U-shaped-well microwave heating method for exploiting natural gas hydrate

Abstract

The invention discloses a U-shaped-well microwave heating method for exploiting natural gas hydrate, and belongs to the technical field of natural gas hydrate exploiting. The method includes the stepsthat geological data is combined, a U-shaped well and matched well-completion practices are arranged for target storage, and after well completion is carried out, depressurizing exploiting is carriedout through the U-shaped well till economic benefits do not exist; then a ground feeding system and an underground microwave heating system are arranged on a horizontal well; a natural gas hydrate layer is heated through a microwave heater, and natural gas and discharged water are collected from a vertical well. According to the U-shaped-well microwave heating method for exploiting the natural gas hydrate, the U-shaped well is arranged for target storage, the storage volume of the available natural gas hydrate is increased, and movable heating storage is achieved through a coiled tubing and the microwave heater; the heating position, the heat output power and the drainage gas recovery speed are changed, optimization exploiting of natural gas hydrate storage can be achieved, the gas recovery efficiency can be improved, and economic benefits are improved.

Description

technical field [0001] The invention discloses a method for exploiting natural gas hydrate by microwave heating in a U-shaped well, which belongs to the technical field of natural gas hydrate exploitation, and in particular relates to a method for exploiting natural gas hydrate by comprehensively utilizing a heating method and a depressurization method. Background technique [0002] Natural gas hydrate (NGH for short) is a non-stoichiometric clathrate compound formed by natural gas and water at a certain low temperature and high pressure, also known as "combustible ice". 1m 3 Natural gas hydrate can contain 164m 3 methane gas and 0.8m 3 of water. "Combustible ice" is a secondary product of natural gas, and its application range is roughly the same as that of natural gas. It is a typical oil substitute. "Combustible ice" is extremely flammable. Under the same conditions, the energy generated by the combustion of "combustible ice" is dozens of times higher than that of coa...

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Problems solved by technology

However, the decomposition driving force provided by the depressurization method alone is small, and the decomposition of natural gas hydrate causes the temperature to drop. When the temperature drops below 0°C, it will also cause ice blockage and stagnation of natural gas hydrate decomposition. CN 20111048906.4 discloses a drainage The natural gas hydrate is exploited by depressurization and heating at the same time, which continuously promotes the decomposition of hydrate. The above two methods use the gas escaping after the hydrate is decomposed, and the water falls due to its own weight. The water pump discharges the water out of the natural gas hydrate production well. But in fact, the decomposed gas carries a large amount of water vapor when it escapes, and the escape speed is very slow, and the extraction efficiency is very low

Moreover, in CN 20111048906.4, horizontal wells are used for combustion and heating. It is unsafe to burn and heat in natural gas hydrate exploitation wells. There are combustible gases inside and outside the natural gas hydrate exploitation wells. It is very dangerous to use open flames for direct heating.

In CN 201310398998.0, microwave generators are used to heat and exploit natural gas hydrates, and the decomposition of natural gas hydrates is promoted by heating. However, the use of vertical wells limits the heated volume of heated natural gas hydrates, and it is more convenient to fix the microwave generators on the upper part of the packer. Further limit the heating volume of gas hydrate

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