共查询到18条相似文献，搜索用时 140 毫秒
1.
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
2.
《应用地球物理》2020,(1)
角度域共成像点道集(angle-domain common-image gathers,ADCIGs)是多波AVA反演和偏移速度分析的基础数据。纵、横波坡印廷矢量的准确求取是获得多分量地震资料ADCIGs的前提。由常规速度-应力弹性波方程得到的坡印廷矢量代表了纵、横两种波的混合波场的传播方向,而非纯纵波或纯横波的传播方向。一阶速度-胀缩-旋转弹性波方程能够求取纯纵波或纯横波的坡印廷矢量,获得单一类型波的传播方向信息。本文基于一阶速度-胀缩-旋转弹性波方程逆时偏移实现纵、横波ADCIGs的求取,具体思路为:利用胀缩振动速度矢量和胀缩标量分别求取炮点和接收点波场中纯纵波的坡印廷矢量,利用剪切振动速度矢量和旋转矢量求取纯横波的坡印廷矢量,取炮点波场中各网格点纵波能量最大时刻的纵波坡印廷矢量为入射纵波传播方向矢量,取接收点波场中各网格点纵(横)波能量最大时刻的纵(横)波坡印廷矢量为反射纵波(反射转换横波)传播方向矢量,据此求取入射角并最终得到纵、横波角道集。模型试算表明:本文方法可以准确求取界面处入射波和反射波的传播方向矢量,得到地震波入射角,实现纵、横波角道集的高精度提取。 相似文献
3.
P-SV转换波处理与传统的P-P波处理有很大的不同,如S波静校正、CCP叠加、P-SV速度分析和偏移等,其中最大的难题就是S波静校正问题.S波速度基本不受潜水面的影响,与纵波静校正没有直接相关性,有时横波静校正量能达到纵波静校正量的十倍,用纵波静校正量乘以比例系数来解决横波静校正问题将导致较大误差.同一接收点X和Z分量存在一定的初至时差,该时差代表了P波和S波在低降速带的走时差,可以利用该时差和近地表纵横波速度比信息去除低降速带对横波的影响,得到准确的静校正量.本文利用多分量初至时差推导了较为精确的横波静校正公式,再结合共检波点叠加求取剩余静校正量的方法,形成了完整的转换波静校正配套方法.利用该方法对苏里格气田二维及三维多波地震资料进行了实际处理,数据处理结果证明了该方法的有效性,该方法尤其适用于其他方法难以奏效的风化层较厚地区的横波静校正量求解,该方法也同时考虑了长波长横波静校正问题. 相似文献
4.
《应用地球物理》2016,(3)
欲实现基于弹性波方程的矢量波场逆时偏移纵、横波独立成像,必须在波场延拓过程中实现纵、横波场的分离,散度和旋度算子分离的纵、横波出现振幅与相位的畸变,导致输出成像结果的振幅失真。本文提出一种在弹性波场延拓过程中实现纵、横波保幅分离的方法,在传统的弹性波方程中加入纵波压力、纵波振动速度和横波振动速度方程,实现纵横波的矢量分解,再对分解后的矢量纵波和矢量横波做标量化合成得到保幅分离的纵、横波场,对保幅分离的纵、横波场应用成像条件,然后实现矢量波场逆时偏移的保幅纵横波成像。该方法可以保证分离后纵、横波的振幅与相位不变;同时,分解后的纵波压力和纵波振动速度可用于层间反射噪音压制和横波极性校正,提高多分量地震资料联合逆时偏移的纵、横波成像质量,从而实现保幅弹性波逆时偏移的目的,为叠前深度剖面应用于叠前反演工作奠定基础。 相似文献
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6.
《应用地球物理》2017,(4)
将偏移后的炮域偏移距道集转换为角度域共成像道集(ADCIGs)可为偏移速度分析(MVA)和叠前反演提供输入道集,并且ADCIGs是理论上没有假象的叠前反演道集,也是目前公认的精度最高的叠前反演道集。本文研究了基于矢量波场逆时偏移的弹性波保幅ADCIGs的提取方法,以保幅弹性波逆时偏移方程为基础,其核心是求取不同震源位置的纵、横波场在地下各成像点的入射角,对于转换波勘探,二者共享一个入射角,即震源纵波入射角。根据几何关系,震源纵波波场的传播角、构造的局部地层倾角之差为震源纵波入射角,震源纵波波场的传播角利用解耦后纵波场的极化向量得到,构造的局部地层倾角利用偏移叠加剖面的复波数得到。对纵、横波的共炮点偏移道集按入射角重新排列即可得到各自的ADCIGs。文中利用水平层状介质模型、倾斜层状介质模型、Marmousi-Ⅱ弹性波部分模型和实测资料验证了算法的有效性,计算结果表明,本文方法计算的纵、横波角度具有较高的精度,提取的角道集具有较好的振幅保真性,能够为MVA和叠前反演提供可靠的输入道集。 相似文献
7.
本文以有限元数值模拟方法为依托,依次从波场快照、地震记录、波场分离、工程实例等四个角度论证了地震波传播规律和波场分离特点.模拟了单界面介质条件下地震波在隧道围岩中传播的全波波场.研究了反射波时距曲线的线性相关系数.比较了τ-p变换和F-K变换的滤波特点.结合工程实例,讨论了这两类线性波场分离方法在提取隧道前方反射波中的可行性和准确性,研究结果表明:当隧道前方地层倾角由直立变为缓倾时,反射纵波和横波的时距关系都能很好的视为线性.地层倾角的改变主要影响反射波走时和视速度.因此,应用τ-p变换和F-K变换进行波场分离,提取隧道前方单独的反射纵波和横波是可行和有效的.但对于缓倾地层,线性变换波场分离的结果存在较大的走时和视速度误差.易误滤除反射信号,需进行偏移处理. 相似文献
8.
动校正拉伸是地震资料处理的一个基本问题，解决拉伸问题的处理方法是切除.现代地震数据大多为长排列采集，动校正拉伸更为严重.依据褶积模型和Fourier变换的基本性质，本文给出频谱代换无拉伸动校正方法.算法实现就是将CMP道集变换到频率域，取参考道的相位谱替换其它偏移距道的相位，同时保持其振幅谱不变，再做Fourier反变换就得到动校正后的地震剖面.通过其实现过程可知该方法不需要地下介质的速度信息，算法可完全自动实现，且具有较高的计算效率.频谱代换无拉伸动校正可适用于任何偏移距的地震资料，而且还可有效保持地震资料的AVO效应.理论模拟数据及其叠加结果显示频谱代换法的有效性和实用性，同时该方法具有较强的抗随机噪音能力. 相似文献
9.
提出了一种有效的多分量地震波波场分解方法, 该方法假设在相邻道集波场的振幅、相位变化不大的情况下, 根据纵波和转换波在传播中相对于不同的极化矢量和慢度得到的垂向和水平向分量, 在最小方差约束下从多分量输入数据中获取纵波和转换波的偏振方向和振幅并重构纵波和转换波, 从而分离纵波和转换波. 这种方法精度较高, 不仅能有效分解一次反射波的多分量波场, 多次反射的纵波和转换波也能被恰当地分解. 该方法不需要输入地层速度等参数信息, 减少了人为误差的影响. 通过对合成资料的处理, 验证了方法的可行性和正确性. 相似文献
10.
在转换波地震勘探数据处理中,接收点的横波静校正一直是较难解决的问题.因为横波速度基本不受潜水面的影响,横波低速带厚且不均匀,速度又比较低,通常会造成转换波接收点的横波静校正量大且横向变化剧烈,与纵波静校正没有直接相关性.针对这种情况,我们采用改进的纵波构造时间控制方法求取转换波接收点的静校正,在转换波的共接收点叠加剖面上追踪拾取多组同相轴,联合纵波对应层位的地下构造时间确定接收点大的横波静校正量.通过不同的时移将几个相邻的层位合成一个反射层位,解决同相轴不能连续追踪的难题,同时利用浅、中和深层多组层位对一个接收点的静校正量求其平均,降低拾取误差对静校正量的影响,兼顾地下浅、中和深层的静校正效果.实际数据处理结果表明,该静校正方法能稳定的解决转换波静校正问题,取得了较好的应用效果. 相似文献
11.
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
12.
Amplitude versus offset concepts can be used to generate weighted stacking schemes (here called geo-stack) which can be used in an otherwise standard seismic data processing sequence to display information about rock properties. The Zoeppritz equations can be simplified and several different approximations appear in the literature. They describe the variation of P-wave reflection coefficients with the angle of incidence of a P-wave as a function of the P-wave velocities, the S-wave velocities and the densities above and below an interface. Using a smooth, representative interval velocity model (from boreholes or velocity analyses) and assuming no dip, the angle of incidence can be found as a function of time and offset by iterative ray tracing. In particular, the angle of incidence can be computed for each sample in a normal moveout corrected CMP gather. The approximated Zoeppritz equation can then be fitted to the amplitudes of all the traces at each time sample of the gather, and certain rock properties can be estimated. The estimation of the rock properties is achieved by the application of time- and offset-variant weights to the data samples before stacking. The properties which can be displayed by geo-stack are: P-wave reflectivity (or true zero-offset reflectivity), S-wave reflectivity, and the reflectivity of P-wave velocity divided by S-wave velocity (or ‘pseudo-Poisson's ratio reflectivity’). If assumptions are made about the relation between P-wave velocity and S-wave velocity for water-bearing clastic silicate rocks, then it is possible to create a display which highlights the presence of gas. 相似文献
13.
Inversion for S-wave velocities from the amplitude variation with offset of P-wave data is far from being a standard routine in the seismic processing sequence. However, the need for tracking the amplitude versus offset (AVO) occurs in several situations, for example in order to estimate the zero-offset amplitude, to reveal areas with particular AVO characteristics, or to compress the AVO so that it is more easily obtainable at a later stage of the seismic processing. Furthermore, weak reflections can occasionally, due to the effect of the angle-dependent reflectivity, have a polarity-shift with offset, resulting in a very poor, or even vanishing, stack response. In such cases, the reflection event has to be represented by some other property than its mean amplitude or stack value. We outline how the AVO of seismic data may be extracted and classified by the use of orthogonal polynomials. The main advantage of this method compared to a general polynomial fit is that the AVO may be classified by a unique Spectrum of polynomial coefficients. This is in analogy to Fourier coefficients where the orthogonal basis is harmonic functions. The set of orthogonal polynomials is constructed entirely from the set of offset coordinates, and these polyno-mials are defined only on the offset window considered. Compared to a Fourier transform, this is a major advantage since there is no effect of a limited spatial bandwidth. The AVO of normal-moveout corrected data may be represented by a data gather where the orthogonal polynomial coefficients are given as time traces with each trace revealing a certain AVO characteristic. For instance, the stack is proportional to the zeroth-order coefficient, the mean gradient is given by the firstorder coefficient, while the second-order coefficient indicates whether the AVO increases and then decreases, or vice versa. 相似文献
14.
Parameters in a stack of homogeneous anelastic layers are estimated from seismic data, using the amplitude versus offset (AVO) variations and the travel-times. The unknown parameters in each layer are the layer thickness, the P-wave velocity, the S-wave velocity, the density and the quality factor. Dynamic ray tracing is used to solve the forward problem. Multiple reflections are included, but wave-mode conversions are not considered. The S-wave velocities are estimated from the PP reflection and transmission coefficients. The inverse problem is solved using a stabilized least-squares procedure. The Gauss-Newton approximation to the Hessian matrix is used, and the derivatives of the dynamic ray-tracing equation are calculated analytically for each iteration. A conventional velocity analysis, the common mid-point (CMP) stack and a set of CMP gathers are used to identify the number of layers and to establish initial estimates for the P-wave velocities and the layer thicknesses. The inversion is carried out globally for all parameters simultaneously or by a stepwise approach where a smaller number of parameters is considered in each step. We discuss several practical problems related to inversion of real data. The performance of the algorithm is tested on one synthetic and two real data sets. For the real data inversion, we explained up to 90% of the energy in the data. However, the reliability of the parameter estimates must at this stage be considered as uncertain. 相似文献
15.
We introduce a processing technique which minimizes the 'stretching effects' of conventional NMO correction. Unlike conventional NMO, the technique implies constant normal moveout (CNMO) for a finite time interval of a seismic trace. The benefits of the proposed method include preservation of higher frequencies and reduction of spectral distortions at far offsets. The need for severe muting after the correction is reduced, allowing longer spreads for stack, velocity and AVO analysis. The proposed technique has been tested on model and real data. The method may improve the resolution of CMP stack and AVO attribute analysis. The only assumptions for this stretch-free NMO correction are (i) all time samples of a digital reflected wavelet at a particular offset have the same normal moveout, and (ii) reflection records have an interference nature. 相似文献
16.
随着地震勘探目标从构造型油气藏向岩性油气藏的转变，地震勘探难度日益增大，这就要求从地震数据中获得更多可靠且具有明确地质含义的属性信息，并充分利用这些属性信息来对储层的岩性、岩相进行分析.AVO三参数反演能够从振幅随炮检距的变化信息中直接提取纵波速度、横波速度以及密度来估计岩石和流体的性质，进而对储层进行预测.然而，AVO反演本身是一个不适定的问题，加上地震纵波反射系数对横波速度和密度的不敏感，会造成单纯利用纵波地震数据进行反演的结果误差大.随着地震接收和数据处理技术的发展，越来越多的学者对PP-PS联合反演方法进行了研究并在实际资料中得以运用.融合转换横波地震数据的联合反演在一定程度上提高了反演的精度，降低了解的不稳定性.但是在信噪比较低的情况下，联合反演的效果受到了限制.本文从优化理论出发，提出了基于粒子滤波提供先验知识的l1范数约束极小化问题的稀疏解算法.并将上述方法运用到了不同的模型中，通过比较分析，证实了该方法在不同信噪比资料中的有效性和在信噪比较低情况下的优势. 相似文献
17.
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
18.
Accurate well ties are essential to practical seismic lithological interpretation. As long as the geology in the vicinity of the reservoir is not unduly complex, the main factors controlling this accuracy are the processing of the seismic data and the construction of the seismic model from well logs. This case study illustrates how seismic data processing to a near-offset stack, quality control of logs and petrophysical modelling improved a well tie at an oil reservoir. We demonstrate the application of a predictive petrophysical model in the preparation and integration of the logs before building the seismic model and we quantify our improvements in well-tie accuracy. The data for the study consisted of seismic field data from a 3D sail line through a well in a North Sea oilfield and a suite of standard logs at the well. A swathe of fully processed 3D data through the well was available for comparison. The well tie in the shallow section from first-pass seismic data processing and a routinely edited sonic log was excellent. The tie in a deeper interval containing the reservoir was less satisfactory: the phase errors within the bandwidth of the seismic wavelet were of the order of 20°, which we consider too large for subsequent transformation of the data to seismic impedance. Reprocessing the seismic data and revision of the well-log model reduced these phase errors to less than 10° and improved the consistency of the deep and shallow well ties. The reprocessing included densely picked iterative velocity analysis, prestack migration, beam-forming multiple attenuation, stacking the near-offset traces and demigration and remigration of the near-offset data. The petrophysical model was used to monitor and, where necessary, replace the P-wave sonic log with predictions consistent with other logs and to correct the sonic log for mud-filtrate invasion in the hydrocarbon-bearing sand. This editing and correction of the P-wave transit times improved the normal-incidence well tie significantly. The recordings from a monopole source severely underestimated the S-wave transit times in soft shale formations, including the reservoir seal, where the S-wave velocity was lower than the P-wave velocity in the drilling mud. The petrophysical model predicted an S-wave log that matched the valid recordings and interpolated between them. The subsequent seismic modelling from the predicted S-wave log produced a class II AVO anomaly seen on the CDP gathers around the well. 相似文献