PRELIMINARY STUDY ON THE DISTRIBUTION PATTERN OF GAS HYDRATE STABILITY ZONE IN THE DEEP-WATER AREAS OF QIONGDONGNAN BASIN

The formation and accumulation of gas hydrate are strictly depending on temperature and pressure, or so-called the stable region of low temperature and high pressure, which directly determines the distribution pattern and scale of the gas hydrate deposits. In this paper, according to Bono Malev's empirical formula, the hydrate stability zone of the deep-water areas of the Qiongdongnan Basin is calculated with three key parameters, namely the gas composition, the geothermal gradient and the water depth. Based on the distribution pattern of the hydrate stability zone of the Qiongdongnan Basin, it is found that the greater the water depth (pressure) and the smaller the geothermal gradient, the greater the hydrate stable thickness. When the water depth reaches 334.1 m, the hydrate stability zone is formed on the seabed. With regards to the general distribution pattern of the hydrate stability zone in the Qiongdongnan Basin, it is thin in the north and south, thick in the middle, and gradually becomes thicker from west to East. The thickness of the zone changes between 200～300 m with a maximum up to 400 m.