【作者】 顾元；

【导师】 朱培民；

【作者基本信息】 中国地质大学 ， 地球探测与信息技术， 2013， 博士

【摘要】 当使用传统地震勘探方法进行构造和沉积地层学研究时,由于使用的地震波主频低,影响地震波传播的主要因素为较大规模的地质构造和沉积不整合面,如向(背)斜、断层、沉积相等。但由于岩石圈中岩石的成分、密度、相态、缝洞中流体的组成、温度和压力等的不均匀性,必然引起介质弹性参数的变化,如弹性模量、速度、泊松比、吸收特性等,因而岩石物性参数在空间分布上必然是非均匀的。由于非均质体的尺度远小于地震波波长的尺度,对地震观测记录影响较小,且仅为少量的不相干的散射波,因而在常规地震数据处理与解释中将其视为干扰而予以消除或忽略。在地震反演中,地下介质也常常被简化为由一系列均匀层状介质所构成的模型,没有考虑散射波的影响。但是,随着高分辨率、宽频带地震信号的应用,地震波波长与介质非均匀性的尺度越来越接近。当地震波波长接近于局部异常体的尺度时,这些小尺度异常对于地震波场的影响就更加明显,地震记录上显现出大量的地震散射特征。这些散射波不同程度地影响了地震处理与解释的准确性。一方面,只有深入研究地下非均匀介质的模型和相应的波场传播理论才能找到减小散射波影响的方法。另一方面,处理或忽略掉这种非均匀介质造成的地震波场,等于放弃了一些有潜在价值的地下介质的(沉积模式、沉积微相、岩性变化等)信息来源。因此,研究和利用这些地震波散射特性,探索出一种地下介质小尺度非均匀性探测的方法是完全有必要的。本文的工作就是这些研究和探索努力的一部分。本论文针对复杂随机介质的描述及建模,和实际介质的非均质特性估计两方面的问题,开展了研究工作,主要工作内容及成果为：1)随机介质的数学描述和建模方法。本研究建立了三维非平稳随机介质自相关函数的表达式,提出了丛于随机过程理论的三维非平稳随机介质的建模方法,可构建更为复杂的三维随机介质模型。2)算法的并行化处理。山于非平稳随机介质建模算法耗费的计算资源较大,计算时间较长,本研究对三维非平稳随机介质建模算法进行了并行化。算法测试表明,并行化建模算法的计算效率得到了大幅的提高。3)叠后地震数据的随机介质参数估计。本研究提出了一种丛于非平稳随机介质理论,从二维叠后地震数据中估计随机介质参数的算法。该算法可估计山随机介质参数的空间分布特征,包括自相关长度a、b和自相关角度θ。理论模型的估计试验说明了算法是正确可行的,并已将其推广到了三维平稳随机介质参数的估计中。4)实际地震数据的随机介质参数估计试验。本研究以大港油田歧口凹陷中较好反映东一下亚段三角洲沉积相的典型二维地震剖面为例,以非平稳随机介质理论为指导对剖面进行了随机介质参数估计试验,依据随机介质参数估计结果对剖面中的三角洲沉积相进行了沉积微相的划分。试验表明,随机介质参数可作为地震属性用于地震资料的解释,为研究实际介质的非均质特性、地震相和沉积相的划分提供一种非常有效的手段,反映了该算法拥有较好的应用前景。本论文主要分五章。第一章,介绍本论文的研究背景、目的、意义和国内外研究现状,以及论文的主要研究内容、主要成果和创新点；第二章,简要介绍了随机介质的基本概念,以及不同类型、不同参数所对应的随机介质的特征：第三章,主要讨论三维平稳与维非平稳随机介质模型的描述方法与建模算法,以及建模算法的并行化处理方案：在第四章中给出了二维非平稳随机介质参数估计算法,并描述了理论数据和实际地震数据的随机介质参数估计试验结果,还讨论了三维平稳随机介质的参数估计算法,以及理论数据的随机介质参数估计试验等：最后一章为第五章,总结了论文的主要工作及结论,提出了论文研究中存在的问题以及今后的研究思路。本论文的创新之处主要表现在两个方面：(1)对三维平稳随机介质建模算法的改进,使其能够构建具有不同角度特征的三维在稳随机介质,并且提出了三维非平稳随机介质建模算法,实现了随机介质参数在三维空间连续变化的三维随机介质建模。因此,相比于前人提出的建模算法,可以构建更为复杂的三维模型,在理论研究方面具有创新性;(2)提出的二维非平稳随机介质的估计算法与前人提出的参数估计算法相比,不仅增加了自相关角度θ参数的估计,且可以对非平稳随机介质的各个参数进行估计：还将二维非平稳随机介质的估计算法推广到了三维情形,可用于估计三维随机介质的从本参数;这些随机介质参数估计算法,对实际地震数据的沉积微相分析和地震相控制的地震波阻抗反演具有重要价值,在应用上具有创新性。更多还原

【Abstract】 In traditional seismic exploration, due to the low dominant frequency of seismic records, the seismic profiles mainly reflect the large-scale tectonic structure and depositional unconformity surface, such as syncline, anticline, fault, and sedimentary facies. However, as a result of the dramatic variation of composition, density of rock, and temperature, pressure of the fluid in the pore, the elastic parameters of earth medium, such as elastic modulus, velocity, Poisson ratio, absorption characteristics, are inevitably heterogeneous. Because the scale of these heterogeneities is much smaller than that of the seismic wave length, these heterogeneities only generate few of incoherent scattering in seismic records. So these scattering have not been taken into account or have been ignored in traditional seismic data processing and interpretation. In seismic inversion, the subsurface medium has also been simplified as a series of uniform layered medium model and has not involved the influence of the seismic scattering.However, for the application of high resolution, wide-band seismic exploration method, the scale of seismic wave wavelength and that of the small scale heterogeneities of medium are closer and closer. So the impact of these heterogeneities on seismic wave field is more obvious, and generate a lot of scattering of seismic waves. These scattered seismic waves, to some extent, have a major influence on the accuracy of the seismic processing and interpretation. On the one hand, only if the seismic wave propagation theory which applied in heterogeneous medium has been systematically studied, we can find a method for diminishing those impact of scattered waves. On the other hand, disposing of or ignoring the seismic wave field caused by inhomogeneous medium, which, namely, makes us give up some potential valuable information sources of subsurface medium, such as sedimentation model, sedimentary microfacies, lithological changes. So, investigating on the characteristics of seismic scattering and finding a kind of method to detect small scale inhomogeneity are completely necessary. The investigation of this dissertation is a part of research and exploration contents mentioned above, and the purposes are as follows:1) provides a flexible, convenient, three-dimensional description and modeling methods of random medium for the study of the seismic wave field in complex medium; 2) find a kind of method to estimate the heterogeneity characteristics of subsurface using post-stack seismic data.The main contents and conclusions of this dissertation are as follows:1) The mathematical description methods of the random medium. This study established the autocorrelation function of the three-dimensional non-stationary random medium, and proposed the modeling method of three-dimensional non-stationary random medium based on stochastic process theory.2) The parallelization of modeling algorithm. Since modeling algorithm of three-dimensional non-stationary random medium is time consuming, this study designed an parallelized algorithm for modeling the three-dimensional non-stationary random medium. Tests show that the efficiency of the parallelized algorithm has been greatly improved.3) The parameter estimation of the random medium from post-stack seismic data. Based on the theory of non-stationary random medium, an estimation algorithm of random medium parameters is proposed from the two-dimensional post-stack seismic data. The algorithm can estimate the spatial distribution characteristics of the random medium parameters, including autocorrelation length of a and b and the relevant angle0. The test with synthetic seismic data shows the algorithm is correct and feasible,which has been extended to the parameter estimates in the three-dimensional stationary random medium.4) The estimation experiment of random medium parameters on the real seismic data. Taking one typical two-dimensional seismic profile which better reflects of delta sedimentary facies in Member1of Dongying Formation in Dagang Oilfield as for instance, this dissertation presents parameter estimation of random medium through the profiles guided by the theory of non-stationary random medium. And then according to the estimation results, the delta sedimentary facies in the profile has been analyzed and divided into three microfacies. This experiment shows that the parameters of random medium can be used as new seismic attributes in the interpretation of the seismic data which reflects the method that has a good prospect and can provides a very effective means to study the heterogeneity of the actual medium and to separate seismic facies and sedimentary facies. This dissertation is mainly divided into five chapters. The first chapter, a brief introduction to the research background, purpose, significance, research progress status at home and abroad, as well as the thesis’s main research content, main achievements and innovations. The second chapter, briefly introducing the basic concepts and different types of random medium, different parameters corresponding to the characteristics of the random medium. The third chapter discusses the description method and the modeling algorithm of the three-dimensional non-stationary random medium model, and the parallelized processing scheme of the modeling algorithm. The fourth chapter mentions parameters estimation algorithm, the estimation test of the theoretical model and actual seismic data in both two-dimensional non-stationary random medium and three-dimensional stationary random medium. The last chapter summarize the thesis’s main work and conclusions and put forward the problems existing in the thesis and the future research direction. The innovation of this dissertation is mainly represented in two aspects:1) the modeling algorithm of the three dimensional non-stationary random medium could build more complex three-dimensional models which random medium parameters change continuously in the three-dimensional space. So this is an innovation in random medium theory and modeling research;2) compared with the previous parameters estimation works of two-dimensional random medium, this thesis not only increases the estimation of autocorrelation angle θ, but also can estimate parameters of the non-stationary random medium and parameters of three dimensional random medium. These parameters of random medium is of great value to sedimentary microfacies analysis by using real seismic data and seismic facies controlled wave impedance inversion. So this is an innovation in application of random medium theory.更多还原