井外爆炸点源激发井孔声波场  

Borehole Acoustic Field Excited by An External Explosive Source in Elastic Formation

作　　者：周来江[1,2] 张玉君[1] 崔志文[1] 王克协[1] 

机构地区：[1]吉林大学物理学院,长春130012 [2]哈尔滨工程大学水声工程学院,哈尔滨150001

出　　处：《吉林大学学报（地球科学版）》2011年第1期299-304,共6页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(10534040;40674059;40974067);声场声信息国家重点实验室开放课题研究基金项目(200807)

摘　　要：利用井外爆炸点源激发的声波场与井孔的相互作用模拟井间地震的物理过程,推导了全频域井孔内外声波场的理论计算公式,并针对不同震源主频、不同源距(震源到井轴的径向距离)和软硬地层进行了井内声场的全波模拟与频率-相速度分析。结果表明:井外爆炸点源激发井孔内外的声场等效于无穷多级声场迭加的结果;震源靠近井壁时的频率-相速度图与震源在井内时相似;震源的主频越高、源距和接收器离井轴的径向距离越大、地层越硬,则顾及的多级声场的项数就要越多;震源主频越低、源距越小,井中激发的斯通利波则越强。A physics model for cross well seismic based on interaction between acoustic field excited by an external explosive source and a borehole has studied.The theoretical expressions of acoustics for all frequency in and out a borehole are obtained.Full waveform simulation and frequency-phase velocity analysis for different center frequency of seismic source,different offset and different formation were studied.The results show that the acoustic fields inside the borehole are composed of infinitude of multiple fields with different orders.It shows the frequency-velocity figures for source nearby borehole wall are similar to those of acoustic logs.The higher center frequency,more formation hardy and more different offset,the more orders should be calculated.The amplitude of Stoneley waves will increase as center frequency and offset are becoming smaller.It is of help us to further understand cross well seismic prospecting by theoretical and numerical simulation.

关 键 词：井孔 声场 井间地震 爆炸点源 频率-相速度分析 

分 类 号：O422.2[理学—声学] TE319[理学—物理]