共查询到16条相似文献，搜索用时 375 毫秒
1.
2.
北黄海盆地东部坳陷地质构造复杂,断裂特征及地层接触关系不清楚,横向凹陷与隆起的构造起伏大,造成速度横向变化剧烈,由时间偏移得到的地质成像不准确,因此必须通过深度偏移得到地震数据的地质成像。从研究区复杂构造地质背景出发,阐述了叠前深度偏移原理和技术路线,对该区三维地震资料分别应用了Kirchhoff积分法叠前深度偏移和逆时叠前深度偏移两种算法。从时间偏移和深度成像效果的对比可以看出,深度偏移较时间偏移更能够表征地下真实成像位置,深度偏移在陡倾角成像上更加合理、陡倾角连续性增强,波组特征明显,尤其在断面成像上更加清晰;从两种深度偏移算法成像效果的对比可以看出,逆时深度偏移算法在陡倾角复杂构造区和深层反射层段的成像效果上较Kirchhoff积分法更佳,前者成果数据的保真性更高,能为叠前反演提供较好的原始资料。 相似文献
3.
4.
三维波动方程叠前深度偏移是复杂介质中进行构造成像、弹性参数反演的重要环节．由于其技术实现不仅涉及波场延拓理论的创新,而且需要大规模计算,因而研究难度较大．本文以实验效果的取得为目的,完整地实现了SEG／EAEG盐丘和推覆体模型的三维波动方程辛几何算法的叠前深度偏移成像计算．文中详细考察了所研制的波动方程三维叠前深度偏移软件系统及其对复杂地质构造的成像能力,具体包括：1)对于盐丘模型,文中讨论了成像参数的选择、地震子波对成像精度的影响、完成二维及三维叠前深度偏移的比较;2)对推覆体模型,文中进行了脉冲响应测试;3)由两个模型的成像结果可见本文的波动方程三维叠前深度偏移软件系统已具有适应强速度横向变化、复杂构造的成像能力。 相似文献
5.
盐丘模型 推覆体模型 波动方程 叠前深度偏移 总被引：4，自引：0，他引：4
三维波动方程叠前深度偏移是复杂介质中进行构造成像、弹性参数反演的重要环节.由于其技术实现不仅涉及波场延拓理论的创新，而且需要大规模计算，因而研究难度较大. 本文以实验效果的取得为目的，完整地实现了SEG/EAEG盐丘和推覆体模型的三维波动方程辛几何算法的叠前深度偏移成像计算. 文中详细考察了所研制的波动方程三维叠前深度偏移软件系统及其对复杂地质构造的成像能力. 具体包括：1）对于盐丘模型，文中讨论了成像参数的选择、地震子波对成像精度的影响、完成二维及三维叠前深度偏移的比较；2）对推覆体模型，文中进行了脉冲响应测试；3）由两个模型的成像结果可见本文的波动方程三维叠前深度偏移软件系统已具有适应强速度横向变化、复杂构造的成像能力. 相似文献
6.
7.
为了处理横向强变速介质中的深度成像问题,本文提出一种基于共炮道集的优化系数的傍轴近似方程叠前深度偏移算子,并在基于反射系数估算的成像条件下,可实现叠前深度偏移成像.该算子具有方程阶数低且能对陡倾角成像的特征,并采用有限差分法波场延拓,能适应速度场的任意变化.当在频率-空间域进行计算时,相对于纯粹的时间-空间域有限差分算法有计算效率高、成像方便的优点.脉冲响应测试和对Marmousi模型进行的叠前深度偏移结果表明,该偏移方法在强横向变速情况下具有非常好的成像效果. 相似文献
8.
淮北某煤矿采区三维地震勘探地质条件极为复杂,区内褶皱、断层构造发育,常规叠后时间偏移处理很难准确成像,给后期资料解释工作带来不利影响.针对这一问题,采用叠前时间偏移技术,结合煤田地震勘探特点,对影响叠前偏移处理质量的关键步骤（预处理、静校正、叠前去噪、时间域速度模型建立）进行了研究,取得了显著效果.利用叠前偏移数据体解释,最终圆满完成了地质任务.本文通过应用实例,说明了煤田地震勘探资料处理利用叠前时间偏移技术对复杂构造成像效果较好,信噪比提高,断点解释更可靠. 相似文献
9.
10.
11.
焉耆盆地地质条件复杂,侏罗纪末燕山运动和第三纪喜山运动的挤压推覆作用在焉耆盆地南缘霍拉山前形成一系列推覆构造.由于地形起伏大,近地表结构复杂,采集的地震资料信噪比较低;以推覆构造为主体的地下地质复杂性给地震成像造成极大的困难.针对该复杂地区低信噪比地震资料,在偏移前资料预处理中,通过采取一系列旨在提高信噪比、重建反射信号的技术,为后续的复杂构造成像处理奠定基础.针对断裂交错的复杂推覆构造成像,采用增强高波数波场成像的半解析Fourier地震偏移方法,能很好地成像强速度对比下的陡倾角大断裂地质构造,有效突出推覆体构造的空间形态,改善推覆体下的成像效果. 相似文献
12.
While seismic imaging for crustal and mantle structures has traditionally relied on surface wave and refraction data, the use of reflection data for crustal-scale targets has been largely limited to the common midpoint (CMP) stack techniques. The rapid increase in the number of seismograph array deployments in recent years in crustal and mantle seismology has reached a level such that a re-examination of the imaging techniques is becoming necessary. In this paper we show the advantage of prestack depth imaging for crustal reflection studies, based on data from two reflection surveys of the Los Angeles Regional Seismic Experiment (LARSE) to map faults and crustal-scale structures. Our analysis indicates that the quality of the previous images of these surveys is limited by the CMP stack technique. For comparison, we present here depth images of the same LARSE data using wave equation prestack depth imaging and a tomographic velocity model based on first arrivals of the LARSE surveys and local earthquakes. Our new images are considerably improved over previous images in terms of resolution and reflector continuity. The new images show reflectors throughout the crust and suggest truncations in the Moho associated with the San Andreas Fault. A series of bright reflector segments, which are associated with the San Gabriel and San Andreas faults have been identified and might represent reflections from the fault zones. Our results suggest that the presence of high noise level, strong lateral velocity heterogeneity and wide angle geometry argue for, rather than against, the use of prestack depth imaging over the simple CMP stack techniques. As demonstrated in this study, it is now viable to conduct prestack depth imaging of crustal reflection data using a velocity model based on earthquake first arrivals thanks to the dense acquisition deployment. 相似文献
13.
A local plane-wave approach of generalized diffraction tomography in heterogeneous backgrounds, equivalent to Kirchhoff summation techniques when applied in seismic reflection, is re-programmed to act as repeated synthetic aperture radar (SAR) imaging for seismic prestack depth migration. Spotlight-mode SAR imaging quickly provides good images of the electromagnetic reflectivity of the ground via fast Fourier transform (FFT)-based signal processing. By calculating only the Green's functions connecting the aircraft to the centre of the illuminated patch, scattering structures around that centre are also recovered. SAR technology requires us to examine seismic imaging from the local point of view, where the quantity and quality of the available information at each image point are what are important, regardless of the survey geometry. When adapted to seismics, a local image of arbitrary size and sampling is obtained by FFT of seismic energy maps in the scattering wavenumber domain around each node of a pre-calculated grid of Green's functions. These local images can be used to generate a classic prestack depth-migrated section by collecting only their centres. However, the local images also provide valuable information around the centre, as in SAR. They can therefore help to pre-analyse prestack depth migration efficiently, and to perform velocity analysis at a very low cost. The FFT-based signal-processing approach allows local, efficient and automatic control of anti-aliasing, noise and resolution, including optimized Jacobian weights. Repeated local imaging could also be used to speed up migration, with interpolation between local images associated with a coarse grid of Green's functions, as an alternative to interpolation of Green's functions. The local images may, however, show distortions due to the local plane-wave approximation, and the velocity variations across their frame. Such effects, which are not necessarily a problem in SAR, should be controlled and corrected to further enhance seismic imaging. Applications to realistic models and to real data show that, despite the distortion effects, the local images can yield similar information to prestack depth migration, including common-image-point gathers for velocity analyses and AVO/AVA effects, at a much lower cost when a small target is considered. 相似文献
14.
15.
Prestack depth migration of multicomponent seismic data improves the imaging accuracy of subsurface complex geological structures. An accurate velocity field is critical to accurate imaging. Gaussian beam migration was used to perform multicomponent migration velocity analysis of PP- and PS-waves. First, PP- and PS-wave Gaussian beam prestack depth migration algorithms that operate on common-offset gathers are presented to extract offset-domain common-image gathers of PP- and PS-waves. Second, based on the residual moveout equation, the migration velocity fields of P- and S-waves are updated. Depth matching is used to ensure that the depth of the target layers in the PP- and PS-wave migration profiles are consistent, and high-precision P- and S-wave velocities are obtained. Finally, synthetic and field seismic data suggest that the method can be used effectively in multiwave migration velocity analysis. 相似文献