Development and application of in-flight centrifuge apparatus for modelling hydrate exploitation

The natural gas hydrate, widely distributed in deep sea sediment and terrestrial permafrost, is considered as an important potential energy to solve the increasingly serious energy crisis. Hydrate is formed under high pressure and low temperature conditions, where the reservoir is tens of meters in thickness. The gravity field of large-scale reservoir significantly affects the process of fluid seepage, skeleton deformation and heat transfer during exploitation, changing the gas production rate and further inducing possible engineering disasters. An in-flight centrifuge apparatus, which is composed of high-pressure vessel, hydrate synthesis module, water pressure control module, hydrate exploitation module and monitoring module, for modelling hydrate exploitation is developed. The apparatus can servo control the pressure and temperature conditions in the high-pressure vessel under 100g hyper gravity, and effectively reproduce the stress, temperature and loading conditions of hydrate reservoir in the model scale. A hydrate exploitation modelling test via depressurization at 100g is then carried out. The evolution of pore pressure at different depths and the gas production characteristics under the field scale stress gradient are analyzed, and the gas production characteristics of field production tests in Nankai trough are reproduced. The developed apparatus provides a novel experimental approach to investigate the multiphase coupling mechanics and disasters prevention during hydrate exploitation.