Molecular-Scale Study of the Interfacial Effects of Kinetic Inhibitors on Hydrate Growth and Crystal Stability

Kinetic hydrate inhibitors (KHIs) have shown significant potential in preventing hydrate blockages and ensuring flow assurance by delaying hydrate nucleation and aggregation. However, the molecular mechanisms by which KHIs influence the early-stage growth and stability of hydrate fluids under oil and gas flow conditions remain insufficiently understood, limiting the optimization and development of more efficient formulations. In this paper, molecular dynamics (MD) simulations were employed to systematically investigate the regulatory effects of two representative KHIs─polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap)─on gas hydrate prevention; and the interaction mechanism between the molecules was elucidated by combining molecular dynamics simulations with Density Functional Theory (DFT). Key parameters, including the number of cage structures, the water molecule ordering parameters, and the potential energy, were also analyzed to assess the inhibitors’ impacts on gas hydrate growth and fluid stability. The results reveal a triple synergistic mechanism involving site-blocking, mass transfer interference, and hydrogen-bond disruption, which provides a theoretical basis for the design and optimization of high-efficiency KHIs in the traditional fossil fuel transportation, particularly in oil and gas flowlines.