Construction method for well structure of heat exchanging type horizontal butt-joint geothermal well

Abstract

The invention provides a construction method for a well structure of a heat exchange type horizontal butt-joint geothermal well. The construction method for the well structure of the heat exchange type horizontal butt-joint geothermal well comprises the following steps that drilling is conducted on the ground surface until drilling into the stable clay layer or under a bedrock surface, a vertical well first opening well hole is formed, then second opening is conducted from the bottom of the vertical well first opening well hole until drilling under an arbitrary mudstone layer with a thickness being greater than 6m in the target heat storage layer, and a vertical well second opening well hole is formed; drilling is conducted in the surface of the ground surface until drilling into the stable clay layer or under a bedrock surface and the distance between a well opening of a vertical well and the surface of the ground surface is at least 250 m, and a horizontal engineering well first opening well hole is formed; then second opening is conducted from the bottom of the horizontal engineering well first opening well hole, and a horizontal engineering well second opening well hole is formed and communicates with the vertical well second opening well hole in a butt-joint mode, thus a horizontal engineering well cylinder and a vertical well cylinder form a U-shaped pipeline in a seamless butt-joint mode, and the structure is large in section surface area, heat exchanging water amount and heat exchanging amount; and according to the construction method for the well structure of the heat exchange type horizontal butt-joint geothermal well, heat exchanging is achieved only by using circulation of cold and heat water, no underground water is pumped, water resources are protected, the underground water is not polluted at the same time, and the environment-friendly effect is achieved.

Description

technical field [0001] The invention belongs to the technical field of geothermal energy development, and relates to a construction method of a well body structure of a heat-exchanging horizontal butt-grounded thermal well. Background technique [0002] At present, there are three methods for the development of hydrothermal geothermal resources in the middle and deep layers of 1500-3000m in China: the first is to drill a vertical well, from which the underground hot water is directly extracted without recharging; the second is to drill a vertical well as a drainage well The first is to drill a number of vertical wells around them as recharge wells, combining drainage and recharge; the third is to drill a vertical well, run concentric pipes into the well, and use the concentric pipes to perform cold and hot water circulation and heat exchange. These three development methods have the following problems: ① all use the water-bearing heat reservoir (sandstone layer) as the targe...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a construction method for the well body structure of a heat-exchanging horizontal butt-grounded thermal well, which solves the problem of "taking both heat and water" in the existing middle-deep hydrothermal geothermal resource development mode, and truly realizes " The purpose of only taking heat but not water"

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