Method for inhibiting hydrate formation

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. Each N-vinyl amide and N-allyl amide unit has two substituent groups, R1 and R2, substituted on the nitrogen where R1 is a hydrogen or hydrocarbon group having one to six carbon atoms and zero to two heteroatoms selected from the group consisting of oxygen, nitrogen, and combinations thereof, where R2 is a hydrocarbon group having one to six carbon atoms and zero to two heteroatoms selected from the group consisting of oxygen, nitrogen, and combinations thereof, and where the sum total of carbon atoms in R1 and R2 is greater than or equal to one, but less than eight. Some preferred examples of such polymers include copolymers of N-vinyl amides and substituted acrylamides. 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.

Description

field of invention [0001] The present invention relates to a method for inhibiting the formation of clathrate hydrates in fluids. More specifically, the present invention relates to a method of inhibiting the formation of gaseous hydrates in pipelines used to transport oil or gas. Background of the invention [0002] Carbon dioxide, hydrogen sulfide, and various hydrocarbons such as methane, ethane, propane, n-butane, and isobutane are present in natural gas and other petroleum fluids. However, water is typically found mixed with these petroleum fluid components in varying amounts. Clathrate hydrates can be formed when these petroleum fluid components or other hydrate formers are mixed with water under conditions of elevated temperature and reduced pressure. Clathrate hydrates are water crystals that form a cage structure around a guest molecule such as a hydrate-forming hydrocarbon or gas. Some hydrate-forming hydrocarbons include, but are not limited to, methane, ethane...

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Problems solved by technology

Also, these solvents are difficult to fully recover from production or delivery streams