Mechanical Analysis Of Testing String In High Temperature And High Pressure Deep Gas Well

The testing string in high temperature and high pressure deep gas well bears complex forces, and the safety of the string has became one of the key factors for the success of testing. Forces absorbed by APR testing string in high temperature and high pressure deep gas well are discussed. Testing process is divided into tripping in, setting, start up, blasting, flowing, shut in and losing effectiveness of packer and tubing anchor. Mechanical analysis for testing string is based on these eight operational modes. The testing string in high temperature and high pressure deep gas well bears gravity, hydraulic pressure, viscous friction force, casing supporting force. These forces make the strings deform at a certain level, and if the deformation is oversized, string and down hole equipment can be destroyed. Forces and temperature fluctuation exert piston effect, helical buckling effect, ballooning effect and temperature effect which can exert effect forces. Based on the study above, an integrated mechanical model of Deep gas well testing string is established. The integrated mechanical model gives simple calculation formulas for various load and axial deformation of string under different working conditions and formulas of string forces at well head and packer. The study conduct intensity check and optimization design on deep gas well testing string according to different working conditions. Then, with the study above, some exceptional cases that usually happen during high temperature and high pressure deep gas well testing are researched like losing effectiveness of packer, abnormal formation pressure, string leakage and string sticking. The study provides calculation criterion and analysis methods for safety in construction of testing string and therefore success rate of testing can be improved.