过套管电阻率测井信号频率对检测的影响分析  

Impact Analysis of Cased Hole Resistivity Logging Signal Frequency on Signal Detection

作　　者：吴银川[1] 张家田[1] 严正国[1] 

机构地区：[1]西安石油大学光电油气测井与检测教育部重点实验室,陕西西安710065

出　　处：《测井技术》2010年第3期262-265,共4页Well Logging Technology

基　　金：陕西自然科学基金(2007D01);西安石油大学创新基金(YS28030533)资助

摘　　要：分析了金属套管的趋肤效应现象,提出过套管测井激励信号的源为超低频。过套管电阻率测井技术直接测量信号的量级为μV级,有用信号的量级为nV级。针对测井信号的特点提出利用数字相敏检波技术提高信号的检测精度。分析了信号频率对检测的影响因素,为准确检测信号,过套管电阻率测井要求激励信号的频率小于10Hz,激励信号的频率稳定度直接影响信号检测的精度。在确定采样数据长度、采样频率条件下,可定量计算激励信号的允许频率偏差范围。该结论可用于指导过套管激励信号以及弱信号检测系统的设计。Analyzed is the skin effect of metal casing, and put forward is that the stimulus signal source is in a ultra-low frequency in cased hole resistivity logging. In this technology, the direct detection signal is in microvolt level, but the useful signal is in nanovoh level. Based on the characteristics of this technology, the digital phase sensitive technique is put forward for improving accuracy of data acquisition. The logging signal frequency effect on detection is analyzed. In order to detect cased hole resistivity logging signal accurately, the stimulus signal frequency should be less than 10 Hz. The stability of the stimulus signal has direct effect on logging signal detecting accuracy. When the sampling data length and sampling frequency are fixed, the allowed frequency deviation range of stimulus signal can be calculated quantitatively. The study result can be applied in design of signal source and weak signal acquisition system.

关 键 词：过套管电阻率测井 信号检测 趋肤效应 相敏检波 激励信号 采样频率 

分 类 号：P631.3[天文地球—地质矿产勘探]