## 1 Introduction  
Natural gas hydrate is a kind of crystalline solid substance formed by gas molecules (mainly methane) and water under certain temperature and pressure conditions; it is commonly known as \"combustible ice\" [1; 2]. Its occurrence environment is mainly under permafrost in high latitudes and in the continental shelf extending to the sea at a depth of several hundred meters [3]. And natural gas hydrate is widely distributed, shallow-buried, clean, and pollution-free and has enormous reserves, it is regarded as the alternative clean energy source in the oil and gas field with the most potential. At present, more than 100 exploration sites in the world have discovered natural gas hydrate [4]. The amount of natural gas resources contained in natural gas hydrates in the world is about 2 \(\times\) 10\({}^{16}\) m\({}^{3}\)[5; 6], and the organic carbon content converted from this reserve is about twice that of existing fossil fuels (coal, oil, and natural gas) [7; 8]. At the same time, gas hydrate is considered to be an alternative resource of fossil fuel with great potential because of its good accumulation and chemical conditions. Therefore, in recent years, natural gas hydrate has been a research hotspot in the scientific community and oil-gas industry [9]. Among such research topics, how to safely, economically, and efficiently extract natural gas from hydrates is a very key technical problem [10]. At present, the development technology of natural gas hydrate in oceans mainly includes the pressure reduction method, solid fluidization method, heat injection method, chemical injection inhibitor, and carbon dioxide replacement method [10; 11]. Each of these technologies has its advantages and disadvantages, and scientists around the world have also conducted numerous experiments on these technologies. Countries around the world have also carried out marine gas hydrate test mining many times. Among such countries, in 2020, China conducted its second test production using a series of advanced technologies including the horizontal well and pressure reduction method. This test production has created two world records for a total gas production of 86.14 \(\times\) 10\({}^{4}\) m\({}^{3}\) and an average daily gas production of 2.87 \(\times\) 10\({}^{4}\) m\({}^{3}\), realizing a major leap from \"exploratory test production\" to \"experimental test production\" [12]. In the study of gas hydrate, the most direct and effective research method is to obtain complete and undisturbed in situ samples of gas hydrate in the seabed and carry out further experimental analyses [13]. When the hydrate is obtained by conventional means, due to the decrease in pressure and the increase in temperature, natural gas hydrate decomposition will occur during or after the core collection process, and gas expansion will destroy the complete structure of the hydrate core. Therefore, the pressure coring system is the only method from which a core is retrieved to the surface in an in situ condition [14; 15]. To sample gas hydrate over a complete gas hydrate stability zone (GHSZ), a number of downhole, wireline-operated pressure coring tools have been developed, such as a PCS (Pressure Core Sampler), a PTCS (Pressure Temperature Core Sampler), an FPC (Fugro pressure core), a PCTB (Pressure Core Tool Ballvalve), and so on [16; 17]. After pressure coring is completed, the core barrel and the core inside are pulled into the pressure chamber by lifting the wireline. The lower end of the pressure chamber is usually sealed with a specially designed flapper valve or ball valve [18]. The first successful wireline pressure coring tool, which was a PCS, was developed by the ODP (Ocean Drilling Program) for the drilling vessel JODES Resolution [19; 20]. By using the PCS, gas-rich or gas hydrate-bearing sediments were successfully retrieved in 1995 and 2002 at Blake Ridge on ODP Leg 164 and at Hydrate Ridge on ODP Leg 204.