共查询到20条相似文献，搜索用时 312 毫秒
1.
Static correction is a common step in a seismic data proccessing flowchart for land data. Here we propose a new algorithm for automatic short‐period static correction. The algorithm is based on the assumption that seismic events after short‐period static correction should be locally plane nearly everywhere. No other assumptions are made. Therefore the proposed method does not require a preliminary velocity analysis. The algorithm consists in two main parts: evaluation of second spatial differences of trajectories and subsequent regularized integration of these differences. The proposed method proves its robustness and shows results comparable with conventional residual static correction based on improving common‐midpoint stacking. In contrast to the conventional residual static, the proposed algorithm can estimate short‐period statics in complex cases where common‐midpoint stacking fails because of non‐hyperbolic events. 相似文献
2.
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.
静校正问题是地震勘探的关键问题，直接影响地震勘探精度和准确性.实际地震采集过程中，当在相同接收点位置上不同时间内插拔布设了不同的检波器时，对于目前基于地表一致性理论假设的基准面静校正和剩余静校正，以及非地表一致性剩余静校正都不具备适用条件.为解决这一问题，本文提出了基于共姿态道集的静校正方法，将相同接收点位置上不同时间布设的检波点所接收的地震数据抽成不同的共姿态道集，在共姿态道集内实施地表一致性静校正；当某接收点位置上具有若干个共姿态道集时，该接收点位置上可能会存在多个检波点静校量；炮点静校问题仍然采用地表一致性静校正方法解决.该方法解决了同一接收点位置上不同共姿态道集之间的非地表一致性静校正问题，同时也解决了全区的检波点和炮点的地表一致性静校正问题，在实际数据应用效果明显. 相似文献
5.
我国北方地区黄土塬覆盖区的静校正问题是地震数据处理中的难点问题之一.黄土塬表层覆盖巨厚黄土，高差起伏较大，地震静校正问题严重；而且黄土塬覆盖区的潜水面普遍较深，常规折射静校正方法无法取得令人满意的处理效果.本文针对黄土塬覆盖区的静校正难题，研究层析反演静校正方法在黄土塬地区的适用性和可靠性.层析反演静校正利用地震波初至走时数据、通过迭代反演的方法构建速度模型，进而依据所得的近地表速度模型对地震数据进行静校正处理.本文的迭代反演采用同步迭代重构算法（SIRT），并且对同步迭代重构算法进行了改进，使得层析反演的迭代过程趋于稳定.但是，因为黄土塬覆盖区地表高程的横向变化剧烈，相邻检波点的高差及其静校正量有时差异很大，在运用层析静校正求取长波长静校正量的同时，还需采用初至波剩余静校正方法求取短波长静校正量.实例证明，综合应用依据初至波走时数据的层析静校正和剩余静校正方法，同时计算长波长和短波长的静校正量，能够有效地解决黄土塬覆盖区实际地震资料的静校正问题. 相似文献
6.
It has been shown on an ‘ideal’ synthetic dataset that PP/PS‐stereotomography can estimate an accurate velocity model without any pairing of PP‐ and PS‐events. The P‐wave velocity model is first estimated using PP data and then, fixing this velocity field, the S‐wave velocity is estimated using the PS data. This method needed to be evaluated further and we present here the first application of PP/PS‐stereotomography to a real dataset: the 2D East‐West Mahogany OBC line (Gulf of Mexico). We are here confronted with data which do not fit our working assumptions: coherent noise (due to an approximate separation of PP‐ and PS‐events and some remaining multiples), probably some anisotropy and 3D effects. With a careful selection of the stereotomographic picks, which allows one to decrease the effect of the picked coherent noise by the automatic picker, our application can demonstrate the relevance of our approach in the upper part of the profile, where anisotropy and 3D effects might be low. We can thus estimate, without any pairing of PP‐ and PS‐events, a velocity field which provides not only flat common image gathers, but also PP‐ and PS‐depth migrated images located at the same positions. For the deeper part of the profile, a significant shift in depth appears. In addition to possible anisotropy, 3D effects and a more complex velocity field (‘salt body’), this is due to the quality of the PZ‐ and X‐components profiles: The PZ‐component profile where the PP‐stereotomographic picking is performed, is polluted by conflicting converted or multiple events and the X‐component profile, where the PS‐stereotomographic picking is performed, is highly noisy. This study emphasizes the need to develop accurate selection criteria for the stereotomographic picks. 相似文献
7.
Shear‐wave statics in marine seismic exploration data are routinely too large to be estimated using conventional techniques. Near‐surface unconsolidated sediments are often characterized by low values of Vs and steep velocity gradients. Minor variations in sediment properties at these depths correspond to variations in the shear‐wave velocity and will produce significant static shifts. It is suggested that a significant proportion of the shear‐wave statics solution can be estimated by performing a separate high‐resolution survey to target near‐surface unconsolidated sediments. Love‐wave, shear‐wave refraction and geotechnical measurements were individually used to form high‐resolution near‐surface shear‐wave velocity models to estimate the shear‐wave statics for a designated survey line. Comparisons with predicted statics revealed that shear‐wave statics could not be estimated using a velocity model predicted by substituting geotechnical measurements into empirical relationships. Empirical relationships represent a vast simplification of the factors that control Vs and are therefore not sufficiently sensitive to estimate shear‐wave statics. Refraction measurements are potentially sensitive to short‐wavelength variations in sediment properties when combined with accurate navigational data. Statics estimated from Love‐wave data are less sensitive, and sometimes smoothed in appearance, since interpreted velocity values represent an average both laterally and vertically over the receiver array and the frequency–depth sensitivity range, respectively. For the survey site, statics estimated from near‐surface irregularities using shear‐wave refraction measurements represent almost half the total statics solution. More often, this proportion will be greater when bedrock relief is less. 相似文献
8.
低信噪比转换波地震资料静校正(英文) 总被引：1，自引：0，他引：1
Converted waves have slow velocity and low signal-to-noise ratio. It is also difficult to pick first-breaks and bin the common-conversion-points （CCP）. Some statics methods, which work well for P-wave data, can＇t be effectively used for solving convertedwave statics problems. This has become the main obstacle to breakthroughs in convertedwave data processing. To improve converted-wave static corrections, first, a statics method based on the common-receiver-point （CRP） stack is used for the initial receiver static correction to enhance the coherency of the CRP stack. Second, a stack-power-maximization static correction which improves the continuity of the CCP stack is used for detailed receiver statics. Finally, a non-surface-consistent residual moveout correction of the CCP gathers is used to enhance the stack power of reflection signals from different depths. Converted-wave statics are solved by the joint use of the three correction methods. 相似文献
9.
由于地表起伏和近地表结构变化产生的静校正问题严重影响了煤田地震资料的成像质量.为此,首先利用低速带分片拟合的广义线性反演技术进行折射波静校正,解决长波长静校正问题和部分短波长静校正问题,然后,利用叠加能量最大静校正技术进一步解决剩余静校正问题,最后,利用非地表一致性剩余时差校正技术,解决速度和射线等误差引起的非地表一致性剩余时差问题.实验结果表明,在以串连的方式应用了三种校正方法之后,在共炮点道集上,折射渡同相轴的线性形态得到了恢复;在动校正后的共中心点道集上,煤层反射的双曲线同相轴被拉平;在叠加剖面上,煤层反射的信噪比得到了改善. 相似文献
10.
In the case of onshore data sets, the acquired reflection events can be strongly impaired due to rough top‐surface topography and inhomogeneities in the uppermost low‐velocity layer, the so‐called weathering layer. Without accounting for these influences, the poor data quality will make data processing very difficult. Usually, the correction for the top‐surface topography is not perfect. The residuals from this correction and the influence of the weathering layers lead to small distortions along the reflection events. We integrated a residual static correction method into our data‐driven common‐reflection‐surface‐stack‐based imaging workflow to further eliminate such distortions. The moveout‐corrected traces and the stacked pilot trace are cross‐correlated to determine a final estimate of the surface‐consistent residual statics in an iterative manner. As the handling of top‐surface topography within the common‐reflection‐surface stack is discussed in a separate paper in this special issue, the corresponding residual static correction will be explained in more detail. For this purpose, the results obtained with a data set from the Arabian Peninsula will be presented. 相似文献
11.
《中国科学D辑(英文版)》2008,(Z2)
Three-component seismic exploration through P-wave source and three-component geophone is an effective technique used in complicated reservoir exploration. In three-component seismic exploration data processing,one of the difficulties is static correction of converted wave. This paper analyzes propagation characteristics of non-converted and converted refracted waves,and discovers a favor-able condition for the formation of converted refracted wave,i.e. the velocity of overlaying medium S wave is much lower than that of underlying medium S wave. In addition,the paper proposes the static correction method of converted wave based on PPS converted refracted wave,and processes the real three-component seismic data with better results of static correction of converted wave. 相似文献
12.
Static shifts from near‐surface inhomogeneities very often represent the key problem in the processing of seismic data from arid regions. In this case study, the deep bottom fill of a wadi strongly degrades the image quality of a 2D seismic data set. The resulting static and dynamic problems are solved by both conventional and common‐reflection‐surface (CRS) processing. A straightforward approach derives conventional refraction statics from picked first breaks and then goes through several iterations of manual velocity picking and residual statics calculation. The surface‐induced static and dynamic inhomogeneities, however, are not completely solved by these conventional methods. In CRS processing, the local adaptation of the CRS stacking parameters results in very detailed dynamic corrections. They resolve the local inhomogeneities that were not detected by manual picking of stacking velocities and largely compensate for the surface‐induced deterioration in the stack. The subsequent CRS residual statics calculations benefit greatly from the large CRS stacking fold which increases the numbers of estimates for single static shifts. This improves the surface‐consistent averaging of static shifts and the convergence of the static solution which removes the remaining static shifts in the 2D seismic data. The large CRS stacking fold also increases the signal‐to‐noise ratio in the final CRS stack. 相似文献
13.
估计转换波的静校正量是一个复杂的非线性问题,常规的线性静校正方法无法取得好的效果.粒子群算法是一种很好的非线性全局最优化方法,但其缺点是"早熟"现象严重.最大能量法是一种常规求取静校正量的方法,局部寻优能力强且收敛速度快是其优点,但是当地震记录含有大的静校正量时易收敛于局部极值.本文在标准粒子群算法的基础上发展出了一种改进的粒子群算法:团体粒子群算法.并且通过对Rastrigin函数的寻优实验证明了其全局寻优能力优于标准粒子群算法.同时为了解决转换波静校正问题串行融合了团体粒子群算法和最大能量法.最后,建立了含一个水平反射层的模型并合成地震记录,加入随机值作为检波点静校正量.对合成的地震数据分别利用团体粒子群和最大能量的串行融合算法、标准粒子群算法和最大能量法求取静校正量并进行静校正.结果证明串行融合算法得到的静校正量与理论值误差很小,静校正后的叠加剖面连续性较好. 相似文献
14.
如何正确地消除复杂地表对地震波场的影响，提高地下构造成像的质量一直是中国西部复杂地区地震勘探中存在的难题.本文在三维复杂表层速度模型层析反演\[1\]的基础上，研究了关于复杂地表的静校正问题，提出用三维波动方程在炮集上对地震波场进行正、反向延拓，消除复杂地表对波场的影响，实现三维复杂表层模型校正.理论和实际应用证明，该方法已超越常规静校正的含义，属时变校正方法.用本方法处理复杂地表问题，不但能消除表层对不同深度反射波产生的不同时差影响，提高叠加剖面质量，而且能使校正后的地震波场保持波动特征不发生畸变，可为建立正确的深层速度模型和波动方程叠前深度偏移奠定良好的基础. 相似文献
15.
The widespread use of common depth point techniques has emphasized the need for accurate static corrections. Manual interpretation methods can give excellent results, but a computer technique is desirable because of the great volumn of data recorded in common depth point shooting. The redundancy inherent in common depth point data may be used to compute a statistical estimate of the static corrections. The corrections are assumed to be time-invarient, surface-consistent, and independent of frequency. Surface consistency implies that all traces from a particular shot will receive the same shot static correction and all traces from a particular receiver position will receive the same receiver correction. Time shifts are computed for all input traces using crosscorrelation functions between common depth point traces. The time shift for each trace is composed of a shot static, a receiver static, residual normal moveout if present, and noise. Estimates of the shot and receiver static corrections are obtained by averaging different sets of the measured time shifts. Time shifts which are greatly in error are detected and removed from the computations. The method is useful for data which has a moderate to good signal to noise ratio. Residual normal moveout should be corrected before estimating the statics. The program estimates the statics for correctly stacking common depth point traces but it is not sensitive to constant or very slowly changing static errors. 相似文献
16.
川东北复杂山地由于地表高程变化大、风化层厚度不均匀、低降速带速度横向变化大、高速层底界不稳定等因素,得到的地震资料具有严重的静校正问题,因此,如何解决山地静校正问题是后续地震资料处理的关键之一,本文首先分析高程静校正、折射静校正、层析静校正的基本原理和适用条件,结合实际复杂山地三维地震资料的特点,进行试验对比,提出了进行山地静校正的基本思路,即：首先进行高程静校正,这样可以利用高程静校正更容易拾取初至时间,然后利用折射静校正结合微测井等资料建立近地表速度-深度模型,以此速度-深度模型作为层析静校正的初始模型进行迭代处理,最后得到最终的近地表速度-深度模型和静校正值.根据以上处理流程,我们建立了适合于川东北山地三维复杂地表地震资料的静校处理正方法,并在实际生产过程中取得了良好的效果. 相似文献
17.
估算剩余静校正量可看作是以激发点及接收点剩余静校正量为模型参数的、以叠加能量为目标函数的全局最优值的搜索问题．当地震记录的剩余静校正量大而信噪比较低时，应用相关统计法不能有效地拾取静校正量．本文分别采用了ＣＭＰ道集内道间互相关法、图像边缘提取的Ｌａｐｌａｃｉａｎ算法及ＤＦＰ算法，三种不同算法联合迭代反演可求取最佳的模型参数，使目标函数值达到或接近于全局最优．理论试算及实际资料处理效果表明，这种方法能够解决低信噪比及大静校正量造成的周期跳跃等静校正问题． 相似文献
18.
We apply interferometric theory to solve a three‐dimensional seismic residual statics problem to improve reflection imaging. The approach calculates the static solutions without picking the first arrivals from the shot or receiver gathers. The static correction accuracy can be significantly improved by utilising stacked virtual refraction gathers in the calculations. Shots and receivers may be placed at any position in a three‐dimensional seismic land survey. Therefore, it is difficult to determine stationary shots and receivers to form the virtual refraction traces that have identical arrival times, as in a two‐dimensional scenario. To overcome this problem, we use a three‐dimensional super‐virtual interferometry method for residual static calculations. The virtual refraction for a stationary shot/receiver pair is obtained via an integral along the receiver/shot lines, which does not require knowledge of the stationary locations. We pick the maximum energy times on the interferometric stacks and solve a set of linear equations to derive reliable residual static solutions. We further apply the approach to both synthetic and real data. 相似文献
19.
In 2005, a multicomponent ocean bottom node data set was collected by BP and BHP Billiton in the Atlantis field in the Gulf of Mexico. Our results are based on data from a few sparse nodes with millions of shots that were analysed as common receiver azimuthal gathers. A first‐order look at P‐wave arrivals on a common receiver gather at a constant offset reveals variation of P‐wave arrival time as a function of azimuth indicating the presence of azimuthal anisotropy at the top few layers. This prompted us to investigate shear arrivals on the horizontal component data. After preliminary processing, including a static correction, the data were optimally rotated to radial (R) and transverse (T) components. The R component shows azimuthal variation of traveltime indicating variation of velocity with azimuth; the corresponding T component shows azimuthal variation of amplitude and phase (polarity reversal). The observed shear‐wave (S‐wave) splitting, previously observed azimuthal P‐wave velocity variation and azimuthal P‐wave amplitude variation, all indicate the occurrence of anisotropy in the shallow (just below the seafloor) subsea sediment in the area. From the radial component azimuthal gather, we analysed the PP‐ and PS‐wave amplitude variation for the first few layers and determined corresponding anisotropy parameter and VP/VS values. Since fracture at this depth is not likely to occur, we attribute the observed azimuthal anisotropy to the presence of microcracks and grain boundary orientation due to stress. The evidence of anisotropy is ubiquitous in this data set and thus it argues strongly in favour of considering anisotropy in depth imaging for obtaining realistic subsurface images, at the least. 相似文献
20.
三维复杂地形近地表速度估算及地震层析静校正 总被引：18，自引：6，他引：18
在地表一致性模型的基础上提出一种可适用于宽线剖面、弯曲测线、传统的二维和目前广泛使用的三维地震观测.在地形及近地表低降速带地质结构复杂的探区，低降速带厚度及速度估算的精度是静校正处理的关键.本研究根据三维地震观测的初至走时数据，利用最小平方与QR分解相结合的算法，在三维空间重建近地表低降速带速度模型，根据重建速度模型实现了静校正长波长分量与短波长分量的同步计算.分析了复杂的近地表低降速带模型初至波的性质，在观测值的自动拾取以及理论值的计算中充分考虑了可能成为初至波的直达波、折射波和反射波的利用，提高了低降速带速度模型反演的精度.在初至走时观测数据的拾取中，本研究采用分形算法克服了初至波波形差异以及折射波相位反转导致的拾取误差，实现了三维初至拾取的大规模全自动化运算.在射线路径与初至波理论走时的计算中，本研究采用一种计算量与模型复杂程度无关的三维射线追踪方法，该方法以最小走时射线路径保证了与观测数据有同等意义的初至波的射线追踪及理论走时的计算.野外实际资料的处理结果表明了方法的有效性. 相似文献