Research And Implementation Of Measurement And Control Circuit In Triaxial Induction Logging Instrument

Induction logging is an advanced technology in oil exploration, this technology can be used to measure the formation resistivity in the situation which borehole is nonconductive. This measure technology is more sensitive to low-resistance layer. This technology is more fit to distinguish between the aqueous layer, low resistivity layer and the transition layer. The design of this system is reducing useless direct coupling signal, improving useful external induction signal to achieve the goal of measuring resistivity. Compared to array induction logging system, the advantage of triaxial induction logging is more effective to get the information of vertical and horizontal conductivity.The technology of triaxial induction logging system in China has already falled behand foreign technology. Many domestic companies are researching triaxial induction logging instrument actively. The project developing instrument which has intellectual property rights is more and more important in oil exploration business.The triaxial induction logging instrument always works in the environment has high temperature and high pressure. Therefore high reliable characteristic improves the research difficulty. This issue will introduce research process of triaxial induction logging instrument, focus on describing measurement and control circuit of instrument. The main function of circuit consists of changing analog signal to digital signal, completing DPSD algorithm, monitoring temperature and critical voltage of instrument, controlling timing of system, uploading data from instrument to PC. According to the principle of instrument and system structure, we determined the index and function of measurement circuit, exploited and debugged hardware circuit based on TMS320F2812 DSP chip and A3P250 FPGA chip, developed interrelated code of FPGA and DSP. Through completing long time test and high temperature test, the instrument is confirmed to complete all functions and achieve targets. All works we finished have established the foundation for the instrument of production.