共查询到19条相似文献,搜索用时 156 毫秒
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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
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复杂构造地震成像主要取决于叠前地震数据品质、偏移速度可靠性和偏移算子成像精度. 库车坳陷异常复杂的近地表条件导致极低信噪比的地震采集数据. 该区逆冲推覆高陡构造刺穿盐体大面积分布, 盐层厚度变化大、顶底面形态复杂, 盐下断裂带破碎、小断块发育, 形成异常复杂的地震成像问题. 本文重点研究三个关键环节:(1)精细的叠前地震预处理研究: 根据该区地震地质复杂性和地震资料特征, 采用一些新的方法技术和技术组合从振幅与时移的大、中、小尺度变化三个层次来解决资料信噪比问题, 重建深部反射信号; (2)三级偏移速度分析研究:利用库车坳陷盐刺穿逆冲推覆构造建模理论及变速成图配套技术解决叠前时间偏移速度场时深转换问题,利用井约束低频速度地震迭代反演技术解决连井层速度场与偏移速度场的融合问题,实现从DMO速度分析、叠前时间偏移速度分析到叠前深度偏移速度分析的有机衔接,建立拓扑结构相对保持的叠前深度偏移速度模型;(3)基于退化Fourier偏移算子的半解析波动方程叠前时间和深度偏移研究, 极大地改善了地震偏移过程中高波数波的成像问题. 通过对库车坳陷大北、博孜、却勒、西秋4和西秋10等复杂高陡构造的叠前时间和深度偏移地震成像处理,取得了较好的应用效果. 相似文献
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复杂观测系统下的三维波动方程叠前深度偏移 总被引:1,自引:6,他引:1
波动方程三维叠前深度偏移是近年应复杂地质构造与地震岩性成像需求而发展的一项关键技术。此项技术与集群式并行机的结合,更是将其价格性能比较低至工业生产规模应用水平,然而,波动方程三维叠前深度偏移的实用化还需要诸如地震资料网络化、并行计算负载平衡等一系列配套技术。本文针对油田实际资料,试验了其应用波动方程三维叠前深度偏移的规则化技术,并结合地震炮集数据的特点,在自组装的集群式并行机上,解决了其节点间的负载平衡问题。本项工作有助于推近复杂观测系统下的地震数据实现三维波动方程叠前深度偏移。 相似文献
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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
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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
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适于窄线三维地震资料的面炮方法 总被引:4,自引:6,他引:4
用小孔径波动方程叠前深度偏移完成大面积数据的成像,不仅总的计算量较大,而且成像畸变较严重。为了进行大孔径波动方程叠前深度偏移,必须将实际的小孔径资料合成大孔径资料,并解决大孔径资料的成像方法。AMO等合成孔径方法,数据合成方式简单,但成像方法是近似的且较复杂。面炮方法从理论上讲数据合成方法较简单,成像方法是精确的且较简单,但其应用适用于远道振幅比近道弱很多的情况。在窄线三维地震资料情况,其联络测线方向不易满足面炮应用条件。针对这种情况,本文将最小二乘原理应用于波场成像,提出适用窄线三维地震资料的面炮方法。为了解三维波动方程叠前深度偏移的面炮方法解决复杂油气藏的可行性、所需计算资源和成像效果,我们利用大庆SW地区三维地震资料进行了实验研究。通过研究,我们获得了面炮方法的实际效果,获得了所需计算资源的测试数据。对实际效果的分析对比表明,面炮方法是一种三维波动方程叠前深度偏移的快速方法,有较好应用前景。 相似文献
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高斯束叠前深度偏移是对地下介质进行精确成像的方法之一,多分量地震资料的叠前深度偏移技术可以对复杂构造进行更准确的成像。由于实际地下介质具有粘滞性,研究粘弹性叠前深度偏移具有一定的现实意义。本文采用高斯束偏移方法对多分量地震数据进行吸收衰减补偿,首先利用高斯束模拟粘弹性介质中传播的地震波,并在模拟中引入与品质因子Q有关的复速度和精确的粘弹性Zoeppritz方程,合成地震记录;然后给出纵波和转换波共炮域高斯束叠前深度偏移原理,在此基础上推导补偿吸收衰减的表达式,校正Q引起的振幅衰减和相位畸变,实现基于吸收衰减补偿的多分量高斯束叠前深度偏移,并分析Q误差对偏移结果的影响。数值实验表明,在考虑地下介质的粘滞性时,本文方法具有更高的成像分辨率。 相似文献
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针对辽河坳陷西部凹陷曙光潜山高陡构造带顶界面断裂成像精度差、内幕地层识别难的问题,开展双井Walkaway VSP应用研究.利用大阵列检波器接收、炸药与震源联合采集方法,获得了高品质采集数据,是高陡构造成像的基础;子波一致性校正、基于射线追踪的矢量波场分离、VSP数据与地面地震数据联合各向异性速度建模、双井Walkaway VSP成像方法对比等针对性处理技术和波阻抗反演、地震属性提取等综合研究方法的应用,精细刻画了潜山顶界面,新识别出井旁小断层,落实了大倾角潜山构造形态,分析了内幕地层的接触关系,对板岩隔夹层及储层分布有进一步认识,展现了Walkaway VSP技术在高陡构造地区的应用前景.研究得到以下认识:(1)逆时偏移成像方法对高陡潜山成像更具适用性;(2)增加检波器进入潜山内幕的深度,避开潜山高速顶界面的能量屏蔽及滑行波、转换波等干扰,对潜山勘探具有重要意义;(3)双井Walkaway VSP联采时,两井距离要控制在一定范围内,防止两井间距离过大对深层偏移成像造成影响. 相似文献
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文中讨论了在浅层地震勘探中地质结构和构造的复杂性以及对浅层地震勘探成果要求精度较高的特殊性,指出了在浅层地震勘探中发展叠前深度偏移的重要性,并对相移法叠前深度偏移的基本原理和实现方法进行了详细论述,编制了相应的软件。通过使用该方法对 2种理论试验模型进行试算,获得的深度偏移剖面层位清晰,构造明显,较准确地体现了理论模型地质结构和构造的特征,效果良好。然后又使用实际浅层地震反射资料进行了叠前偏移计算,所得结果与已知地质结构和构造相吻合,也取得了较好的结果,证实了该方法及软件的可靠性和实用性,可用于实际浅层地震反射勘探资料的叠前深度偏移处理 相似文献
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苏北大陆科学钻探靶区深反射地震的叠前深度偏移 总被引:4,自引:2,他引:2
由于深反射地震数据具有信噪比低和记录长度长等特点,叠前深度偏移方法的应用有许多困难.为此,我们研究了一种适合于深反射地震的叠前深度偏移方法;包括:用逆风有限差分方法计算程函方程;在常规速度扫描的基础上,用协方差控制提高速度分析精度;用联合反演算法计算层速度,再插值后得到初始速度模型;用Kirchhoff法作为偏移速度分析工具,求得最终的速度模型;最终的速度模型作为有限差分深度偏移的输入,求得最终的偏移结果.用该方法对“中国大陆科学深钻工程”东海二维深反射地震数据DH-4线进行了叠前深度偏移,取得了良好的效果。 相似文献
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Migration velocity analysis and waveform inversion 总被引:3,自引:0,他引:3
William W. Symes 《Geophysical Prospecting》2008,56(6):765-790
Least‐squares inversion of seismic reflection waveform data can reconstruct remarkably detailed models of subsurface structure and take into account essentially any physics of seismic wave propagation that can be modelled. However, the waveform inversion objective has many spurious local minima, hence convergence of descent methods (mandatory because of problem size) to useful Earth models requires accurate initial estimates of long‐scale velocity structure. Migration velocity analysis, on the other hand, is capable of correcting substantially erroneous initial estimates of velocity at long scales. Migration velocity analysis is based on prestack depth migration, which is in turn based on linearized acoustic modelling (Born or single‐scattering approximation). Two major variants of prestack depth migration, using binning of surface data and Claerbout's survey‐sinking concept respectively, are in widespread use. Each type of prestack migration produces an image volume depending on redundant parameters and supplies a condition on the image volume, which expresses consistency between data and velocity model and is hence a basis for velocity analysis. The survey‐sinking (depth‐oriented) approach to prestack migration is less subject to kinematic artefacts than is the binning‐based (surface‐oriented) approach. Because kinematic artefacts strongly violate the consistency or semblance conditions, this observation suggests that velocity analysis based on depth‐oriented prestack migration may be more appropriate in kinematically complex areas. Appropriate choice of objective (differential semblance) turns either form of migration velocity analysis into an optimization problem, for which Newton‐like methods exhibit little tendency to stagnate at nonglobal minima. The extended modelling concept links migration velocity analysis to the apparently unrelated waveform inversion approach to estimation of Earth structure: from this point of view, migration velocity analysis is a solution method for the linearized waveform inversion problem. Extended modelling also provides a basis for a nonlinear generalization of migration velocity analysis. Preliminary numerical evidence suggests a new approach to nonlinear waveform inversion, which may combine the global convergence of velocity analysis with the physical fidelity of model‐based data fitting. 相似文献
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Quantitative imaging of complex structures from dense wide-aperture seismic data by multiscale traveltime and waveform inversions: a case study 总被引:3,自引:0,他引:3
S. Operto C. Ravaut L. Improta J. Virieux A. Herrero P. Dell'Aversana 《Geophysical Prospecting》2004,52(6):625-651
An integrated multiscale seismic imaging flow is applied to dense onshore wide‐aperture seismic data recorded in a complex geological setting (thrust belt). An initial P‐wave velocity macromodel is first developed by first‐arrival traveltime tomography. This model is used as an initial guess for subsequent full‐waveform tomography, which leads to greatly improved spatial resolution of the P‐wave velocity model. However, the application of full‐waveform tomography to the high‐frequency part of the source bandwidth is difficult, due to the non‐linearity of this kind of method. Moreover, it is computationally expensive at high frequencies since a finite‐difference method is used to model the wave propagation. Hence, full‐waveform tomography was complemented by asymptotic prestack depth migration to process the full‐source bandwidth and develop a sharp image of the short wavelengths. The final traveltime tomography model and two smoothed versions of the final full‐waveform tomography model were used as a macromodel for the prestack depth migration. In this study, wide‐aperture multifold seismic data are used. After specific preprocessing of the data, 16 frequency components ranging from 5.4 Hz to 20 Hz were inverted in cascade by the full‐waveform tomography algorithm. The full‐waveform tomography successfully imaged SW‐dipping structures previously identified as high‐resistivity bodies. The relevance of the full‐waveform tomography models is demonstrated locally by comparison with a coincident vertical seismic profiling (VSP) log available on the profile. The prestack depth‐migrated images, inferred from the traveltime, and the smoothed full‐waveform tomography macromodels are shown to be, on the whole, consistent with the final full‐waveform tomography model. A more detailed analysis, based on common‐image gather computations, and local comparison with the VSP log revealed that the most accurate migrated sections are those obtained from the full‐waveform tomography macromodels. A resolution analysis suggests that the asymptotic prestack depth migration successfully migrated the wide‐aperture components of the data, allowing medium wavelengths in addition to the short wavelengths of the structure to be imaged. The processing flow that we applied to dense wide‐aperture seismic data is shown to provide a promising approach, complementary to more classical seismic reflection data processing, to quantitative imaging of complex geological structures. 相似文献
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Sylvain Nguyen † Reda Baina Mathias Alerini ‡ Gilles Lambaré Vincent Devaux Mark Noble 《Geophysical Prospecting》2008,56(5):613-625
Depth velocity model building remains a difficult step within the seismic depth imaging sequence. Stereotomography provides an efficient solution to this problem but was limited until now to a picking of seismic data in the prestack time un-migrated domain. We propose here a method for stereotomographic data picking in the depth migrated domain. Picking in the depth migrated domain exhibits the advantage of a better signal-to-noise ratio and of a more regular distribution of picked events in the model, leading to a better constrained tomographic inverse problem. Moreover, any improvement on the velocity model will improve the migrated results, again leading to improved picking. Our strategy for obtaining a stereotomographic dataset from a prestack depth migration is based on migration of attributes (and not on a kinematic demigration approach!). For any locally coherent event in the migrated image, migration of attributes allows one to compute ray parameter attributes corresponding to the specular reflection angle and dip. For application to stereotomography, the necessary attributes are the source/receiver locations, the traveltime and the data slopes. For the data slope, when the migration velocity model is erroneous, some additional corrections have to be applied to the result of migration of the attributes. Applying these corrections, our picking method is theoretically valid whatever the quality of the migration velocity model. We first present the theoretical aspects of the method and then validate it on 2D synthetic and real seismic reflection data sets. 相似文献
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非零偏VSP地震资料是一种多分量资料,处理非零偏VSP资料,弹性波叠前逆时深度偏移技术无疑是最适合的处理技术.本文从二维各向同性介质的弹性波波动方程出发,研究了对非零偏VSP资料进行叠前逆时深度偏移的偏移算法,讨论了逆时传播过程中的边值问题和数值频散问题及其相应的解决方案;采用求解程函方程计算得到地下各点的地震波初至时间作为成像时间,实现了非零偏VSP资料的叠前逆时深度偏移.最后进行了模型试算和非零偏VSP地震资料的试处理,结果表明该方法不受地层倾角限制,较适用于高陡构造地区或介质横向速度变化较大地区的非零偏VSP地震资料处理. 相似文献