Research On The Small Size Underground Storage Casing Damage Detector

The casing plays an important role in the process of oil and gas exploitation.The commonly use of fracturing technology in shale gas exploitation can easily cause casing deformation,which seriously affects the subsequent construction work.Therefore,it is quite significant to measure casing deformation.In view of the complex working conditions of shale gas wells,the small size underground storage casing damage detector is designed and studied in this thesis.The working method and control logic of the instrument is clarified,respectively,the short sections of the probe,the centralizer and the power are discussed in detail.A method is put forward that using the instrument body as the sensor package to meet the pressure-resistant requirements and the feasibility of this method is proved by tests.The force condition during running down the instrument is analyzed and the centralizer is designed to ensure centrality and reduce the frictional resistance torque.For the torque output of power short section under high pressure environment,a pressure balance device combining piston and capsule is designed,which can not only reduce the pressure difference between inside and outside of the short section,but also protect O-ring effectively.Based on the compressibility of the liquid,the oil volume change under high-temperature and high-pressure environment is studied.Finally,the finite element software is used to optimize the size,check the strength and analyze the thermodynamic problem for the corresponding short section.Based on the overall design requirements of the instrument,this thesis completed the design of the small size underground storage casing damage detector.Compared with the traditional logging tool,the instrument's passability is excellent while the resistance to high-temperature and high-pressure environment is better,which can contribute to the development of casing deformation detection technology.