Effects of shear loading rate on tetrahydrofuran Hydrate Adhesion strength for enhanced flow assurance

Abstract

Hydrate formation and accumulation pose significant challenges in oil and gas pipelines, leading to flow assurance issues and safety hazards. It is crucial to understand hydrate adhesion to prevent the accretion of hydrate in petro-pipelines. In this study, the adhesion strength (AS) of tetrahydrofuran (THF) hydrate on various solid surfaces with different elastic moduli subjected to shear loading rates ranging from 10 to 10000 μm/s is comprehensively investigated by shear force experimental measurements and finite element (FE) simulations. The results reveal that the hydrate AS is primarily influenced by the elastic modulus of the substrates, and the shear-induced detachment properties are strongly dependent on the shear loading rate. Specifically, when the hydrate is synthesized on a soft polydimethylsiloxane (PDMS) substrate, the AS exhibits minimal changes at low and high shear loading rates. However, under intermediate shear loading rates, the AS rapidly increases by approximately 500 %. In contrast, when the hydrate is formed on stiff polytetrafluoroethylene (PTFE) and polyethylene (PE) substrates, the AS is increased by approximately 200 % and 230 %, respectively as shear loading rate increases. Interestingly, for the hydrate on a stiff hydrophobic coated glass slide (CG) substrate, the AS anomalously decreases with increasing shear loading rates. These findings provide valuable insights into the effects of substrate properties and shear loading rate on hydrate adhesion. The results are of significance for the design of optimal coatings that ensure flow assurance of oil and gas in pressure-variant petro-pipelines.