Improved Gas Hydrate Kinetic Inhibition for 5-Methyl-3-vinyl-2-oxazolidinone Copolymers and Synergists

Kinetic hydrate inhibitors(KHIs) are used to prevent depositsand plugging of oil and gas production flow lines by gas hydrates.The key ingredient in a KHI formulation is a water-soluble amphiphilicpolymer. Recently, polymers of a new commercially available 5-ringvinylic monomer 5-methyl-3-vinyl-2-oxazolidinone (VMOX) were investigatedas KHIs and shown to perform better than some commercial KHI polymerssuch as poly(N-vinyl pyrrolidone). This initial studyusing slow constant cooling (SCC) in rocking cells with a syntheticnatural gas has now been expanded to further explore low molecularweight PVMOX homopolymers and VMOX copolymers as well as blends withnonpolymeric synergists. A PVMOX homopolymer with improved KHI performancewas found using 3-mercaptoacetic acid as a chain transfer agent inthe radical polymerization of VMOX. Among a range of copolymers, VMOX:n-butyl acrylate copolymers in particular gave good KHIperformance, better than the PVMOX homopolymer. Among the potentialsynergists, trialkylamine oxides (alkyl = n-butylor iso-pentyl) and tetra(n-pentyl)ammonium bromideto 2500 ppm were found to be antagonistic with PVMOX at the test concentrationswhile some alcohols and glycols were synergetic. The best synergistwas 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD). For example, a mixtureof 2500 ppm TMDD with 2500 ppm PVMOX (M (w) 2400 g/mol) performed significantly better than 5000 ppm PVMOX.Addition of 1250 ppm TMDD to 2500 ppm VMOX:n-butylacrylate 6:4 copolymer lowered the hydrate onset temperature in SCCtests by a further 3 & DEG;C compared to the copolymer alone givinghydrate onset at 4.2 & DEG;C.

Automated summary

Kinetic hydrate inhibitors (KHIs) are being studied to prevent the formation of gas hydrates and blockage in oil and gas production flow lines. Recent research has shown that polymers made from the commercially available monomer VMOX perform better than some existing KHI polymers. This study explored the use of low molecular weight PVMOX homopolymers, VMOX copolymers, and blends with nonpolymeric synergists to improve the performance of KHIs.