基于平面波解构滤波的速度无关时差校正方法研究

发布时间：2018-03-25 04:02

本文选题：速度无关　切入点：平面波解构　出处：《吉林大学》2015年硕士论文

【摘要】：现代地震勘探数据处理过程的关键途径之一就是时差校正，时差校正主要包含正常时差校正和倾角时差校正。多次波干扰能否通过水平叠加被有效压制，，动校正处理的精度起很大影响作用，同时动校正也是一种用于速度分析的重要手段。常规动校正处理是将拉平局部同相轴，但双曲线走时的假设只适用于偏移距等于和小于反射界面深度的条件。倾角时差校正主要应用于经过NMO处理后的叠前数据，很好地保持不同倾角地层的不同叠加速度。DMO校正后的剖面比NMO校正后的CMP道集剖面更接近于零偏移距剖面,为后续的偏移处理做好基础。动校正的基础是建立在已知速度参数前提上进行处理的，通过速度分析途径,可以获取所需要的参数。现如今已经发展了很多简化后的半自动化速度拾取过程,但是速度分析仍旧是一项工作量大、费时费力的任务。此外,所拾取的相关速度参数往往不准确，使得之后进行的动校正处理效果不佳，并导致工作时间的增加和复杂性的增大。对于速度分析处理过程，为了避免拾取速度参数引起的繁复费时、拾取参数不准确导致的校正效果不佳和传统动校正存在的拉伸畸变问题，利用速度无关校正方法进行相关处理。本文首先对数据进行平面波分解，获取局部同相轴斜率，然后通过解析这一同相轴斜率与速度之间的关系，可以发现利用局部斜率可以直接获得进行动校正所需的速度以及其他的全部时差参数，也就是说地震同相轴局部斜率的信息可以替代相关速度参数进行动校正处理。倾角时差校正是针对倾斜反射层的情况下共中心点道集的各道不包含在一个共反射点上而进行校正的一种地震处理方法，DMO能有效地校正倾斜反射叠加时产生的反射点模糊现象。叠前数据首先需要进行NMO处理，而后需要进行DMO校正，以便于叠加过程中保持各个倾角地层的各自叠加速度。倾角时差校正后的剖面更接近零偏移距剖面，以便于随后进行的零偏移距偏移处理。与速度无关的DMO方法，是对应于更贴近实际情况的校正处理。对于NMO只适用于水平反射层而言，速度无关倾角时差校正能使得大倾角很好的归位。并且速度无关DMO方法不需要使用叠加速度，消除了倾角的影响，经过非零偏移距偏移到零偏移距处理后，可以得到3-D偏移数据体，进一步可以进行叠前时间偏移，与传统DMO校正方法对比，可以证明与速度无关方法的处理效果同样很好。最后通过模拟数据和实际数据进行与速度无关时差校正的实验计算，显示了此方法同样可以达到传统方法的处理效果甚至更好更高效，从而证明了该方法在理论上和实际中的有效性。
[Abstract]:One of the key approaches in the process of data processing for modern seismic exploration is moveout correction, which mainly includes normal moveout correction and obliquity moveout correction, and whether multiple interference can be effectively suppressed by horizontal stacking. The accuracy of NMO processing plays an important role, and NMO is also an important means for velocity analysis. However, the hypothesis of hyperbolic travel time is only applicable to the condition that the offset is equal to or less than the depth of the reflection interface. The dip time difference correction is mainly applied to prestack data after NMO processing. The profiles of different stacking velocities with different dip angles. DMO corrected profiles are closer to zero migration distance profile than the CMP gather profile after NMO correction, which provides a good basis for the subsequent migration processing. The foundation of NMO is based on the premise of known velocity parameters. Through velocity analysis, the required parameters can be obtained. Nowadays, a lot of simplified semi-automatic speed pick-up processes have been developed. However, velocity analysis is still a heavy and time-consuming task. In addition, the speed parameters picked up are often inaccurate, which makes the NMO processing effect poor. And lead to the increase of working time and complexity. For the speed analysis and processing process, in order to avoid the complexity caused by picking up speed parameters, The correction effect caused by inaccurate picking parameters and the problem of stretch distortion existing in traditional NMO are processed by velocity independent correction method. Firstly, the data are decomposed by plane wave, and the local cophase slope is obtained. Then by analyzing the relationship between the phase axis slope and the velocity, we can find that the velocity needed for NMO can be directly obtained by using the local slope, and all other moveout parameters can be obtained. That is to say, the information of local slope in the same phase axis of earthquake can replace the correlation velocity parameters for NMO processing. Dip time difference correction is a seismic processing method that corrects the tracks of the common central point gathers without a common reflection point in the case of inclined reflectors. DMO can effectively correct the tilt reflection stacking. Reflection point ambiguity. Prestack data needs to be processed by NMO, Then DMO correction is needed in order to maintain the respective stacking velocity of each dip stratum during the stack process. The profile corrected by dip moveout is closer to zero offset profile. To facilitate the subsequent zero offset migration processing. The velocity-independent DMO method is a correction process that is closer to the actual situation. For NMO, it is only applicable to horizontal reflectors. Velocity-independent dip time difference correction can make large dip angle very good, and velocity independent DMO method does not need to use stack velocity, eliminating the influence of dip angle, after the non-zero offset offset migration to zero offset processing, the velocity independent DMO method does not need to use stacking velocity to eliminate the influence of inclination angle, after the non-zero offset migration to zero offset processing, The 3-D migration data volume can be obtained, and further prestack time migration can be carried out. Compared with the traditional DMO correction method, it can be proved that the processing effect of the velocity independent method is also very good. Finally, through the experimental calculation of velocity independent time difference correction with simulated data and actual data, it is shown that this method can also achieve better and more efficient processing effect of the traditional method. The validity of the method in theory and practice is proved.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4

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