Research on the Phase Equilibrium and Formation Rate of Hydrates in Silt Sand Systems Considering the Influence of Inhibitors

Deepwater shallow gas reservoirs exhibit low compaction and poor cementation, posing a high risk of sand production during natural gas extraction. Concurrently, deepwater wellbores face challenges such as inefficient gas-liquid separation at the well bottom and low-temperature high-pressure conditions. This results in a coexisting state of methane, sand particles, and water within the wellbore, creating a risk of hydrate formation and blockage across most areas. Methane hydrate phase equilibrium experiments under silt sand-containing conditions were conducted using a low-temperature, high-pressure stirring kettle. The study examined the effect of silt sand on the phase equilibrium and formation rate of methane hydrates when treated with ethylene glycol, a commonly used hydrate inhibitor in engineering applications. Results indicate that silt sand content ranging from 0.2% to 2.5% shifts the hydrate phase equilibrium curve to the right by 0.6–1.2 °C. At a silt sand concentration of 2.5%, the induction time for hydrate formation was reduced by 53.125%. The presence of silt sand diminished the inhibitory effect of ethylene glycol on hydrate formation; at a 2.5% silt sand concentration, the ethylene glycol-containing hydrate phase equilibrium curve shifted rightward by an average of 0.4–1.4 °C, and the hydrate formation rate at different ethylene glycol concentrations decreased by an average of 0.02–0.21 mol/(100·min). This study provides a theoretical basis for identifying hydrate formation risks during deepwater natural gas extraction.