【作者】 杨其强；

【导师】 冯恩民； 张叔伦；

【作者基本信息】 大连理工大学 ， 运筹学与控制论， 2009， 博士

【摘要】 本论文围绕三维合成震源记录交互剩余偏移速度分析课题开展研究并进行了拓展.内容包括地震波数值模拟,以提高计算效率为目的的合成震源记录叠前深度偏移算法和叠后偏移算法,以及利用控制照明的交互剩余偏移速度分析.地震数值模拟是在假定地下介质结构模型和相应物理参数己知的情况下,模拟研究地震波在地下各种介质中的传播规律,并计算在地面或地下各观测点所应观测到的数值地震记录中的一种地震模拟方法,它在地震勘探和天然地震领域中具有广泛的运用.在地震数据处理中,地震数值模拟计算出来的记录数据可以检验各种反演方法的正确性.波场数值模拟技术的发展主要体现在两个方面,即模拟精度和运算速度.傅里叶变换方法正演模拟由于具有较高的计算效率和精度而被广泛运用在地震波数值模拟中.本文对利用傅里叶变换的地震波数值模拟进行了改进和推广,并提出用哈特莱变换取代傅里叶变换的方法,以便利用当前的计算机资源有效快速地模拟地震波传播;尽管如此,用数值模拟方法提供三维合成数据以验证一些地震处理方法(如本文中的三维剩余偏移速度分析方法)仍因计算量庞大、计算时间长而有困难,为此,我们提出了合成震源正演模拟和线形震源正演模拟,合成震源正演模拟可以有效地提供合成震源记录以验证一些涉及合成震源记录相关的地震处理方法,而且不需要耗时较长的合成过程,利用线形震源正演模拟可以将合成数据用于需要利用控制照明的地震处理方法中.由于哈特莱变换具有比傅里叶变换效率高的特点,我们还把它引进到零炮检距正演模拟和偏移中.波动方程叠前深度偏移具有成像精确的特点,但速度较慢影响了其应用,特别是三维偏移.合成震源记录叠前深度偏移基于面炮合成技术减少了需要偏移的地震记录,提高了计算效率.在此基础上,我们利用大步长深度延拓和相位移波场插值,并与稀疏频率方法组合使用,大大减少了计算量,对二维盐丘模型、二维Marmousi模型、二维实际资料和三维盐丘模型试算表明,此方法计算时间可缩减一半以上而不影响成像质量.基于合成震源记录偏移的三维剩余偏移速度分析方法,建立在共成像点道集拉平的剩余曲率分析思想之上,并引进了控制照明技术.该方法使用大步长延拓与稀疏频率方法结合的合成震源记录叠前深度偏移方法,成像精确且具有较高的效率.偏移后可以从结果中直接抽取共成像点道集进行剩余曲率分析.每次迭代可对所有层位进行校正而不需要层剥离过程,这样可以减少迭代次数从而提高效率.控制照明技术的利用消除了平面波在非均匀介质中传播而发生的畸变,保证了剩余速度校正公式的平面波假设条件.三维合成数据和陆上实际资料的试算验证了该方法的有效性和实用性.并基于Qt编程技术和东方地球物理石油勘探公司开发的底层库编制了偏移速度分析软件包.更多还原

【Abstract】 In this paper,a 3-D residual migration velocity analysis based on the synthesized source -record prestack depth migration is studied.We also extend the study to some other related topics including seismic numerical forward modeling and seismic data migration.Seismic numerical modeling,based on the assumption that the structure and parameters of the subsurface media are known,simulate the wavefield and calculate the numerical seismic record that should be observerd,is applied extensively in seismic exploration and earthquake seismology.In the process of seismic data,seismic numerical modeling can be used to test some inverse methods.The accuracy and the efficiency are the two issues to develop for the wavefied modeling. The Fourier transform method is used widespread for its high efficiency and accuracy.In the paper,the method is discussed and developed.Further,the Fourier transform method is replaced by the Hartley transform method in many cases.Theses schemes are to utilize current computer facilities to provide seismic data efficiently for testing purposes.However, to provide 3-D data for testing some seismic processing methods such as the 3-D residual migration velocity analysis is still time consuming.To overcome the obstacle,we present modeling with synthesized areal sources and linear sources.The data from modeling of the synthesized areal sources can be used to test some methods that deal with the synthesized area record without the synthesis,while the data from modeling of the linear source can be used to test some schemes in which the controlled illumination is necessary.Since the Hartley transform has advantages over the Fourier transform,we also bring the method into zero-offset forward modeling and migration.The prestack depth migration methods based on the wave equation are accurate. However,they are restricted by the low efficiency,especially for the 3-D cases.In the areal shot-record migration,the extrapolations need not be done for all the individual shot records,but for the areal shot record only.We use a large step to extrapolate the wavefields in the migration,and use the method in the limited-frequencies method to further improve the migration efficiencies.The numerical examples on the Marmousi model,filed data and 3-D SEG model demonstrate the method is feasible and efficient. The 3-D residual migration velocity analysis method based on the synthesized areal shot-record prestack depth migration is established on the idea of residual curvature.And the controlled illumination technique is brought in.The migration method adopted is the above mentioned efficient methods.After the migration,the common image gathers can be extracted directly.The utilization of the controlled illumination avoids the wave distortion during the propagation in the inhomogeneous media and make the hypothesis of the correction formula hold.With Qt programming technique and the lower libraries developed by Dongfang Geophysical Petroleum Exploration Corporation,we develpe a software package.更多还原