随钻脉冲中子密度测井的蒙特卡罗模拟研究  

Monte-Carlo Simulation Method in Pulsed Neutron Density Logging While Drilling

作　　者：于华伟[1] 孙建孟[1] 朱文娟 杨锦舟[3] 

机构地区：[1]中国石油大学地球资源与信息学院,山东东营257061 [2]长城钻探工程公司测井公司,辽宁盘锦124010 [3]胜利油田钻井工艺研究院,山东东营257000

出　　处：《测井技术》2009年第6期521-524,538,共5页Well Logging Technology

基　　金：国家高技术研究发展计划863项目随钻测井核心探测器关键技术研究(2006AA060105);中国石油大学(山东)优秀博士学位论文培育项目(B2009-13)资助

摘　　要：为取代随钻密度测井仪器中的化学放射源,在Odom等人的脉冲中子密度测井模型研究的基础之上,利用蒙特卡罗模拟对其求取地层密度的方法和精度进行了分析,并对数据处理方法加以改进。通过研究,得到了改进前后地层密度与各探测器通量之间的关系和计算精度。研究结果表明,以往转换网格法所求地层密度精度较低,仍受非弹伽马源分布的影响;快中子通量的对数和伽马扩散长度的乘积与地层密度之间呈良好的指数关系,且所求结果精度更高,可以降低非弹伽马源的影响;源距较大的探测器组合所求密度精度更高。为兼顾对于薄地层的分辨率,最好保留3个伽马探测器。In order to replace the chemical radial source of LWD density logging tools,Monte-Carlo Simulation was applied to analyze the method and accuracy of obtaining formation density based on the Odom＇s model of pulsed-neutron density log,and to improve the data processing method.The relationships between formation density and the flux of all detectors were obtained using simulation data.The obtained results show that the precision of density calculated from a transformation grid was lower because of the size variety of inelastic gamma distribution.However,there was the exponential relationship between density and the product of gamma diffusion length and the logarithm of fast neutron flux,so the precision was higher.In order to keep the higher resolution to thin beds,three gamma ray detectors were used.

关 键 词：随钻密度测井 脉冲中子源 地层密度 蒙特卡罗模拟 影响因素 

分 类 号：TE122.22[石油与天然气工程—油气勘探] O482.532[理学—固体物理]