共查询到18条相似文献，搜索用时 281 毫秒
1.
反馈迭代法多次波衰减分为预测和相减两个步骤.在匹配相减过程中,当多次波和一次波同相轴不满足正交性,以及去除多次波后的地震记录不满足能量最小的情况下,最小二乘自适应匹配滤波方法不能获得正确的匹配,因此多次波的衰减产生误差.针对这两个问题,本文提出了基于1范数最小的均衡多道自适应匹配滤波法.该方法通过在空间方向上对地震记录进行均衡,避免了多次波和一次波同相轴正交的假设条件.同时利用了1范数对于大异常值保持稳健的特点,因此可以有效地解决去除多次波后的地震记录能量最小的问题.通过对模型数据和野外实际数据的多次波压制结果显示,该方法可以有效、准确地衰减多次波. 相似文献
2.
3.
针对常规多次波压制(SRME)方法存在的缺陷进行了改进.首先在多次波模型道预测阶段,采用数据相关和迭代更新的策略预测多次波模型道,该方法降低了SRME方法采用数据空间褶积对输入数据要求严格的限制,提高了对近偏移距缺失和空间假频数据的适应性.在匹配相减阶段,本文设计了一种非因果非平稳的匹配滤波器,该滤波器可以对整道多次波模型进行处理,而且当预测多次波模型道滞后于实际多次波时,也能够对多次波模型道进行很好的匹配.模型数据和实际数据试算证明该方法在多次波模型道预测和匹配相减阶段的优越性. 相似文献
4.
多次波预测与自适应相减是基于波动方程表面多次波压制的两个重要环节.文中利用具有并行计算优势的GPU加速表面多次波预测,使得预测效率大为提高.在自适应相减算法中,文中将预测的多次波道、预测多次波道的Hilbert变换道、预测多次波道的高频重建道、以及它们的平移道用作自适应相减中的多次波模型道.Hilbert变换道用以补偿预测多次波的相位信息,高频重建道用以改善预测多次波的高频信息,补偿频带能量差异.文中在预测和相减过程中均采用迭代算法,迭代预测,可较好地获得多次波的运动学特性,迭代相减,可较好地获得多次波的动力学特性,迭代预测与相减使预测的多次波与地震数据中实际的多次波更好地匹配.将该方法应用于理论模拟的SMAART模型和实际海洋数据中,测试结果表明,该方法预测多次波效率较高,在保持有效波振幅条件下可有效地压制地震数据中的表面多次波. 相似文献
5.
泰勒展开近似 带连续性约束的L1范数方法用于多次波自适应相减(英文) 总被引：1，自引：0，他引：1
一次波L1范数最小化的多次波自适应相减方法,简称L1方法,是基于匹配滤波器设计的多次波自适应相减算法中的一种常用方法.当一次波和多次波混杂在一起时,L1方法有时会伤害一次波,导致一次波同相轴的连续性变差.本文利用预测误差滤波器度量一次波同相轴的连续性,在L1方法的皋础上,提出一种能够在压制多次波的同时,尽量保持一次波同相轴连续性的多次波自适戍相减算法,简称连续性约束L1方法.利用Pluto模犁数据进行多次波相减的结果表明,连续性约束L1方法能够在有效压制多次波的同时,更好地保护一次波. 相似文献
6.
多道自适应匹配滤波方法压制表面多次波 总被引：2，自引：0，他引：2
表面多次波压制是海洋地震数据处理的关键环节,基于波动方程的多次波压制方法可由多次波模型预测和自适应相减两步实现.因此,除了采用有效的算法实现高精度的多次波预测外,多次波的自适应相减也是改善多次波压制效果的重要手段.文中采用多道自适应滤波器完成表面多次波的自适应相减,利用数据驱动的基于波动方程预测多次波模型的高频重建道、Hilbert变换道、以及它们相应的上下延拓道改善预测多次波模型的振幅、相位、旅行时以及频带信息,使得修正后多次波模型与实际地震数据中的多次波更好地匹配.实际数据测试表明,文中所述方法可有效地完成表面多次波的自适应相减.通过讨论分析交叠时窗和滤波器的长度对自适应相减效果的影响,表明合理地利用时窗以及选择滤波器长度将有效地改善自适应相减的效果. 相似文献
7.
有效压制多次波一直是地震勘探中的难点问题.尽管已发展了多种多次波压制方法,但仍存在多次波压制不全、计算耗时长等缺陷,使得应对复杂地质地震数据多次波压制具有挑战性.为了突破现有多次波压制方法的局限性,本文提出了一种基于深层神经网络的多次波压制方法,采用的深层神经网络是一种改进的具有卷积编码器和卷积解码器的U-net网络.不同于常规方法依赖于滤波或波动理论,该方法仅依赖于大量训练数据.训练数据以含多次波的原始地震数据作为输入,不含多次波的地震数据作为输出,通过最小化损失函数来优化神经网络参数.训练成功的网络模型具备较好地分离多次波和一次波的能力,可直接用来快速压制地震数据中的多次波,避免了常规方法涉及的大规模计算.工业界模型数据测试结果表明,本文提出的深层神经网络方法能有效压制复杂地质地震数据中的多次波,同时还具有较高的泛化能力和多次波压制效率. 相似文献
8.
《应用地球物理》2019,(4)
水体相关多次波是海上地震数据处理主要的噪声来源之一,模型驱动类方法 (Model-Drived-Method, MDM)可以有效地对水体相关多次波进行预测和压制,其中多次波贡献道集(multiples contribution gathers, MCG)的质量是影响该类方法多次波预测精度的主要因素。本文利用基于L0范数稀疏约束优化MCG,减弱多次波预测过程中所产生的假象,不但提高预测精度,而且在理论上减少了一定的计算量。同时对MDM类方法压制多次波进行了改进,通过对多种类型水体相关多次波的统一预测,弱化了常规MDM在压制水体相关多次波时对自适应减去过程的依赖程度,提高了方法的稳定性。理论模型证明了本文方法的有效性,实际资料案例进一步说明方法的应用潜力。 相似文献
9.
常规滤波方法对浅海多次波压制不能取得理想效果.通过改变模型表面边界条件,求解波动方程实现多情景地震数值模拟.利用自由边界条件模拟时获得含海平面强反射多次波地震记录,而利用吸收边界条件时得到理想条件下无多次波地震记录.对比分析多次波对有效地震信号的影响得到海平面强反射多次波改变了有效地震信号的振幅、频率和相位.利用归一化方法计算得到压制多次波滤波器算子,并作用于含海平面强反射多次波地震记录.叠加地震剖面对比分析表明,归一化滤波器算子较好的压制了地震记录中的多次波,提高地震资料分辨率.最后,根据多次波产生条件,给出了利用实际区域简化地质模型的地震数值模拟结果计算归一化滤波器算子的方法,从而利用该方法压制实际地震数据中多次波. 相似文献
10.
传统地震数据稀疏重建方法面临着:(1)叠前共炮点道集或CMP道集反射波为双曲线型同相轴,地震数据重建会损害有效波;(2)地震信号存在噪声和畸变,要求重建方法具有较好的噪声鲁棒性.针对这两个问题,提出一种基于L_1-L_1范数稀疏表示的共偏移距道集地震数据重建方法.该方法利用了共偏移距道集中地震波为水平同相轴,无道间时差,满足空间重建要求,和L_1-L_1范数稀疏表示具有较好的噪声鲁棒性.首先抽取共偏移距道集地震数据,并根据地震采集信息构造复合采样矩阵,然后采用L_1-L_1范数稀疏表示对数据稀疏重建后,再将数据反变换回共炮点道集或CMP道集,能够同时实现地震信号稀疏重建和随机噪声压制.理论模型和实际数据试算结果验证所提方法具有较好重建精度和噪声鲁棒性. 相似文献
11.
Estimating primaries by sparse inversion of the 3D curvelet transform and the L1-norm constraint 总被引：2，自引：0，他引：2
In this paper, we built upon the estimating primaries by sparse inversion (EPSI) method. We use the 3D curvelet transform and modify the EPSI method to the sparse inversion of the biconvex optimization and L1-norm regularization, and use alternating optimization to directly estimate the primary reflection coefficients and source wavelet. The 3D curvelet transform is used as a sparseness constraint when inverting the primary reflection coefficients, which results in avoiding the prediction subtraction process in the surface-related multiples elimination (SRME) method. The proposed method not only reduces the damage to the effective waves but also improves the elimination of multiples. It is also a wave equationbased method for elimination of surface multiple reflections, which effectively removes surface multiples under complex submarine conditions. 相似文献
12.
对于被动源地震数据,运用常规的互相关算法得到的虚拟炮记录中,不仅含有一次波反射信息,还包括了表面相关多次波.然而,通过传统的被动源数据稀疏反演一次波估计(EPSI)方法,可以求得只含有一次波,不含表面相关多次波的虚拟炮记录.本文改进了传统的被动源数据稀疏反演一次波估计问题的求解方法,将被动源稀疏反演一次波估计求解问题转化为双凸L1范数约束的最优化求解问题,避免了在传统的稀疏反演一次波估计过程中用时窗防止反演陷入局部最优化的情况.在L1范数约束最优化的求解过程中,又结合了2DCurvelet变换和小波变换,在2DCurvelet-wavelet域中,数据变得更加稀疏,从而使求得的结果更加准确,成像质量得到了改善.通过简单模型和复杂模型,验证了本文提出方法的有效性. 相似文献
13.
Adaptive subtraction is an important link for removing surface-related multiples in the wave equation-based method. In this paper, we propose an adaptive multichannel subtraction method based on the L1-norm. We achieve enhanced compensation for the mismatch between the input seismogram and the predicted multiples in terms of the amplitude, phase, frequency band, and travel time. Unlike the conventional L2-norm, the proposed method does not rely on the assumption that the primary and the multiples are orthogonal, and also takes advantage of the fact that the L1-norm is more robust when dealing with outliers. In addition, we propose a frequency band extension via modulation to reconstruct the high frequencies to compensate for the frequency misalignment. We present a parallel computing scheme to accelerate the subtraction algorithm on graphic processing units (GPUs), which significantly reduces the computational cost. The synthetic and field seismic data tests show that the proposed method effectively suppresses the multiples. 相似文献
14.
《中国科学:地球科学(英文版)》2015,(3)
The South China Sea where water depth is up to 5000 m is the most promising oil and gas exploration area in China in the future.The seismic data acquired in the South China Sea contain various types of multiples that need to be removed before imaging can be developed.However,compared with the conventional reflection migration,multiples carry more information of the underground structure that helps provide better subsurface imaging.This paper presents a method to modify the conventional reverse time migration so that multiple reflections can migrate to their correct locations in the subsurface.This approach replaces the numerical impulsive source with the recorded data including primaries and multiples on the surface,and replaces the recorded primary reflection data with multiples.In the reverse time migration process,multiples recorded on the surface are extrapolated backward in time to each depth level,while primaries and multiples recorded on the surface are extrapolated forward in time to the same depth levels.By matching the difference between the primary and multiple images using an objective function,this algorithm improves the primary resultant image.Synthetic tests on Sigsbee2 B show that the proposed method can obtain a greater range and better underground illumination.Images of deep water in the South China Sea are obtained using multiples and their matching with primaries.They demonstrate that multiples can make up for the reflection illumination and the migration of multiples is an important research direction in the future. 相似文献
15.
A new method for predicting different kinds of multiples and peg-leg reflections in unstacked seismic data is discussed. The basis for this method is the fact that kinematic properties of multiples can be represented as a combination of kinematic properties of primary reflections. The prediction is made using a two-step process. In the first step, the values for the angle of emergence and radius of curvature of the wavefront for primary reflections from ‘multiple-generating’ interfaces are obtained. These parameters are estimated directly from unstacked data for every source point using the homeomorphic-imaging technique. The second step consists of prediction of multiples from primary reflections that satisfy a so-called ‘multiple condition’. This condition is the equality of the absolute values of the angles of emergence calculated from the first step. This method is effective even in complex media and information on the subsurface geology is not required. The parameters are estimated directly from the unstacked data and do not require any computational efforts such as in wavefield extrapolation of data. 相似文献
16.
Migration methods for imaging different-order multiples 总被引：2，自引：0，他引：2
Zhiyong Jiang Jianming Sheng Jianhua Yu Gerard T. Schuster Brian E. Hornby 《Geophysical Prospecting》2007,55(1):1-19
Multiples contain valuable information about the subsurface, and if properly migrated can provide a wider illumination of the subsurface compared to imaging with VSP primary reflections. In this paper we review three different methods for migrating multiples. The first method is model-based, and it is more sensitive to velocity errors than primary migration; the second method uses a semi-natural Green's function for migrating multiples, where part of the traveltimes are computed from the velocity model, and part of the traveltimes (i.e., natural traveltimes) are picked from the data to construct the imaging condition for multiples; the third method uses cross-correlation of traces. The last two methods are preferred in the sense that they are significantly less sensitive to velocity errors and statics because they use “natural data” to construct part of the migration imaging conditions. Compared with the interferometric (i.e., crosscorrelation) imaging method the semi-natural Green's function method is more computationally efficient and is sometimes less prone to migration artifacts. Numerical tests with 2-D and 3-D VSP data show that a wider subsurface coverage, higher-fold and more balanced illumination of the subsurface can be achieved with multiple migration compared with migration of primary reflections only. However, there can be strong interference from multiples with different orders or primaries when multiples of high order are migrated. One possible solution is to filter primaries and different orders of multiples before migration, and another possible solution is least squares migration of all events. A limitation of multiple migration is encountered for subsalt imaging. Here, the multiples must pass through the salt body more than twice, which amplifies the distortion of the image. 相似文献
17.
在深水陡坡带和复杂海底构造区域,即使采用长电缆,由绕射产生的自由表面相关多次波因为传播方向的异变,仍然难以避免在自由表面发生下行反射的反射点位置位于电缆长度范围之外,造成预测多次波的近偏移距信息不足或者负偏移距信息缺失等问题,以致不能准确地预测和压制陡坡带的绕射多次波.本文在常规反馈迭代自由表面多次波压制方法的基础上做出相应改进,将邻炮的炮记录依照炮点、检波点互换原理引入到反馈迭代循环当中,补充绕射多次波预测所需要的近偏移距和负偏移距信息.经过Sigsbee2b模型和实际资料测试,达到较好压制深水陡坡带的自由表面相关绕射多次波的目地. 相似文献
18.
在常规地震资料处理中,多次反射波被视为噪声并从地震数据中去除,以免在之后的地震资料解释中造成误解.而事实上,多次波也是地震信号,是照明波场的一部分,能够对地下构造成像的精度做出贡献.本文分析了多次波在传统单程波叠前深度偏移中产生构造假象的机制和表现,为实现基于单程波偏移算子的多次波成像,修改了单程波叠前深度偏移的边界条件,即将输入的震源波场用包含多次波的记录来替代,输入的记录波场用预测出的表层相关多次波来替代,实现了基于单程波偏移算子的地表相关多次波成像,并从理论上给出了其成像依据.通过基于二范式最小能量差原则求取的匹配因子,将多次波成像结果与一次波成像结果进行匹配叠加,应用多次波成像来弥补一次波成像的不足.简单模型验证了基于单程波偏移算子的多次波成像方法的有效性,最后对Sigsbee2B模型进行了一次波与多次波联合成像试算,盐边界高陡构造成像质量得到了明显改善. 相似文献