Development And Performance Evaluation Of Poly Vinyl Caprolactam Hydrate Inhibitors

The formation of gas hydrates in natural gas or oil pipelines has long been a serious problem in gas and oil industries. Adding inhibitors is the most effective way to solve the hydrate plugging. Composite inhibitors can overcome the short comings of single inhibitors, which become the focus of the development of inhibitors in special conditions.In this study, based on vinyl caprolactam amide monomer, diethylene glycol butyl ether as solvent, a series of inhibitor HYs(with different dosages of inhibitors) was synthesized. The product structures were characterized by infrared spectrum, GPC and the viscometer. The product molecular weight(23419~34866) and features viscosity(0.55856L·g-1~0.75503 L·g-1)increases as the dosage of initiator(0.1%~0.4%).Through hydrate inhibitor evaluation device, rapid cooling method and constant temperature method is used to compare the HYs series inhibitors effects of THF hydrate. The performance of HY 121 is the best among the HYs, and the performance of HY 122, HY 123, and HY 124 decreased in turn. From that for HY 121(molecular weight minimum) with less dosage of initiator, the inhibition performance is better. The performance of HY 121 in THF hydrate is much better than PVCap(HY 121 exclusive of diethylene glycol butyl ether HY 121), The former’s induction time is 289 min at- 5 ℃, the latter is only 67 min.Using the uniform design method, HY 121 kinetic inhibitors were compounded with methanol(MA), ethanol(ET) and ethylene glycol(EG). From the Formula between the concentration and induction time about HY 121 and methanol,the effects of concentration of HY 121 on induction time is more significant.Comparing the several kinds of compound inhibitor, inhibition performance of methanol is the best, followed by ethylene glycol, and ethanol is the worst.When the performance of these three composite inhibitors is the same, used of ICI company environment load analysis and fuzzy comprehensive evaluation, and compared environment load of Methanol, ethanol, and ethylene glycol(mass ratio is 1:7.1:1.7). Ethylene glycol to the environment load is the smallest.The performance of different kinetic inhibitors on gas hydrate formation was studied. The inhibitory effect of HY121 at 1% was compared with commercial inhibitor HY1, Inhibex501. HY 121 showed the best inhibition effect, which could inhibit gas hydrate formation for 78.3h at 4MPa, and for 62.55 h at 6.0MPa.