Abstract: A wellbore fluid comprising a base fluid and a particulate bridging agent comprised of a sparingly water-soluble material selected from the group consisting of melamine (2,4,5-triamino-1,3,5-triazine), lithium carbonate, lithium phosphate (Li3PO4), and magnesium sulfite.

Abstract: Wellbore fluid having a continuous aqueous phase, and containing at least one polymer which (a) has a number average molecular weight in the range of from 10,000 to less than 100,000; (b) contains hydrophilic units such that the polymer is at least 2% soluble in water at a temperature of 20° C. wherein none of said hydrophilic units comprise —CH2.CH2.O— units; and (c) contains pendant alkyl groups having at least 10 carbon atoms. The combined molecular weight of the pendant alkyl groups is in the range of from 15 to 70% by weight based on the weight of the polymer.

Abstract: Wellbore fluid having a continuous aqueous phase, and comprising at least one polymer which has a number average molecular weight in the range of from 10,000 to less than 100,000, wherein the polymer is selected from a copolymer of at least one hydrophilic monomer and at least one hydrophobic monomer containing an alkyl group having at least 8 carbon atoms. The hydrophilic monomer is selected from acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid and itaconic acid, and sulfonate groups have been introduced into the copolymer by reaction of at least a portion of the carboxylic acid and/or anhydride groups with a compound of general formula R12N(CH2)nSO3X (I) or a compound of general formula HO(CH2)nSO3X (II). Each R1 is independently selected from hydrogen, methyl or ethyl, X is either H or a Group IA metal, and n is an integer of from 1 to 6.

Abstract: A wellbore fluid comprising a base fluid and a particulate bridging agent comprised of a sparingly water-soluble material selected from the group consisting of melamine (2,4,5-triamino-1,3,5-triazine), lithium carbonate, lithium phosphate (Li3PO4), and magnesium sulfite.

Abstract: Wellbore fluid containing a base fluid and a particulate bridging agent comprised of melamine. A method is also described of forming a removable filter cake on the walls of a wellbore that penetrates a porous and permeable rock formation by placing in the wellbore a wellbore fluid containing a base fluid and melamine, and permitting the melamine to deposit from the wellbore fluid onto or into the walls of the wellbore to form the filter cake, whereby fluid loss to the formation through the removable filter cake is reduced.

Abstract: There is provided a wellbore fluid having a continuous aqueous phase, and comprising at least one polymer which:—has a molecular weight in the range of from 2,000 to less than 100,000; contains hydrophilic units such that the polymer is at least 2% soluble in water at 20° C., and such that less than 50% by weight of said hydrophilic units comprise —CH2—CH2O— units; and contains pendant alkyl groups having at least 10 carbon atoms, the combined molecular weight of said pendant alkyl groups being in the range of from 15 to 70% by weight based on the weight of the polymer. Such aqueous based wellbore fluids exhibit significantly improved fluid loss properties when used in wellbore operations, such as drilling, completion or workover.

Abstract: There is provided a wellbore fluid having a continuous aqueous phase, and comprising at least one polymer which contains both hydrophilic units and hydrophobic units, at least some of said hydrophilic units containing sulfonate groups, and less than 50% by weight of said hydrophilic units comprising —CH2.CH2.O— units; and at least some of said hydrophobic units containing pendant alkyl groups having at least 8 carbon atoms. Such aqueous based wellbore fluids exhibit significantly improved fluid loss properties when used in wellbore operations, such as drilling, completion or workover.

Abstract: A wellbore fluid comprising a base fluid and a particulate bridging agent comprised of a sparingly water-soluble material selected from the group consisting of melamine(2,4,5-triamino-1,3,5-triazine), lithium carbonate, lithium phosphate (Li3PO4), and magnesium sulfite.

Abstract: A method of inhibiting scale formation in a subterranean formation comprising: (a) injecting a suspension comprising particles of a controlled release scale inhibitor suspended in an aqueous medium into a formation through an injection well wherein the particles have a mean diameter of less than 10 microns, preferably less than 5 microns, more preferably less than 1 micron; (b) allowing the suspension to percolate through the subterranean formation towards a production well; and (c) controllably releasing the scale inhibitor from the particles in the near well bore region of the production well. Suitably, the particles of the controlled release scale inhibitor comprise an esterifiable scale inhibitor cross-linked with a polyol via ester cross-links.

Abstract: A process for removing metal ions from crude oil comprising contacting a non-ionic amphiphilic solvent with the crude oil, optionally, in the presence of water, so as to produce a metal ion-containing phase, and separating the metal ion-containing phase from the crude oil.

Abstract: This invention relates to a process for deacidifying a crude oil system, said process comprising the steps of: a) contacting the crude oil system with a polar solvent, such that at least part of the organic acid present in the oil is extracted into the solvent as an extract phase, and b) separating said extract phase from the treated crude oil system of step a).

Abstract: A method of inhibiting or retarding formation of hydrates from water and a lower alkane, such as methane or ethane, involves adding additives which comprise (i) a corrosion inhibitor and (ii) a salt which is of formula [R1(R2)XR3]+Y−, wherein each of R1, R2 and R3 is bonded directly to X, each of R1 and R2, which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR4 or PR4, wherein each of R3 and R4 which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R3 and R4 is an organic group of at least 4 carbons, and Y is an anion, the additives being added in an amount effective to inhibit or retard hydrate formation, to a medium susceptible to hydrate formation.

Abstract: Inhibitors of wax deposition for crude oils are polymers of a monomer with structural units derived from at least one ester (i) of an aliphatic carboxylic acid with an aliphatic alcohol, wherein one of the acid and alcohol is ethylenically unsaturated and the other of the acid and alcohol has a long chain group of 14-40 carbons, and a monomer with structural units derived from a corresponding ester (3) with structural units derived from an aliphatic carboxylic acid and an aliphatic alcohol, wherein one of the acid and alcohol is ethylenically unsaturated and the other has an aliphatic group of 1-13 carbons, such that at least 30% preferably 50-90% of the said aliphatic groups have 15-35 carbons. They are preferably made by transesterification. Blends of such polymers and/or the corresponding homopolymers or copolymers of ester 1 and/or polyalkylene imines with long side chains, and optionally with monomeric polar additives may be used as inhibitors.

Abstract: A hydrate inhibitor comprising a blend of an additive (i) and at least one of an additive (ii) and an additive (iii) wherein additive (i) is a polymer of an ethylenically unsaturated N-heterocyclic carbonyl compound, with 6-8 ring atoms in the heterocyclic ring, additive (ii) is a corrosion inhibitor and additive (iii) is a salt of formula (I):[R1(R2)XR3]+Y− 1/v, I wherein each of R1, R2 and R3 is bonded directly to X, each of R1 and R2, which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR4 or PR4, wherein each of R3 and R4 which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R3 and R4 is an organic group of at least 4 carbons, especially at least 5 carbons, and Y is an anion of valency v, wherein v is an integer of 1-4.

Abstract: A method of reducing the deposition of wax from a crude oil containing wax which comprises adding thereto at least one N-substituted polyalkylene imine which has at least one organic substituent that is a hydroxy-substituted alkyl group of 12-24 carbon atoms.

Abstract: A method of inhibiting or retarding formation of hydrates from water and a lower alkane, such as methane or ethane, involves adding additives which comprise (i) a corrosion inhibitor and (ii) a salt which is of formula [R.sup.1 (R.sup.2)XR.sup.3 ].sup.+ Y.sup.-, wherein each of R.sup.1, R.sup.2 and R.sup.3 is bonded directly to X, each of R.sup.1 and R.sup.2, which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR.sup.4 or PR.sup.4, wherein each of R.sup.3 and R.sup.4 which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R.sup.3 and R.sup.4 is an organic group of at least 4 carbons, and Y is an anion, the additives being added in an amount effective to inhibit or retard hydrate formation, to a medium susceptible to hydrate formation.