海相碳酸盐岩储层叠前保幅成像技术研究
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摘要
选取四川盆地某个正在进行海相碳酸盐岩储层研究的勘探区域,根据野外地震数据特点,分析了造成振幅畸变的影响因素,并结合OMEGA地震处理系统,从应用角度重点研究开发了几项关键性振幅保真叠前成像处理技术:采用折射波层析静校正方法迭代修改近地表模型,缩小计算的旅行时与地震初至拾取值的差异,获得较为准确的近地表模型,解决了地表速度横向变化造成的静校正问题;采用非地表一致性剩余静校正方法解决高速层直接出露地表带来的残余高频静校正问题;采用分频、时变的非线性异常噪声衰减技术去除炮集数据中存在的振幅异常和频率异常的噪声,去噪同时不改变有效信号的相对振幅关系;采用规则化技术消除偏移距不均匀分布造成的叠前时间成像假象,得到振幅保真的共成像点道集和角道集。经过叠前保幅成像技术处理后,研究区域的叠前共成像道集的振幅相对关系保持良好,信噪比、分辨率得到明显提高,由此计算的角度道集中目的层附近的振幅呈现明显的AVO变化特征,海相碳酸盐岩天然气储层叠前反演和精细解释取得了满意效果。
Based on conducting marine carbonated reservoir research on one exploration area in the Sichuan Basin,according to the characteristics of field seismic data,the factors resulting in amplitude distortion are analyzed.Combined with the OMEGA SPS(seismic processing system),research and development of key pre-stack image processing technologies with true amplitude are emphasized for application.Refraction tomographic static correction is applied to iterative correction of near surface models,aiming at reducing the difference between the travel time calculated and the first-arrival picking value and developing near surface models with high accuracy.So the problem of static correction caused by horizontal change of near surface velocity is solved.Non-surface consistent residual statics is applied to solve the problem of residual high-frequency statics caused by the outcrop of high-velocity layers.Nonlinear abnormal noise attenuation of separate frequency and time variation is applied to eliminate the noise with abnormal amplitude and frequency of shots,meanwhile,the relative amplitudes among effective signals will be not been changed.False pre-stack time image caused by heterogeneous offset distribution is wiped out based on the application of regularization technologies,so common imaging gathers and angle gathers with true amplitude are obtained.Through pre-stack amplitude-preserved processing,the relative amplitudes among pre-stack common imaging gathers are kept well in the studied area,the signal-to-noise ratio and resolution are improved greatly.Therefore,the amplitude near the target layers of calculated angle gathers feature in obvious variation.Pre-stack inversion and fine interpretation in marine carbonate gas reservoirs are fulfilled successfully.
Based on conducting marine carbonated reservoir research on one exploration area in the Sichuan Basin,according to the characteristics of field seismic data,the factors resulting in amplitude distortion are analyzed.Combined with the OMEGA SPS(seismic processing system),research and development of key pre-stack image processing technologies with true amplitude are emphasized for application.Refraction tomographic static correction is applied to iterative correction of near surface models,aiming at reducing the difference between the travel time calculated and the first-arrival picking value and developing near surface models with high accuracy.So the problem of static correction caused by horizontal change of near surface velocity is solved.Non-surface consistent residual statics is applied to solve the problem of residual high-frequency statics caused by the outcrop of high-velocity layers.Nonlinear abnormal noise attenuation of separate frequency and time variation is applied to eliminate the noise with abnormal amplitude and frequency of shots,meanwhile,the relative amplitudes among effective signals will be not been changed.False pre-stack time image caused by heterogeneous offset distribution is wiped out based on the application of regularization technologies,so common imaging gathers and angle gathers with true amplitude are obtained.Through pre-stack amplitude-preserved processing,the relative amplitudes among pre-stack common imaging gathers are kept well in the studied area,the signal-to-noise ratio and resolution are improved greatly.Therefore,the amplitude near the target layers of calculated angle gathers feature in obvious variation.Pre-stack inversion and fine interpretation in marine carbonate gas reservoirs are fulfilled successfully.
引文
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[2]Mosher C C,Keho T H,Weglein A B.et al.The impact of migration on AVO[J].Geophysics,1996,61(5):1603～1615.
[3]吴常玉,等.叠前预处理技术[J].石油地球物理勘探,2007,42(1):34～37.
[4]Canning A,Gardner G H F.Reducing3-D acquisition footprint for3-D DMO and3-D prestack migration[J].Geophysics,1998,63(3):1177～1183.
[5]伊尔马滋著.刘怀山等译.地震资料分析[M].北京:石油工业出版社,2006.
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