逆时偏移的研究及应用

发布时间：2018-02-09 05:14

本文关键词： 逆时偏移复杂构造有限差分成像优势　出处：《中国石油大学(华东)》2015年硕士论文　论文类型：学位论文

【摘要】：复杂的地形会对地震成像问题造成很大影响,这与复杂的射线路径和速度在横向上的急剧变化有关,在复杂构造条件下,地震数据通常带有低振幅和低频率噪声使得不容易偏移成像,没有好的成像结果,直接限制了下一步的地震解释,不利于进行AVO反演,为一个高预期勘探性盆地的结构不确定性增加风险。偏移成像是确定地球介质形态的重要环节,而近些年提出的叠前深度偏移更是对精细地区成像的更为准确的方式,逆时偏移相对于单程波动方程偏移算法和克希霍夫偏移算法等射线偏移算法在处理陡倾角构造和复杂速度模型上有着明显的优势。逆时偏移因为采用全波波动方程外推波场,能够准确地模拟所有方向的波场传播,包括反射波和透射波,最终的成像算法不受倾角限制,它甚至可以对倒转波和棱柱波成像,不仅拥有更高的成像精确程度而且具有更丰富的有效信息。然而,低频、强振幅噪声在传统RTM成像结果里很是常见,这已经成为主要关心并解决的问题,因为这些噪声如果没有得到好的处理会严重掩盖成像中的有效信号。除此之外,逆时偏移还有存储大,计算量大的特点,因此,怎样有效去除低频噪声提高成像精度,提高运算效率,是研究逆时偏移的一大重要课题。本文提出了传统的RTM成像噪声产生原理的物理解释,分析了不同的低频噪声压制方法进行了分析,并比较其的优势和实用性。本文采用高阶交错网格有限差分算法并对其波场延拓公式进行了推导,采用亥姆霍兹分解对弹性波进行纵横波分离,运用震源归一化成像条件对震源检波波场进行互相关成像,并对多分量逆时偏移成像进行了极性校正,取得了很好的效果,最后对理论模型和实际资料进行处理,并与其它成像方法进行对比,证明本文成像方法的优势和处理复杂构造模型的有效性。
[Abstract]:The complex terrain will cause a great impact on the imaging problems, which is related to the complex ray path and speed sharp changes in the transverse direction, in complex geologic condition, seismic data are usually with low amplitude and low frequency noise which is not easy migration, no good imaging results, directly limits the next step seismic interpretation, which is not conducive to the AVO inversion, increase the risk of a high expectations of the basin exploration uncertainty. Migration is an important link to decide the shape of the earth medium, and the recent proposed prestack depth migration is of fine area more accurate imaging method, reverse time migration relative to the one-way wave equation migration Kirchhoff algorithm and migration algorithm and ray migration algorithm has obvious advantages in dealing with steep dip structures and complex velocity model. The reverse time migration because of the full wave equation outside Push the wave field, can accurately simulate wave propagation in all directions, including the reflection wave and transmission wave imaging algorithm, the final is not restricted by the dip angle, it can even reverse the wave and wave of prism imaging, not only has a higher degree of precision imaging and has more effective channel information. However, low frequency, strong the amplitude noise in traditional RTM imaging results is very common, it has become a major concern and solve the problem, because if the noise did not get a good deal will seriously cover effective signal processing. In addition, reverse time migration and storage of the large, large amount of calculation, therefore, how to effectively remove noise to improve the imaging accuracy, improve operation efficiency, is one of the important issues of reverse time migration. This paper introduces the physical principle of RTM imaging traditional interpretation, analysis of the different low frequency noise suppression method The analysis and comparison of the advantages and practicability. This paper uses the high-order staggered grid finite difference algorithm and the wave field continuation formula is deduced, using the Helmholtz decomposition of wave separation of elastic wave, using the normalized cross-correlation imaging condition are the source of seismic wave field imaging detector, and the multiple component the reverse time migration imaging of polarity correction, and achieved good results, the theoretical model and practical data processing, and comparing with other imaging methods, this paper demonstrate the effectiveness and advantage of imaging methods dealing with complex structure model.

【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4

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