Method for inhibiting hydrate formation

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.

We claim: 
     
       1. A method for inhibiting the formation of clathrate hydrates in a fluid having water and other hydrate forming constituents, said method comprising treating said fluid with a first additive and a second additive, said first additive comprising a substantially water soluble polymer and having a first independent effect on the formation of clathrate hydrates in said fluid, said second additive comprising a substantially polar part and a substantially nonpolar part, wherein said nonpolar part is an alkyl, alkenyl, or alkynyl group with 12 or fewer carbon atoms and having a second independent effect on the formation of clathrate hydrates in said fluid, thereby producing a total inhibition effect for said fluid which is greater than the combination of said first and second independent effects for said fluid. 
     
     
       2. The method of claim 1 wherein said second additive has a concentration in said fluid between about 0.05% and about 6% by weight of said water in said fluid. 
     
     
       3. The method of claim 1 wherein said fluid is treated substantially simultaneously with said first and second additive. 
     
     
       4. The method of claim 1 wherein said fluid is treated first with said first additive and treated second with said second additive. 
     
     
       5. The method of claim 1 wherein said fluid is treated first with said second additive and treated second with said first additive. 
     
     
       6. The method of claim 1 wherein said first additive is selected from the group consisting of polyvinyllactams, polyalkylacrylamides, polyalkyloxazolines, polyvinylcarboxylates, and copolymers thereof. 
     
     
       7. The method of claim 1 wherein said second additive is selected from the group consisting of non-ionic, anionic, cationic, zwitterionic organic compounds and mixtures thereof. 
     
     
       8. The method of claim 7 wherein said organic compound is selected from the group consisting of alcohols, ethers, and organic salts.