Inhibition of N-vinylpyrrolidone on hydrate in high-pressure flow system under the synergistic effect of ether compounds

Abstract

Through the experimental tests as performed on a high-pressure flow loop test bench, the synergistic effect of diethylene glycol monoethyl ether (DEGEE), propylene glycol methyl ether (PM), and ethylene glycol phenyl ether (EPH) on the inhibition of inhibitors on hydrate growth was explored under the same initial temperature (285.15 K), pressure (5.0 MPa) and flow rate (230 L/h). The average particle size, relative inhibition performance factor (RIP), and initial formation rate of methane hydrate in the system with a single kinetic inhibitor (or monoalcohol ether synergistic agent) were obtained by experiments, and compared with the relevant parameters in the system with a kinetic inhibitor and a synergistic agent. The experimental results show that the presence of PVP in the system increases the average particle size, which may be due to the adsorption of kinetic inhibitors on hydrate crystals. When the relative inhibition performance factor was used as the index, all the three kinds of synergistic agents promoted the inhibition performance of PVP. DEGEE had the best promotion effect, EPH was the weaker, and PM was the weakest. The synergistic agents in the composite system had little effect on the initial formation rate of hydrate. The addition of kinetic inhibitors and synergistic agents would transform the hydrate formation medium from the wall to the gas–water interface, while the presence of the oil phase in the system significantly weakened the inhibition performance in the kinetic inhibitor-synergist system. The results and theories obtained in this experiment can provide a theoretical basis for the flow guarantee in actual pipelines.