Effects of Pipeline Wall Surface Corrosion and PVP\non Adhesion Behavior between Cyclopentane Hydrate and Inner Surface\nof Pipeline

In\nthe process of deep-water oil and gas pipeline transportation,\nthe cohesive force between hydrate particles and solid wall surfaces\nis a key parameter determining the aggregation and deposition of hydrates,\nand the surface morphology of the pipeline is one of the main factors\naffecting the magnitude of this cohesive force. To clarify the impact\nof corroded pipeline wall surfaces on the cohesive force, this study\nused a micromechanical force device to directly measure the cohesive\nforce under different pipeline wall surface conditions. It was found\nthat when the inner wall surface of the oil and gas pipeline corrodes,\nthe contact area between the hydrate particles and the liquid layer\non the solid pipeline wall surface increases with changes in wall\nsurface roughness, leading to the formation of larger liquid bridges\nand, consequently, increasing the cohesive force between hydrate particles\nand the solid wall surface. As corrosion time increases, the cohesive\nforce between hydrate particles and the solid wall surface shows a\ngradual increase; after 48 h of corrosion on X80 steel, this cohesive\nforce increased by 36.08% compared to the noncorroded state. On this\nbasis, the effect of the kinetic inhibitor PVP on the cohesive force\nunder corroded wall surfaces was investigated. The results showed\nthat the presence of PVP can alter the thickness of the quasi-liquid\nlayer on the hydrate particle surfaces and the formation state of\nthe hydrate particles, thereby changing the volume of the liquid bridges\nformed between the hydrate particles and the solid wall surfaces,\nfurther affecting the cohesive force. Compared to pure water systems,\nthe addition of low concentrations of PVP (below 1.0 wt %) reduces\nthe adhesion of hydrate particles to the solid wall surfaces in all\ncases. However, when the concentration increases to 1.5 wt % or higher,\nthe effect of reducing adhesion disappears and instead increases the\ncohesive force between hydrate particles and the solid wall surfaces.\nThis study explores the impact of corrosion conditions on the adhesion\nbehavior of hydrate particles to solid surfaces and reveals the role\nof the low-dose kinetic inhibitor PVP in resisting hydrate particle\naggregation. This is crucial for ensuring the safety of pipeline operations.