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1.
Lei Xing Huaishan Liu Xilai Zheng Xueqin Liu Jin Zhang Linfei Wang Zhihui Zou Yiming Xu 《中国海洋大学学报(英文版)》2016,15(5):815-824
Air guns are important sources for marine seismic exploration. Far-field wavelet of air gun arrays, as a necessary parameter for pre-stack processing and source models, plays an important role during marine seismic data processing and interpretation. When an air gun fires, it generates a series of air bubbles. Similar to onshore seismic exploration, the water forms a plastic fluid near the bubble; the farther the air gun is located from the measurement, the more steady and more accurately represented the wavelet will be. In practice, hydrophones should be placed more than 100 m from the air gun; however, traditional seismic cables cannot meet this requirement. On the other hand, vertical cables provide a viable solution to this problem. This study uses a vertical cable to receive wavelets from 38 air guns and data are collected offshore Southeast Qiong, where the water depth is over 1000 m. In this study, the wavelets measured using this technique coincide very well with the simulated wavelets and can therefore represent the real shape of the wavelets. This experiment fills a technology gap in China. 相似文献
2.
建立针对大容量气枪震源的气泡振荡方程及压力子波方程，引入多个对模拟结果具有重要影响的修正因子，包括基于开口的热力学模型、枪口节流作用、蒸发冷凝、枪体影响、气体释放率等来改善传统的单枪压力子波计算方法。利用模型及与水库实测的子波比对结果，分析各修正因素对子波模拟的影响，通过改进的单枪信号进一步计算大容量枪阵的压力子波。对比改进的模拟方法预测的子波波形与实测信号，结果显示，改进的模型比原有模型能更好地模拟单枪和枪阵的震源子波。最后，分析了模型产生模拟误差的原因。 相似文献
3.
为了对JCZ系列超宽频带地震仪采集到的地震数据进行有效去噪,探讨小波阈值法在不同地震数据中去噪的实际效果。首先介绍小波法的基本理论与去噪标准,探讨不同小波基的选取、不同分解、重建尺度与阈值的选取及处理方式对小波阈值法最终去噪效果产生的影响;使用控制变量法,选取武汉水院地震台的记录数据,探讨如何获得较好的去噪效果。为了比较小震和中强震两种情况下相同方法的处理效果,将选择好的小波基与几何尺度用于震例数据去噪发现,在实际地震去噪处理中基于样本数估计选取的阈值具有一定局限性,且相同阈值在不同震级的震例数据中具有不同的去噪结果。最后使用小波阈值对JCZ系列超宽频带地震仪采集到的地震数据进行去噪发现,小波阈值去噪对于P波初动的识别判断也具有一定意义。 相似文献
4.
利用小波多尺度分析方法对江苏沿海地区重力场进行波场分离,得到多阶小波细节信息。通过对不同阶次小波细节进行分析研究,获得不同深度凹陷及隆起的空间展布情况,并推断研究区内7条深大断裂的走向及倾向,发现以兴化-大丰一带为界,北部断裂大部分走向为NNE向,倾向NW,且坡度较陡;南部断裂大部分走向NEE向,倾向SE,且坡度较缓,这种南北差异可能是下扬子对冲构造格局的反映。结合地震资料分析认为,地震分布与NE向和NEE向、NW向、近EW向（活动）断裂关系密切,东海-赣榆西北部和大丰港沿海一带断裂的活动性较强,应力场相对不稳定,发生地震的风险较高。 相似文献
5.
《中国海洋湖沼学报》2017,(5)
Elastic waves in the seabed generated by low-frequency noise radiating from ships are known as ship seismic waves and can be used to detect and identify ships.To obtain the propagation characteristics of ship seismic waves,an algorithm for calculating seismic waves at the seafl oor is presented based on the staggered-grid fi nite diff erence method.The accuracy of the algorithm was tested by comparison with analytical solutions.Numerical simulation of seismic waves generated by a low-frequency point sound source in a typical shallow sea environment was carried out.Using various source frequencies and locations in the numerical simulation,we show that the seismic waves in the near fi eld are composed mostly of transmitted S-waves and interface waves while transmitted P-waves are weak near the seafl oor.However,in the far fi eld,the wave components of the seismic wave are mainly normal modes and interface waves,with the latter being relatively strong in the waveforms.As the source frequency decreases,the normal modes become smaller and the interface waves dominate the time series of the seismic waves. 相似文献
6.
基于多尺度球面小波分析云南地区应变特征 总被引：1，自引：0，他引：1
使用GAMIT/GLOBK软件处理2011~2016年云南地区GPS区域站观测数据，扣除同震影响、区域欧拉均匀旋转矢量后，得到该区域的GPS水平速度场，并采用多尺度球面小波模型获取分解尺度分别为6、7、8和9时的云南地区GPS应变场，然后结合云南地区历史MS5.0以上地震信息，以及小江、红河等区域断裂活动情况分析该区域应变场的空间分布特征。结果显示，在区域应变场整体解算中，利用球面小波方法能够适应测站点的疏密变化，多尺度估计地表应变场。主应变、面膨胀和剪应变等分析结果与区域历史地震信息及对应区域断裂活动性质具有较好的吻合性。从应变结果看，红河断裂可能是具有重要构造意义的活动断裂，应变特征显示云南区域被红河断裂划分为2个特征区域；云南地区的鲁甸、腾冲、普洱、大理区域可能是地震活动较为剧烈的区域；小江断裂带中的嵩明区域在不同应变特征中均表现出高度异常，后期应予重点关注。 相似文献
7.
在未来大地震发震构造已知的前提下，提出用经验公式确定大地震断层长度、宽度、地震矩和滑动分布等参数，并用随机有限断层方法预测未来大地震。用随机有限断层方法模拟2016-11-13新西兰MW7.8地震的12个基岩台站地震动时程和反应谱，并用模拟的频谱幅值与记录频谱幅值平均比值确定模拟误差。结果表明，在周期为0~10 s的范围内，模拟误差在0.92~1.08之间，不同频率模拟误差的标准差变化范围不超过1。95%的置信区间宽度随频率无明显变化，模拟结果反映了地震动记录的平均效果。用准随机方法重新获取新西兰大地震断层初始破裂点和位错滑动分布，模拟地震动并计算模拟误差随频率的变化，得到与最初模型相似的结论，从而进一步证实了本文提出的获取震源参数并用随机有限断层方法预测未来大地震的可靠性，且其特别适用于大地震远场模拟。 相似文献
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9.
The fourth-order B spline wavelet scaling functions are used to solve the two-dimensional unsteady diffusion equation. The calculations from a case history indicate that the method provides high accuracy and the computational efficiency is enhanced due to the small matrix derived from this method.The respective features of 3-spline wavelet scaling functions, 4-spline wavelet scaling functions and quasi-wavelet used to solve the two-dimensional unsteady diffusion equation are compared. The proposed method has potential applications in many fields including marine science. 相似文献
10.
瞬变电磁法应用于矿产资源、环境工程等领域。目前主流的瞬变电磁三维正演模拟方法包括积分方程法、有限差分法、有限体积法和有限元法。随着观测环境的复杂化以及探测精度要求的提高,有必要研究瞬变电磁法高精度三维模拟计算,以便推动数据处理解释方法的进步。本文系统介绍了瞬变电磁三维正演计算研究进展,分析了准静态差分方程的构建和发射源的加载及边界的处理等有限差分法的关键技术,厘定出空间和时间离散以及大型线性方程组的求解等有限元法的难题。瞬变电磁数值模拟今后的发展方向是深入开展近源情况下受场源效应、复杂地形、极化效应等影响的三维模拟,以及特殊场情况下的多源多分量响应计算,为瞬变电磁法精细探测提供理论支撑。 相似文献
11.
《世界地质(英文版)》2015,(4)
The study on seismic anisotropy is one of the difficult problems in the field of geophysics nowadays.As a method of ray theory,the seismic anisotropy ray tracing is an important means to study the anisotropic seismic wave propagation. The traditional ray tracing system formulated in terms of elastic parameters in the anisotropy is more complicated than that in the isotropic case. Considering the difficulty,a kind of ray tracing system formulated in terms of phase velocity and group velocity is introduced. The new method is similar to the expressions for isotropic media,and avoids the trouble of determining the eigenvalue vector at each time. Besides the ray tracing numerical simulation of different models of vertical transversely isotropic( VTI) medium is carried out,in order to verify the accuracy and applicability of the method and further study the characteristics of wave field propagation in different VTI mediums. The study is certainly valuable in reference for later processing of the anisotropic seismic data. 相似文献
12.
?????????????????????????ο??????????????????????????????????????????????????????????NGA?????????????????????????飬??????????????????????о?????????????????????????????????????????2012?????4.7??????????е?????????????????????????????????????PGA??????S??a??T???????б????о?????????????????????????????????????????????????????????????????????????????????????????????? 相似文献
13.
采用有限元方法模拟隧道地震波场,采用波场快照与时间记录相结合的方法,研究空洞对隧道地震波场传播的影响,并对含空洞模型的时间记录进行处理,得到数值模型的速度云图和反射层位图。经数据处理表明,采用TSPwin设定默认值处理得到的速度云图与模型设定的空洞位置比较一致,在提取反射层位图上,空洞反射层呈现条带状特征,需要结合速度云图来确定空洞位置,且P波预报的准确性相对较高。对TSP系统的抗噪性进行研究,表明其具有良好的抗噪性能。最后通过对工程实例的处理,验证了数值模拟所得的结论。 相似文献
14.
Acoustic-elastic coupled media is often encountered in most marine explorations, and accurate simulation of acoustic-elastic coupled media is of great significance. At present, the study of acoustic-elastic coupled media still assumes that the solid of the acoustic-elastic coupled media is isotropic, but this assumption is not in accordance with the actual situation. In this paper, we derive the solid media of acoustic-elastic coupled media from isotropic media to anisotropic media, and propose an acoustic-elastic coupled medium based ontransverse isotropic media with vertical symmetric axes(VTI) to improve the accuracy of forward modeling. Based on the relationship between the Thomsen parameter and the coefficient matrix of the anisotropic elastic wave equation, we transform the Thomson parameter into a velocity model with anisotropic properties. We use a staggered grid finite difference method to simulate the propagation of a wavefield in a three-dimensional acoustic-elastic coupled media. We obtain the snapshots of the wave field when the solid of the acoustic-elastic coupled media is an isotropic medium and a VTI media. When the solid of the acoustic-elastic coupled media is considered VTI media, we can observe the qP wave and qS wave that cannot be observed in the isotropic medium from the wave field snapshot. We can also find that the seismic records obtained by the method we use are more realistic. The algorithm proposed in this paper is of great significance for high-precision ocean numerical simulation. 相似文献
15.
基于20世纪80年代以来的跨断层短水准资料，利用“点-线-面”相结合的研究方法，全面分析甘肃地区1990~2016年8次5.5级以上地震的震前应变背景、断层活动和短期形变异常的时空演化特征。结果显示，多个地震震前不同层面上出现如下典型的异常特征：1）地震往往发生在垂直形变累积率的高值区或差异显著的高梯度带上，震前出现有序的形变场分布；2）震前不同断裂带之间或断裂带的不同段之间常存在显著的运动差异，发震断裂震前中短期运动速率显著增强，造成区域运动的不均衡；3）随着强震的逼近，显著异常场地在空间分布上明显向近震区迁移和集中，或近震源区的一些跨断层场地异常强度逐渐增大。地震震前典型异常的时、空、强演化特征说明，断层运动失稳前，近震区附近断层活动、应力应变场均有一定程度的显现，地震发生前断层活动存在不同往常的失稳波动现象，应力出现向近震源区传递的特征。 相似文献
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使用内蒙古地震台网2008-01~2017-12记录的数字地震波形观测资料,采用基于P波初动和振幅比联合求解（FOCMEC）方法计算震源机制,获得内蒙古东部地区发生的138个ML≥2.5地震的震源机制解。对震源机制解特征进行分析显示,研究区地震震源类型以走滑型为主,兼有一定比例的逆冲型,而正断型相对较少,P轴和T轴走向的优势方向分别为NEE-SWW向和NNW-SSE向。将研究区划分为1°×1°的网格,采用阻尼区域应力反演（MSATSI）方法获得研究区的应力张量和应力场图像。应力场反演结果显示,内蒙古东部地区应力状态主要表现为走滑,局部区域存在剪切、挤压,最大主应力方向主要分布在NEE-SWW向,由北向南顺时针旋转。 相似文献
17.
根据弹性理论的叠加原理，研究了有限元分析中的单元划分问题。通过有限元结点位移反演边界力系数与理论边界力系数进行比较来判别断裂区单元划分是否合理，应用模拟数据定量分析了二维和三维有限元法的单元划分，为有限元法在地学研究中的实际应用提供参考依据。 相似文献
18.
Magnetotelluric(MT)inversion and seismic inversion are important methods for the interpretation of subsurface exploration data,but separate inversion of MT and seismic produces ambiguous and non-unique results due to various factors.In order to achieve accurate results,the authors propose a joint inversion method of two-dimensional MT and seismic data in the frequency domain.The finite element method is used for numerical simulation of electromagnetic data in the forward modelling,and the Gauss-Newton method is used for the inversion.The 9-point-finite-difference method is used to solve the seismic wave field in the acoustic wave equation,and the inverse problem of seismic data is solved by full waveform inversion with a conjugate gradient,a simple and fast method.Cross gradient functions are used to provide constraint structure between resistivity and velocity parameters to carry out the joint inversion.The joint inversion algorithm is tested by double-rectangular model synthesis data,and the accuracy of the algorithm is verified.The results show that the joint inversion results are better than those from separate inversion.The algorithm is applied to a geophysical model of a metalliferous deposit in Jinchuan and is compared with the separate inversion results.It shows that the results obtained with joint inversion are much closer to the real model. 相似文献
19.
]?????????????????????????????????????С???任????????????????????????????С???????????????????????????????С???任??????????????????HaarС????db4С????db6С????sym6С?????????С?????????????????????FIR????????????????б??,?????????С??????????????????????????FIR??????????????????????????db???С????????????????????????????????????????????????????????db???С??????????????sym8С???? 相似文献
20.
庙西南凸起蓬莱A构造区馆陶组有良好油气发现,但储层厚度多小于5 m,难以被精确识别刻画。以薄层砂体为研究对象,综合地震、测井、钻井岩心、古生物等基础资料,明确研究区馆陶组沉积时期受北东向物源供给沉积,发育河流-浅水三角洲相。基于90°相位化处理确定砂体地震响应特征;分频解释处理判断相对等时地震同相轴,构建馆陶组高频层序地层格架（三级层序SQ1-3）,优选60Hz地震数据体进行地层切片划分;地层切片高精度沉积学解释揭示研究区馆陶组SQ1层序至SQ3层序依次发育河流-席状化浅水三角洲-朵叶状浅水三角洲-水下河道型浅水三角洲。其中SQ1层序中河道砂体以及SQ2-3层序中浅水三角洲前缘砂体皆为有利储层。此次研究丰富发展了渤海海域河流-浅水三角洲相中地震沉积学在砂体预测中的研究成果。 相似文献