【作者】 赵俊省；

【导师】 李录明；

【作者基本信息】 成都理工大学 ， 地球探测与新技术， 2010， 硕士

【摘要】 针对目前正在发展的斜井三维VSP勘探中的若干问题,研究了逐段迭代射线追踪进行斜井三维VSP多波正演模拟方法。通过正演模拟,不但可以得到斜井三维VSP多波记录,而且可得到反射点分布、叠加次数分布、入射角分布、AVA特征等参数,这些参数在三维斜井VSP观测系统设计、储层特征分析及参数反演等方面均有应用价值。本研究分三方面内容:一是任意复杂的层状介质中射线正演模拟方法;二是复杂层状介质斜井三维VSP多波射线正演模拟;三是斜井三维VSP多波射线正演参数分析及应用。文中从程函方程出发,研究了能适应任意复杂层状介质的逐段迭代射线正演方法。该方法是根据Snell定理和费马原理发展出的一种射线正演方法,其主要思路是将旅行时方程按泰勒级数展开,并忽略二次项,得到一个计算反射点(透射点)修正量的计算公式。从给定的初始路径出发,逐点计算射线路径与地层的交点,直到整个射线路径的总修正量达到精度要求为止。迭代计算式中只包含有加、减、乘、除计算,提高了计算效率。在复杂层状介质斜井三维VSP多波射线正演模拟中,通过对水平层状介质模型、倾斜层状介质模型和任意起伏层状介质模型的正演模拟,验证逐段迭代射线正演方法在斜井三维VSP射线正演中的应用效果;通过射线路径和AVA能量特征来分析该方法在三维VSP射线正演中的可行性和有效性。斜井三维VSP射线正演在得到VSP记录的同时,可以得到各反射层上反射点的覆盖范围、覆盖次数和入射角。这些参数对斜井三维VSP观测系统设计具有重要作用。通过研究炮点分布、炮点缺失、炮间距、检波点深度和检波距的变化对不同深度目的层的P波和P-SV波的反射点覆盖范围和覆盖次数的变化,为斜井三维VSP观测系统设计选择最佳参数提供依据。最后,针对歧口18-2油田P6井地区的地层模型,使用该井的实测观测系统进行正演模拟,分析该模型的VSP波场特征,以及不同深度地层的覆盖次数和入射角分布特征,并分析其AVA特征。更多还原

【Abstract】 Be aimed at a number of issues in the 3D-VSP seismic exploration, this paper uses iteration segment by segment to realize 3-D deviated well VSP ray tracing. Through numerical tests, not only the availability of 3-D well deviated well VSP multi-wave records, and obtain the distribution of reflection points, superimposed frequency distribution, the incident angle distribution, AVA characteristics and so on. All of these parameters have application value in 3-D deviated well VSP geometry designing, reservoir characterization analyzing and parameter inversion.In this study, three aspects: First, any complex layered media-ray forward modeling methods; the second part is that a complex multi-layered media three-dimensional deviated VSP forward ray-tracing; the third part is analysis and application the parameters of 3-D deviated well VSP multi-wave forward ray-tracing From the Eikonal equation, this paper study iteration segment by segment ray tracing that can adapt to any complex layered media. This method is based on Snell theorem and Fermat’s principle .The main idea is by use of one-order Taylor incomplete expansion to expand Travel time equation, and ignore the second entry point to get a computational reflection (transmission point) formula. Starting from an arbitrary given initial ray path, ray-t racing is iteratively calculated segment by segment. The procedure is kept on until the sum of adjustment quantity in the whole path is in the range of precision. Formula contains only include add, subtract, multiply, divide calculated to improve the computational efficiency.In complex multi-layered media three-dimensional inclined VSP forward ray-tracing, through the horizontally layered model, tilted layered model and a random fluctuation layered media model modeling, iteration segment by segment to realize 3-D deviated well VSP ray tracing in the application of results; by using the ray path and the AVA to analyze the method’s feasibility and effectiveness in 3D VSP ray tracing forward.3-D VSP ray-trace forwarding can get reflected point coverage of the reflective layer, the number of covering and angle of incidence. These parameters have a significant role on the 3D deviated VSP survey design. By studying the change of the distribution of shot, shot missing, shot distance, depth and distance of receiver points in the purpose of the different depth layers of the P wave and P-SV wave reflection point coverage and frequency of change, provide the basis for three-dimensional deviated VSP survey designing to select the best parameters.Forward ray tracing applications: using P6 QK 18-2 oil field well’s 3D observation system, forward the stratigraphic model of this region, and analyze this model’s VSP wave field characteristics, and different depth layer’s covering of the frequency and incidence angle distribution, and characteristics of the AVA.更多还原