PNN测井热中子时间谱的多尺度滤波研究  

Study of Thermal Neutron Time-spectrum of PNN Logging Based on Multiscale Filtering

作　　者：房文静[1] 范宜仁[2] 张峰[2] 

机构地区：[1]中国石油大学物理科学与技术学院,山东东营257061 [2]中国石油大学地球资源与信息学院,山东东营257061

出　　处：《核电子学与探测技术》2010年第3期385-389,共5页Nuclear Electronics & Detection Technology

基　　金：国家自然科学基金资助(40774058)

摘　　要：PNN(脉冲中子-中子)测井是利用He-3管记录热中子时间谱,进而求取地层宏观俘获截面的一种测井方法。热中子时间谱滤波处理是获取有效地层宏观俘获截面值的研究基础。针对热中子时间谱的特点,以X井为研究对象,在探讨小波基及阈值的量化处理基础上,采用了基于阈值收缩的多尺度滤波方法,分别在纵向和横向对热中子时间谱进行了多尺度滤波处理。滤波结果显示热中子计数随时间呈指数规律衰减,满足时间谱后处理的需要。这些探索为PNN测井时间谱的滤波处理提供了一种新方法。Pulsed neutron-neutron logging is applied to calculate the formation macroscopic capture cross section through thermal neutron time-spectrum recorded by He-3 neutron detector. On the basis of filte- ring of time-spectrum, the effective formation macroscopic capture cross section can be obtained. As a case study, effective solutions for selecting optimized wavelet basis and threshold quantization are investi- gated from the characteristics of thermal neutron time-spectrum, and further the method of multiscale filtering based on threshold shrinkage is applied to filtering of thermal neutron time-spectrum of X well by longitudinal depth and transversal time respectively. The results indicate thermal neutron count decays as an exponential function of time. The research provide a new method to the filtering of thermal neutron time-spectrum of Pulsed neutron-neutron logging.

关 键 词：PNN测井 热中子时间谱 小波变换 多尺度分析 滤波 

分 类 号：TN911.6[电子电信—通信与信息系统]