PROCEDURE FOR EXTRACTION OF GAS AND FRESH WATER FROM UNDERWATER GAS-HYDRATE BY DROPPING HYDRO-STATIC PRESSURE Russian patent published in 2010 - IPC E21B43/01 E21B43/36 

FIELD: oil and gas production.

SUBSTANCE: convex catcher of products of gas-hydrates decomposition (CPGHD) is lowered to sea bottom on suspended device from water-craft board. Internal volume of CPGHD is isolated from external sea medium. Sea water with bottom sediments is pumped off from the catcher by means of an electric pump; thus reduced hydro-static pressure in the catcher facilitates decomposition of gas-hydrate under the catcher into fresh water and gas. Gas is withdrawn into reservoirs of the water-craft or into gasholders, or to the shore for successive utilisation via a flexible pipe. If necessary, produced fresh water is pumped via another flexible pipe with its own electric pump to the water-craft or to the shore. Under effect of proper weight CPGHD sinks into a basin till process of decomposition of gas-hydrate reaches sole of its reservoir. CPGHD is lifted to bottom surface and is transferred to a neighbour section of a gas-hydrate deposit.

EFFECT: raised efficiency of extraction of methane and fresh water on shelf and continental slope of World ocean in arid regions.

1 dwg