【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。更多还原

【Abstract】 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 filtering 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 investigated 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.更多还原