Cased Hole Resistivity Logging’ Signal Detection System Design In Downhole Temperature Environment

With the international and domestic market demand for oil increases, the oil industry booming, many former high-yield oil, high oil production fell there; to grasp the dynamics of the reservoir, adjust the development, mining plan, to ensure that oil, the yield and oil yield, the urgent need for a log in the cased instruments, while the use of formation resistivity through casing formation resistivity logging techniques for logging work is a practical, cost-effective solution was.In this paper, through casing formation resistivity logging tool acquisition signal characteristics, the use of lock-in amplifier circuit in the multi-level nested Butterworth low-pass filter technology to effectively extract the very weak low-frequency test signals, and power sectors using a variety of noise reduction technology, the noise level control system can tolerate very low levels, while using the latest, special electronic components, the stability of the system hardware to provide reliable protection.This paper also printed circuit board design, done in-depth analysis and research, presented in the printed circuit board level to prevent electromagnetic interference, crosstalk ways and means, that in the printed circuit board design should pay attention to the problem and solutions. The system’s printed circuit board has been planning and design for the4-layer high-temperature circuit board.Cased Hole resistivity signal detection system is a modular design in Downhole high-temperature environment, implementation of the system from the formation of a weak signal acquisition and analysis.