Method for vertical shaft electric-heating-assisted depressurizing production of natural gas hydrate reservoir

Abstract

The invention discloses a method for vertical shaft electric-heating-assisted depressurizing production of a natural gas hydrate reservoir. An electrode is mounted at the lower end of an oil pipe mainly, in combination with depressurizing production of natural gas hydrates, current is forced to pass through the natural gas hydrate reservoir, a current loop is formed, thermal production of the natural gas hydrates is realized, and the recovery ratio of the natural gas hydrate reservoir is increased. The specific method comprises steps as follows: the electrode is mounted at the lower end of the oil pipe, ground electric power adjusting equipment transmits the current to the downhole electrode through a cable, the natural gas hydrates are partially decomposed through depressurizing production, water produced through decomposition of the natural gas hydrates is used as an electric conductor and the natural gas hydrate reservoir is used as a resistor for heating, and thermal production of the natural gas hydrates is realized. The method is simple in structure, energy-saving, environment-friendly and easy to control, and an effective measure is provided for development of the natural gas hydrate reservoir.

Description

technical field [0001] The invention relates to a method for exploiting a natural gas hydrate reservoir, in particular to a method for exploiting a natural gas hydrate reservoir by using electric heating in a vertical well to assist depressurization. Background technique [0002] Gas hydrate is a crystalline substance produced by natural gas and water under high pressure and low temperature conditions, and is mainly distributed in seabed sediments and some terrestrial permafrost zones. Natural gas hydrate is widely distributed and has high energy density. Its organic carbon content is twice the total carbon content of coal, oil, and natural gas. [0003] The exploitation of natural gas hydrate is to destroy the phase balance of natural gas hydrate, make it decompose into natural gas and water and carry out exploitation. At present, the mining methods of natural gas hydrate are mainly divided into the following four categories: depressurization mining method, heat injection ...

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Problems solved by technology

Among the above mining methods, the depressurization mining method has a very slow mining speed and is a relatively passive mining method; the heat injection method needs to directly inject hot water or steam into the natural gas hydrate reservoir, which is costly and easy to cause reservoir damage; Inhibitor injection method has serious environmental pollution and the inhibitor is expensive; the key to carbon dioxide replacement method is to find a suitable carbon dioxide gas source, and its application is relatively limited

The use of electric heating to exploit natural gas hydrate reservoirs can convert electrical energy into thermal energy for exploiting natural gas hydrate reservoirs. The equipment is simple and the energy utilization rate is high, and it has attracted more and more attention. However, there is no one that uses vertical well electric heating to assist The method of reducing pressure to exploit gas hydrate reservoirs seriously restricts the research progress of gas hydrate reservoir development

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