核磁共振测井仪接收机设计与实现  

Receiver design and implementation of NMR logging tools

作　　者：阳松波 李仙芝[2] 程晶晶[1] 

机构地区：[1]华中科技大学自动化学院测量科学与仪器系,武汉430074 [2]中海油田服务股份有限公司,北京101149

出　　处：《国外电子测量技术》2014年第4期54-57,共4页Foreign Electronic Measurement Technology

基　　金：博士学科点专项科研基金20130142120065

摘　　要：受激发条件和氢核响应机理的限制,核磁测井原始回波信号极其微弱。高信噪比的回波信号在反演算法中能够更加真实的反映地层信息,于是设计一个高增益、低噪声的接收机非常关键。基于核磁原始回波信号的幅频特性分析,利用低噪声前置放大器、滤波单元、A/D转换器、改进的数字相敏检波处理单元,设计实现了一个高信噪比多频数字接收机。该接收机已经成功应用于中海油自主研发的核磁共振测井仪(elis magnetic resonance tool,EMRT)上,在渤海油田得到的测井曲线CHI值表明该接收机工作稳定,提取信号信噪比高。Limited by the excitation condition and the way proton responses for it,the original echo signal of NMR-LWD（nuclear magnetic resonance-logging while drilling） is extremely weak.As inversion calculation based on echo signal of high signal-tonoise ratio （SNR） can reflect layer information more accurately,so it is of great importance to design a receiver which has little noise and a high gain.Based on the analysis of the amplitude-frequency characteristic of original NMR-LWD echo signal,a multi-frequency digital receiver of high SNR is designed by using a low noise preamplifier,a filter unit,an A/D converter and an improved digital phase-sensitive processing unit.The receiver has already been applied in EMRT （elis magnetic resonance tool）,the NMR-LWD equipment developed by CNOOC.The CHI values of logging curves obtained in Bohai oilfields show that this receiver can successfully extract echo signal with high SNR and work stability.

关 键 词：核磁共振 信噪比 数字接收机 微弱信号 CHI值 

分 类 号：TN014[电子电信—物理电子学]