Copolymers comprising C.sub.14 to C.sub.50 olefins and at least two different olefindicarboxylic esters and optionally maleic acid or maleic acid derivatives. The olefindicarboxylic esters are firstly esters with linear C.sub.18- to C.sub.50-alkyl groups and secondly esters with short-chain linear, branched or cyclic alkyl groups, or esters with aromatic groups. The invention further relates to a process for preparing copolymers of this kind and to the use thereof as pour point depressant for crude oil, mineral oil and/or mineral oil products, preferably as pour point depressant for crude oil.

Disclosed are paraffin inhibitors, paraffin suppressant compositions, and methods of making and using them. The paraffin inhibitors comprise polymers of a maleic moiety polymerized with at least two olefins having hydrocarbon chains of a different length from each other. When added to hydrocarbon media such as crude oils to form crude oil compositions, the paraffin inhibitors inhibit the precipitation of paraffin waxes in the crude oil compositions and exhibit reduced precipitation, gelling, and/or crystallization from the hydrocarbon media when the media are subjected to sustained low temperatures.

This disclosure relates to winterized pour point depressant compositions for petroleum fluids. Such compositions exhibit stability and are flowable at temperatures down to as low as 47 C., without the need for further dilution.

Fouling and/or asphaltene agglomeration (or flocculation) in midstream processes and transportation and in upstream transportation of a hydrocarbon oil is reduced by providing in the oil an additive combination including; (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) a metal detergent system comprising a hydrocarbyl-substituted hydroxybenzoate metal salt or a hydrocarbyl-substituted sulfonate metal salt or a mixure of both salts or a complex thereof,
where the mass:mass ratio of (A) to (B) is in the range of 20:1 to 1:20 and the treat rate of the additive is in the range of 5 to 10000 ppm by mass.

A liquid hydrocarbon marine fuel oil includes a marine distillate fuel or a heavy oil or a blend thereof containing an additive combination including: (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) a metal hydrocarbyl-substituted hydroxybenzoate and/or sulfonate detergent, where the mass:mass ratio of (A) to (B) is in the range of 20:1 to 1:20 and the treat rate of the additive combination is in the range of 5 to 10000 ppm by mass.

Compositions may include a wax modifier that is the product of a reaction between a polysaccharide having a number of sugar subunits in the range of 2 to 60 and one or more fatty acid reagents, and a reservoir fluid produced from a subterranean formation comprising one or more components capable of producing waxes. Methods may include contacting a hydrocarbon fluid with a wax modifier, wherein the wax modifier is the product of the reaction of a polysaccharide and one or more fatty acid reagents. Methods may also include introducing a wax modifier into a wellbore penetrating a subterranean formation, wherein the wax modifier is the product of a reaction between a polysaccharide and one or more fatty acid reagents; producing hydrocarbons from the subterranean formation; and allowing the wax modifier to inhibit the precipitation of a wax.

Compositions may include a wax modifier that is the product of a reaction between a polysaccharide having a number of sugar subunits in the range of 2 to 60 and one or more fatty acid reagents, and a reservoir fluid produced from a subterranean formation comprising one or more components capable of producing waxes. Methods may include contacting a hydrocarbon fluid with a wax modifier, wherein the wax modifier is the product of the reaction of a polysaccharide and one or more fatty acid reagents. Methods may also include introducing a wax modifier into a wellbore penetrating a subterranean formation, wherein the wax modifier is the product of a reaction between a polysaccharide and one or more fatty acid reagents; producing hydrocarbons from the subterranean formation; and allowing the wax modifier to inhibit the precipitation of a wax.

A method for minimizing power loss, reducing a fuel consumption and/or for reducing and/or avoiding deposits in a fuel system in the direct injection diesel engines. The method contains adding a copolymer to a fuel composition, wherein the copolymer contains, in a copolymerized form: (A) an ethylenically unsaturated mono- or dicarboxylic acid or a derivative thereof, (B) an -olefin having from 12 to 30 carbon atoms, (C) optionally an additional aliphatic or cycloaliphatic olefin which has at least 4 carbon atoms and is different from monomer (B) and (D) optionally an additional copolymerizable monomers other than monomers (A), (B) and (C), anhydride or carboxylic acid functionalities present in the copolymer are partly reacted with at least one compound (E) comprising an alcohol group and/or an amino group, and the anhydride functionalities present in the copolymer are hydrolysed and/or carboxylic ester functionalities present in the copolymer are partly hydrolyzed.

Disclosed are cloud point depressants and methods of making and using them. The disclosed cloud point depressants comprise copolymers of an unsaturated anhydride polymerized with alkyl -olefins and then contacted with a phenyl alkyl alcohol or alkyl phenol alkoxylate, fatty alcohol and primary or secondary fatty amine to provide a cloud depressant reaction product. When the disclosed reaction products are added to middle distillate fuels or blends of middle distillate fuels with biodiesel, the cloud point depressants inhibit the precipitation of waxes and/or biowaxes in the fuels and the fuels exhibit reduced precipitation, gelling, and/or crystallization when subjected to low or cold temperatures.

Mixtures of certain olefin-carboxylic acid copolymers (A) with at least one additive with detergent action, preferably at least one quaternary nitrogen compound (B), and optionally further fuel additives, are useful for improving the stability of additive packages for fuels, especially fuel oils and gasoline fuels.