Mechanical and jet flow combined exploitation method and mechanical and jet flow combined exploitation device for natural gas hydrates in non-stratified rock of shallow strata in seabed

Abstract

The invention discloses a mechanical and jet flow combined exploitation method and a mechanical and jet flow combined exploitation device for natural gas hydrates in non-stratified rock of shallow strata in seabed. The mechanical and jet flow combined exploitation method and the mechanical and jet flow combined exploitation device are used for crushing and exploiting the natural gas hydrates in the non-stratified rock of the shallow strata in the seabed in a composition manner. The mechanical and jet flow combined exploitation method includes drilling pilot holes by an intelligent guide drilling tool, unfolding a mechanical crushing cutter arm after the intelligent guide drilling tool reaches preset locations, carrying out rotary cutting and crushing, starting to carry out jet flow crushing by spray nozzles, opening a flow regulating device, isolating recovery regions from goaves, separating hydrates from sediment by a downhole separator, filling the sediment with CO2, realizing effects of curing backfilled particles and backfilling the sediment in an in-situ manner. The mechanical and jet flow combined exploitation method and the mechanical and jet flow combined exploitation device have the advantages that the crushing radiuses and the exploitation spaces can be enlarged; crushed particles and the backfilled particles can be prevented from being mixed with one another; the sediment which is sorted by the downhole separator is filled with the CO2, accordingly, natural gas in the sediment can be displaced, effects of curing agents can be realized, the strength of backfilled layers can be enhanced, and the goaves can be prevented from collapsing.

Description

technical field [0001] The invention relates to the technical field of natural gas hydrate exploitation, in particular to a method and device for combined mechanical jet-flow exploitation of non-diagenetic natural gas hydrate in seabed shallow layers. 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. Its carbon content is equivalent to twice that of the world's total known reserves of energy sources such as coal, oil and natural gas. Therefore, natural gas hydrate, especially marine natural gas hydrate, is generally considered to be a new type of clean energy resource to replace coal, oil and natural gas in the 21st century, and it is also a new energy source with large reserves that have not yet been developed. [0003] The main forms of hydrates are sandstone type, sandstone fract...

AI Technical Summary

Problems solved by technology

However, the working radius of jet crushing is small, the mining space is limited, and the backfill particles are easy to be mixed with crushed particles, resulting in low crushing fluidization collection efficiency, low structural strength of the sediment backfilled in situ, and easy collapse of the natural gas hydrate layer, making the shallow layer non-destructive. Exploitation of diagenetic gas hydrates is not conducive to commercialization

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