Marine natural gas hydrate production method adopting double-branch-well pressure reduction assisted by water flow erosion method

Abstract

The invention belongs to the technical field of marine natural gas hydrate production and relates to a marine natural gas hydrate production method adopting double-branch-well pressure reduction assisted by a water flow erosion method. A double-branch-well production well is drilled in the portion, close to a hydrate storage layer, of the bottom of a production well. Mechanical sand prevention devices are correspondingly mounted at the bottoms of the branch wells. When the double branch wells work at the same time, when one branch well is communicated with the production well for pressure reduction production, the other branch well is used for water flow erosion assisted production; the two branch well shaft modes can be exchanged by a selective switch, the original pressure reduction production branch well is convened into the water-flow-erosion-assisted production branch well, meanwhile a branch well centrifugal pump is started, and seabed seawater is injected into the hydrate storage layer; reverse water injection not only can assist in production, but also can remove deposited sand in branch well shafts; the sand deposition amount in the original water-flow-erosion-assisted production branch well is little or even no; after being communicated with the production well, the original water-flow-erosion-assisted production branch well is converted into the pressure reduction production branch well, and the gas production capacity can reach the requirement; and when the gas production capacity is insufficient, the selective switch is used to continue to convert the two branch well modes, and continuous efficient production of the seabed natural gas hydrate is achieved.

Description

technical field [0001] The invention belongs to the technical field of marine natural gas hydrate exploitation, and relates to a double split well depressurization marine natural gas hydrate exploitation method assisted by a water flow erosion method. Background technique [0002] Natural gas hydrate is an energy source with huge energy reserves. It not only has the characteristics of high efficiency and high energy accumulation, but also is an environmentally friendly energy source. Therefore, many countries have researched and carried out trial production of natural gas hydrate. The main mining techniques used are depressurization method and heat injection method. According to the mining effect, the depressurization method is the simplest and most economical mining method, and the depressurization method is the main method, combined with other auxiliary mining methods, the effect is better. [0003] The problem of sand production in the test production process is the key ...

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Problems solved by technology

[0004] Aiming at the problem of sand production in the current natural gas hydrate mining method, the present invention proposes a new natural gas hydrate mining method

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