Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is claimed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitors used for practicing the method comprise substantially water soluble polymers having N-vinyl amide or N-allyl amide units. Specific examples of such copolymers include, N-vinyl-N-methylacetamide (VIMA) copolymerized with acryloylpyrrolidine (APYD) or acryloylpiperidine (APID), and more preferably, VIMA copolymerized with N-substituted methacrylamides, such as N-isopropylmethacrylamide (iPMAM) and methacryloylpyrrolidine (MAPYD) to produce inhibitors for practicing the claimed method.

Abstract: Novel maleimide copolymers have at least two monomeric units, a maleimide unit and a vinyl unit having a pendant group, the pendant group having two to twenty-one carbon atoms, at least one nitrogen atom and at least one oxygen atom. The copolymer has an average molecular weight between about 1,000 and about 6,000,000. Preferred maleimide copolymers include acrylamide/maleimide copolymers, N-vinyl amide/maleimide copolymers, vinyl lactam/maleimide copolymers, alkenyl cyclic imino ether/maleimide copolymers, and acryloylamide/maleimide copolymers. The substantially water soluble maleimide copolymers are useful for inhibiting the formation of clathrate hydrates in a fluid having hydrate-forming constituents by reducing the rate of nucleation, growth, and/or agglomeration of gas hydrate crystals in a petroleum fluid stream, thereby inhibiting the formation of a hydrate blockage in the pipe conveying the petroleum fluid stream.

Abstract: A method for inhibiting the formation and/or agglomeration of clathrate hydrates in a petroleum fluid stream containing water is disclosed. The disclosed method uses predetermined inhibitors having a guest group, a polymer backbone, and an anchor group positioned between the guest group and the polymer backbone. The inhibitor predetermination method comprises selection of the polymer backbone, anchor group and guest group using several types of criteria. The polymer backbone should produce a substantially water soluble polymer in combination with the anchor group and the guest group. The anchor group should be a hydrophilic moiety with between one and four hydrogen bonding atoms. The guest group should be either a hydrophobic or amphiphilic moiety with a carbon atom to heteroatom ratio greater than or equal to about two to one and an average van der Waals diameter between about 3.8 angstroms and about 8.6 angstroms.

Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is disclosed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The hydrate inhibitor used for practicing the method is selected from the family of substantially water soluble copolymers formed from N-methyl-N-vinylacetamide (VIMA) and one of three comonomers, vinylpyrrolidone (VP), vinylpiperidone (VPip), or vinylcaprolactam (VCap). VIMA/VCap is the preferred copolymer. These copolymers may be used alone or in combination with each other or other hydrate inhibitors. Preferably, a solvent, such as water, brine, alcohol, or mixtures thereof, is used to produce an inhibitor solution or mixture to facilitate treatment of the petroleum fluid stream.

Abstract: Novel maleimide copolymers have at least two monomeric units, a maleimide unit and a vinyl unit having a pendant group, the pendant group having two to twenty-one carbon atoms, at least one nitrogen atom and at least one oxygen atom. The copolymer has an average molecular weight between about 1,000 and about 6,000,000. Preferred maleimide copolymers include acrylamide/maleimide copolymers, N-vinyl amide/maleimide copolymers, vinyl lactam/maleimide copolymers, alkenyl cyclic imino ether/maleimide copolymers, and acryloylamide/maleimide copolymers. The substantially water soluble maleimide copolymers are useful for inhibiting the formation of clathrate hydrates in a fluid having hydrate-forming constituents by reducing the rate of nucleation, growth, and/or agglomeration of gas hydrate crystals in a petroleum fluid stream, thereby inhibiting the formation of a hydrate blockage in the pipe conveying the petroleum fluid stream.

Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate forming constituents is disclosed. More specifically, the method can be used in treating a petroleum fluid stream such as natural gas conveyed in a pipe to inhibit the formation of a hydrate restriction in the pipe. The method uses a mixture comprising a first additive and a second additive. The mixture produces a synergistic hydrate inhibition effect. The first additive is selected from the class of substantially water soluble polymers. The second additive is selected from the class of ionic or non-ionic organic compounds which have a polar part and nonpolar part with the nonpolar part having an alkyl, alkenyl, or alkynyl group with 12 or fewer carbon atoms.