海洋拖缆与海底节点资料联合全波形反演

Full waveform inversion for combined towed-streamer and ocean buttom node seismic data

全波形反演(FWI)能够建立地下介质的高精度速度模型。受检波器制约,海洋拖缆资料通常缺少可靠的低频成分,因此基于拖缆资料的FWI容易发生周期跳跃,导致目标函数收敛于局部极值。海底节点(OBN)资料含有比拖缆资料更丰富的低频成分,联合使用OBN资料与拖缆资料进行波形反演,能够弥补低频缺失问题。然而,拖缆资料与OBN资料的震源子波不同,而波形反演结果受震源子波的严重约束。为此,提出一种不依赖震源子波的拖缆与OBN资料联合波形反演方法。在构建目标函数时将模拟数据和观测数据分别与对方的平均道进行褶积,以消除联合波形反演中的震源子波误差,达到不依赖震源子波的反演效果。使用Marmousi模型合成的拖缆资料与OBN资料进行了模型测试,验证了所提方法的可行性和有效性。

Full waveform inversion(FWI)can establish high-precision velocity models of subsurface media.Due to geophone limitations,towed-streamer data often lacks reliable low-frequency components.Consequently,FWI based on towed-streamer data often encounters the cycle-skipping problem,resulting in the objective function converging to a local extremum.Ocean bottom node(OBN)seismic data contains more low-frequency components compared to towed-streamer data.Combining OBN data with towed-streamer data in waveform inversion can compensate for the low-frequency deficiency in towed-streamer data.However,the source wavelet of towed-streamer data is different from that of OBN data,and the joint waveform inversion is more severely affected by the source wavelet.This paper proposes a joint waveform inversion method for towed-streamer and OBN data that does not depend on source wavelets.When constructing the objective function,the simulated and observed data are respectively convolved with the average traces of the other,solving the problem of wavelet error in joint waveform inversion and achieving the effect of not relying on the source wavelet.The feasibility and effectiveness of the proposed method are verified through model testing using the Marmousi model synthesized towed-streamer data and OBN data.