海洋混合震源波场分离方法与应用研究

发布时间：2018-04-25 13:28

本文选题：混合震源采集 + 混合震源观测系统　；参考：《吉林大学》2016年博士论文

【摘要】：混合震源采集技术(也称多震源混合采集)具有改善成像质量、提高采集作业效率的优势,自形成伊始就受到了学者们和各大油气公司的青睐。但混合震源采集引入的混合噪声、混合震源观测系统中比传统采集可记录更多信息的道集的缺失以及其它随机噪声严重影响了地震数据的信噪比;在常规震源混合采集理论上发展的变频震源采集技术具有以更简单、更保真的方式实现宽频采集的优势,但采用一般方法分离混合波场时,分离信噪比将受到影响;由于震源激发方式和采集成本的制约,海洋混合震源采集的发展速度远慢于陆地。鉴于混合震源采集技术发展中遇到的上述限制,本文对混合震源采集技术作了系统研究:针对海洋混合采集开展了混合震源采集基本理论、波场分离方法以及变频震源混合采集技术的研究,并首次在国内开展了海洋混合震源采集及混合数据处理研究,为未来海洋混合震源采集技术的产业化提供了理论支持与技术储备。本文分别从观测系统和数学物理两个角度阐释了混合震源采集的基本原理,通过引入合成震源算子和面源的概念,类比地阐释了混合震源算子和混合震源的原理。并解释了震源密度比和采集时间比两个重要参数,二者分别量化了混合震源观测系统提高空间采样率和采集效率的优势。按照混合算子的类型将混合震源采集分为“适定型混合震源采集”和“欠定型混合震源采集”,从数学角度分析了两类采集方式的数据混合形式以及对相应波场分离方法的影响。同时阐述了海洋多船混合震源和单船混合震源观测系统,并对两类观测系统开展了正演模拟。分别从理论和震源数据响应的角度介绍了“伪分离”的概念,其在波场分离及后续常规处理中有规则化数据及校验混合震源编码的作用。本文提出将混合噪声的去除、缺失道集的插值以及随机噪音的衰减描述为同类反问题,将其统一在一个稀疏反演框架内同时求解,在改善混合震源数据信噪比的同时提高了数据的处理效率。将统一在同一反演框架内的此三类问题纳入L1范数约束的正则化模型,并将快速迭代收缩阈值算法引入正则化模型的求解中,该算法在保留了收缩阈值算法实现简单的优点的同时提高了运算效率,通过模拟数据和实际数据的分离结果验证了算法的有效性。本文提出基于压缩小波变换的变频震源混合波场分离方法,在震源频谱重合度较高的情况下,获得了高质量的分离信噪比,同时提高了分离效率。受采集装备或者采集环境的约束,宽频采集将复杂化震源端或整个观测系统,在常规震源混合采集基础上发展的变频震源采集,通过利用多个主频不同的窄频带震源代替单独使用宽频震源,可以在采集装备技术复杂程度更低的条件下解决宽频采集问题。本文分析了变频震源混合采集在海洋和陆地宽频采集中的应用及发展趋势。变频震源混合采集可进一步拓展为分散式混合采集,其在具备前者优势的同时还具有作业简单、高效采集的特点。然而,当变频震源混合波场数据采用一般方法分离时,分离信噪比将在一定程度上低于常规震源混合采集,针对变频震源混合采集子震源时频差异性的特点,本文提出了基于压缩小波变换的波场分离方法,通过模拟算例证明其具有高质量的分离信噪比及高效运算的优势。鉴于混合震源编码直接影响后续波场分离质量,本文重点研究了影响混合震源编码的两个主要因素,即激发时间的随机延时范围和最小激发时间间隔,并结合我国首次海洋拖缆混合震源2D、3D采集的观测系统和作业任务,研究出了最佳混合震源编码的设计方法。通过与传统采集数据的常规处理方法的融合研究,针对我国首次采集到的海洋混合震源数据,研究设计了一套混合波场数据处理模式,开展了混合震源数据预处理、分离及偏移成像。并在同等的计算机硬件、软件及参数条件下,与同一地区的传统震源采集数据开展了同步处理,通过偏移成像结果对比,本文提出的混合采集数据分离方法及数据处理模式的正确有效性得到了进一步证实。本文提出了混合波场分离中预先衰减直达波噪声的新方法,提高了分离信号的保真度,减少了有效信号能量的遗漏,将分离信噪比提升至了传统方法的一倍左右。
[Abstract]:Mixed source acquisition technology (also called multi source mixed acquisition) has the advantage of improving the imaging quality and improving the efficiency of the collection operation. Since the beginning of the formation, it has been favored by scholars and the major oil and gas companies. But mixed source collection is introduced by mixed source of noise, and the mixed seismic source observation system can record more information than traditional collection. The loss and other random noise seriously affect the signal to noise ratio of seismic data; the frequency conversion source acquisition technology developed in the conventional source mixed acquisition theory has the advantage of realizing broadband acquisition in a simpler and more fidelity way, but the separation signal to noise ratio will be affected when the mixed wave field is separated by the general method; the source excitation side is due to the source of the seismic source. In view of the above constraints encountered in the development of mixed seismic source acquisition technology, this paper makes a systematic study of the mixed seismic source acquisition technology. The basic theory of mixed seismic source acquisition, wave field separation method and frequency conversion source mixing are carried out in this paper in view of the mixed seismic source acquisition technology. The study of collection technology and the study of mixed data acquisition and mixed data processing have been carried out in China for the first time. It provides theoretical support and technical reserve for the industrialization of future marine mixed seismic source acquisition technology. This paper explains the basic principle of mixed seismic source acquisition from two angles of observation system and mathematics physics. The concept of synthetic source operator and surface source is introduced, and the principle of mixed source operator and mixed source are explained by analogy, and two important parameters are explained by the density ratio of the source and the time of acquisition, and the advantages of the mixed seismic source observation system to improve the spatial sampling rate and the acquisition efficiency are quantified respectively. The mixed seismic source is based on the type of mixing operator. The collection is divided into "the collection of the suitable mixed source" and "the collection of the unstructured mixed source". From the mathematical point of view, the data mixing form of the two kinds of collection methods and the influence on the corresponding wave field separation methods are analyzed. At the same time, the marine multi ship mixed seismic source and the single ship mixed seismic source observation system are expounded, and the two kinds of observation systems are carried out. This paper introduces the concept of "pseudo separation" from the perspective of theory and source data response respectively. It has regularized data in wave field separation and subsequent conventional processing. This paper proposes the removal of mixed noise, the interpolation of the missing path set and the attenuation of random noise as the same inverse problem. It is solved simultaneously in a sparse inversion framework, improving the data processing efficiency while improving the signal to noise ratio of the mixed seismic source data. The three kinds of problems which are unified in the same inversion framework are incorporated into the regularization model of the L1 norm constraint, and the fast iterative shrinkage threshold algorithm is introduced to the solution of the regularization model. The effectiveness of the algorithm is improved by preserving the simple advantages of the shrinkage threshold algorithm, and the effectiveness of the algorithm is verified by the results of the separation of simulated data and actual data. This paper presents a hybrid wave field separation method based on the compressed wavelet transform, which has high quality in the case of high frequency coincidence of the source spectrum. It can separate the signal to noise ratio and improve the separation efficiency. Under the constraints of the acquisition equipment or the acquisition environment, the wide-band acquisition will combine the complex source end or the whole observation system, and collect the frequency conversion source on the basis of the conventional source mixed collection. This paper analyzes the application and development trend of the mixed acquisition of frequency conversion source in ocean and land wide frequency acquisition. The mixed acquisition of frequency conversion source can be further extended to disperse mixed collection, which has the advantages of the former with simple operation and high efficiency. However, when the mixed wave field data of the frequency conversion source is separated by the general method, the separation signal to noise ratio will be lower to a certain extent than the conventional source mixed collection. In view of the characteristic of the time frequency difference of the source mixture of the frequency conversion source, a wave field separation method based on the compression wavelet transform is proposed in this paper, which is proved by a simulation example. It has the advantages of high quality separation signal noise ratio and high efficient operation. In view of the direct influence of the hybrid source code on the separation quality of the subsequent wave field, this paper focuses on two main factors affecting the coding of the hybrid source, namely the random time delay range of the excitation time and the minimum time interval of excitation, and combined with the first marine towing hybrid source of 2 in China. D, 3D collected the observation system and the task task, and studied the design method of the best hybrid source coding. Through the fusion of conventional processing methods with traditional data acquisition, a set of mixed wave field data processing mode was designed and designed for the first collection of marine mixed seismic source data in China, and the data pre location of mixed source was carried out. Under the same computer hardware, software and parameter conditions, the traditional seismic source acquisition data in the same area are synchronized with the same area. The correctness and validity of the mixed acquisition data separation method and data processing model proposed in this paper are further confirmed by the comparison of the migration imaging results. A new method to attenuate the direct wave noise in the mixed wave field separation is proposed, which improves the fidelity of the separation signal, reduces the leakage of the effective signal energy, and improves the separation signal to noise ratio to about twice the traditional method.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P631.46

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