核磁共振测井仪中的信号检测模块设计

测井技术是一项横向涉及面广,纵向技术难度大的综合性技术。核磁共振测井中技术难度最大的部分,就是对微弱信号的检测放大及采集,需要采集的几纳伏的正弦信号伴随有极大的噪声。鉴于此,提供了一种性能优良的信号放大及数据采集模块设计。其中前置放大由2级放大组成,共可以将信号放大约1550倍,主要器件采用军品级或者工业级,可耐150℃高温及高压,适用于井下微弱信号的放大;信号采集部分由A/D转换及DSP组成,具有高精度、速度快等特点。

Design of signal-detecting module in NMR logging system

Logging technology is an all-around technology that involves many technologies.The most difficult part in NMR logging system is the detecting,amplifying and acquiring modules of the weak signals.The sine signals needing to be acquired are only several nV with much noise.Therefore,an excellent signal amplifying and data acquiring module is designed.The pre-amplification circuit includes 2-level amplifying module,which can amplify the signals by 1 550 times.The main parts need to use the military-grade or industry-grade parts,which can work normally under high temperature of 150℃ and high pressure.It is fit for amplifying the downhole weak signals.The signal acquisition module is made up of A/D transfer part and DSP,which features high accuracy and rapid response speed.