Design of Auxiliary Parameter Monitoring System for Oil-based Microscan Instrument Based on FPGA

To monitor the working status of each electronic sub-section and the operating environment of the oil-based mud micro-resistivity scanning imaging logging tool during downhole operations, this paper designs an auxiliary parameter monitoring system suitable for such logging tools. The monitoring system utilizes an FPGA as the control core to drive the analog-to-digital converter AD7606, which collects 8 channels of signals including the working power supply and temperature of other electronic sub-sections. Within the FPGA, error correction is performed on the collected data, including zero offset correction, nonlinearity correction, and temperature drift correction. After completing the error correction, the data is uploaded to the upper computer via the SPI bus for display. Tests have shown that the data acquisition module and SPI communication module of the system can work normally, with an acquisition error of less than $0.5 \%$, successfully achieving the monitoring of the instrument’s working status. The design of the auxiliary parameter monitoring system for oil-based micro-scanning instruments has promoted the independent research and development of oil-based logging instruments in China.