Development And Evaluation Of New-type Gas Hydrate Inhibitors

Hydrate plug in oil-gas-water multiphase pipelines has become a serious problem.The traditional measure to treat it is injecting high dosage of thermodynamic inhibitors into pipeline.Kinetic hydrate inhibitors(KHIs)have drawn wide attention in recent years because of their low dosages and environmental friendship.This work has been performed with respect to evaluating inhibition performances of mixed proteins(inhibitor-P)and Alkyl Polyglucoside(APG)to the formation of natural gas hydrate and methane hydrate respectively.Main contents are as follows:(1)The influences of inhibitor-P upon the induction time for natural gas hydrate to form from aqueous solution under different dosages and subcoolings were investigated.At the same time,the morphology of hydrate formation was observed and the kinetic inhibition mechanism was discussed.Comparison tests show that the kinetic inhibition performance of inhibitor-P is close to that of one commercial inhibitor PVP.(2)The kinetic inhibition performances of the mixtures of inhibitor-P with different kind of thermodynamic inhibitors to the hydrate formation from natural gas + water system have been investigated.The result demonstrates that the best inhibition performance could be achieved when inhibitor-P works together with methanol(M).Further investigations show that the suitable mass ratio of inhibitor-P to methanol is 1:9 and the suitable total dosage the mixing inhibitor in water is 5 wt%,under which the maximum subcooling could achieve 5.20 K.(3)The kinetic inhibition performance of Alkyl polyglycoside(APG)to the hydrate formation from methane + water system was investigated in a high-pressure transparent sapphire cell.Subsequently,by using Particle Video Microscope(PVM)and Focused Beam Reflectance Measurement(FBRM)probes,morphology evolvement and distribution of hydrate particle chord length during the hydrate formation from methane + oil/water system was investigated in the presence of APG as kinetic inhibitor and Span 20 as emulsifier.It was demonstrated that the average chord length of hydrate particles became shorter when APG worked together with Span 20.This result implies that addition of Span 20 could improve the flow behavior of system after the hydrate formation.(4)Biodegradabilities of inhibitor-P,APG and PVP have been tested by using microbiological cultivation method.The results show that P and APG have good biodegradability while PVP has poor biodegradability.