摘要
地震信号在传播过程中受到近地表和深地层吸收衰减的影响,能量变弱,高频成分衰减比低频成分更为严重,接收与识别反射系数较小或高频的弱反射信号是高密度地震勘探的瓶颈问题。笔者通过建立典型的粘弹性地质模型,分析了弱反射信号与近地表、震源主频、炮检距以及与深地层的关系,得出以下认识:在近地表吸收衰减严重的低噪比地区,由于截止频率的存在,高密度采集的宽频优势难以体现;良好的激发条件对提高弱反射信号能量、拓宽频带作用较大;中小炮检距是弱反射信号有效反射系数较好的区域,是提取弱反射信号的最佳区域。
The seismic signal received by sensors is very weak because the energy is absorbed and attenuated by subsurface and deep layer during signal propagating. The high frequency component was much more seriously absorbed and attenuated than low frequency component. The key issues for high density seismic acquisition are to receive and identify low reflection coefficient or high frequency weak signal. In this paper,the relationship of weak signal to subsurface,dominant frequency,offset and deep target layer was analyzed based on a typical elastic-viscoelastic earth model. The results show that it is very difficult to give expression to the advantages of broad band frequency in high density seismic acquisition in the area with strong subsurface attenuation and low S /N ratio due to the existence of the cut off frequency. Good condition excitation can improve weak signal energy and give more contribution to broaden frequency band. The effective reflection coefficient can be better presented in small and middle receiver-source offset and can be well extracted.
出处
《物探与化探》
CAS
CSCD
2014年第4期701-710,741,共11页
Geophysical and Geochemical Exploration
基金
国家科技重大专项(2011ZX05006)
中石化石油工程地球物理有限公司胜利分公司地震勘探基础研究实验室资金项目
关键词
吸收衰减
高密度地震采集
弱反射信号
截止频率
有效反射系数
absorption and attenuation
high density seismic acquisition
weak signal
cut-off frequency
effective reflection coefficient
