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1.
《世界地质(英文版)》2016,(2):95-101
With the increasing complexity of prospecting objectives,reverse time migration (RTM)has attracted more and more attention due to its outstanding imaging quality.RTMis based on two-way wave equation,so it can avoid the limits of angle in traditional one-way wave equation migration,image reverse branch,prism waves and multi-reflected wave precisely and obtain accurate dynamic information.However,the huge demands for storage and computation as well as low frequency noises restrict its wide application.The normalized cross-correlation ima-ging conditions based on wave field decomposition are derived from traditional cross-correlation imaging condition, and it can eliminate the low-frequency noises effectively and improve the imaging resolution.The practical proce-dure includes separating source and receiver wave field into one-way components respectively,and conducting cross-correlation imaging condition to the post-separated wave field.In this way,the resolution and precision of the imaging result will be promoted greatly. 相似文献
2.
Ocean-Bottom Node(OBN) acquisitions provide both non-converted and converted reflection energy. There is a clear advantage to independently imaging both P-and S-waves, as they provide more information collectively than either does alone. In many conventional converted-wave pre-stack migration algorithms, density is treated as a constant, which is not the real-life case on earth. S-wave velocity and density information is crucial for hydrocarbon detection because it helps in the identification of porefilling fluids. In this paper, we focused on the effect of density on imaging, and developed a method of reverse-time migration(RTM) on converted s-waves of varying densities(VD-RTMCS). Phase correction was required prior to pre-stack migration to avoid constructive interference between data from adjacent sources. Synthetic data examples showed that when density variations were included, image profiles showed advantages in signal-to-noise ratio, vertical resolution and imaging of complex structures. 相似文献
3.
基于GPU并行加速的叠前逆时偏移方法 总被引：1，自引：1，他引：0
为了提高复杂地下介质的成像精度和偏移算法的计算效率,提出可高效对地下复杂构造进行准确成像的GPU加速叠前逆时偏移方法.该方法采用双程声波方程进行波场延拓,突破倾角限制,借助于高阶有限差分方法实现叠前逆时偏移成像;利用GPU(Graphic Processing Unit)并行加速技术对波场延拓和成像进行计算,相比于传统算法,其计算效率有较大提高,可以解决叠前逆时偏移算法计算量过大问题;在获取波场信息过程中,也采用随机边界条件,实施以计算换存储策略,解决逆时偏移计算中的海量存储问题.模型测试结果表明,该方法能够高效和高精度地对地下复杂地质体成像. 相似文献
4.
Reverse Time Migration(RTM) is a high precision imaging method of seismic wavefield at present,but low-frequency noises severely affect its imaging results.Thus one of most important aspect of RTM is to select the proper noise suppression method.The wavefield characteristics of the Poynting vector are analyzed and the upgoing,downgoing,leftgoing and rightgoing waves are decomposed using the Poynting vector of the acoustic wave equation.The normalized wavefield decomposition cross-correlation imaging condition is used to suppress low-frequency noises in RTM and improve the imaging precision.Numerical experiments using the Mamousi velocity model are performed and the results demonstrate that the upgoing,downgoing,leftgoing and rightgoing waves are well decomposed using the Poynting vector.Compared with the normalized cross-correlation imaging and Laplacian filtering method,the results indicate that the low-frequency noises are well suppressed by using the normalized wavefield decomposition cross-correlation imaging condition. 相似文献
5.
Strong fluctuation of seabed, abrupt variation in depth and dip of seabed bring seismic imaging problems, such as irregular reflection waves, obvious multiple waves, serious lateral wave development, poor imaging on base surface and depression structure, low signal-to-noise ratio of middle and deep layers. In this paper, Gaussian beam migration imaging method is used to analyze the imaging effect of rugged seabed in deep water area, and the ray tracing method of wavefront construction method is used to analyze the kinematic characteristics of seismic waves. By improving the design of seismic data acquisition and observation system, imaging quality of fine structures is improved. 相似文献
6.
Remigration is an imaging method that maps migrated image fields of different migration velocity fields to each other.It is mainly used for migration velocity analysis, wave mode transformation, and data regu-larization.Theoretically, this kind of mapping can be realized by differential operator, or by integral operator. Compared between the two, the integral operator achieves higher computational efficiency and has more adapta-bility to the irregularity of the input data.Given the fact, the authors worked out the depth domain remigration method based on the Kirchhoff integral theory with the basic theory and workflow of the Kirchhoff remigration. The calculation results on the gradient model and Marmousi model verify the effectiveness of this method.In ad-dition, numerical experiments show that integral method is faster than the differential method. 相似文献
7.
Kirchhoff beam migration is a beam migration method, which focuses on rapid imaging of geological structures. Although this imaging method ignores the amplitude information in the calculation process, it can calculate multi-arrival traveltime. This migration method takes into account both imaging accuracy and computational efficiency. Kirchhoff beam migration employs coarse grid techniques in several key steps such as traveltime calculation, weight function calculation, and imaging calculation. The selection of the coarse mesh size has an important influence on the computational efficiency and imaging accuracy of the migration imaging method. This paper will analyze this influence and illustrate the analysis results by the Marmousi data sets. 相似文献
8.
介绍了反射波和折射波的 Ｖ Ｓ Ｐ Ｃ Ｄ Ｐ 同时成象方法，通过模型资料试算证实，对于大偏移距与深度比 Ｖ Ｓ Ｐ 资料或速度梯度大的 Ｖ Ｓ Ｐ 资料，反射波和折射波 Ｖ Ｓ Ｐ Ｃ Ｄ Ｐ 同时成像方法行之有效，而反射波 Ｖ Ｓ Ｐ Ｃ Ｄ Ｐ 迭加方法会得到错误的成像结果。 相似文献
9.
利用EGM2008计算重力场模型高程异常,结合SRTM和DTM2006.0计算剩余地形模型,进而计算RTM高程异常,以弥补EGM2008重力场模型短波信号缺失的不足。从实测高程异常中减去重力场模型高程异常以及RTM高程异常,得到残余高程异常。利用曲面拟合方法拟合残余高程异常模型,解决高程基准系统偏差问题。通过实际GPS/水准数据计算证明,该方法能显著提高GPS点的高程异常计算精度,达到精化区域似大地水准面的目的。 相似文献
10.
Improvement of pseudo-static method for slope stability analysis 总被引：2，自引：0，他引：2
traditional In this paper, two drawbacks pseudo-static method （vertical of the slice method） in the slope stability evaluation have been studied. First, the sliding mass is divided into vertical slices according to this method, which is irrational to some extent in the seismic design of slope. Second, only peak ground acceleration （PGA） is considered, and the effects of shaking frequency and duration on slope stability are neglected. And then, based on the theory of elastic wave and the summarized geological model, this paper put forwards an improved method of pseudo-method by using the theory of elastic wave and Hilbert-Huang transform. The improved pseudostatic method gives reasonable considerations to the time-frequency effects of seismic wave and its rationality has been verified by the shaking table test. This method can evaluate the safety of a slope, the happening time and the scale of landslides. At the same time, this method also can improve the high accuracy of the evaluation of the safety of the slope. 相似文献
11.
1 ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｃｏｍｐｕｔｉｎｇｔｅｃｈｎｉｑｕｅｓｔｈｅｒｅｓｅａｒｃｈｏｆｉｎｖｅｒｓｅｐｒｏｂｌｅｍｓｈａｓｅｘｔｅｎｓｉｖｅｌｙｂｅｅｎｕｓｅｄｉｎｍａｎｙｓｃｉｅｎｔｉｆｉｃｆｉｅｌｄｓ .Ｔｈ 相似文献
12.
《中国海洋大学学报(英文版)》2019,(6)
This paper introduces an internal multiple prediction method based on imaging profile prediction and Kirchhoff demigration. First, based on an inputted prestack time migration profile, the method predicts the prestack time migration profile that only includes internal multiples by inverse scattering series method. Second, the method uses velocity-weighted Kirchhoff demigration to create shot gathers that contains only internal multiples. Internal multiple prediction based on the prestack time migration profile effectively reduces the computational cost of multiple predictions, and the internal-multiple shot gathers created by Kirchhoff demigration remarkably reduces the complexity of the practical problem. Internal multiple elimination can be conducted through the combined adaptive multiple subtraction based on event tracing. Synthetic and field data tests show that the method effectively predicts internal multiples and possesses considerable potential in field data processing, particularly in areas where internal multiples develop seriously. 相似文献
13.
以构建剩余地形模型高程异常的数字地形模型的分辨率及其参考面的选择为研究对象,系统分析两者对剩余地形模型高程异常计算效率及精度的影响。实验结果表明：1）将DTM2006.0模型作为参考面时,在海岸带区域产生较大的误差,而在陆地与RET2012和RET2014模型的计算结果相差不大;2）在构建我国东部地区剩余地形模型高程异常时,为保证计算效率及精度,计算时内外圈的积分半径分别取50 km和200 km,SRTM数据的分辨率分别采用7.5″和15″,参考面模型使用RET2012。 相似文献
14.
Acoustic-elastic coupled media is often encountered in most marine explorations, and accurate simulation of acoustic-elastic coupled media is of great significance. At present, the study of acoustic-elastic coupled media still assumes that the solid of the acoustic-elastic coupled media is isotropic, but this assumption is not in accordance with the actual situation. In this paper, we derive the solid media of acoustic-elastic coupled media from isotropic media to anisotropic media, and propose an acoustic-elastic coupled medium based ontransverse isotropic media with vertical symmetric axes(VTI) to improve the accuracy of forward modeling. Based on the relationship between the Thomsen parameter and the coefficient matrix of the anisotropic elastic wave equation, we transform the Thomson parameter into a velocity model with anisotropic properties. We use a staggered grid finite difference method to simulate the propagation of a wavefield in a three-dimensional acoustic-elastic coupled media. We obtain the snapshots of the wave field when the solid of the acoustic-elastic coupled media is an isotropic medium and a VTI media. When the solid of the acoustic-elastic coupled media is considered VTI media, we can observe the qP wave and qS wave that cannot be observed in the isotropic medium from the wave field snapshot. We can also find that the seismic records obtained by the method we use are more realistic. The algorithm proposed in this paper is of great significance for high-precision ocean numerical simulation. 相似文献
15.
基于主成分分析(principal component analysis, PCA)方法构建理论模型进行三分量地震偏振分析试算,获得较准确的检波器的水平方位角和垂直倾角,然后对地震响应进行坐标旋转,从而校正检波器方向。将该方法应用于跨孔井间弹性波波速测试,对实测资料进行偏振分析可知,初至P波与初至S波分别在HP分量和R分量中得到加强,不仅有利于初至起跳的拾取,还可以获得较准确的波速资料,为岩土工程设计提供更精确的动力学参数。 相似文献
16.
The inverse problem of wave equation is the importance of study not only in seismic prospecting but also in applied mathematics. With the development of the research, the inverse methods of 1 - D wave equations have been trending towards the multiple parameters inversion . We have obtained an inverse method with double -parameter, in which medium density and wave velocity can be derived simultaneously. In this paper, to increase the inverse accuracy, the method is improved as follows. Firstly, the formula in which the Green Function is omitted are derived and used. Secondly, the regularizing method is reasonable used by choosing the stable function. With the new method, we may derive elastic parameter and medium density or medium density and wave velocity. Thus, lithology parameters for seismic prospecting may be obtained.After comparing the derived values from the new method with that from previous method, we obtain the new method through which substantially improve the derived accuracy . The new method has been applied to real depths inversion for sedimentary strata and volcanic rock strata in Chaoyanggou Terrace of Songliao Basin in eastern China. According to the inverse results,the gas - bearing beds are determlned. 相似文献
17.
The inverse problem of wave equation is the importance of study not only in seismic prospecting but also in ap-plied mathematics. With the development of the research, the inverse methods of 1 - D wave equations have been trending to-wards the multiple parameters inversion . We have obtained an inverse method with double - parameter, in which medium density and wave velocity can be derived simultaneously. In this paper, to increase the inverse accuracy, the method is im-proved as follows. Firstly, the formula in which the Green Function is omitted are derived and used. Secondly, the regulari-zing method is reasonable used by choosing the stable function. With the new method, we may derive elastic parameter and medium density or medium density and wave velocity. Thus, lithology parameters for seismic prospecting may be obtained. After comparing the derived values from the new method with that from previous method, we obtain the new method through which substantially improve the derived accuracy . The new 相似文献
18.
《世界地质(英文版)》2015,(4)
The study on seismic anisotropy is one of the difficult problems in the field of geophysics nowadays.As a method of ray theory,the seismic anisotropy ray tracing is an important means to study the anisotropic seismic wave propagation. The traditional ray tracing system formulated in terms of elastic parameters in the anisotropy is more complicated than that in the isotropic case. Considering the difficulty,a kind of ray tracing system formulated in terms of phase velocity and group velocity is introduced. The new method is similar to the expressions for isotropic media,and avoids the trouble of determining the eigenvalue vector at each time. Besides the ray tracing numerical simulation of different models of vertical transversely isotropic( VTI) medium is carried out,in order to verify the accuracy and applicability of the method and further study the characteristics of wave field propagation in different VTI mediums. The study is certainly valuable in reference for later processing of the anisotropic seismic data. 相似文献
19.
通过限定震群集中区范围,剔除同一台站记录的震中位置相近且具有相同路径的地震波,使用双差波速比两次差分的方法,对2017~2018年长岛地区发生的2个震群的波速比值开展特征分析。通过对震相数据敏感性分析得出,双差波速比方法对Pg波到时较为敏感,资料处理时需要将Pg、Sg波震相误差分别控制在0.02 s和0.20 s以内。最终分析结果显示,长岛震群波速比值在1.69~1.78范围内波动,波速比变化与震群活动过程密切相关;震群几次较大余震发生前,波速比呈现低值状态;主震和余震的波速比变化存在差异,可能反映二者发震机理有所不同。 相似文献
20.
虚谱法利用付里叶变换和有限差分求解波动方程 ,是地震波场正演模拟的重要方法之一 ,但其常规算法运算量大 ,运算时间长。为此 ,我们在常规算法的基础上作了些改进 ,主要是提出了反付里叶变换的快速算法 ,并运用正反付里叶变换的快速算法和避免重复运算等手段 ,使运算量大大减少 ,可节省运算时间三倍多 相似文献