In the study of natural gas hydrates, the maintenance of the low-temperature and high-pressure state of the core sample under in situ conditions is highly important for cutting, transferring, and subsequent analysis. The pressure maintenance and temperature control device (PMTCD) for natural gas hydrate core samples described in this paper is a subsystem of the pressure-retaining and transfer device. The device consists of a water tank, seawater chillers, a plunger pump and a thermoelectrical refrigeration device. The device cools the seawater to 2 °C, and then pressurizes it to inject it into the sample cylinder. Due to the inevitable heat generated by the pressurization and heat exchange with environment, there is a thermoelectrical refrigeration device to compensate for temperature rise. Finally, the seawater temperature entering the sample cylinder is no higher than 3 °C, effectively preventing the decomposition and deterioration of the natural gas hydrate core in the sample cylinder. In this paper, the temperature increase of the device and its compensation capacity are analyzed in detail on the basis of calculation and simulation. On the basis of testing with the device, it is verified that even at the ambient temperature, the water temperature can still be maintained at 3 °C.

With the development of marine survey techniques, more and more equipment is being used to investigate marine physical properties, marine biological resources and seabed resources. In the exploration of such things as seabed sediments, oil, gas hydrates and seabed crust, there are a variety of drill rigs used to take the mission. However, since the drill rig can only be placed on

Submarine landslides in gas hydrate areas are a significant geo-hazard that can cause considerable damage to offshore infra-structures such as drilling platform, sub-sea pipelines and communication cables; such risks can dramatically change the marine environment and seriously threaten human lives and property. Gas hydrates have the potential to be a new energy source, a factor in