近地表连续介质区Q值调查应用研究

Investigation and application of Q-value in near-surface continuous medium area

为了提高地震资料的分辨率,对原始资料进行吸收补偿,需要提高近地表Q模型的精度。针对结构疏松、速度变化快且风化层厚度较大的连续介质近地表对地震波吸收衰减严重的问题,开展了品质因子调查、近地表Q建模等方面研究工作。结果表明:1)井中激发、地表和井底同时接收的双井微测井调查方式,可提高品质因子的精度;2)涵盖了不同风化层速度、厚度且样点数据充分的近地表Q值调查结果保证了Q-v经验公式的统计规律;3)微测井调查的高精度近地表模型为构建层状近地表Q模型奠定了基础;4)连续介质近地表Q模型更加真实地反映了实际近地表Q值的分布规律。以上成果认识,对近地表为连续介质的沙漠、黄土塬等工区提高分辨率地震勘探采集具有一定指导意义。

In order to improve the resolution of seismic data,absorption compensation must be applied to the original data,and the accuracy of the near-surface Q model must be enhanced.In view of the serious absorption and attenuation of seismic waves near the surface of continuous media with loose structure,fast velocity change and large thickness of the weathered layer,quality factor investigation and near-surface Q modeling were researched.The results showed that:1)The uphole in two holes survey method of excitation in the well while receiving at the surface and bottom of the well can improve the accuracy of quality factor;2)The Q-value in near-surface survey results covering the velocity and thickness of different weathered layers together with sufficient sample data ensure the statistical law of Q-v empirical formula;3)The high-precision near-surface model of uphole survey lays a foundation for the construction of layered near-surface Q model;4)The continuous medium near-surface Q model more truly reflects the distribution law of the actual near-surface Q-value.The above results show that improving resolution has certain guiding significance for seismic exploration and acquisition in desert,loess tableland and other work areas where the near surface is a continuous medium.