时频空间域低频约束AVO响应校正方法

AVO response correction constrained by low-frequency components in time-frequency-space domain

由于渤海新近系高孔隙度欠压实地层和复杂断裂等因素的存在,吸收衰减作用明显,使叠前道集高频能量衰减严重、AVO保幅性较差。具体表现为叠前道集的AVO响应在低频段可以匹配正演道集,但在高频段不能匹配,进而导致基于AVO响应的叠前油气检测技术难以有效应用。针对该问题,将高分辨率分频技术与AVO技术有机结合,提出了一种基于低频约束的时频空间域AVO响应校正方法。该方法以AVO趋势保持更好的低频能量为参考,根据低频段叠前道集和不同频段叠前道集的AVO响应趋势之间的关系构建并使用基于数据驱动的三维时频空间域校正因子,弥补远、近炮检距高频衰减差异对AVO分析的影响,能够有效改善叠前道集AVO保幅性。理论合成数据和实际数据处理结果表明,该校正方法较好地恢复了叠前道集的真实AVO规律,进而为基于AVO响应的叠前油气检测方法在渤海油田的广泛应用提供了可靠的资料基础。

Due to the presence of the Neogene unconsolidated clastics with high porosity and complex fault systems,absorption and attenuation to seismic signals is very strong,resulting in serious attenuation of high-frequency energy and poor amplitude-preserved property of pre-stack gathers in the Bohai Bay Basin.Specifically,the AVO responses of prestack gathers are consistent with the corresponding synthetics at low frequency,but not at high frequency,so that the pre-stack hydrocarbon detection techniques based on AVO response cannot be effective.An AVO response correction method in time-frequency-space domain is proposed.It is constrained by low-frequency components,and combines high-resolution time-frequency analysis technology.Following the AVO trend,the method takes better low-frequency energy as a reference,and builds a data-driven three-dimensional timefrequency-space-domain correction factor according to the relationship between the AVO response trend of pre-stack gathers at low frequency and pre-stack gathers at other frequency.The correction factor can make up for the influence of the high-frequency attenuation difference between far and near offsets on AVO analysis,and effectively improve the AVO amplitude-preserved property of pre-stack gathers.Applications to synthetic data and actual data show that the AVO response correction method we proposed can restore the real AVO law of pre-stack gathers and provide reliable basic data for the application of pre-stack hydrocarbon detection methods in Bohai Oilfield.