Circuit Design of Fluid Scanning Imaging Logging Tool Working in Shale Gas Well

In order to improve oil and gas recovery, dynamic monitoring of shale gas horizontal wells must be considered and very urgent. The fluid scanning imaging logging tool can measure the three-phase flow state of the fluid, and then provide information such as horizontal section production and main production interval, which is necessary technical support for dynamic monitoring of shale gas horizontal wells. The fluid scanning imaging logging tool is an assembled string of instruments, composed of three independent units, to complete logging test with fluid scanning imaging functions. The three independent units are gas holdup logging instrument, hydraulic power sub, and eccentric sub. The gas holdup logging instrument takes multi-array sensors, which can measure parameters such as gas holdup, water holdup, and flow rate at different liquid levels for a certain logging depth section in the current wellbore; The hydraulic power sub controls the movement of the mechanical arm of the gas holdup test unit to complete operations such as opening and closing; The eccentric sub keeps the mechanical arm of the gas holdup logging instrument in an upright position, ensuring that the entire fluid scanning imaging logging tool string works vertically in the borehole. The circuit system design of the gas holdup logging instrument is novel and has the following characteristics compared to other similar tools: modular design concept, that can be subdivided into functional modules such as acquisition module, gas holdup module, water holdup module, flow module, optical fiber sensors, and so on; multi-array sensor installation to simultaneously measure the fluid state at different vertical depths of the wellbore; high speed data transmission capability; circuit miniaturization. This design solves the problem of large amount of measurement information and fast data transmission speed in traditional measurement, and at the same time, the tool is small in size and easy to operate in borehole. The function of the hydraulic power sub circuit system is to drive a DC brushless motor, which is composed of a three-phase full-bridge module, an over-current protection module, and a control module. During the development of circuit system to the gas holdup logging instrument and hydraulic power sub, we made great progress in key core technologies, which benefits to accelerate the development of domestic instruments, and met the requirements of fluid scanning imaging logging test in horizontal wells.