Technology for improving heat production capacity of geothermal wells

Abstract

The invention relates to the technical field of geothermal energy development, in particular to a geothermal well novel technology. The technology improves the ability of leading geothermal energy inrock strata into geothermal wells through a heat conduction well cementing technology and a enhanced conductivity fracturing technology, and achieves high efficiency heat taking and heat transferringusing through spiral plate type condensing section gravity heat pipe heat exchanger. The technology comprises the following concrete process that after completing drilling a geothermal well and casinga sleeve pipe, the heat conduction well cementing is carried out, that is, thermal insulation cement slurry is injected in the low temperature section of the formation, and heat conduction cement slurry is injected into a stratum high temperature section to complete well cementing; after solidification of the heat insulation cement slurry and the heat conduction cement slurry of the well cementing, subsection perforation fracturing is carried out in the sleeve pipe of the stratum high temperature section, cracks are produced in high temperature strata, and heat conduction material is filled into the cracks to form a heat guiding belt extending from the sleeve pipe to the stratum; and finally, the condensing section of gravity heat pipe heat exchanger connected with the sleeve pipe is installed on the ground to form a high-yield geothermal well system in which rapid heat transfer in the stratum and high efficiency heat transfer in a well cylinder finally.

Description

technical field [0001] The invention relates to the technical field of geothermal energy development, in particular to a process for improving the heat production capacity of a geothermal well. Background technique [0002] There is abundant geothermal energy available for mining within 10km of the earth's surface. Geothermal resources are a kind of clean and renewable energy without pollution. With the gradual depletion of traditional energy sources such as oil and coal, geothermal resources will become an important part of future energy. Geothermal can be divided into three categories: shallow geothermal energy, hydrothermal geothermal resources, and hot dry rock. Traditional geothermal usually refers to geothermal water, but geothermal water resources are limited and require specific conditions to form, while hot dry rocks are widely distributed. Geothermal extraction technology should only extract heat, not water, and protect groundwater resources while utilizing geothe...

AI Technical Summary

Problems solved by technology

Since the thermal conductivity of the rock is only 1.6-3.6 W / (m K), the thermal conductivity is low, and after the cement slurry is injected outside the casing, the thermal conductivity of the cement slurry is only 0.19 W / (m K) - 0.65 W / (m·K), which is equivalent to forming a layer of heat insulation between the casing and the rock. The thermal resistance is very large. It is difficult for the heat of the high-temperature rock formation far away from the geothermal well to be introduced into the well. The water entering the well is heated by the high-temperature rock formation. After passing through the low-temperature section of the formation, heat exchange occurs, resulting in heat loss and a drop in temperature. It is difficult for the heat of the high-temperature rock mass in the high-temperature section of the formation to be transferred to the vicinity of the wellbore.

In addition, the heat exchange capacity between the existing geothermal wells and rocks is poor, so it is necessary to excavate multiple interconnected geothermal wells to improve the heat exchange effect, which will not only increase the engineering amount, but also change the structure of the underground rock formation and increase the risk of land subsidence

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