Exploitation method and extraction device for jet crushing and reverse circulation transport of slurry marine natural gas hydrate

Abstract

The invention discloses a slurry marine gas hydrate mining method and mining device achieved by means of jet breaking and reverse circulation delivering. The method comprises the steps that a marine gas hydrate stratum is broken through a high-pressure water jet method, and a multi-phase slurry mixture is jointly formed by jet water, broken rock soil and broken hydrates; the slurry mixture is delivered to a decomposition device and a separation device which are arranged on the sea level through a reverse circulation method; reduced pressure decomposition, solid-liquid separation and gas-liquid separation are conducted on the slurry mixture through the decomposition device and the separation device which are arranged on the sea level, and gas, solids and liquid are obtained separately and utilized and collected accordingly. Devices used in the method comprise a rock jet breaking and slurrying system, a reverse circulation delivering system, a decomposition, separation and collection system and an auxiliary system. According to the mining device and method, the defect that in existing marine gas hydrate mining, the mining efficiency is low is overcome, the hydrate deposit utilization rate is increased, the mining cost is reduced, the economic benefit is increased, and quick and sustainable mining is achieved.

Description

technical field [0001] The invention relates to a mining method and a mining device of a marine natural gas hydrate deposit. Background technique [0002] Natural gas hydrate is an ice-like crystalline compound with a cage structure formed by water molecules and hydrocarbon molecules at a certain temperature and pressure, because the gas molecules are formed by methane (CH 4 ) mainly (content greater than 90%), so it is also called methane hydrate. Natural gas hydrate is a kind of green energy with shallow burial, high energy density and large reserves. Its organic carbon content is equivalent to twice the sum of proven coal, oil and natural gas in the world, and has huge potential development value. [0003] my country drilled gas hydrate samples in the Shenhu area of ​​the South China Sea and the Pearl River Mouth Basin in 2007 and 2013 respectively. The discovered gas hydrate samples have four main characteristics: shallow burial, large thickness, multiple types, and hig...

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Problems solved by technology

Since natural gas hydrates in sea areas usually occur in unconsolidated formations, the decomposition of hydrates may cause deformation and destruction of formations, which will have a great impact on the rock and soil mechanical properties of wells and formations, and may cause wellbore instability and large scale failures. Mass production of sand, causing accidents in the hole or failure of depressurization equipment

In addition, in the process of decompression mining, particle migration may lead to changes in reservoir permeability, and formation damage caused by compaction has become an important factor affecting the stability and sustainability of gas production

On March 12, 2013, Japan carried out the first sea area natural gas hydrate trial production project using the decompression method in the eastern South China Sea plate sea area off the coast of Aichi County and Mie County. Although it arranged sand control devices (gravel filling), but on the sixth day of the production test, a serious sand production problem occurred (the total sand production exceeded 30 cubic meters), and the test production was forced to terminate. Since the production well was filled with sand, the downhole production equipment could not be recovered, AT1-P well abandoned

[0005] Combined with the mining test in the sea area of ​​Japan, it can be seen that the in-situ mining method of natural gas hydrate in the sea area using the depressurization method has a long production cycle and requires complex sand isolation measures, but the effect is average, and it is not effective in terms of efficiency or economy means of mining

The shale content of hydrate reservoirs in my country is relatively high, the reservoir permeability is low, and the efficiency of the depressurization method will be relatively lower. Therefore, this patent proposes a method of jet crushing and reverse circulation to transport slurry marine natural gas hydrate Mining methods to increase mining efficiency

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