Enhanced geothermal system designing method capable of preventing earthquake from being induced, and using method of enhanced geothermal system

Abstract

The invention discloses an enhanced geothermal system designing method capable of preventing an earthquake from being induced, and a using method of an enhanced geothermal system. Through the enhancedgeothermal system designing method capable of preventing the earthquake from being induced, and the using method of the enhanced geothermal system, the technical problem that in the prior art, suddenshearing slip of initial fissures is caused by injection of high-pressure water, and consequently, the earthquake is induced is solved. The enhanced geothermal system designing method comprises the steps that a single large-hole-diameter production well is drilled in the center of a hot dry rock target area through a medium-radius well drilling technology, and a plurality of equidistant small-hole-diameter water injection wells are arranged around the production well; inside a hot dry rock reservoir, all the water injection wells horizontally extend to the production well and pass through theproduction well through a horizontal direction drilling technology, and thus an artificial heat exchange space is formed; and the production well is reinforced through rigid segmented sleeves, and the junctions of the water injection wells and the production well are reinforced through concrete slurry. According to the enhanced geothermal system designing method, earthquake activities can be effectively prevented, the leakage problem of injected water can be solved, and possibility is provided for operation of scale and commercial hot dry rock development.

Description

technical field [0001] The present invention relates to the design and use of a novel enhanced geothermal system for preventing induced earthquakes. Background technique [0002] The application process of hot dry rock is to use drilling equipment to establish injection wells and production wells, and form a fracture communication system through hydraulic fracturing, and finally form an "artificial geothermal field". High-pressure water is pumped from the injection well into the ground, and the cold water flows through dry heat. The artificial fractures in the rock are heated to become high-temperature water or water vapor (temperature can reach 150-200°C), and pumped out from the production well, and the geothermal energy in the fractures is extracted through heat exchange, so as to achieve geothermal power generation and comprehensive heating utilization. Target. The heat stored in the hot dry rock is extracted by the system described above, often referred to as an enhanc...

AI Technical Summary

Problems solved by technology

In 2017, the EGS geothermal development project in Pohang, South Korea, induced multiple earthquakes with a magnitude of 2.0 to 3.0 on the Richter scale during the high-pressure water injection process. After the water injection was completed, an earthquake with a magnitude of 5.4 occurred in the same area, causing personal injuries and huge property losses. loss

[0003] At the same time, the EGS production process will face a serious problem of fracturing fluid loss

During the production of hot dry rock EGS in Hijiori, Japan, it was found that 70% of the injected water flowed away along natural fractures and faults. Although the water injection well and the production well are only separated by 50m, the production well cannot pump out a sufficient amount of high-temperature water , causing the project to be suspended

During the hydraulic fracturing of the third phase of the hot dry rock geothermal reservoir in Soultz-sous-Forets, France, 90% of the injected water quickly flowed into the fault, resulting in no effective communication between the injection well and the production well

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