Abstract: The invention provides alkaline water base well drilling and servicing fluids which deposit an easily degradable and removable filter cake on the sides of a borehole during well drilling and servicing operations. The fluids contain one or more polysaccharide polymers, sized bridging particles, and a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof. The fluids deposit a filter cake containing the peroxide.

Abstract: The invention provides alkaline water base well drilling and servicing fluids which deposit an easily degradable and removable filter cake on the sides of a borehole during well drilling and servicing operations. The fluids contain one or more polysaccharide polymers, sized bridging particles, and a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof. The fluids deposit a filter cake containing the peroxide. The invention also provides processes for enhancing the removal of the filter cake which comprises depositing a peroxide-containing filter cake on the sides of the borehole, or on the filter cake already present on the sides of the borehole, and thereafter contacting the peroxide-containing filter cake with an acidic solution to activate the peroxide which thereafter degrades the polysaccharide polymers in the filter cake.

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: The invention provides a process for the removal of filter cakes containing one or more polysaccharide polymers and bridging particles from the sides of a borehole in a hydrocarbon-producing formation which comprises contacting the filter cake with a novel soak solution comprising an aqueous liquid, a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof, and an acidic substance to provide the soak solution with a pH in the range from about 1 to about 8, and optionally, an activator for the peroxide, for a period of time at least sufficient to decompose the polysaccharide polymers therein to such an extent that the filter cake forms a loosely adherent mass on the sides of the borehole, and thereafter contacting the filter cake with a wash solution in which the bridging particles are soluble to remove the remaining filter cake solids from the sides of the borehole.

Abstract: Disclosed are well working and treating fluids comprising a saturated aqueous saline solution, a particulate water soluble salt which is insoluble in the saturated saline solution, xanthomonas gum, and an epichlorohydrin crosslinked hydroxypropyl starch derivative wherein the xanthomonas gum and the epichlorohydrin crosslinked hydroxypropyl starch derivative interact to synergistically enhance the suspension characteristics of the fluid and to decrease the fluid loss of the fluid.Also disclosed is an additive composition for enhancing the suspension characteristics and reducing the fluid loss of saturated brine based well treating fluids comprising specified proportions of xanthomonas gum and epichlorohydrin crosslinked hydroxypropyl starch.

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.

Abstract: A well completion and workover method wherein a subterranean formation is contacted with a high density, nondamaging treating fluid which comprises a saturated, aqueous saline solution with at least one water soluble salt that is substantially insoluble in the saturated saline solution. The water soluble salt has a particle size range of about 5 microns to about 800 microns, and greater than about 5 percent of the particles are coarser than 44 microns to control the pressure in the formation; to bridge and seal off the formation; to avoid particle invasion; and also to minimize fluid loss to the formation. A minor amount of a fluid loss additive is included in the treating fluid to inhibit loss of fluid into the formation and a minor amount of a suspension additive is included in the treating fluid to prevent settling of the water soluble salt particles in the aqueous saline solution. The aqueous saline solution should have a density of at least about 10 pounds per gallon.

Abstract: Caking of potassium chloride and sodium chloride in the particle size range of 20 mesh and finer is inhibited by adding one or more alkaline earth or multi-valent metal salts of lignosulfonate in an amount by weight within the range of about 1% to about 20% to the potassium chloride or sodium chloride.

Abstract: A nondamaging work over and completion fluid having water soluble bridging agents includes a saturated brine solution having at least one water soluble salt which is insoluble in the saturated brine solution and having particle size range of about 5 microns to about 800 microns and wherein greater than about 5% of the particles are coarser than 44 microns. Viscosifier and suspension additive is added to provide the desired viscosity and assist in maintaining the water soluble sized salt suspended in the saturated brine solution. If desired or necessary a fluid loss control agent may be added to enhance the fluid loss control or filtration control of the completion fluid.The invention 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: A nondamaging work over and completion fluid having water soluble bridging agents includes a saturated brine solution having at least one water soluble salt which is insoluble in the saturated brine solution and having particle size range of about 5 microns to about 800 microns and wherein greater than about 5% of the particles are coarser than 44 microns. Viscosifier and suspension additive is added to provide the desired viscosity and assist in maintaining the water soluble sized salt suspended in the saturated brine solution. If desired or necessary a fluid loss control agent may be added to enhance the fluid loss control or filtration control of the completion fluid.The invention 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: A process for removing oil base mud adhering to cuttings obtained in well drilling operations, comprising contacting the cuttings with a solvent consisting essentially of a mixture of ethyleneglycol monoisobutyl ether, diethyleneglycol monobutyl ether acetate, ethyl butyl ketone, ethyleneglycol monobutyl ether, ethyleneglycol monomethyl ether acetate, diethyleneglycol diethyl ether, and diethyleneglycol mono-n-hexyl ether, together with paraffin oil, in relative proportions of from 10:90 to 80:20. This forms a mixture of oil and solvent on the cuttings which is readily removable; as by washing or centrifuging or a combination of the two.

Abstract: The invention provides water base drilling fluids containing lime and potassium compounds which have the following advantages as compared to prior art lime muds and potassium muds: (a) provide better borehole stability than lime muds; (b) easier to control than lime muds and potassium muds; (c) drilled solids have much less effect on the rheological properties of these drilling fluids as compared to lime muds and potassium muds; (d) the thermal gelation of these drilling fluids after contamination with shale is much less severe than that of shale contaminated lime muds or potassium muds; and (e) bit balling and cuttings agglomeration when drilling mud making shales is much less than when using lime muds or potassium muds. These drilling fluids comprise a suspension of clay, lime and 10-30 ppb of a lignitic material in an aqueous phase, the drilling fluid having a Pm in the range from 1 to 40 and a pH in the range from 12.4 to 13.

Abstract: An improved method of consolidating the surface of a borehole in an incompetent formation and simultaneously strengthening the bond between the surface of the borehole and cement placed in the borehole is achieved by forcing an aqueous solution of a multivalent cation salt into the formation, thereafter forcing an alkali metal silicate solution which has a pH less than 12.0 containing at least 12% by weight silica into the formation, and thereafter forcing an aqueous cement slurry containing at least 2% by weight of a water soluble multivalent cation salt to contact the surface of the borehole. A cementitious piling intimately bonded to the formation is prepared by filing the stabilized borehole with an aqueous cement slurry and allowing the cement to harden.