Green mining method and mining device for submarine shallow non-diagenetic natural gas hydrate

Abstract

The invention discloses a green mining method and mining device for submarine shallow non-diagenetic natural gas hydrate. The green mining method comprises the following steps that on the condition that the ambient temperature and pressure of a submarine natural gas hydrate stratum are not changed, the natural gas hydrate is mined in a submarine mining mode and broken for two times to obtain a mixture of natural gas hydrate particles and seawater; thermal decomposition is directly performed on the mixture of the natural gas hydrate particles and the seawater at the bottom of sea in a sealed environment to obtain natural gas, wherein energy needed by thermal decomposition comes from energy generated through gas expansion work during thermal decomposition of the natural gas hydrate; the natural gas is delivered to the sea surface to be subjected to aftertreatment, and liquefied natural gas is obtained. The green mining device comprises a mining and breaking unit, a first transportation pipe, a decomposition unit, a natural gas transportation pipe, an energy supplying unit and a sea surface supporting unit.

Description

technical field [0001] The invention relates to the technical field of seabed natural gas hydrate exploitation, and more specifically relates to a green mining method and mining device for non-diagenetic natural gas hydrate in shallow seabed. Background technique [0002] Natural gas hydrate, also known as combustible ice, is a "cage compound" formed by methane-based hydrocarbon gas and water under certain temperature and pressure conditions, and has a white crystalline structure. Gas hydrate reserves are huge, more than twice the sum of known carbon fossil fuels, and mainly exist in terrestrial permafrost and oceanic seabeds. The reserves of oceanic seabed gas hydrates far exceed those in land permafrost areas. [0003] The United States, Japan, Russia and other countries have carried out test production research on natural gas hydrate respectively. The main test production methods include heat injection method, depressurization method, inhibitor method and a combination of...

AI Technical Summary

Problems solved by technology

[0005] Solid-state fluidization provides a new idea for the exploitation of non-diagenetic natural gas hydrate in deep sea and shallow layers. However, this method also has various technical difficulties, especially the problem of non-equilibrium decomposition of hydrate particles under multiphase flow conditions during pipeline transportation. If this problem cannot be effectively solved or avoided, the application of solid fluidization mining method will be severely restricted

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