Current perspectives on pressure-core analysis technology for gas-hydrate-bearing sediments

： Gas hydrates are clathrate compounds in which guest molecule such as methane is in a cage formed by water molecules. Huge amount of carbon is considered to be stored in natural gas hydrates. Thus, gas hydrates attract much attentions as a major reservoir of carbon cycle and a possible future energy resource. It is important to understand reservoir properties of gas-hydrate-bearing sediments for prediction of gas hydrate dissociation behaviors. However, analysis of sediment samples containing gas hydrates is quite difficult because gas hydrates dissociate during coring, handling, and measuring processes. In this paper, we review a pressure-core analysis technology that is a unique technology keeping sample pressure within the equilibrium conditions of gas hydrates during handling and measuring processes. We categorize the pressure-core analysis technology into three generations according to the technological progress and summarize scientific findings. Finally, we discuss perspective of this technology within and beyond gas hydrate research.