Nitrogen Is Part Of A Hetero Ring Patents (Class 507/242)
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Patent number: 7833945Abstract: Additives and treatment fluids with improved shale inhibition, and associated methods of use in subterranean operations, are provided. The additives and treatment fluids used generally comprise a shale-inhibiting component and one or more silicates.Type: GrantFiled: July 15, 2005Date of Patent: November 16, 2010Assignee: Halliburton Energy Services Inc.Inventors: Elaine Harrower, Arthur Youngson, Colin Temple
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Publication number: 20100263867Abstract: A downhole wellbore filtercake breaker is disclosed comprising one or more breaker chemicals (or activators thereof) capable of being activated with radiation to form one or more breaker reaction products which in turn are capable of reacting with the filtercake to chemically break down the filtercake. There is also disclosed a conventional reservoir drilling fluid modified to include an inactive, delayed, or sequestered breaker chemical or an activator thereof, wherein the breaker chemical (or activator) may be activated directly or indirectly by radiation, such as, microwave, visible, uV, soft x-ray, or other electromagnetic radiation. Also disclosed are methods for creating these filtercakes, and then breaking them via deploying a source of radiation that can be energized proximate to the filtercake. The breaker may be regenerated downhole by reaction with the filtercake breakdown products, and subjected again to a source of radiation to continue the breakdown of filtercake.Type: ApplicationFiled: April 20, 2010Publication date: October 21, 2010Inventors: Amy C. Horton, Robert L. Horton
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Patent number: 7795186Abstract: Provided herein are methods and compositions for generating acids for use downhole, for example, to break fluid-loss control pills. The delayed-release acid breakers of the present invention comprise orthoesters and/or poly(orthoesters).Type: GrantFiled: June 22, 2009Date of Patent: September 14, 2010Assignee: Halliburton Energy Services, Inc.Inventors: Rajesh K. Saini, Karen Savery, Bradley L. Todd
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Patent number: 7786049Abstract: The present invention relates to subterranean drilling operations, and more particularly, to drilling fluids that may be used to drill a well bore in a subterranean formation that may demonstrate improved shale inhibition and methods of using such drilling fluids in subterranean formations. One embodiment of the methods of the present invention provides a method of drilling a well bore in a subterranean formation comprising providing a drilling fluid comprising an aqueous-based fluid and a shale inhibiting component comprising a nanoparticle source; and placing the drilling fluid in the well bore in the subterranean formation. Another embodiment of the present invention provides a method of flocculation comprising providing a fluid comprising suspended particles, and adding a shale inhibiting component comprising a nanoparticle source to the fluid comprising suspended particles to form flocculated particles.Type: GrantFiled: February 11, 2004Date of Patent: August 31, 2010Assignee: Halliburton Energy Services, Inc.Inventors: Colin Temple, Arthur Youngson
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Patent number: 7772160Abstract: Pellets can be injected into oil and gas production equipment that may contain stagnant or slow moving system fluids to treat the stagnant or slow moving system fluids to prevent conditions such as corrosion. The pellets have a density such that they may be moved through the equipment by system fluids passing therethrough. When the pellets come into contact with the stagnant or slow moving system fluids, sufficient pellets enter the stagnant or slow moving system fluids to treat it. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.Type: GrantFiled: August 30, 2007Date of Patent: August 10, 2010Assignee: Baker Hughes IncorporatedInventors: Michael Greaves, Steven Jeremy Weghorn, Hani S. Zaki
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Patent number: 7772164Abstract: There is a viscoelastic fluid. The fluid has one or more cationic surfactants selected from the group consisting of certain quaternary salts, certain amines, and combinations thereof; one or more anionic polymers/anionic surfactants; one or more of certain zwitterionic/amphoteric surfactants; and water. There is also a method of fracturing a subterranean formation. The viscoelastic fluid is pumped through a wellbore and into a subterranean formation at a pressure sufficient to fracture the formation. There is also a method for gravel packing a subterranean formation.Type: GrantFiled: February 9, 2007Date of Patent: August 10, 2010Assignee: Rhodia, Inc.Inventors: Fang Li, Manilal Dahanayake, Allwyn Colaco
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Patent number: 7745379Abstract: A method of insulating pipeline bundles used in recovering hydrocarbons from wells is disclosed. A polymeric substance, such as an orthophosphate ester, is injected into the annulus between a carrier pipe and the hydrocarbon conveying tubulars. A ferric salt, such as ferric sulphate, may be added as a gelling agent. The mixture results in a gel having a dynamic viscosity of greater than (1000) PaS. The gel insulates the inner hydrocarbon-conveying tubulars from the surrounding seawater thus helping to maintain the relatively high temperature therewithin. This in turn reduces the likelihood for chemicals, such as hydrates, to be precipitated out of the oil phase.Type: GrantFiled: June 3, 2004Date of Patent: June 29, 2010Assignee: Aubin LimitedInventor: Patrick Joseph Collins
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Publication number: 20100130389Abstract: Compositions are provided for removing an organic material, especially asphaltenes, from a portion of a wellbore or a subterranean formation. The composition comprises: (A) water; (B) an organic solvent blend further comprising: (i) a non-polar organic solvent; and (ii) at least two polar organic solvents; and (C) a surfactant adapted for forming an emulsion of the organic solvent blend and the water. According to another aspect of the invention, the compositions comprise: (A) water, wherein the water is greater than 25% by volume of the composition; (B) an organic solvent blend further comprising: (i) a non-polar organic solvent; and (ii) a polar organic solvent; and (C) a surfactant adapted for forming an emulsion of the organic solvent blend and the water. Methods are provided for removing an organic material from a portion of a wellbore or a subterranean formation.Type: ApplicationFiled: November 20, 2006Publication date: May 27, 2010Inventors: Stephen Charles Lightford, Franco Armesi, Franco Reynaldi
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Publication number: 20100130384Abstract: Compositions are provided for removing an organic material, especially asphaltenes, from a portion of a wellbore or a subterranean formation. The composition comprises: (A) water, wherein the water is greater than 50% by volume of the composition; (B) an organic solvent blend that is immiscible with water, wherein the organic solvent comprises: (i) a non-polar organic solvent; and (ii) a polar organic solvent; and (C) a surfactant adapted for forming an emulsion of the organic solvent blend and the water. Methods are provided for removing an organic material from a portion of a wellbore or a subterranean formation. The method comprises the steps of: (A) forming a composition according to the invention; and (B) introducing the composition to the portion from which the organic material is to be removed.Type: ApplicationFiled: May 5, 2006Publication date: May 27, 2010Inventors: Stephen Charles Lightford, Franco Armesi, Fuanco Reynaldi
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Publication number: 20100081587Abstract: A method comprising contacting a zwitterionic surfactant, co-surfactant, and water to form a microemulsifier, and contacting the microemulsifier with an oleaginous fluid under low shear conditions to form a microemulsion. A method comprising introducing a first wellbore servicing fluid comprising at least one oleaginous fluid into a wellbore, wherein the first wellbore servicing fluid forms oil-wet solids and/or oil-wet surfaces in the wellbore, and contacting the oil-wet solids and/or oil-wet surfaces in the wellbore with a second wellbore servicing fluid comprising a zwitterionic surfactant, a co-surfactant, and a brine to form a microemulsion.Type: ApplicationFiled: September 26, 2008Publication date: April 1, 2010Applicant: HALLIBURTON ENERGY SERVICES, INC.Inventors: Ryan van Zanten, Douglas J. Harrison
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Patent number: 7651981Abstract: A process for recovering materials from a subterranean formation, for example in enhanced oil recovery, comprises: (A) (a) (i) selecting a first polymeric material having a repeat unit of formula (A) wherein A and B are the same or different, are selected from optionally-substituted aromatic and heteroaromatic groups and at least one comprises a relatively polar atom or group and R1 and R2 independently comprise relatively non-polar atoms or groups; or (ii) selecting a first polymeric material prepared or preparable by providing a compound of general formula (B) wherein A, B, R1 and R2 are as described above, in an aqueous solvent and causing the groups C?C in said compound to react with one another to form said first polymeric material; (b) selecting a second polymeric material which includes a functional group which is able to react in the presence of said first polymeric material to form a third polymeric material; (c) causing the formation of said third polymeric material by a reaction involving said firsType: GrantFiled: March 28, 2003Date of Patent: January 26, 2010Assignees: Advanced Gel Technology Limited, Aubin LimitedInventors: Donald Eagland, Nicholas John Crowther, James Murray, Austin Tobin
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Patent number: 7651982Abstract: Methods and aqueous acid solutions for acidizing wells containing sludging and emulsifying oil are disclosed. An aqueous acid solution of the invention comprises water, hydrochloric acid, a cationic hydrochloric acid corrosion inhibitor and a conjugate ion pair of a cationic amine oxide surfactant and an anionic surfactant that does not react with the cationic hydrochloric acid corrosion inhibitor.Type: GrantFiled: August 21, 2004Date of Patent: January 26, 2010Assignee: Halliburton Energy Services, Inc.Inventors: Juanita M. Cassidy, Chad E. Kiser, Jim L. Lane
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Publication number: 20090151944Abstract: A method of treating a subterranean formation penetrated by a wellbore is carried out by forming a treatment fluid comprising an aqueous carrier fluid and a solid-form polyimide homopolymer or copolymer capable of hydrolyzing to form polycarboxylates and/or polycarboxylic acids. The treatment fluid is introduced into the formation through the wellbore. In another method, a treatment fluid comprising an aqueous carrier fluid, a solid-form polysuccinimide homopolymer or copolymer and at least one of a viscosifying agent, proppant and an acid capable of dissolving materials of the formation is formed. This is introduced into the formation through the wellbore. A method of treating a sandstone-containing formation penetrated by a wellbore may also be carried out by forming a treatment fluid comprising an aqueous solution containing a hydrogen fluoride source, ammonium hydroxide and at least one of a polyimide and a polycarboxylate, which is introduced into the formation through the wellbore.Type: ApplicationFiled: December 14, 2007Publication date: June 18, 2009Inventors: Michael J. Fuller, John W. Still
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Patent number: 7544640Abstract: Methods and compositions are provided for treating fluids, especially spacer fluids and cement compositions as well as drilling, completion and stimulation fluids including, but not limited to, drilling muds, well cleanup fluids, workover fluids, conformance fluids, gravel pack fluids, acidizing fluids, fracturing fluids and the like for introduction into a subterranean zone penetrated by a wellbore, wherein the treating fluid comprises zeolite and a carrier fluid. The treating fluid may additionally include one or more of a viscosifier, organic polymer, dispersants, surfactants and weighting materials.Type: GrantFiled: July 18, 2003Date of Patent: June 9, 2009Assignee: Halliburton Energy Services, Inc.Inventors: Karen Luke, Sears T. Dealy
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Corrosion and gas hydrate inhibitors having improved water solubility and increased biodegradability
Patent number: 7435845Abstract: Corrosion and gas hydrate inhibitors having improved water solubility and increased biodegradability The invention thus provides the use of compounds of the formula (1) where R1, R2 are each independently C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, R3 is C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, —CHR5—COO? or —O?, R4 is M, hydrogen or an organic radical which optionally contains heteroatoms and has from 1 to 100 carbon atoms, B is an optionally substituted C1- to C10-alkylene group, D is an ethylene group substituted by an organic radical having from 1 to 600 carbon atoms, X, Y are each independently O or NR6, R5, R6 are each independently hydrogen, C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, and M is a cation as corrosion and gas hydrate inhibitors, and also the compounds of formula 1.Type: GrantFiled: February 20, 2004Date of Patent: October 14, 2008Assignee: Clariant Produkte (Deutschland) GmbHInventors: Uwe Dahlmann, Michael Feustel -
Patent number: 7398824Abstract: A formulation containing a copolymer derived from a cationic monomer effectively inhibits and controls the formation of inorganic scales. Suitable copolymers include those comprising an acrylamide unit and a quaternary ammonium salt group, and optionally an acrylate and/or nitrogen heterocyclic monomer including those wherein the quaternary ammonium salt is a unit of the formula: wherein R is methyl or hydrogen; R4 is a C1 to C6 alkyl group, optionally substituted with halogen, hydroxyl and alkoxy groups, X is halogen; and R1, R2 and R3 are independently selected from the group consisting of alkyl and alkoxy groups. Suitable nitrogen heterocyclic compounds include N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinylcaprolactam, N-vinylimidazole and N-vinylpyridine.Type: GrantFiled: February 1, 2006Date of Patent: July 15, 2008Assignee: BJ Services CompanyInventors: Xiaolan Wang, Qi Qu, Mingjie Ke
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Patent number: 7219735Abstract: A packer fluid is provided for use with a wellbore fluid in an annulus or casing bore, having an aqueous portion which contains additives for preventing corrosion, microbiological activity, salt and scale deposition, and an environmentally-acceptable capping fluid which resides at a top of the wellbore to act as freeze protection and as thermal insulation in a the frost penetration layer. The additives in the packer fluid are particularly selected to exist in the aqueous additive fluid and in the wellbore fluid and to be substantially immiscible with the capping fluid and thereby prevent significant migration of the additives into the capping fluid which would compromise its environmental acceptability.Type: GrantFiled: October 30, 2003Date of Patent: May 22, 2007Assignee: Innovative Chemical Technologies Canada Ltd.Inventors: Clayton Smith, Dan Skibinski
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Patent number: 7178610Abstract: The present invention relates to subterranean treatment fluids. In particular, the present invention relates to subterranean treatment fluid compositions that comprise polyoxazoline compositions and methods for using such compositions in subterranean applications. In one embodiment, the present invention provides a method of controlling shale swelling in a subterranean formation comprising introducing a treatment fluid into the subterranean formation, wherein the treatment fluid comprises a base fluid and a polyoxazoline composition. In another embodiment, the present invention provides a method of treating a portion of a subterranean formation comprising the steps of: introducing a treatment fluid that comprises a base fluid and a polyoxazoline composition; and treating a portion of the subterranean formation. Other embodiments are provided.Type: GrantFiled: August 11, 2004Date of Patent: February 20, 2007Assignee: Halliburton Energy Services, Inc.Inventor: Stephen A. Bell
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Patent number: 7060661Abstract: The present invention generally relates to aqueous, acidic compositions thickened with an amidoamine oxide gelling agent and/or viscoelastic surfactant of the general formula I: wherein R1 is a saturated or unsaturated, straight or branched chain aliphatic group of from about 7 to about 30 carbon atoms, R2 is a divalent alkylene group of 2–6 carbon atoms which may be linear or branched, substituted or unsubstituted, and R3 and R4 are independently C1–C4 alkyl or hydroxyalkyl groups or together they form a heterocyclic ring of up to six members, and R5 is hydrogen or a C1–C4 alkyl or hydroxyalkyl group. The aforementioned gelling agents advantageously provide gels that do not undergo phase separation over extended periods of time and exhibit high heat stability. The thickened acid gels of the invention have applications in household and industrial cleaners and degreasers, oilfield stimulation applications and the like.Type: GrantFiled: May 29, 2002Date of Patent: June 13, 2006Assignee: Akzo Nobel N.V.Inventors: Randy Ezell Dobson, Sr., David Kelly Moss, Raman Sarasamma Premachandran
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Patent number: 6939483Abstract: It has been discovered that ammonia and amines are useful to increase the pH and corrosion resistance of high density brines, such as zinc bromide brines, without significantly reducing their densities. The ammonia or amine additive is preferably incorporated by contacting the brine with the additive which is in the vapor phase. Optionally, a substituted carboxylic acid, such as hydroxy carboxylic acid, may be used to increase the amount of ammonia or amine that can be included in the high density brine without precipitation of salts.Type: GrantFiled: October 11, 2001Date of Patent: September 6, 2005Assignee: PABU Services, Inc.Inventor: Michael L. Walker
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Patent number: 6936574Abstract: The present invention provides a cement composition and a process for using the cement composition to inhibit gas migration from a subterranean zone into the cement. The process comprises displacing a gelling additive, preferably comprised within a cement composition, into a well bore such that the gelling additive passes into the subterranean zone, and allowing the gelling additive to form a crosslinked gel in the subterranean zone to inhibit gas migration from the subterranean zone. The crosslinked gel acts as a barrier to gas in the subterranean zone and thereby inhibits the gas from passing into the cement and forming flow channels therein before the cement can set.Type: GrantFiled: August 30, 2002Date of Patent: August 30, 2005Assignee: Halliburton Energy Services, Inc.Inventors: Bach Dao, Ewout Biezen, Jan Pieter Vijn, Thien Pham
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Patent number: 6905605Abstract: A method for inhibiting hydrate formation in a hydrocarbon flow by adding an amount of a dendrimeric compound effective to inhibit formation of hydrates at conduit temperatures and pressures, and flowing the mixture containing the dendrimeric compound and any hydrates through the conduit. Preferably, a hyperbranched polyester amide is used as hydrate formation inhibitor compound.Type: GrantFiled: April 6, 2001Date of Patent: June 14, 2005Assignee: Shell Oil CompanyInventor: Ulfert Cornelis Klomp
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Publication number: 20040259740Abstract: The use of a compound according to formula I, in particular, thiohydantoin, as a corrosion inhibitor or a corrosion inhibitor synergist.Type: ApplicationFiled: March 12, 2004Publication date: December 23, 2004Applicant: TR Oil Services LimitedInventor: Henry Alfred Craddock
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Patent number: 6608005Abstract: Non-aqueous base wellbore fluids characterized by enhanced electrical conductivity due to formulation with specified ionic liquids are disclosed. Drilling, completion, and workover methods utilizing the wellbore fluids are also disclosed.Type: GrantFiled: April 9, 2001Date of Patent: August 19, 2003Assignee: Schlumberger Technology CorporationInventors: Bentley J. Palmer, Diankui Fu, Roger Card, Edgar Volpert
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Patent number: 6544932Abstract: An additive for inhibiting the formation of gas hydrates in connection with hydrocarbon production and transportation comprising the water-soluble polymers comprising structural elements of the formula wherein each R is independently H or C1-C5-alkyl; X is H, an alkaline or earth alkaline metal or a quaternary ammonium group; R1 is H or C1-C18-alkyl; and R2 is C1-C18-alkyl; and wherein the alkyl groups represented by R1 and R2 optionally carry a hydroxy or amino substituent; and, optionally, a minor proportion of structural elements of the formula wherein R, R1, R2 and X may have the meaning as above, and Alk is a C1-C5-alkylene chain.Type: GrantFiled: July 20, 2001Date of Patent: April 8, 2003Assignees: Clariant GmbH, RF-Rogaland ResearchInventors: Peter Klug, Malcolm Kelland
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Patent number: 6506710Abstract: A method for controlling the rheology of aqueous systems, particularly for those intended for underground use, includes injecting an aqueous viscoelastic fluid containing a surfactant gelling agent into the system. The viscoelastic surfactant composition of the invention comprises, as a gelling agent, at least one fatty aliphatic amidoamine oxide in a glycol solvent. The composition also maintains the levels of free fatty acid and free amine within critical parameters in order to achieve superior performance. The additives may be incorporated in the viscoelastic fluid to tailor its use in stimulation fluids, drilling muds, fracture fluids, and in applications such as permeability modification, gravel packing, cementing, and the like.Type: GrantFiled: April 20, 2000Date of Patent: January 14, 2003Assignee: Akzo Nobel N.V.Inventors: Michael D. Hoey, Ralph Franklin, Douglas M. Lucas, Maurice Dery, Randy E. Dobson, Michael Engel, James F. Gadberry, Ramanair S. Premachandran, Glenda Del Carmen Vale
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Publication number: 20020147114Abstract: The present invention generally relates to aqueous, acidic compositions thickened with an amidoamine oxide gelling agent and/or viscoelastic surfactant of the general formula I: 1Type: ApplicationFiled: May 29, 2002Publication date: October 10, 2002Inventors: Randy Ezell Dobson, David Kelly Moss, Raman Sarasamma Premachandran
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Patent number: 6369004Abstract: An additive for inhibiting the formation of gas hydrates in connection with hydrocarbon production and transportation comprising the water-soluble polymers comprising structural elements of the formula wherein each R is independently H or C1-C5-alkyl; X is H, an alkaline or earth alkaline metal or a quaternary ammonium group; R1 is H or C1-C18-alkyl; and R2 is C1-C18-alkyl; and wherein the alkyl groups represented by R1 and R2 optionally carry a hydroxy or amino substituent; and, optionally, a minor proportion of structural elements of the formula wherein R, R1, R2 and X may have the meaning as above, and Alk is a C1-C5-alkylene chain.Type: GrantFiled: November 24, 1997Date of Patent: April 9, 2002Assignees: Clariant GmbH, RF-Rogaland ResearchInventors: Peter Klug, Malcolm Kelland
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Patent number: 6350721Abstract: Liquids comprised solely of anions and cations (“ionic liquids”) are disclosed as novel components of fluids (and techniques relying upon those fluids) for stimulation of hydrocarbon wells. In particular, the fluids disclosed are useful in matrix acidizing. Formation of the ionic liquids of the present Invention is highly exothermic, hence the heat generated can be used, for instance, to melt de-watered drilling fluid in the near-wellbore region of the formation. Further, reaction of the ionic liquids with water results in acid generation; this acid can be used to, for instance, to stimulate a formation, either by conventional matrix acidizing or fracture acidizing. In addition, certain preferred species of the ionic liquids of the present Invention are highly stable solvents, hence they can be used as carrier fluids for highly reactive super acids (e.g., SbF5+HF) in connection with matrix acidizing.Type: GrantFiled: December 1, 1998Date of Patent: February 26, 2002Assignee: Schlumberger Technology CorporationInventors: Diankui Fu, Roger J. Card
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Patent number: 6124246Abstract: Improved high temperature epoxy resin compositions, additives and methods are provided. A hardenable epoxy resin composition of the present invention is comprised of an epoxy resin, an aromatic diluent, a hardening agent and a hardening retarder for delaying the hardening of the epoxy composition at high temperatures comprised of a liquid which is soluble in the epoxy resin composition having a halide salt dissolved therein.Type: GrantFiled: November 17, 1997Date of Patent: September 26, 2000Assignee: Halliburton Energy Services, Inc.Inventors: James F. Heathman, Rick L. Covington, Bill W. Loughridge
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Patent number: 5922653Abstract: A composition and a process for using the composition for applications in a subterranean formation are provided. The composition comprises a clay, a polymer, and a liquid. The polymer comprises repeat units derived from a nitrogen-containing olefinic monomer and optionally an olefinic comonomer. The composition can be used as or in drilling fluids, workover fluids, completion fluids, or combinations of any two or more thereof.Type: GrantFiled: October 3, 1996Date of Patent: July 13, 1999Assignee: Phillips Petroleum CompanyInventors: Iqbal Ahmed, Ahmad Moradi-Araghi, Bharat B. Patel, Wayne S. Stewart
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Patent number: 5779938Abstract: The invention is an effective, easy to produce, and economical corrosion inhibitor which can be used in a variety of environments. The corrosion inhibitor of the present invention is the salt of certain tertiary amines. The corrosion inhibitor is the reaction product of one or more tertiary amines and certain carboxylic acids, preferably a mixture of mercaptocarboxylic and carboxylic acids.Type: GrantFiled: August 24, 1995Date of Patent: July 14, 1998Assignee: Champion Technologies, Inc.Inventors: Ali Naraghi, Philippe Prince
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Patent number: 5756004Abstract: The present invention provides improved quaternary ammonium compounds useful as metal corrosion inhibitors in aqueous acid solutions, methods of preparing the compounds, metal corrosion inhibited aqueous acid solutions containing the compounds and methods of protecting metal surfaces from acid corrosion using the compounds. The compounds are prepared by contacting the still bottoms residue produced in the distillation of quinoline from coal tar with oxygen to oligomerize aromatic amines contained therein and then reacting the oligomerized amines with a benzylhalide.Type: GrantFiled: May 13, 1997Date of Patent: May 26, 1998Assignee: Halliburton Energy Services, Inc.Inventor: Michael M. Brezinski
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Patent number: 5690176Abstract: Process for the dissolution of asphaltene sediments in oil wells which consists in introducing a solubilizing composition for the above asphaltenes into the oil wells, characterized in that the solubilizing composition comprises:(a) a basically hydrocarbon fraction consisting of at least 70%, preferably at least 80% by weight, of aromatic and alkyl aromatic hydrocarbons, the alkyl group being from C.sub.1 to C.sub.4 ;(b) a fraction basically consisting of quinoline and isoquinoline as such or alkyl substituted, preferably as such, the alkyl group being from C.sub.1 to C.sub.4 ; the weight ratio between fraction (a) and (b) being from 97.5/2.5 to 75/25, preferably from 97/3 to 90/10.Type: GrantFiled: March 12, 1996Date of Patent: November 25, 1997Assignee: Agip S.p.A.Inventors: Alberto Delbianco, Fabrizio Stroppa