Research and Field Test of a Pressure-Stabilizing Transfer Device for Natural Gas Hydrate Samples

Natural gas hydrate is an ice-like crystalline substance formed by natural gas and water at high pressure and low temperature.It is extremely sensitive to changes in temperature and pressure.If the disturbed hydrocarbon gas escapes due to changes in temperature and pressure,the hydrate will tend to disintegrate in a potentially explosive manner,thereby destabilizing the borehole.Therefore,after drilling of natural gas hydrate samples,a core transfer devices must be carefully aligned with the coring tools to transfer samples to the laboratory,it is important to maintain pressure during the transfer and preservation of the the samples of natural gas hydrates.After many years of research on the stabilization of pressure in the natural gas hydrate thermal pressure sampling tools and equipment and core transfer technologies,one core pressure-holding transfer device was developed with hydraulic cylinder to pull and push the pressure sampling tube.Both indoor and field tests demonstrated that the pressure-holding transfer device could be operated flexibly,and had high pressure resistance,good sealing performance.Thus is could successfully transfer the natural gas hydrate samples under pressure from the sampling zone to test lab.This new technique provided technical support for independent exploration of natural gas hydrate sampling in China.