Natural gas hydrate exploitation system and method based on CO2 fracturing

Abstract

The invention belongs to the field of natural gas hydrate exploitation, and provides a natural gas hydrate exploitation system and method based on CO2 fracturing, the system comprises a fracturing system, a gas production system, a data monitoring system and a main well, and fracturing wells and depressurization wells in the main well are alternately arranged in a star shape along the axis of the main well. The method comprises the steps that firstly, free gas in a reservoir is released, after the reservoir is stabilized, supercritical CO2 fluid is injected, heat is provided for the reservoir, CO2 hydrate is generated while hydrate decomposition is promoted, and the strength of the stratum is enhanced. And when the gas production rate is reduced again, the supercritical CO2 fluid is injected for the second time to carry out secondary fracturing and reservoir strengthening on the reservoir. The fracturing mode is carried out in the mode that fracturing fluid nozzles are spirally arranged on a fracturing well, and multi-angle transformation of the hydrate reservoir is achieved. The depressurization wells and the fracturing wells are separately arranged in a star-shaped arrangement mode, pressure regulation and control are facilitated, the mining range is effectively enlarged, the stability of gas production and the safety of the whole system are guaranteed, and the mining efficiency and the CO2 storage amount are improved through cooperation of multiple wells.

Description

technical field [0001] The invention belongs to the technical field of natural gas hydrate exploitation, and relates to a CO 2 Fracturing gas hydrate production efficiency and reservoir strengthening systems and methods. Background technique [0002] Because of its huge reserves and clean and pollution-free combustion, many researchers believe that natural gas hydrates can replace traditional fossil fuels such as coal and oil as a new generation of energy and alleviate the global energy crisis; the reserves of natural gas hydrates in seabed sediments in my country huge. [0003] Conventional mining methods for terrestrial hydrates include depressurization method, heat injection method, chemical inhibition and so on. These will have a certain impact on the structure and composition of the formation during the mining process. When the depressurization method is used for mining, a large amount of hydrate will be decomposed, absorb a large amount of heat, and cause ice formati...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the current mining problem of seabed hydrate, the present invention adopts different well types combined with existing mining methods to improve the mining efficiency, and proposes a method based on CO 2 Fracturing natural gas hydrate production efficiency enhancement and reservoir strengthening methods

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