利用地震勘探炮井随钻振动信号反演近地表结构

地形起伏的山地地震勘探通常采用井炮激发方式。在炮井钻进过程中柴（汽）油机、钻头和支架构成的连接体形成一个在地表连续振动的噪声源，产生的近地表振动以井架为中心，向四周辐射传播，这种地表振动的传播规律与近地表的速度结构密切相关。文中提出利用这种随钻振动信号反演近地表结构的方法，即在以该连接体为中心的一条辐射线上布置一系列检波器连续记录振动信号，然后对每道信号进行去均值、去趋势、时间域归一化和谱白化等处理，最后用距离钻机连接体最近的一道分别与其余各道进行互相关，相关结果的时间导数即是钻机振动产生地震波场的经验格林函数，进而采用多道分析方法从中提取面波频散曲线以反演近地表速度结构。实际数据的分析结果表明，所述方法提取的拟面波与多道瞬态方式采集的实际面波非常接近，反演得到的近地表速度结构也与微测井成果对应一致。

Near-surface structure inversion using vibration signals while drilling shot holes in seismic exploration

The deep-hole dynamite source is usually adopted for seismic exploration in mountain areas due to the undulating terrain. In the process of drilling shot holes, the connector comprised of the diesel (gas) engine, drilling bit, and support equipment forms a noise source that continuously vibrates on the surface. The near-surface vibration generated radiates to the surroundings with the derrick at its center, and the law of this vibration closely correlates with the near-surface velocity structure. Therefore, this paper proposes a me-thod of utilizing this type of vibration signal while drilling to acquire the near-surface structure through inversion. Specifically, geophones are arranged on a radiation line centering around the connector to continuously record the vibration signals, and then each signal is processed through mean removal, detrending, time-domain normalization, and spectral whitening. Finally, the one closest to the connector of the drilling rig is cross-correlated with the rest of the signals. The time derivative of the correlation result is the empirical Green's function of the seismic wave field generated by the drilling rig vibration. The multichannel analysis is employed to extract the surface wave dispersion curve to obtain the near-surface velocity structure through inversion. The analysis of the pilot field experiment shows that the extracted pseudo surface wave by the proposed method is highly close to the surface wave acquired by the multichannel transient method, and the near-surface velocity structure obtained through inversion is also consistent with the uphole survey measurement.