Application and development of permanent magnet torque motor in down-hole tools for oil and gas drilling and production

Permanent magnet torque motor is a kind of a power driving device with great development potential. It has several advantages, such as high torque density, fast response speed, strong overload capacity, high efficiency and energy saving, therefore, it possesses wide application prospects in many fields in both industrial production and daily life and so on. In view of the current application overview and technical requirements of permanent magnet torque motors in oil and gas drilling and production down-hole intelligent tools, firstly, this paper briefly introduces the structure composition and working principle of permanent magnet torque motor. Then, it elaborates the application status of permanent magnet torque motor in the field of oil and gas drilling and production down-hole tools, including down-hole smart sliding sleeves, down-hole packers, down-hole water flow regulator, and down-hole blowout preventers. The structural characteristics of various down-hole tools and the driving characteristics of permanent magnet torque motor are systematically introduced. Furthermore, this paper makes a summary that as a power source of down-hole tools, the structure and size of permanent magnet torque motor are mainly limited by the sealing environment of high temperature and high pressure, the diameter of tubing and convenience of transmission. Additionally, there are still some major problems have to be settled, including low magnetic power efficiency, poor ability of high temperature and voltage resistance, and low power reliability. Last but not the least, the main research direction and development trend of the motor in down-hole tools for oil and gas drilling and production are discussed. It recommends doing some research on increasing the output torque per unit length of permanent magnet torque motor, design of thermal stability, power optimization, research and development of new permanent magnet materials, intellectualization, and miniaturization, to cater for the needs of down-hole operation conditions and further expand the potential market.