Synergistic Effect Of Hydrophilic Amino Acids And Hydrate Kinetic Inhibitors

Natural gas hydrate is crystalline clathrate compounds composed of natural gas and water at low temperature and high pressure.During the hydrate drilling & production of deep-sea and long-distance pipeline transportation of crude oil and natural gas,hydrate can easily form again and cause a series of safety accidents.In order to prevent and control hydrate formation,chemical inhibitors have been added to it.In recent years,amino acids have become a research hotspot because of their environmental-friendly and hydrate inhibitory advantages.However,the mechanism of their action,especially the synergistic mechanism of their combination with hydrate kinetic inhibitors,is still unclear.Therefore,in this paper,through the formation of tetrahydrofuran hydrate simulation experiment,the influence rule and inhibition mechanism of hydrophilic amino acids and their combination with kinetic inhibitors were studied.The effects of glycine and L-arginine on hydrate formation and phase equilibrium were studied by laboratory experiments,and the internal mechanism of hydrophilic amino acids inhibiting hydrate was revealed.The results showed that glycine and L-arginine not only increased the equilibrium pressure of methane hydrate at the same temperature,but also had the ability to disturb the molecular structure of water.In addition,it was found that glycine distributed more evenly in the solution due to its own chain length,which could effectively prevent hydrate nucleation and make the time of glycine inhibiting hydrate formation(312.67min)far away The inhibition time of L-arginine was longer than that of L-arginine(216.71 min).The effects of glycine and khis on hydrate and its inhibition mechanism were studied by laboratory experiments.The results showed that when glycine was mixed with pvpk90 and VC-713,the amount of glycine was more than 3.0wt% and 1.5wt%respectively,the hydrate was no longer formed,and the inhibition effect was better than that of the single system,because amino acids blocked the formation of "cage structure" of water molecules and inhibited the nucleation of hydrate;pvpk90 and VC-713 wrapped on the surface of "cage hydrate" by adsorption Growth.Finally,the influence of the mixture of L-arginine and khis on hydrate formation was clarified through the simulation experiment,and the synergistic inhibition mechanism was revealed.Pvpk90 molecular structure is monomer unit,VC-713 is terpolymer,VC-713 is easier to adsorb and wrap on the surface of hydrate cage structure,and VC-713 is easier to combine with hydrophilic amino acids,so VC-713 has stronger synergistic inhibition effect in inhibiting hydrate formation.The research results can provide theoretical basis for safe drilling,production and long-distance transportation of natural gas hydrate and conventional oil and gas.