Microscopic forces between methane hydrate particle and droplet-wetted sand grain surface in a high-pressure system: Experiments and mechanisms

Solving the issue of hydrate formation and blockage in pipelines during deepwater oil and gas development and hydrate-based green energy extraction is a crucial flow assurance safety concern. The micro-forces between hydrate particles and wetted surfaces are key parameters in studying the aggregation or detachment behavior of hydrates on pipe walls. Current research primarily focuses on carbon steel surfaces, with a lack of studies on the micro-forces between hydrates and wetted sand grain surfaces in oil and gas pipeline flow systems and hydrate extraction processes. In this study, a visual particle micro-force measurement device was designed to investigate the micro-forces between hydrates and wetted sand grain surfaces in a high-pressure system. The results showed that at subcooling degrees of 1, 3, 5, 7, and 10 ℃, the micro-forces between hydrate particles and wetted sand grain surface droplets ranged from 4242.46 to 8315.27 mN·m⁻¹. The micro-force increased by 196.88%, 217.99%, 219.92%, 209.92%, and 218.47% compared to the micro-forces between hydrate particles and wetted carbon steel surfaces. Subcooling and contact time are strong functions of the micro-force between hydrate particles and wetted sand grain surfaces. The enhancement of the micro-force on the wetted sand grain surfaces is primarily attributed to the increased supporting force provided by the hydrate shell. The increase in micro-force is governed by the superposition of multi-scale adhesion forces. Factors such as the hydrophilic nature of sand grain surfaces, pore effects, blockage of pore channels, localized pressure concentration, and mechanical interlocking effects contribute to the increased micro-force between hydrate particles and the wetted sand grain interface. This study lays a foundation for elucidating the coupling deposition mechanism of hydrates and sand grains during deepwater oil and gas production, and further provides a theoretical reference for the safe, efficient, and continuous exploitation of hydrate-based green energy.