近地表Q因子估算影响因素分析

doi:10.6038/pg2018BB0153

摘要/Abstract

摘要：

利用微测井资料对近地表吸收结构进行观测和估算,消除近地表吸收衰减对地震数据分辨率的影响,是近年来高分辨率地震勘探的重要尝试.为提高近地表Q值建模的可靠性,本文结合微测井资料,指出近地表Q值建模的主要问题,就各个影响因素进行了讨论和分析.分析结果表明:震源子波和检波器耦合响应一致性假设并不成立,激发和接收因素差异对近地表Q值建模的影响不容忽视.另外,利用微测井资料进行Q值建模要合理的选取频带范围,避免近场分量对信号低频端的影响.有效的提取高质量的直达波,避免面波、浅层折射波和虚反射等噪声干扰,是近地表Q值建模成功的关键.在此基础上,针对不同的影响因素,提出了相应的解决策略,这对于提高近地表Q值建模的精度具有重要的现实意义.

关键词: 近地表, Q因子, 微测井, 吸收衰减

Abstract:

Q compensation is widely used to eliminate absorption and attenuation effect on the seismic resolution via accurate near surface Q factor estimated from uphole survey, which is an important trial for high resolution seismic exploration in recent years. To improve the reliability of near surface Q modelling, this paper stated the main factors affecting the inversion results and discussed in detail based on the in-situ data. From the analysis, it’s clearly that the hypothesis of consistency on the source and geophone coupling is inappropriate in a way, and the influence of source and geophone differences on near surface Q estimation is nonnegligible. Effective frequency band is also needed to avoid the effect of near field on low frequency end. In addition, the direct signals should be carefully extracted to avoid interference effects from ground-surface wave, shallow refraction wave and ghost reflection. Based on the analysis, certain strategies are proposed to solve the problems, leading to practical importance to enhance the accuracy of near surface Q modelling.

Key words: near surface, Q factor, uphole survey, seismic attenuation

中图分类号:

P631

蔡杰雄, 郑浩, 刘定进, 倪瑶. 2018. 近地表Q因子估算影响因素分析. 地球物理学进展, 33(2): 547-553. doi: 10.6038/pg2018BB0153.

Jie-xiong CAI, Hao ZHENG, Ding-jin LIU, Yao NI. 2018. Analysis of influencing factors of near surface Q estimation. Progress in Geophysics. 33(2): 547-553. doi: 10.6038/pg2018BB0153.

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