Structure and method of back-type well for exploitation of marine hydrate pool by using geothermal energy

Abstract

The invention relates to the technical field of exploitation of marine hydrate reservoirs, and discloses a back-type well structure and method for utilizing geothermal energy to exploit marine hydrate reservoirs. The invention adopts the back-type well structure and uses the heat-carrying fluid to transfer the energy of the geothermal layer to the hydrate layer to promote the decomposition of natural gas hydrate, which can realize the recycling of the heat-carrying fluid while enhancing the heat transfer efficiency, and has a production speed Fast, low mining cost, small energy loss, high thermal energy utilization and other advantages.

Description

technical field [0001] The invention relates to the technical field of exploitation of marine hydrate reservoirs, in particular to a back-type well structure and method for utilizing geothermal energy to exploit marine hydrate reservoirs. Background technique [0002] Natural gas hydrate is a clathrate structure complex, which has the characteristics of abundant reserves, wide distribution, high energy density, and relatively clean combustion, so it is regarded as a new type of alternative energy with great potential in the 21st century. Natural gas hydrate is formed by combining small molecular gases with water molecules under high pressure and low temperature conditions. Small molecular gases mainly include hydrocarbon gases such as methane and ethane. According to many years of research, the original gas hydrates in nature are mainly distributed in the polar tundra in high latitudes and in the deep seabed, continental slope, land base and trenches around the world. Natur...

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Problems solved by technology

Among them, the depressurization method generally changes the phase balance of hydrates by reducing the pressure of the reservoir system to promote the decomposition of natural gas hydrates. Its advantages are low cost, simple operation, and low energy loss, but it has the disadvantages of slow development speed and poor controllability. Defects; chemical agent injection method is to inject chemical agents such as alcohols and brine to promote the decomposition of natural gas hydrate, which has the advantages of simple operation and remarkable effect, but has the disadvantages of high cost and environmental pollution; CO 2 The replacement method uses the property that CO2 is easier to form hydrate than CH4, and replaces the methane gas in the natural gas hydrate. Its advantage is to realize the win-win goal of not only collecting natural gas but also storing greenhouse gases, while maintaining However, it has the disadvantages of low cost performance and slow development speed; while the thermal shock method usually refers to the use of hot fluid injection or electromagnetic heating to increase the system temperature in the reservoir to promote the decomposition of natural gas hydrate. Its advantage is that it is easy to operate , fast development speed and good controllability, but there are defects of high cost, large energy loss and low heat energy utilization

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