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1.
共炮检距二维弹性波地震剖面的偏移方法 总被引：4，自引：0，他引：4
共均匀各向同性介质的分界面上入射纵波时，除产生纵波反射Ｐ－Ｐ波外，还会产生转换横波的反射Ｐ－ＳＶ波。同样，当入射波为ＳＶ横波时，在分界面上会同时产生ＳＶ－ＳＶ反射波和ＳＶ－Ｐ反射转换波。对这种二维弹性波地震记录如何进行偏移是探讨的问题。为了能够处理实际地震数据，本文提出在共炮检距剖面上进行二维弹性波记录的偏移方法。 相似文献
2.
共炮检距二维弹性波地震剖面的偏移方法 总被引：1，自引：0，他引：1
在均匀各向同性介质的分界面上入射纵波时，除产生纵波反射Ｐ－Ｐ波外，还会产生转换横波的反射Ｐ－ＳＶ波。同样，当入射波为ＳＶ横波时，在分界面上会同时产生ＳＶ－ＳＶ反射波和ＳＶ－Ｐ反射转换波，对这种二维弹性波地震记录如何进行偏移是正在探讨的问题。为了能够处理实际地震数据，本文提出在共炮检距剖面上进行二维弹性波记录的偏移方法。具体做法是，首先用弹性波方程将两分量的地震记录分解为Ｐ－Ｐ（或ＳＶ－ＳＶ）波和Ｐ－ＳＶ（或ＳＶ－Ｐ）波，然后用我们已导出的适合于处理共炮检距剖面的叠前偏移方法对它们进行处理。用模拟数据进行的试验说明方法正确，效果良好。 相似文献
3.
陈秋英 《地震地磁观测与研究》1998,19(3):37-41
利用南平台ＤＤ－１地震仪所记录到地核界面反射波ＰｃＰ、地核界面反射转换波ＳｃＰ、ＰｃＳ测定震源深度。结果表明,用这些震相测定地震震源深度,提高了台站测定远震震源参数的精度 相似文献
4.
陈秋英 《地震地磁观测与研究》1998,(3)
利用南平台ＤＤ－１地震仪所记录到的地核界面反射波ＰｃＰ、地核界面反射转换波ＳｃＰ、ＰｃＳ测定震源深度。结果表明,用这些震相测定地震震源深度,提高了台站测定远震震源参数的精度。 相似文献
5.
在水平分量的炮集记录中,数字三分量检波器直达波的椭圆率明显呈现出线性偏振的形态,并具有较高的分辨率,而模拟三分量检波器直达波的线性偏振不清晰,抗干扰能力差.在频谱分析和能量曲线分析的对比中,数字检波器的性能也高于模拟检波器.在PP波弱波阻抗界面的沙河组沙三12段,PS波表现出强反射界面,而且构造幅度比PP波剖面明显.在PS波剖面上,剖面深处两边的构造联系清晰可见,而在PP波剖面上很难解释剖面两边构造之间的关系,表明PS波资料对深层界面的成像能力有时不比PP波能力差,多分量资料在构造勘探上具有互补性.在沙四层底钻遇气层的马62井和马11井的测线CDP位置上,PP波和PS波的振幅比剖面上表现出低振幅比异常区,与钻井结果吻合.用多分量衰减系数或衰减比剖面,能够识别砂岩含气/水产生所产生的高频衰减异常.多分量地震属性及其比值剖面是储层含气异常指示的有效参数. 相似文献
6.
由于自由表面、海底等强反射界面的影响,海底电缆采集资料中鸣震等干扰往往非常严重且与有效波耦合在一起,降低了资料品质。海底电缆双检合成技术利用速度检波器和压电检波器对于下行波场的不同极性响应可以有效压制检波点端多次波,突出有效反射,提高地震资料的分辨率。本文在深入研究双检合成理论及匹配滤波技术的基础上,提出了基于均衡伪多道自适应匹配滤波方法的双检匹配合成方法压制检波点端多次波,不依赖于传统的求取反射系数的匹配合成方法,完全数据驱动,并在合成记录和实际资料的处理过程中均取得了良好的效果,证明了方法的有效性。 相似文献
7.
多年来,胜利探区多波多分量地震采集所得资料的信噪比和分辨率较低,无法取得较好的应用效果.为此,以胜利垦71区块为先导实验区开展了多波采集方法研究.首先,通过单点三分量检波器与常规检波器小面积组合分析了该区转换波发育情况,认为该区转换界面较强,转换波特征明显,转换横波速度约为纵波速度的1/2;然后,通过数字三分量检波器的室内各种组合研究,进行了超线元叠加,由此可以有效地改善资料的信噪比,并对分辨率基本没有影响;最后,利用三分量检波器扩展排列进行转换波最佳偏移距的设计,通过垂直排列追踪放炮进行最佳非纵距设计,从而得出该区多波采集的最佳观测系统参数.通过上述合理的设计和多项试验研究,在垦71地区多波采集中,数字检波器Z分量剖面的频率优势非常明显,分辨率明显高于常规检波器的纵波剖面,对于搞清小断层及微幅度构造具有重要的意义;同时,转换横波能量强、信噪比和分辨率高,使多波采集取得了较好的效果. 相似文献
8.
煤矿井下巷道煤层中采集的槽波地震数据中包含多种类型地震波,对这些波组认识存在争议.通过正演模拟获得的槽波波场过于理想化,与现场采集槽波数据存在一定偏差.针对煤矿实际采集的典型槽波数据,采用时频域极化滤波方法,利用槽波数据中的纵波在波传播方向能量最强、垂直方向能量最弱的特点,将目前国内煤矿常用的德国SUMMIT槽波地震仪水平双分量检波器接收到的信号,校正到平行波传播方向和垂直波传播方向,有利于判定地震波极化运动特征.经过槽波波场分离,得到三个特征明显的波组,按照时间到达先后顺序,认为分别是折射纵波、瑞利型槽波和勒夫型槽波.其中折射纵波传播速度最快,在共炮点道集上表现为双曲线特征;瑞利型槽波主频最低,水平平行分量和垂直分量都能接收到;勒夫型槽波振动方向垂直波传播方向,只在检波器水平垂直分量有显示. 相似文献
9.
10.
用波函数展开法求解界面圆孔的SH波散射问题 总被引：2，自引：1，他引：1
研究了ＳＨ波绕界面圆孔散射的波函数展开理论。由入射,反射和透射波组成的自由波场与孔的散射场叠加成总波场。将定义于两个半平面的散射场按一定方式延拓到全平面。通过Ｈａｎｋｅｌ－Ｆｏｕｒｉｅｒ型积分来满足界面与孔缘处的边界条件,得到了确定特定系数的封闭代数方程组。给出了具体算例,计算了孔缘处的动应力系数分布。 相似文献
11.
J. W. M. DANKBAAR 《Geophysical Prospecting》1985,33(7):970-986
In combined P- and SV-observations with vertical and in-line horizontal geophones, recognition and separation of the individual P- and S-arrivals may form a considerable problem. Due to the geophone receiving characteristics, P- and S-waves are observed on both horizontal and vertical geophones. A new method of separating P- and S-waves is presented that inverts the geophone records for the receiving characteristics, thereby separating the two wavetypes. The filter coefficients are determined from the near-surface P- and S-wave velocity and from the geometry of the geophone groups. The P/S-separation filter was tested on synthetic data with good results. Even PS- and SP-converted reflections, which are completely coinciding for horizontal reflectors, could be well separated. The filter appears to be stable and to have low sensitivity to noise in the data or to errors in the near-surface P- and S-wave velocity. The filter is superior to other separation methods, which were applied to the same dataset for comparison. This method can also be applied to VSP data. 相似文献
12.
多波多分量地震勘探方法在油气田勘探开发中日益受到重视,但在工程和活动断裂探测中过去还没有开展多波多分量地震勘探的先例.本文简要介绍了在北京黄庄—高丽营断裂上开展的三分量浅层地震反射试验数据采集和资料处理方法,以及取得的初步结果.试验结果表明,采用纵波震源或横波震源激发、三分量接收的浅层地震勘探方法,可获得较高信噪比的浅层地震纵波、横波和转换波剖面,特别是水平分量采集的横波和转换波可提供很有意义的地下结构和构造信息.综合利用纵波、横波和转换波剖面特征进行的地质分层和断层解释结果取得了与跨断层的钻孔联合地质剖面结果较好的一致性. 相似文献
13.
In two-component seismic observations with vertical and in-line horizontal geophones, the compressional (P-) wave amplitudes, as well as the vertically polarized shear (SV-) wave amplitudes, are observed on both vertical and horizontal geophones. In our case, we use a P-wave source, while the SV waves are the result of mode conversion. The mode-conversion mechanism considered here is related to the near-surface layers, i.e. we have a P-leg from the source and mode conversion at/in the weathered layer. The resulting SV waves therefore will show lateral variations because the elastic parameters of the near-surface layers vary along the seismic line, but these variations will be consistent at the surface. This effect is demonstrated by a synthetic example based on elastic parameters representative of the actual seismic line being considered. To separate the individual P and SV arrivals, we apply a two-dimensional convolution filter designed to meet the wavenumber-frequency (k-f) domain transfer function for P-SV separation which can be derived from thek-f domain geophone-receiving characteristic and the near surface P- and S-wave velocities. The reason for P-SV separation filtering in the offset-traveltime (X-T) domain instead of directly filtering in thek-f domain, is a great saving in computer time, asX-T filters, with few coefficients, can be used. In this paper, after a short summary of thek-f domain P-SV separation filters and their transformation to theX-T domain, we apply theX-T filters to synthetic data in order to demonstrate that our design is correct. We also work on actual data and discuss the problems being faced, which mainly, originate from the different geophone groups and, as a consequence, the different scalings of vertical and horizontal geophones. The main advantage of two-component seismic observations is two-fold: firstly, a clean P-wave section is obtained (SV-energy arriving at the receivers is cancelled by applying the foresaid separation filter) and, secondly we obtain an additional SV-wave section at almost no cost to data acquisition. These two sections contribute towards distinguishing between true and false bright spots, so they are, used as direct hydrocarbon indicator tools. 相似文献
14.
Wide-angle multicomponent ocean-bottom cable (OBC) data should further enhance sub-basalt imaging by using both compressional and converted shear wavefields. The first step in analysing multicomponent OBC data is to decompose the recorded wavefields into pure P- and pure S-wavefields, and extract the upgoing P- and S-waves. This paper presents a new scheme to separate P- and S-wavefields from wide-angle multicomponent OBC data in the τ–p domain. By considering plane-wave components with a known horizontal slowness, the P- and S-wavefields are separated into the directions of observed P- and S-wave oscillations using the horizontal and vertical components of the data. The upgoing P- and S-waves are then extracted from the separated P- and S-wavefields. The parameters used in the separation are the seismic wave velocities and the density at the receiver location, which can be estimated from the first reflection phase observed on the horizontal and vertical components. Numerical tests on synthetic data for a plane-layered model show good performance and demonstrate the accuracy of the scheme. Separation of wavefields from a basalt model is performed using synthetic wide-angle multicomponent OBC data. The results show that both near-offset and wide-angle reflections and conversions from within and below basalt layers are enhanced and clearly identified on the separated wavefields. 相似文献
15.
Imaging the PP- and PS-wave for the elastic vector wave reverse-time migration requires separating the P- and S-waves during the wave field extrapolation. The amplitude and phase of the P- and S-waves are distorted when divergence and curl operators are used to separate the P- and S-waves. We present a P- and S-wave amplitude-preserving separation algorithm for the elastic wavefield extrapolation. First, we add the P-wave pressure and P-wave vibration velocity equation to the conventional elastic wave equation to decompose the P- and S-wave vectors. Then, we synthesize the scalar P- and S-wave from the vector Pand S-wave to obtain the scalar P- and S-wave. The amplitude-preserved separated P- and S-waves are imaged based on the vector wave reverse-time migration (RTM). This method ensures that the amplitude and phase of the separated P- and S-wave remain unchanged compared with the divergence and curl operators. In addition, after decomposition, the P-wave pressure and vibration velocity can be used to suppress the interlayer reflection noise and to correct the S-wave polarity. This improves the image quality of P- and S-wave in multicomponent seismic data and the true-amplitude elastic reverse time migration used in prestack inversion. 相似文献
16.
Characterizing the expressions of seismic waves in elastic anisotropic media depends on multiparameters. To reduce the complexity, decomposing the P-mode wave from elastic seismic data is an effective way to describe the considerably accurate kinematics with fewer parameters. The acoustic approximation for transversely isotropic media is widely used to obtain P-mode wave by setting the axial S-wave phase velocity to zero. However, the separated pure P-wave of this approach is coupled with undesired S-wave in anisotropic media called S-wave artefacts. To eliminate the S-wave artefacts in acoustic waves for anisotropic media, we set the vertical S-wave phase velocity as a function related to propagation directions. Then, we derive a pure P-wave equation in transversely isotropic media with a horizontal symmetry axis by introducing the expression of vertical S-wave phase velocity. The differential form of new expression for pure P-wave is reduced to second-order by inserting the expression of S-wave phase velocity as an auxiliary operator. The results of numerical simulation examples by finite difference illustrate the stability and accuracy of the derived pure P-wave equation. 相似文献
17.
《应用地球物理》2006,3(3):163-168
In multi-component seismic exploration, the horizontal and vertical components both contain P- and SV-waves. The P- and SV-wavefields in a seismic record can be separated by their horizontal and vertical displacements when upgoing P- and SV-waves arrive at the sea floor. If the sea floor P wave velocity, S wave velocity, and density are known, the separation can be achieved in ther-p domain. The separated wavefields are then transformed to the time domain. A method of separating P- and SV-wavefields is presented in this paper and used to effectively separate P- and SV-wavefields in synthetic and real data. The application to real data shows that this method is feasible and effective. It also can be used for free surface data. 相似文献
18.
Dispersion analysis is an important part of in-seam seismic data processing, and the calculation accuracy of the dispersion curve directly influences pickup errors of channel wave travel time. To extract an accurate channel wave dispersion curve from in-seam seismic two-component signals, we proposed a time–frequency analysis method based on single-trace signal processing; in addition, we formulated a dispersion calculation equation, based on S-transform, with a freely adjusted filter window width. To unify the azimuth of seismic wave propagation received by a two-component geophone, the original in-seam seismic data undergoes coordinate rotation. The rotation angle can be calculated based on P-wave characteristics, with high energy in the wave propagation direction and weak energy in the vertical direction. With this angle acquisition, a two-component signal can be converted to horizontal and vertical directions. Because Love channel waves have a particle vibration track perpendicular to the wave propagation direction, the signal in the horizontal and vertical directions is mainly Love channel waves. More accurate dispersion characters of Love channel waves can be extracted after the coordinate rotation of two-component signals. 相似文献
19.
The analytical study of the reflection and transmission coefficient of the seafloor interface is essential for the characterization of the ocean bottom in marine seismic exploration. Based on the boundary conditions of the seafloor interface, the analytical expression of the reflection and transmission coefficient at the submarine interface is derived in this study by using the steady-state wave solution of the elastic wave in a homogeneous, isotropic medium. With this analytical expression, the characteristics of the reflection and transmission coefficient at the submarine interface are analysed and discussed using critical angles. The results show that the change in the reflection and transmission coefficient with the incidence angle presents a “segmented” characteristic, in which the critical angle is the dividing point. The amplitude value and phase angle of the coefficient at the submarine interface change dramatically at the critical angle, which is related to the P- and S-wave velocities in the seabed layer. Compared with the stiff seabed, the soft seabed has a larger P-wave critical angle and an absence of the converted S-wave critical angle, owing to the low P- and S-wave velocities in the solid seabed layer. By analysing and discussing the special changes that occur in the coefficient values at the critical angle, the reflection and transmission characteristics of the different incident angles are obtained. Synthetic models of both stiff and soft seafloors are provided in this study to verify the analytical results. Finally, we compared our synthetic results with real data from the Gulf of Mexico, which enabled the validation of our conclusions. 相似文献
20.
Pure-mode wave propagation is important for applications ranging from imaging to avoiding parameter tradeoff in waveform inversion. Although seismic anisotropy is an elastic phenomenon, pseudo-acoustic approximations are routinely used to avoid the high computational cost and difficulty in decoupling wave modes to obtain interpretable seismic images. However, such approximations may result in inaccuracies in characterizing anisotropic wave propagation. We propose new pure-mode equations for P- and S-waves resulting in an artefact-free solution in transversely isotropic medium with a vertical symmetry axis. Our approximations are more accurate than other known approximations as they are not based on weak anisotropy assumptions. Therefore, the S-wave approximation can reproduce the group velocity triplications in strongly anisotropic media. The proposed approximations can be used for accurate modelling and imaging of pure P- and S-waves in transversely isotropic media. 相似文献