Study on the performance of downhole spiral-cyclone coupling separator for natural gas hydrate

Aiming at the problems of reservoir collapse and pipeline blockage caused by serious sand production in the exploitation of natural gas hydrate, the downhole spiral-cyclone coupled in-situ separator is used for sand removal. The separator structure is determined by the physical parameters and empirical formulas. The structure is analyzed and optimized by CFD numerical simulation. The optimal structural parameters of the separator are obtained: the position of the vortex guide plate is 28 mm, the number of inlets is 6, the spiral flow channel structure is a circular section, the number of spiral lines is 2, and the depth of the overflow pipe is 100 mm. At this time, the sand removal efficiency of the separator is 89.55 %. The experimental verification was carried out. The maximum sand removal efficiency of the indoor test was 84.46 %, and the relative error with the simulation was 5.51 %. Through the comparison between experimental phenomena and numerical simulation, it is clear that the spiral-cyclone coupling separator has good performance in the separation and sand removal of natural gas hydrate underground mining. The research in this paper can provide some reference for the design and optimization of natural gas hydrate downhole in-situ separators.