Editorial office of ACTA PETROLEI SINICA ›› 2012, Vol. 33 ›› Issue (5): 835-840.DOI: 10.7623/syxb201205013

• Petroleum Exploration • Previous Articles     Next Articles

Numerical simulation of monopole acoustic reflection imaging logging in the logging-while-drilling condition

CHEN Xuelian WEI Zhoutuo   

  • Received:2012-02-01 Revised:2012-06-28 Online:2012-09-25 Published:2012-11-27

随钻单极子声反射测井数值模拟

陈雪莲 魏周拓   

  1. 中国石油大学地球科学与技术学院 山东青岛 266580
  • 通讯作者: 陈雪莲
  • 作者简介:陈雪莲,女,1976年2月生,2006年获中国石油大学(华东)地质资源与地质工程专业博士学位,现为中国石油大学(华东)副教授,主要从事声波测井方法及岩石物理的教学和科研工作。
  • 基金资助:

    国家青年自然科学基金项目(No.40804020)、山东省自然科学基金项目(ZR2011DQ020)和中央高校基本科研业务费专项资金项目(10CX04007A)资助。

Abstract:

In view of practical demand of drilling geology, we compared distributions of the monopole exciting acoustic field both inside and outside a borehole between homogeneous formations and near-borehole geological interfaces in a logging-while-drilling (LWD) condition by applying numerical simulation of the 3D rectangular-coordinate and time-domain finite difference, and examined the influence of a drill collar on radiation intensity of the acoustic field outside a borehole. Because of the shielding effect of a large diameter drill collar, there is a significant difference in the reflected P wave amplitude received from eight different azimuths evenly distributed on the drill collar when the reflection of near-borehole formation interfaces exists. The reflected P wave information on near-borehole formation interfaces can be extracted through vector calculus of signals received from different azimuths. By comparing the reflected P wave intensity of different azimuthal receivers, one can determine the azimuth information of formation interfaces. As the reflected compressional wave is a weak signal in a waveform, it is recommended to keep the distance between the source and receiver within 4 m for data acquisition. The results provided a reference for the development of LWD acoustic reflection tools and data processing as well.

Key words: 3D finite difference, acoustic logging while drilling, reflected P wave, effect of sound field, receiver distribution

摘要:

从随钻地质导向的实际需求出发,通过三维直角坐标时域有限差分数值模拟的方法对比了均匀地层和井旁存在地质界面时随钻环境下单极子声源激发的井孔内外声场分布特征,考察了钻铤的存在对井外辐射声场强度的影响。由于硕大钻铤的声场屏蔽效应,井旁存在地层界面时,井周8个方位上接收到的反射纵波信息具有明显差异,通过对不同方位上接收的信号做矢量计算,得到了来自井旁地层界面的反射纵波信息;通过对比不同方位上接收器接收到的反射纵波信号的强弱,还可确定地层界面的方位信息。由反射纵波幅度随源距的变化曲线可知,为了采集到反射纵波,建议随钻声波测井的测量源距控制在0~4m。数值计算结果为随钻反射声波仪器的研制和数据资料的处理提供了参考。

关键词: 三维有限差分, 随钻声波测井, 反射纵波, 声场效应, 接收器布局