钻铤偏心对随钻四极子横波测井影响:理论与实例分析  

Influence of drill collar eccentricity on quadrupole shear-wave logging while drilling:theory and field case

作　　者：饶博 苏远大[1,2] 李盛清 孙云涛[3] 陈文轩[3] 唐晓明[1,2] RAO Bo;SU YuanDa;LI ShengQing;SUN YunTao;CHEN WenXuan;TANG XiaoMing(Key Laboratory of Deep Oil and Gas,China University of Petroleum,Qingdao 266580,China;Laboratory for Marine Mineral Resources,Laoshan Laboratory,Qingdao 266071,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国石油大学(华东)深层油气重点实验室,青岛266580 [2]崂山实验室海洋矿产资源评价与探测技术功能实验室,青岛266071 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2023年第1期111-121,共11页Chinese Journal of Geophysics

基　　金：中国科学院A类战略性先导科技专项(XDA14020302);国家自然科学基金(U21B2064,41821002,42074137,42174145);山东省自然科学基金(ZR201911120382);中央高校基本科研业务费专项基金(20CX06077A)联合资助.

摘　　要：随钻四极子声波测井技术主要用于测量地层的横波速度.但在复杂旋转钻进过程中钻具的偏心会对测量的四极子波形质量及横波速度产生不利影响.本文建立以钻铤和井孔分别为基准的双柱坐标系偏心随钻声波测井模型,利用贝塞尔函数的平移加法定理构建边界条件和井中响应函数,数值模拟了钻铤居中和偏心时四极子声源激发的声场.发现偏心后的随钻四极子声场中除地层四极子波外,还有单极斯通利波和偶极弯曲波的多阶模式波共存且相互耦合,尤其是在软地层钻铤严重偏心时四极子模式波受斯通利波模式和弯曲波模式干扰更为严重,不利于地层横波速度的测量.现场随钻四极子声波测井仪器实验样机在居中和偏心的状态下实测的数据表明:当随钻四极子样机居中测井时,可测量到高质量的四极子波形,处理得到相关性较强的地层横波时差,与单极测量横波时差吻合较好;但钻铤偏心测量时采集的波形成分复杂,偏心引起的低频斯通利波模式对地层四极子模式的耦合干扰非常严重,导致地层横波时差的相关性很差,测量值介于横波与斯通利波时差之间,与实测单极横波时差差异很大甚至无法使用,尤其在疏松软地层中影响更为突出.本文从偏心随钻四极子井孔声场理论出发,结合现场实测数据,重点分析钻铤偏心对四极子横波测井的影响,为指导偏心状态下随钻四极子横波时差处理与校正方法提供理论基础.The shear-wave velocity of formation is measured by using a acoustic logging-while-drilling(ALWD)quadrupole tool,while the eccentricity of drill collar will seriously influence the quality of the quadrupole waveforms and the shear-velocity measurement during the complicated rotary drilling process.In this study,an eccentric ALWD model is established in the dual-cylindrical coordinate systems based on locations of the drill collar and borehole.The translational addition theorem of Bessel functions is utilized to construct the boundary conditions and borehole response functions.Then the wave-field excited by quadrupole sources under the conditions of the centered and eccentric drill collar models is numerically simulated.The results show that an eccentric tool causes multipole wave modes including the formation quadrupole mode,and the Stoneley-wave and the flexural wave coexist and couple with each other.It should be noted that when the drill collar is seriously eccentric in the slow formation,the quadrupole mode is seriously disturbed by Stoneley-wave and the flexural wave modes,which is not conducive for the shear velocity measurement.Field data analysis results show that high quality and pure quadrupole waveforms of the formation can be measured,and accurate shear-wave slowness can be obtained,which is in good agreement with the shear-wave velocity of ALWD monopole mode.However,the waveform has complex components when the ALWD tool is eccentric.The coupling interference of low-frequency Stoneley-wave causes poor correlation of formation quadrupole waveforms and unreliable shear-wave slowness.The measurement of slowness is between the actual shear-wave and Stoneley-wave,which is extremely different from the result of monopole measurement of the ALWD tool.This discrepancy become obvious in the slow formation.Therefore,based on the eccentric quadrupole ALWD theory and combined with the measured data,this study concentrates on the analysis of the influence of drill collar eccentricity on quadrupole-wave data,which p

关 键 词：随钻声波测井 四极子 仪器偏心 横波速度 

分 类 号：P631[天文地球—地质矿产勘探]