Progress on Laboratory-Scale Reactors for Simulating Gas Production from Hydrate Reservoir

Enormous laboratory efforts have been made to establish a better understanding of gas production behaviors from hydrate reservoirs. This involves an artificial synthesis and decomposition of hydrate samples in various reactors. The reactors should play a crucial role in the behaviors of hydrate formation and decomposition as well as their feasibility to scale-up. Therefore, a comprehensive summary of the current equipment is necessary. In this work, typical reactors used to study gas production behaviors from hydrate-containing sediments are introduced, involving their sizes, sensors, pressure and temperature controlling systems, and special features; the significant findings based on these reactors are also discussed. Through the results of laboratory experiments, the state of hydrate reservoirs and the changes in their characteristics during the production process can be understood; this may involve the kinetics of hydrate decomposition and its influencing factors and the seepage process of multiphase flow in sediments. Consequently, the primary control factors and control methods that affect the gas production rate and environmental safety can be given. The real-time measurement of hydrate reservoir temperature, pressure, sonic velocity, resistivity, stress, and other parameters can be determined; thus, the research on natural gas hydrate in the laboratory requires very strict equipment for support. Nevertheless, the space of the indoor simulated reactors was limited; the diameter of the largest reactor was no more than 2 m, which is not comparable to the actual reservoir. Therefore, it is still very challenging to upscale the laboratory findings to guide the on-site operation; multiscale approaches involving numerical simulation are of crucial importance as well.