MIT阵列感应测井微弱信号检测采集系统设计

Design of MIT Array Induction Weak Logging Signal Detection and Acquisition System

微弱信号检测是阵列感应测井精确测量的关键。介绍了以ADSP2181为核心处理器的数据采集系统实现MIT阵列感应测井仪的微弱信号检测。该系统通过硬件调理电路优化，采用多DSP主从复合结构的模块化功能设计，利用自动增益控制、实时刻度校正和数字相敏检波技术，有效实现对阵列感应线圈系多道多频大动态范围微弱信号的采集处理。测试结果表明，在地层电阻率0．1-100Ω·m范围内能实现准确测量，相对误差小于5％。

The design of the weak signal detection system is a key technology for performing precise measurements of the Multi-array Induction Tool （MIT）. The presented data acquisition system based on the ADSP2181 is used to perform MIT weak signal detection. Through optimizing regulation circuits and applying modular function design based on multi-DSP, auto gain control, in-time calibration correction and digital phase-sensitive detection, the multi-channel and multi- frequency weak signals of MIT coils array may be acquired and processed accurately in a great dy- namic measurement range. The test results show that the precise measurement of MIT may be performed and the relative measurement error is less than 5% within the range of 0. 1--100 Ω·m of formation resistivity.