利用可控震源谐波提高地震数据分辨率

由于可控震源机械系统的非线性等因素造成子波中包含谐波畸变,在相关后成为噪声进而降低地震资料质量,所以可控震源谐波通常被当作噪声进行去除。实际上谐波包含基波所不具有的频率成分,将其用于展宽地震记录的频带,既能提高采集资料的分辨率,又能改善信噪比。为此本文首先分析谐波信号的理论表达,并提出谐波应该被看作有效信号的观点,然后扩展了纯相位滤波器(PPSF)方法并用于谐波信号的分离,最后对分离后的谐波记录分别进行相关并叠加得到最终记录。理论和实际资料的测试结果说明了该方法的有效性。

Broadband seismic data with vibroseis harmonics

There is harmonic distortion in vibroseis wavelet due to the nonlinearity of the vibrator mechanical system.And after correlation,harmonics become noise in correlated data and degrade seismic data quality.Therefore,harmonics are removed as noise conventionally.However,harmonics contain more extra frequency component than fundamental signal.And they can broaden the bandwidth and enhance the S/N ratio.In this paper,the theoretical representation of harmonics is analyzed and a new viewpoint about vibrator harmonics as signal is presented. And the pure phase shift filter(PPSF)method is further extended to separate harmonics from records.And then the separated harmonics are correlated with their own sweep signals to generate different orders of correlated shot records.Finally these correlated shot records are stacked to generate broadband shot record.Numerical results on both model dataset and field dataset demonstrate the feasibility of this method.