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401.
首先概述了数字地震波形分析的重要性及该领域一些主要波形分析软件的概况,然后介绍了《数字地震波形分析-WAVE Version 2005》软件的设计目标、研制思路、系统特点、框架结构、操作界面、技术特点、方法功能等;最后给出了一个应用的实例. 相似文献
402.
403.
Offset-dependent characteristics of seismic scattering are useful for characterizing fractured reservoirs. We use two models that have different background medium properties and different azimuthal AVO responses to study elastic wave propagation and scattering in gas-saturated, heterogeneously fractured reservoirs. Heterogeneous fracture density distributions are built through stochastic modelling. Synthetic seismograms are generated by 3-D finite difference modelling, and waveforms along crack-normal and strike directions are considered in this paper. The multiple signal classification (MUSIC) frequency estimator is used in waveform estimation to provide frequency-domain attributes related to seismic wave scattering by fracture heterogeneity. Our results indicate that the strength of the scattering field is a function of the background medium. The strength also increases with increasing fracture scatterer density and with decreasing correlation length of spatial variations of fracture density. The scattering field is weak at the top of the fractured reservoir. The first-order results are dominated by velocity anisotropy of the mean fracture density field. However, the base of the fractured reservoir corresponds to a strong scattering field on which fracture heterogeneity has a larger effect and is characterized by the loss of coherence. 相似文献
404.
?????????????С??????????????????????????????????????????????????????????λ????????λ????????????????????????????????????????????????,????200 km???????????????????????????????? 相似文献
405.
Full waveform inversion using oriented time‐domain imaging method for vertical transverse isotropic media 下载免费PDF全文
Full waveform inversion for reflection events is limited by its linearised update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate, the resulting gradient can have an inaccurate update direction leading the inversion to converge what we refer to as local minima of the objective function. In our approach, we consider mild lateral variation in the model and, thus, use a gradient given by the oriented time‐domain imaging method. Specifically, we apply the oriented time‐domain imaging on the data residual to obtain the geometrical features of the velocity perturbation. After updating the model in the time domain, we convert the perturbation from the time domain to depth using the average velocity. Considering density is constant, we can expand the conventional 1D impedance inversion method to two‐dimensional or three‐dimensional velocity inversion within the process of full waveform inversion. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearised representations of the reflection response. To eliminate the crosstalk artifacts between different parameters, we utilise what we consider being an optimal parametrisation for this step. To do so, we extend the prestack time‐domain migration image in incident angle dimension to incorporate angular dependence needed by the multiparameter inversion. For simple models, this approach provides an efficient and stable way to do full waveform inversion or modified seismic inversion and makes the anisotropic inversion more practicable. The proposed method still needs kinematically accurate initial models since it only recovers the high‐wavenumber part as conventional full waveform inversion method does. Results on synthetic data of isotropic and anisotropic cases illustrate the benefits and limitations of this method. 相似文献
406.
407.
针对目前阵列声波测井信号的信息提取主要集中在纵波、横波、斯通利波等组分波的速度、衰减的处理分析上, 对频率特征的分析还缺少足够的重视的不足, 引入了Hilbert-Huang变换(HHT) 时频分析方法及瞬时频率的概念, 给出了阵列声波信号的经验模态分解及其时频分布, 并对实际阵列声波的波形信号进行了HHT时频处理与剖析.把这种方法用于区分和识别岩石构造破碎带取得了理想的效果.从阵列声波测井信号处理和构造异常的地球物理意义两方面表明, IMF序列能更好反映原始数据固有的物理特性, 所使用的EMD分解是有效和易行的, 为HHT分析在阵列声波测井信号处理中的应用, 进行了有益的探索. 相似文献
408.
利用辽宁区域地震台网记录分析"重复地震" 总被引:10,自引:3,他引:7
将Schaff和Richards所选的通过远震波形相关得到的分布在辽宁地区的23对ldquo;重复地震rdquo;,利用辽宁区域地震台网记录的波形资料进行相关计算,得到辽宁区域台网波形相关意义上的ldquo;重复地震rdquo;,并与Schaff和Richards的结果进行了对比分析. 利用辽宁区域台网得到的ldquo;重复地震rdquo;对辽宁区域地震台网的震相拾取和地震定位进行了评估. 结果表明,远震波形相关意义上的ldquo;重复地震rdquo;与区域台网波形相关意义上的ldquo;重复地震rdquo;有一定差别,它们只有部分交集. 但是,从总体上评估辽宁区域台网的定位能力和震相拾取误差,用两种方法得到的ldquo;重复地震rdquo;所给出的评估结果无实质差别——尽管用区域台网得到的ldquo;重复地震rdquo;似乎效果更好. 基于ldquo;重复地震rdquo;之间在理论上距离应小于1 km的工作假定,可以得到辽宁区域台网地震目录中的定位误差在5 km之内,平均为2 km;Pg震相的拾取误差94%在plusmn;1 s之间,Sg震相的拾取误差88%在plusmn;1 s之间. 相似文献
409.
Improving the wind and wave estimation of dual-frequency altimeter JASON1 in Typhoon Shanshan and considering the rain effects 总被引:2,自引:1,他引:1
Altimetry data have been widely used in various fiehts of oceanography, including the extreme weather events such as tropical cyclones, typhoons, and hurricanes. The performance of JASON1 in Typhoon Shanshan is assessed by examining the sensor geophysical data record and illustrates how the measured return waveform, significant wave height, and backscatter are all affected by various factors associated with the typhoon, with details by the rain are illustrated. The correction method to maintain accurate wave height and wind speed measurements in Typhoon Shanshan and the results are presented. Furthermore, the additional results of rain rate and typhoon eye diameter can be retrieved. Because of the lack of in-situ measurements of wind, wave, and rain rate at Typhoon Shanshan, results are compared with the forecasted typhoon data and a good agreement is found. 相似文献
410.