Hot dry rock single well closed-type development method

Abstract

The invention relates to a hot dry rock single well closed-type development method. The method includes the steps of determining the buried depth of dry hot rock, designing a well drilling engineeringscheme, and drilling a vertical well or a horizontal well to a reservoir to form a main borehole; lowering a micro-borehole branch well drilling device into the main borehole of the dry hot rock, adopting a high-pressure jet drilling manner to drill a micro-borehole fishbone branch well in the reservoir of the dry hot rock; injecting cement paste containing a high thermal conductivity material into the micro-borehole fishbone branch well and the main borehole located in the dry hot rock; lowering a downhole heat exchange completion device containing a capillary metal pipe network into the main borehole to reach the well bottom; and installing a ground wellhead device and a heat exchanger, and exploiting heat energy of the hot dry rock. The hot dry rock single well closed-type developmentmethod has the advantages of simple construction, high heat exchange efficiency, low cost and long pipe string life.

Description

technical field [0001] The invention relates to the field of thermal energy exploitation, in particular to a method for developing hot dry rock in a closed circulation of a single well. Background technique [0002] Hot dry rock refers to the dense and impermeable hot rock mass without water or steam that is ubiquitous in the depths of the formation (deeply buried more than 2000m), mainly various metamorphic rocks or crystalline rock masses. At present, the development and utilization of hot dry rock is mainly for power generation. [0003] The existing hot dry rock development schemes mainly include the following two types: [0004] (1) Development and utilization of hot dry rock by hydraulic fracturing. Inject high-pressure water into the rock formation 2000-6000 meters underground through the water injection well, so that it can penetrate into the cracks created by artificial fracturing in the rock formation and absorb geothermal energy; then through another development...

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Problems solved by technology

[0009] In order to solve the above existing problems in the prior art, the present invention adopts the high-pressure jet drilling method to drill micro-hole fishbone branch wells in hot dry rock reservoirs, and then drill micro-hole fishbone branch wells and main wells in dry hot rocks. The wellbore is injected with cement slurry containing high thermal conductivity materials, and then the downhole heat exchange completion device equipped with capillary metal pipe network is lowered into the main wellbore. High thermal conductivity materials improve the thermal conductivity of the materials around the heat exchange device, and the capillary metal pipe network is used to increase the heat exchange area of ​​the downhole heat exchange device, which can effectively improve the heat exchange efficiency and sustainability of single well closed cycle development and utilization of hot dry rock , used to overcome the defects of existing hot dry rock development and utilization schemes such as high fracturing cost, poor fracturing effect, polluting the environment, and low heat transfer efficiency

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