment with a low fluid loss treating fluid having an aqueous phase in which the water soluble particulate sized salt is substantially insoluble, and thereafter, when desired, removing the low permeability film from the surface of the salt pack and dissolving the salt pack in an aqueous fluid in which the water soluble particulate sized salt is soluble before placing gravel within the perforation channels or before placing the well on production.

Abstract: Nondamaging treating fluids containing sparingly soluble hydrated borate bridging agents having a particle size distribution within the range about 1 micron to about 2000 microns are disclosed. The treating fluids comprise an aqueous salt solution having a density from about 1.0 g/cm.sup.3 to about 1.20 g/cm.sup.3, the hydrated borate bridging agent in an amount sufficient to bridge and seal off a subterranean formation contacted by the treating fluid, and a viscosifier and suspension additive in an amount to provide sufficient viscosity to maintain the bridging agent in suspension. A fluid loss control additive may be added to enhance the fluid loss control and formation sealing capacity of the treating fluid.Well treatments may be practiced by pumping or discharging the fluid or a slug or pill of the fluid into an oil, gas, water, injection or storage well where operations are to be conducted in which it is desired to temporarily plug the permeable zone while such operations are carried out.

Abstract: Disclosed are hydraulic fracturing fluids of enhanced temperature stability containing boron crosslinked galactomannan polymers and methods of producing same. The temperature stability of fracturing fluids containing galactomannan polymers is increased by adding to the fracturing fluid a sparingly soluble borate having a slow solubility rate as defined herein. The sparingly soluble borate provides a pH in the range from about 8 to about 10, provides a source of boron for solublizing at elevated temperature thus enhancing the crosslinking of the galactomannan polymer, and it also decreases the leak-off properties of the fracturing fluid.