Research on pressure-stabilizing system for transfer device for natural gas hydrate cores

To broaden the analysis means for natural gas hydrate (NGH)-pressured cores, long-columnar cores are usually cut into smaller segments with a pressure-retaining transfer device for NGH. The pressure-stabilizing system is the core part of a transfer device for NGH, providing a stable high-pressure environment for the transfer process to avoid NGH decomposition. In this study, the characteristics of the pressure-stabilizing system were thoroughly studied, and the factors affecting the pressure fluctuations in the transfer device were discussed. Accordingly, the pressure-stabilizing system was modeled with AMESim software, and the model parameters were set according to the actual working conditions. The simulated pressure fluctuations in the transfer process of transfer device for NGH confirm the theoretical results, which indicate that the precharge pressure of the accumulator should be 0.8-0.9 times the working pressure. In addition, an increased accumulator volume decelerates the response of the system. Experiments were conducted to test the reliability of the pressure-stabilizing system. During the transfer process of the NGH sample, the operating pressure can reach 20 MPa, and the fluctuations of the inner pressure are below 20%.