Bp Exploration Operating Company Limited

Simon Neil Duncum

Christopher George Osborne

Christopher Alan Sawdon

Antony Roland Edwards

Keith James

Ian Ralph Collins

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 (LiPO), and magnesium sulfite.

Wellbore fluid comprising a base fluid and a particulate bridging agent

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&#xb0; C. wherein none of said hydrophilic units comprise &#x2014;CH.CH.O&#x2014; 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. The polymer is selected from (A) a homopolymer of a compound of general formula HO(O)CCH&#x2550;CHC(O)OR where R is a Cto Calkyl group; and (B) a copolymer of (i) at least one hydrophilic monomer selected from acrylic acid, methacrylic acid, hydroxyethylmethacrylate, hydroxypropylmethacrylate, maleic acid, maleic anhydride, fumaric acid, itaconic acid, vinyl acetate, acrylamide, N,N-dimethylacrylamide, and N-vinyl pyrrolidone, and (ii) at least one hydrophobic monomer that provides a pendant alkyl group selected from a Cto Calpha-olefin, a Cto Calkyl vinyl ether, an acrylamide of the general formula CH&#x2550;CRC(O)NHR(I) where Ris selected from H and Cto Calkyl groups and Ris a Cto Calkyl group, and an acrylate of the general formula CH&#x2550;CRC(O)OR(II) where Ris H or methyl and Ris a Cto Calkyl group; and additionally containing at least one additive selected from additional fluid loss control agents, bridging particulate materials, finely dispersed additives for increasing the fluid density, thinners, and shale inhibitors.

Wellbore fluid comprising at least one polymer containing pendant alkyl groups

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 RN(CH)SOX (I) or a compound of general formula HO(CH)SOX (II). Each Ris 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. The combined molecular weight of the pendant alkyl groups that are introduced into the copolymer by the hydrophobic monomer is in the range of from 15 to 70% by weight based on the molecular weight of the polymer such that the polymer has a solubility of at least 2% in water at 20&#xb0; C. The fluid further comprises at least one additive selected from additional fluid loss control agents, bridging particulate materials, finely dispersed additives for increasing the fluid density, thinners, and shale inhibitors.

Wellbore fluid comprising sulfonated copolymers with pendant alkyl groups

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.

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.

Method for scale inhibition in oil wells

Process for deacidifying a crude oil system

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 &lsqb;R (R )XR &rsqb; Y , wherein each of R , R and R is bonded directly to X, each of R and R , which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR or PR , wherein each of R and R which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R and R 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.

Hydrate inhibition

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):&lsqb;R,(R,)XR,&rsqb;,Y,1/v, I wherein each of R,, R,and R,is bonded directly to X, each of R,and R,, which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR,or PR,, wherein each of R,and R,which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R,and R,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.

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.

Wax deposit inhibitors

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.

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Bracknell, United Kingdom

Simon Neil Duncum