各向异性介质高斯束偏移方法研究

发布时间：2018-12-16 10:43

【摘要】：地震勘探技术作为发现油气藏的重要手段,一直以来是地球物理学中的研究重点。而随着地震勘探技术发展,目前的勘探目标主要为中小复杂隐蔽性油气藏,这也对地震勘探技术的要求越来越高。地震偏移成像技术是将海量的地震数据转化成能够反映地下地质构造地震剖面的重要手段,也是地震勘探技术中重要的一环。而传统的地震偏移成像技术大都基于地球介质为各向同性的假设,但是大量的观察和实验表明地球内部介质的各向异性是普遍存在的,如果运用传统基于各向同性假设的偏移成像方法来对处理各向异性探区的地震数据,那么将会导致最终得到的地震剖面中反射波不能准确归位,绕射波收敛效果不好等问题,进而对后续的地震资料处理解释研究产生不利影响。另外,因为我们要处理的是海量的地震数据,在进行偏移成像处理中不仅要考虑偏移方法的成像精度还要兼顾其计算效率问题。高斯束偏移方法作为近年来新兴的一种改进的几何射线类偏移方法,不但保留了射线类偏移方法灵活高效和对陡倾构造成像的优点,而且还能够处理焦散区等问题,成像精度相对于Kirchhoff提高很多,接近单程波成像精度,具有很高的应用前景和研究价值。本文我们主要研究各向异性介质中的高斯束偏移方法,一方面扩展了高斯束方法的应用范围,另一方面也考虑到其实用性。为了将高斯束偏移方法扩展到各向异性介质中,本文主要包括以下内容:(1)从波动方程出发,推导了各向同性介质和各向异性介质中的运动学和动力学射线追踪方程组,介绍了高斯束的表达式和基本性质(2)在前人工作的基础上,结合各向异性介质射线追踪方程组,推导了各向异性介质中的叠后高斯束偏移和叠前高斯束偏移成像公式,并通过模型试算验证了其正确性(3)为了充分利用多分量数据中波场的矢量特征,本文从弹性波Kirchhoff偏移方法的思想出发,推导了各向异性介质中的无需波场分离的多分量数据成像公式。并通过对模型进行试算,验证了该方法的可行性。(4)在本文成像方法的基础上,我们还讨论了参数场,初始束宽,束中心间隔和射线参数间隔等参数的选取准则及其对各向异性高斯束偏移的影响。
[Abstract]:As an important means to discover oil and gas reservoirs, seismic exploration technology has been the focus of geophysics all along. With the development of seismic exploration technology, the current exploration targets are mainly small and medium complex hidden reservoirs, which also have higher and higher requirements for seismic exploration technology. Seismic migration imaging technology is an important means to transform massive seismic data into seismic profiles of underground geological structures and is also an important part of seismic exploration technology. Traditional seismic migration imaging techniques are mostly based on the assumption that the earth medium is isotropic, but a large number of observations and experiments show that the anisotropy of the earth's inner media is universal. If the traditional migration imaging method based on isotropic assumption is used to process seismic data in anisotropic exploration area, it will lead to the problem that the reflected wave in the final seismic profile cannot be accurately located, and the convergent effect of diffraction wave is not good. Then it has a negative effect on the subsequent seismic data processing and interpretation research. In addition, because we have to deal with massive seismic data, we should not only consider the imaging accuracy of migration methods, but also take into account the computational efficiency in migration imaging processing. Gao Si beam migration method, as an improved geometric ray migration method in recent years, not only preserves the advantages of ray migration method, but also can deal with the problem of caustic region. The imaging accuracy is much higher than that of Kirchhoff. It is close to the accuracy of single pass wave imaging and has high application prospect and research value. In this paper, we mainly study Gao Si beam migration method in anisotropic media. On the one hand, we extend the application range of Gao Si beam method, on the other hand, we consider its practicability. In order to extend Gao Si beam migration method to anisotropic media, this paper mainly includes the following contents: (1) from the wave equation, the kinematic and dynamic ray tracing equations in isotropic and anisotropic media are derived. This paper introduces the expression and basic properties of Gao Si beam (2) on the basis of previous work, combined with the ray tracing equations of anisotropic medium, the imaging formulas of post-stack Gao Si beam migration and pre-stack Gao Si beam migration in anisotropic media are derived. In order to make full use of the vector characteristics of wave field in multi-component data, this paper starts from the idea of elastic wave Kirchhoff migration method. An imaging formula for multicomponent data in anisotropic media without wave field separation is derived. The feasibility of the method is verified by the experimental calculation of the model. (4) on the basis of the imaging method in this paper, we also discuss the parameter field, the initial beam width, The selection criteria of beam central interval and ray parameter interval and their influence on anisotropic Gao Si beam migration.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4;P618.13

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