Downhole heterogeneous heat transfer characteristics and rock stress distributions induced by liquid nitrogen jet

Abstract

Liquid nitrogen jet is expected to provide a new idea for the breaking of deep dry hot rock due to its low temperature. In order to study the characteristics of het?erogeneous temperature and stress fields during liquid nitrogen jet impingement, the downhole flow and stress characteristics induced by liquid nitrogen jet were studied by a thermal-hydraulic-mechanical coupling model. The results showed that under the same conditions, the potential core and the maximum velocity of liquid nitrogen jet were higher than water jet. The liquid nitrogen jet had a larger region of high turbulent kinetic energy, and the heat transfer efficiency with the bottom rock was obviously higher than water jet. Compared with the water jet, the liquid nitrogen jet formed a tensile stress zone in the bottom rock. The research was expected to provide a theoretical basis for the rock breaking mechanism of liquid nitrogen jet.