一种可控震源非线性扫描信号设计方法及应用

A vibrator nonlinear sweeping signal design method and its application

西部沙漠等地区存在严重的吸收衰减及低信噪比问题,为提高地震资料的品质,文中研究了一种基于目的层反射波频率特征的非线性扫描信号设计方法,改善目的层反射资料信噪比。根据主要目的层反射资料频谱特征和勘探任务要求,制定期望的频谱特征曲线,作为扫描频率与能量分布关系,控制扫描频率的驻留时间,求取非线性时频关系,获得非线性扫描信号。这一方法突出扫描信号期望的优势频率能量,优化可控震源输出地震波频谱特征。通过正演模拟和单炮记录试验,验证了本方法正确性和有效性,通过应用试验取得了较好效果。

Severe attenuation by earth absorption and low S/N ratio exists in western China＇s desert areas.In order to improve the seismic exploration quality of geological targets,the authors put forward a nonlinear sweeping signal design method based on reflection frequency characteristics of target strata to enhance reflection data signal-to-noise ratio of purpose layers.According to characteristics of reflection data frequency spectrum and exploration mission requirements of major purpose layers,the expected frequency spectrum characteristic curves are designed,which are used as distribution relationship between sweeping frequency and energy and applied to controlling the dwell time of sweeping frequency. Then,nonlinear time-frequency relationship is computed and nonlinear sweeping signals are obtained.This method highlights the anticipated dominant frequency energy of sweeping signals and optimizes the seismic wave frequency spectrum of vibrator outputs.Forward modeling and single shot seismic record tests have verified the correctness and validity of this method.Good results are obtained through application tests.