Effects of Pipeline Wall Surface Corrosion and PVP on Adhesion Behavior between Cyclopentane Hydrate and Inner Surface of Pipeline

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