低计数特征的自然伽马能谱测井数据滤波方法研究  

A Study on the Filtering Method of Natural Gamma Energy Spectrum Logging Data for Low-Count Features

作　　者：祝倩 于华伟[1,2] 葛云龙 岳爱忠 童茂松 陈瑾泓 杨树 ZHU Qian;YU Huawei;GE Yunlong;YUE Aizhong;TONG Maosong;CHEN Jinhong;YANG Shu(National Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao,Shandong 266580,China;School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Logging Technology Research Institute,China National Logging Corporation,Xi'an,Shaanxi 710077,China;Well Logging Key Laboratory,China National Petroleum Corporation,Xi'an,Shaanxi 710077,China;Oil Reservoir Dynamic Monitoring Center,Shengli Oilfield,SINOPEC,Dongying,Shandong 257000,China)

机构地区：[1]深层油气全国重点实验室(中国石油大学(华东)),山东青岛266580 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油集团测井有限公司测井技术研究院,陕西西安710077 [4]中国石油天然气集团有限公司测井重点实验室,陕西西安710077 [5]中国石化胜利油田分公司油藏动态监测中心,山东东营257000

出　　处：《测井技术》2024年第5期586-594,共9页Well Logging Technology

基　　金：山东省自然科学基金“可控X射线源高分辨率岩性密度测井方法研究”(ZR2022MD019);中央高校基本科研业务费“随钻井筒信息一体化地质导向关键技术研究与基础软件开发”(22CX01001A-2);中国石油大学(华东)探究性实验项目“提升‘两性一度’目标的自然伽马测井实验课程建设”(TJ-202201);中国石油集团测井有限公司开放基金“低计数能谱数据处理技术”(CNLC2022-9C06)。

摘　　要：岩石天然放射性强度较弱,自然伽马能谱测井所测得的能谱计数较低,低计数特征使得地层衰变随机误差影响被放大,造成测量能谱质量差、测井曲线统计噪声大的情况。该文通过对比多种能谱滤波结果,使单深度点能谱最大程度还原准确能谱信息;利用曲线形态,针对求解的U、Th、K含量曲线进行深度域的滤波处理,综合从高噪声、低计数的数据中准确提取地层信息;利用中国石油集团测井有限公司的过钻具自然伽马能谱仪器的实测数据验证该方法的有效性。结果表明:对于计数低、谱形差的自然伽马能谱,高斯滤波、卷积滤波效果相对较好,该文提出结合这2种方法的复合滤波可以准确地还原出高保真的能谱形状;深度域的滤波,卡尔曼滤波相对自适应滤波方法有一定优势;依次经过能谱滤波和深度滤波后,结果的准确性和重复性有了大幅提升。该文所介绍的针对低计数特征的自然伽马能谱测井滤波方法,可以有效提高U、Th、K的测量精度。The natural radioactivity intensity of rocks is low,and the energy spectrum count measured by natural gamma spectrum logging is low.The low count characteristic magnifies the influence of random error of formation decay,resulting in poor quality of energy spectrum measurement and large statistical noise of logging curve.In this paper,a variety of spectral filtering results are compared,so that the single depth point spectral information can be restored to the maximum extent.By using the curve shape,depth domain filtering is carried out for the U,Th and K content curves to comprehensively extract formation information from the data with high noise and low count.The validity of the proposed method is verified by the measured data of the natural gamma-ray spectrometer of the drilling tool of China National Logging Corporation.The results show that the effect of Gaussian filter and convolution filter is relatively good for the natural gamma spectrum with low count and poor spectral shape,and the composite filter combining the two methods in this paper can accurately restore the accurate spectral shape.In depth domain filtering,Kalman filtering has some advantages over adaptive filtering.After energy spectrum filtering and depth filtering,the accuracy and repeatability of the results are greatly improved.The filtering method of natural gamma energy spectrum logging for low-count features introduced in this paper can effectively improve the measurement accuracy of U,Th and K.content curves to comprehensively extract formation information from the data with high noise and low count.The validity of the proposed method is verified by the measured data of the natural gamma-ray spectrometer of the drilling tool of China National Logging Corporation.The results show that the effect of Gaussian filter and convolution filter is relatively good for the natural gamma spectrum with low count and poor spectral shape,and the composite filter combining the two methods in this paper can accurately restore the accurate spectral shape.

关 键 词：自然伽马能谱测井 低计数率 统计误差 能谱滤波 曲线处理 

分 类 号：P631.84[天文地球—地质矿产勘探]