A safe and efficient marine natural gas hydrate decompression and decomposition production device and method

Abstract

A safe and efficient marine natural gas hydrate depressurization decomposition production device and method, the device includes a sand production prevention device, a gas-water separation device and a safety protection device, and can also be provided with a hydrate secondary generation prevention device. The method for decomposing and exploiting marine natural gas hydrate by using the device includes the following steps: the decomposed gas, water and sand flow to the wellbore, the mud and sand in the sedimentary layer are blocked, and the gas and water enter the wellbore; the gas and water go upward along the wellbore under the extraction action of the water pump The flow is separated into the respective pipelines, and finally lifted to the production platform or ship; the well pressure is detected in real time, and once an abnormality occurs, the gas and water pipelines are disconnected and the gas production is suspended. The invention can well prevent quicksand formed by hydrate decomposition from entering the wellbore, realize gas-water separation in the wellbore, prevent secondary generation of hydrate in the wellbore, etc., and realize safe and efficient exploitation of marine natural gas hydrate.

Description

technical field [0001] The invention belongs to the technical field of marine oil and gas reservoir exploitation, and relates to a safe and efficient marine natural gas hydrate decompression and decomposition exploitation device and method. Background technique [0002] Natural gas hydrate is widely distributed in seabed sediments and terrestrial permafrost. It is a clean energy with huge reserves and is expected to become the main energy to replace oil and coal. The production methods of natural gas hydrates are roughly divided into depressurization method, heat injection method and chemical inhibitor injection method. The main purpose of these three types of production methods is to change the stable environment of natural gas hydrates and make them decompose to generate flowing gas and After the water is mined. The heat injection method needs to provide a large number of heat sources, and the economy is poor; the chemical inhibitor injection method may cause pollution to...

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Problems solved by technology

[0003] The depressurization method is the most economical natural gas hydrate mining method at present, but there are many problems in its implementation, such as: only relying on the energy of the natural gas hydrate layer itself, and there is no external energy supply for mining. Gas production rate, but as the natural gas hydrate decomposes and absorbs heat, the formation energy gradually decreases, which slows down the hydrate decomposition rate, and even causes formation water to freeze, and the secondary generation of natural gas hydrate will completely stop gas production; at the same time, After the hydrate is decomposed, the sediment particles lose their support, and under the action of formation pressure, compaction and flow effects occur, which greatly reduces the permeability of the formation. In severe cases, the pipeline will even be blocked and production will be interrupted.

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