海洋气枪远场子波模拟技术及应用

Ocean air gun far-field wavelet simulation and its application

在海洋地震勘探中,获取精确气枪震源子波对地震数据提高分辨率处理和震源质量监控等具有重要意义。针对已有的气枪震源子波模拟算法不能充分考虑气枪实时状态,模拟的子波和实际情况差异较大的问题,提出了基于近场水听器信号,考虑通过单枪激发试验测量的水听器相对灵敏度、通过气泡上浮计时试验和枪阵实时导航数据计算的气泡相对运动,以及考虑海面虚反射等因素,在频率域模拟气枪震源远场子波的方法。并测试了这几种因素对模拟结果的影响程度和适用条件。与常规基于震源设计参数理论模拟方法进行了实际数据应用对比,结果表明,所提出的远场子波模拟方法模拟出的远场子波能反映气枪震源真实激发状态和条件,具有高保真性,用于地震数据子波处理后能更好地压制气泡效应,大幅提高地震资料的分辨率,具有重要的实用意义。

In marine seismic exploration,obtaining accurate air-gun source wavelets is of great significance for high-resolution processing and source quality monitoring.To address the problem that existing algorithms of air-gun source wavelet simulation cannot fully consider the real-time state of the air gun,leading to great differences between the simulated wavelet and the actual situation,a method is proposed to simulate the far-field wavelets of air-gun sources in the frequency domain based on the near-field hydrophone signals.Some internal and external factors taken into account involve hydrophone sensitivity measured by using single-gun excitation tests,relative bubble motion calculated by using bubble upward-floating timing tests and real-time navigation data of gun array,as well as ghost reflections from sea surface.The impact and applicability of these factors on the simulation results are also tested.Compared with the conventional method for wavelet simulation based on source design parameters,the far-field wavelet with high fidelity simulated using the proposed method can reflect the real excitation state of an air-gun source.The simulated wavelet can be used for seismic wavelet processing to mitigate bubble effect and improve seismic resolution significantly,which is of great practical significance.