西南石油大学学报(自然科学版)

• 地质勘探 •    下一篇

井中偶极声源激励下的反射横波实验研究

魏周拓,陈雪莲   

  1. 中国石油大学(华东)地球科学与技术学院,山东青岛266580
  • 出版日期:2013-12-01 发布日期:2013-12-01
  • 基金资助:

    山东省自然科学基金(ZR2011DQ020)。

Experimental Study on Shear Wave Reflection of a Borehole Dipole
Source Excitation

Wei Zhoutuo, Chen Xuelian   

  1. School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China
  • Online:2013-12-01 Published:2013-12-01

摘要:

针对偶极横波远探测测量模式开展相关的实验研究,模拟研究了井中偶极声源激励下来自井旁地层界面的反
射横波,分别测量了不同声源位置、不同声源振动方向和不同地层界面特性下的地层和井孔全波。实验结果表明:井中
偶极声源除了激发出沿井传播的直达弯曲波之外,还会向地层中辐射SH 和SV 两种类型的横波。随着偶极声源振动方
向与地层界面走向的夹角从0° 增至90°,反射横波幅度逐渐减小,验证了偶极声源对于井旁反射体具有明显的方位指向
特性,可以用来反演井旁反射体的走向。在固–液或固–气地层界面特性下,SH 波在界面处会发生全反射,而SV 波则会
在界面处发生模式转换,SH 反射横波更有利于进行远探测反射波成像,尤其对于井旁裂缝研究具有独特的优势。

关键词: 偶极声源, 反射横波, 物理模拟, 振动方向, 界面特性

Abstract:

Through related experimental studies on dipole shear wave remote detection measurement-mode,we study shear
wave reflection of a borehole dipole source excitation from near-borehole formation interface,and measure full waveform inside
and outside borehole under different source positions,different polarization directions and different formation interface
characteristics. The experimental results show that a dipole source in a fluid-filled borehole excites direct flexural wave propagating
along borehole and outside borehole,but also radiates two types of shear wave,which are SH-wave and SV-wave,
respectively. Along with the dipole polarization direction from 0° to 90°,reflected shear wave amplitude gradually decreases,
and verified that the dipole source for near-borehole reflector has obvious azimuthal directivity characteristics,which can be
used for determining near-borehole geological structure strike. Under the solid-liquid or solid-gas formation interface characteristic,
total reflection of SH-wave at the reflector interface will happen,and mode conversion occurs to SV wave,so SH-wave
reflection helps to remote detection imaging,and has unique advantages for fractures.

Key words: dipole source, reflected shear wave, physical simulation, polarization directions, interface properties