Analysis of rock cracking characteristics during pyrolysis drilling

Thermal jet rock breaking technology refers to the use of high temperature medium such as supercritical water for a rapid local heating rocks break rocks. Because low thermal conductivity matrix, stress will only form on surface. When exceeds strength rock, micro-cracks appear in and continue expand, resulting cracking surface, which cause surface fall off from body rock. Based thermal-solid coupling theory, pyrolysis drilling model was established, distribution law field bottom hole during obtained by using finite element method. The results show that process, heated part increases rapidly, producing gradients radial axial directions. expansion volume is affected compressive direction, buckling direction shear stress. This very important application drilling.