Abstract: The present invention provides a method of controlling fluid loss to a permeable formation penetrated by a wellbore. A novel fluid loss agent is prepared by forming a crosslinked polymer gel which then is sheared to break the gel into discrete particles. A slurry then is formed of the particles by dispersing the particles in an aqueous fluid having a density similar to that of the gel particles. The slurry then is introduced into contact with the permeable formation and a filter cake of the particles is formed upon contact with the formation and loss of the slurrying fluid to the formation. The filter cake provides further fluid loss control to the permeable formation.

Abstract: Improved well drilling fluids and methods which prevent damage to water sensitive formations while drilling are provided. The drilling fluids include a formation stabilizing compound which contains an organic quaternary ammonium cation and an inorganic, organic or combination anion.

Abstract: The present invention provides a method of gravel packing a subterranean formation using a gel of a graft copolymer of a hydroxyalkyl cellulose prepared by a redox reaction with vinyl phosphonic acid. The gel is formed by hydrating the graft copolymer in an aqueous liquid. The gel in crosslinked by the addition of a crosslink initiator comprising a Lewis base or Bronsted-Lowry base, which is substantially free of polyvalent metal ions, to the gel in an amount sufficient to effect crosslinking of the graft copolymer. The viscosity of the crosslinked gel is reduced by contacting the gel with an acidic fluid whereby the pH of the gel is caused to decrease. The reduction in gel viscosity facilitates formation of the gravel pack.

Abstract: A method of stimulating a subterranean formation using a foamed cement composition. When hardened, the cement composition has a permeability of at least about 0.3 darcies. The inventive formation stimulation method comprises the steps of: (a) injecting the foamed cement composition into the formation at a pressure sufficient to fracture the formation and (b) allowing the cement composition to harden in the formation.

Abstract: The present invention provides a method of cleaning a pipeline using a gel pig of a graft copolymer of a hydroxyalkyl cellulose prepared by a redox reaction with vinyl phosphonic acid. The gel pig is formed by hydrating the graft copolymer in an aqueous liquid. The gel pig is crosslinked by the addition of a Lewis base or Bronsted-Lowry base, to the gel in an amount sufficient to initiate crosslinking of the graft copolymer. Contaminants entrained in the crosslinked gel pig during the cleaning process may be separated by the addition of a pH reducing agent to the pig whereby the viscosity of the gel is caused to decrease. The gel may be used for further cleaning after contaminant separation by addition of an additional quantity of the Lewis base or Bronsted-Lowry base.

Abstract: A method of cementing a well casing or liner in a well bore wherein an annulus exists around the exterior of the casing or liner. The method comprises the step of placing a foamed cement slurry composition in the annulus. A method of treating a well bore comprising the steps of: (a) filling an uncased portion of the well bore with a foamed cement slurry composition; (b) allowing the cement composition to harden; and (c) drilling a hole through the hardened cement composition along at least a portion of the uncased portion of the well bore.

Abstract: A method of treating a clay-containing subterranean formation with an aqueous fluid is disclosed. The method features the use of quaternary ammonium compounds as additives to control formation damage caused by contacting the formation with the aqueous fluid.

Abstract: A method of temporarily reducing fluid loss into a subterranean formation from a well bore penetrating the formation by way of at least one perforation is provided. A first soluble particulate solid material is introduced into the formation by way of the perforation having a particle size whereby it bridges on the face of the formation and fills the perforation but allows fluid flow therethrough. A second soluble particulate solid material is introduced into the well bore having a particle size such that it bridges on the first particulate solid material and forms a seal over the perforation within the well bore.

Abstract: A method of treating a clay-containing subterranean formation with an aqueous fluid is disclosed. The method features the use of quaternary ammonium compounds as additives to control formation damage caused by contacting the formation with the aqueous fluid.

Abstract: A method of substantially preventing the adsorption of polysaccharides or removing polysaccharides from clay surfaces in subterranean formations which are present as a result of contact by gravel packing, fracturing or other treatment fluids, by contacting the formation with a treatment fluid containing at least one member selected from the group consisting of tetraalkylammonium halides wherein the alkyl radical is selected from methyl, ethyl, propyl and butyl radicals and trimethylammonium halides present in an amount sufficient to substantially remove any polysaccharides adsorbed by said clays whereby the permeability of the formation is substantially maintained.

Abstract: A method of substantially preventing the adsorption of polysaccharides or removing polysaccharides from clay surfaces in subterranean formations which are present as a result of contact by gravel packing, fracturing or other treatment fluids, by contacting the formation with a treatment fluid containing at least one member selected from the group consisting of tetraalkylammonium halides wherein the alkyl radical is selected from methyl, ethyl, propyl and butyl radicals and trimethylammonium halides present in an amount sufficient to substantially remove any polysaccharides adsorbed by said clays whereby the permeability of the formation is substantially maintained.

Abstract: A controllable breaker for use in viscosified fluids utilized in the treatment of subterranean formations comprising a low molecular weight condensation product of hydroxyacetic acid with up to 15 wt % cocondensing compounds containing other hydroxy-, carboxylic-acid, or hydroxycarboxylic-acid moieties. The condensation product has an average molecular weight in the range of from about 200 to about 4000, a generally crystalline structure, a melting point above about 100.degree. C. and is substantially insoluble in the viscosified fluid at ambient temperatures. The breaker is admixed with the viscosified fluid in an amount sufficient to effect controlled breaking of the fluid upon being heated to a temperature above 70.degree. F. within a subterranean formation.

Abstract: A formation control additive is utilized in stimulation fluids to minimize formation permeability damage as a result of formation contact by the stimulation fluid. The formation control additive can comprise N-alkypyridinium halides, N,N,N-trialkylphenylammonium halides, N,N,N-trialkylbenzylammonium halides, N,N-dialkylmorpholinium halides, alkyl quaternary ammonium salt of 2 mole oligomer of epihalohydrin wherein the alkyl radical is selected from the group of methyl, ethyl, propyl and butyl radicals and compounds of the general formula: ##STR1## wherein R is independently a methyl, ethyl, propyl or butyl radical and X is a compatible anion.

Abstract: A process for treating clayey geological formations to prevent, inhibit or reduce swelling or migrating clay particles in a formation by treating the formation with an effective amount of a quaternized oligomer which comprises a methyl quaternary amine containing an average of from about 3 to about 6 moles of epihalohydrin. The treatment is effected by introducing the oligomer into the formation in an aqueous fluid which can comprise brine, salt solutions, acid solutions, gelled fluids and the like.

Abstract: The present invention relates to a thermally stable crosslinked gel gravel packing fluid for use in the treatment of highly deviated well bores penetrating a subterranean formation. The gravel packing fluid comprises an aqueous liquid, a gelling agent comprising a selected modified cellulose ether, a crosslinking agent, a breaker, a particulate agent and any additional additives that may be present.