Natural gas hydrate fire flooding mining method

Abstract

The invention provides a natural gas hydrate fire flooding mining method. The natural gas hydrate fire flooding mining method comprises the following steps of deploying a vertical mining well and performing well completion on a natural gas hydrate reservoir portion and forming a jet hole in a mining well portion which is located on the natural gas hydrate reservoir portion; installing a pump and an ignition device at the well bottom of the mining well; starting the pump and reducing the pressure in the mining well to be 0.1 to 3 Mpa; injecting the air into the mining well when the mining rate is reduced to be 20% of the initial mining speed and closing a well opening of the mining well when the pressure in the mining well is 7 to 25 Mpa; starting the ignition device and opening the well opening of the mining well, collecting the gas and achieving the fire flooding mining of the natural gas hydrate after 10 to 100 days that the temperature in the mining well is restored into the formation temperature. According to the natural gas hydrate fire flooding mining method, the depressurization mining is performed on the natural gas hydrate, then the replacement mining is performed on the natural gas hydrate, and accordingly the natural gas hydrate fire flooding mining method is scientific and reasonable and the cost is low due to the fact that the air serves as raw materials.

Description

technical field [0001] The invention relates to a method for exploiting natural gas hydrate, in particular to a method for exploiting natural gas hydrate by fire driving, and belongs to the technical field of natural gas hydrate exploitation. Background technique [0002] Natural gas hydrate (NGH) is a non-stoichiometric clathrate crystal hydrate formed by natural gas and water at a certain temperature and pressure. [0003] According to statistics, the amount of natural gas hydrate contained in the shallow lithosphere with a global depth of less than 2000m is equivalent to more than twice the sum of proven conventional fossil fuels. [0004] At present, natural gas hydrate production methods include thermal excitation method, depressurization method and chemical reagent method. These methods all achieve the purpose of decomposing natural gas hydrate by destroying the balance of natural gas hydrate under the original conditions. [0005] Among them, the depressurization me...

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Problems solved by technology

The decompression method decomposes the natural gas hydrate quickly when the pressure is reduced, but since the decomposition of the natural gas hydrate is an endothermic reaction, when the temperature of the natural gas hydrate layer drops to a certain level, the natural gas hydrate will freeze. If the decomposition front of natural gas hydrate is closed, the driving force of depressurization cannot continue to advance, or the decomposed gas and water will form secondary hydrate during the process of flowing into the production well, which will affect the effect of depressurization production

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