Mid-Deep Geothermal Energy Development Technology of Vertical and U-Shaped

Under the general trend of energy conservation, environmental protection and carbon emission reduction, the development technology of middle-deep geothermal energy has attracted more and more attention from all walks of life. The traditional Chinese mid-deep geothermal energy development forms are mainly characterized by "heat extraction without water consumption and recharge in the same layer". In recent years, in order to strengthen environmental protection and scientific heat extraction, " downhole heat transfer" technology without exploiting geothermal fluids and closed circulation heat extraction has become an increasingly urgent development mode. This paper investigates the development of vertical coaxial casing and U-shaped "downhole heat transfer" in middle-deep geothermal storage. The calculation method of "downhole heat transfer", drilling and completion engineering technology, existing engineering tests, and economic applicability analysis are summarized. The results provide reference for the engineering design and management of "downhole heat exchange" geothermal development in middle and deep layers in related enterprises.