A marine natural gas hydrate mortar replacement mining method and mining device

Abstract

The invention discloses a marine natural gas hydrate mortar replacement mining method and a mining device. The mining method properly relaxes the sand-retaining precision of the mechanical screen so that the formation muddy and sandy fine particles flow into the wellbore production string under controllable conditions and At the same time, the coarse-grained mortar is continuously injected into the hydrate reservoir, and the replacement of the coarse-grained mortar with the formation fine particles and the hydrate space is realized through the cooperation of the hydrate reservoir sand production management technology and the mortar injection technology; The production equipment includes production casing, production tubing, wellbore water injection pipe and mortar reinjection pipe. The lower end of the production casing is connected with a mechanical screen, and the upper and lower ends of the mechanical screen are respectively installed with an upper mechanical packer and a lower mechanical seal. Spacer; the gas separation device is installed at the inlet end of the production tubing, the wellbore water injection pipe is connected with the production tubing above the upper mechanical packer, and the mortar reinjection pipe extends through the upper mechanical packer and the lower mechanical packer to the hydration zone. The bottom boundary of the production layer of the material reservoir is connected with the gravel packing tool, and the purpose of continuous and efficient production is achieved through the above method and device.

Description

technical field [0001] The invention belongs to the field of high-efficiency exploitation of marine natural gas hydrates, and in particular relates to a mortar replacement mining method and a mining device for natural gas hydrates in sea areas, which are suitable for mining by the depressurization method or formation fluid extraction method. Background technique [0002] Gas hydrate is a kind of energy that has existed stably for millions of years and has huge reserves. More than 90% of the gas hydrate resources are stored in deep-sea shallow sediments. Strong research interests. If the natural gas hydrates in the surrounding seas of my country can be exploited safely and effectively, it will greatly promote the improvement of my country's energy structure. In 2017, my country's first sea area natural gas hydrate trial production project hosted by the China Geological Survey achieved a historic breakthrough of continuous drainage for 60 days and an average daily gas product...

AI Technical Summary

Problems solved by technology

[0006] To sum up, the process of gas hydrate decomposition from solid phase to gas and water two-phase production will lead to formation deficit, and the production of formation mud and sand will further aggravate the large-area deficit in the hydrate decomposition area around the wellbore, which has a negative impact on formation stability. Extremely unfavorable

CO 2 The displacement method cannot meet the demand for replacing the above-mentioned shortfall space and will cause a decrease in the seepage capacity of the formation near the wellbore

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