NATURAL GAS EXTRACTION METHOD FROM GAS HYDRATE DEPOSIT Russian patent published in 2019 - IPC E21B43/22 C09K8/52 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to gas industry, particularly, to development of gas hydrate deposits. Method of producing natural gas from a gas hydrate deposit comprises constructing a well on a gas-permeable gas-hydrate formation, this formation is opened and periodical is injected into the bottomhole formation zone of the primary agent capable to decompose methane hydrates in thermobaric conditions of the formation, and then pumping into the bottomhole formation zone of a gaseous secondary agent containing carbon dioxide in an amount which enables formation of carbon dioxide gas hydrates in thermobaric conditions of the formation, and extraction of the produced gas is then carried out. Primary agent used is gas which does not contain carbon dioxide or has low content of carbon dioxide not more than 20 mol%, for example, nitrogen, or air, or flue gases, which simultaneously with decomposition of methane hydrates displacement of natural gas into the formation. Secondary agent used is, for example, nitrogen dioxide enriched with carbon dioxide or flue gas with carbon dioxide content of not less than 50 mol%.

EFFECT: invention increases recovery of gas due to exclusion of reduced permeability of bottomhole formation zone by water; increasing methane-containing gas extraction factor from formation.

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