Development of a pressure-retained transfer system of seafloor natural gas hydrates

Abstract

In order to improve the utilisation rate of the cores of natural gas hydrate samples from the seafloor and broaden the means of the analysis of pressured cores, long-columnar cores obtained by the gravity-piston pressure corer are usually cut into smaller segments, which are then transferred to pressure chambers before they are sent to the laboratory for further analysis. The transfer system for the core of the natural gas hydrate sample in this paper is able to keep the in situ pressure during the transfer process, which can prevent the changing of physicochemical properties of the cores. In addition, the system can also realise the actions of core pushing, cutting and subsampling. The pressure-retaining feature of the transfer system is discussed in this paper, and an experiment was carried out to test the reliability of the pressure retaining of the system. Moreover, the transfer system was tested in the South China Sea twice and showed an excellent performance of pressure maintenance.