Development and feasibility test of a fan-shaped hydrate simulator with a radius of 3 m

Large-scale physical simulation is essential for advancing our understanding of natural gas hydrates exploitation mechanism. However, cylinder-shaped simulators often face challenges in balancing large volume, controllability, and comprehensive monitoring. In this study, we developed a fan column-shaped hydrate simulator (FCHS) with an internal angle of 6°, a radius of 3 m, and an inner height of 0.3 m, resulting in an effective volume of ~142 L. Moreover, the FCHS is equipped with an integrated "thermal-pressure-acoustic" sensing system, enabling in-situ monitoring of temperature, pressure, and P-wave velocity evolution during hydrate formation and dissociation process. The experimental results indicate that a pressure gradient successfully established from the reservoir center toward its boundaries during depressurization stage, and pressure propagation is relatively slow, resulting in a radial pressure difference of 3–4 MPa within a 3 m range. Once the system reaches pressure equilibrium, the pressure difference decreases to 0.3–0.4 MPa. The depressurization at the wellbore promotes hydrate dissociation in the near-well region, resulting in the radial temperature difference reaches ~1.5 ℃ along the radial direction. The acoustic data reveals that a radial gradient in hydrate saturation gradually forms from the center to the boundary during depressurization-induced gas production. The evolutions of spatio-temporal multi-fields obtained in the FCHS are consist with that of field production. The FCHS proves to be a cutting-edge platform for experimental simulation of NGH exploitation and carbon sequestration processes.