In general, in addition to gas hydrates associated with the permafrost in high latitudes, natural gas hydrates found on the seabed typically have water depths of 300-500 m (determined by temperature) and are mainly associated with slopes, Surface sediments or sedimentary rocks in islands and basins can also be scattered on the ocean floor in the form of particles. The pressure and temperature conditions at these sites maintain the structure of natural gas hydrates. From the point of view of the geotectonic structure, natural gas hydrates are mainly distributed in the conglomerate continental margin continental slope, passive continental margin continental slope, seamounts, inland sea, marginal sea deepwater basin, and submarine expansion basin structural units. It is estimated that 20.7% of the land and 90% of the ocean floor have favorable conditions for the formation of natural gas hydrates. The vast majority of natural gas hydrates are distributed in the oceans and their resources are more than 100 times that of land. Under standard conditions, the decomposition of one unit volume of natural gas hydrate can produce up to 164 units of methane gas, which is an important potential future resource.
Formation conditions of natural gas hydrates
The formation of natural gas hydrates has three basic conditions that are indispensable. According to experts, the first temperature can not be too high; the second pressure should be large enough, but not too much; at 0 °C, more than 30 atmospheric pressure can be generated; Third, the ground must have air. Natural gas hydrates are limited to specific geographical locations and geological tectonic units because of their special properties and the conditions required for their formation.