Method of combining gas replacement with vibration field for extracting natural gas hydrate reservoir

Abstract

The invention discloses a method of combining gas replacement with a vibration field for extracting a natural gas hydrate reservoir. The method includes the steps that (1) a CO2 medium injection welland a natural gas production well are deployed on the natural gas hydrate reservoir; (2) partial free gas is extracted, and the pressure of the hydrate reservoir is decreased to 3-5 MPa; (3) a vibrator is put into the hydrate reservoir, and a CO2 medium is injected into the reservoir to achieve replacement of the natural gas in hydrates; (4) the vibrator is continuously or intermittently turned on, and vibration waves are utilized to promote dispersion of CO2 in a settled layer; (5) when the concentration of CO2 in the free gas of the reservoir is unchanged or changes slowly, the work load ofthe vibrator is increased, and the energy of the vibration waves is utilized to generate cracks in a CO2-natural gas hydrate mixed reservoir and the hydrate reservoir; (6) when the concentration of CO2 in the free gas of the hydrate reservoir is lower than 30 mol%, production of natural gas is carried out. By means of the method, the efficiency of CO2 medium replacement for extraction of natural gas hydrates can be improved, and the speed of the CO2 medium replacement for the extraction of the natural gas hydrates can be increased. Meanwhile, the stability of the reservoirs is maintained, anda broad application prospect is provided.

Description

technical field [0001] The invention relates to a method for exploiting natural gas hydrate reservoirs in the field of marine natural gas hydrate development, in particular to a method for exploiting natural gas hydrate reservoirs by combining gas replacement and vibration field. Background technique [0002] Gas hydrate is considered to be one of the important alternative energy sources in this century due to its huge reserves. According to statistics, the global land area favorable for the formation and distribution of natural gas hydrate accounts for 27% of the global land area, and the ocean area accounts for 90% of the global ocean area. At present, the proven natural gas reserves in hydrate reservoirs have reached 2*10 16 m 3 , its organic carbon content is twice that of conventional conventional fossil energy sources (coal, oil and natural gas) combined. How to realize the effective exploitation of natural gas hydrate reservoirs is the current research hotspot. ...

AI Technical Summary

Problems solved by technology

The invention has the characteristics of economy, environmental protection and safety, and CO is buried while exploiting natural gas. 2 , which solves the conventional CO 2 Replace the problem of low mining rate and efficiency, and keep the reservoir at a high pressure during the mining process without completely destroying the cemented state between the hydrate-rock particles, effectively protecting the stability of the reservoir

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