基于模型的三维观测系统优化设计

发布时间：2019-04-10 12:15

【摘要】：在地震勘探中,观测系统是指炮点与检波点的相互位置关系。观测系统优化设计的最终目的是提高地震采集资料的质量。本文从CMP面元属性分析和CRP面元照明分析两个方面出发,分别对三维层状水平模型和二维层状起伏模型的观测系统进行了优化设计。在CMP面元属性分析方面,首先从观测系统参数统计出发,总结了一组独立参数。在此基础上,统计出三维观测系统CMP而元三个属性——覆盖次数、方位角和炮检距分布情况,并提出了基于炮检对密度的覆盖次数计算方法。随后,给出了目标函数,根据目标函数分别对三个属性进行局部寻优得到寻优曲线。在CMP面元全局寻优时,为了克服计算量问题,笔者首先研究了约束条件,在强约束的条件下,实现了覆盖次数属性的全局寻优并得到观测系统寻优参数表格,最后通过炮检距和方位角属性的目标函数值进行寻优结果筛选,得到了一组基于CMP理论的最佳观测系统参数。在CRP面元照明分析方面,首先建立了一个目标层起伏的二维层状模型,并针对该模型实现了基于逐段迭代方法的射线追踪。通过统计CRP面元的覆盖次数,得到了目的层照明曲线。为了克服观测系统离散采样造成的照明曲线高频振荡以及射线路径的唯性造成照明强度的极值和空白等失真现象,笔者从两个方面对CRP面元照明方法进行改善和进化。其一,通过增加采集密度和增大面元尺寸实现了照明曲线的平缓过度；其二,实现了多路径射线追踪的照明分析方法,并对二维层状起伏模型进行了单炮排列照明分析和多炮照明分析。本文得到若干结论和认识。第一、笔者提出了基于炮检对密度的覆盖次数计算公式,与传统的覆盖次数经验公式相比,该公式更加究备合理,综合考虑观测系统参数与覆盖次数的关系；第一、笔者实现了CMP面元三个属性的统计和局部寻优,覆盖次数局部寻优曲线表明,在纵测线方向上,当排列的接收道数是滚动道数的2N(N为正整数)倍时,覆盖次数完全均匀；在横向上较为复杂,讨论结果较为复杂；第三、CMP面元全局寻优计算量极大,笔者在强约束条件下,实现了覆盖次数属性全局寻优,并通过炮检距和方位角属性的寻优筛选,得到了基于CMP面元属性理论上的最佳观测系统参数；第四、传统CRP面元覆盖次数照明分析射线路径具有单一性,对于起伏模型容易出现照明曲线的强烈振荡,增加采样密度或者增大面元尺寸能够改善照明结果；第五、笔者实现了基于多路径射线追踪的照明分析方法,该方法能够显著减小地层起伏造成照明曲线的失真现象,照明结果更加合理。
[Abstract]:In seismic exploration, observation system refers to the relationship between gunpoint and detection point. The final goal of optimal design of observation system is to improve the quality of seismic acquisition data. In this paper, the observation systems of three-dimensional layered horizontal model and two-dimensional layered undulating model are optimized from the aspects of CMP surface element attribute analysis and CRP surface element illumination analysis. In the aspect of CMP surface element attribute analysis, a set of independent parameters are summarized from the observation system parameter statistics. On this basis, the distribution of coverage number, azimuth and offset of the three-dimensional observation system CMP and its elements are calculated, and a method for calculating the number of coverage based on the density of gun detection is put forward. Then, the objective function is given. According to the objective function, the local optimization curve of three attributes is obtained. In order to overcome the computation problem in the global optimization of CMP surface element, the constraint condition is studied firstly. Under the condition of strong constraint, the global optimization of coverage number attribute is realized and the optimization parameter table of the observation system is obtained. Finally, a set of optimal observation system parameters based on CMP theory is obtained by screening the optimal results by the target function values of offset and azimuth attributes. In the aspect of CRP panel illumination analysis, a two-dimensional layered model of object layer fluctuation is established firstly, and the ray tracing based on step-by-step iterative method is realized. The illumination curve of the target layer is obtained by counting the covering times of the CRP surface elements. In order to overcome the distortion phenomena such as high frequency oscillation of illumination curve caused by discrete sampling of observation system and the extreme value and blank of illumination intensity caused by the only ray path, the CRP panel illumination method is improved and evolved from two aspects. First, by increasing the sampling density and increasing the size of the surface element, the lighting curve is over-smooth; Secondly, the illumination analysis method of multi-path ray tracing is realized, and the single shot arrangement illumination analysis and multi-gun illumination analysis are carried out for the two-dimensional layered undulation model. Some conclusions and understandings are obtained in this paper. Firstly, the author puts forward a formula for calculating the number of coverage based on the density of gun detection. Compared with the traditional empirical formula of covering times, the formula is more reasonable and takes into account the relationship between the parameters of observation system and the number of coverage. First, the author realizes the statistics and local optimization of the three attributes of CMP element. The local optimization curve of covering times shows that in the direction of longitudinal measurement line, when the number of received channels is 2N (N is a positive integer) times of the number of rolling channels, the number of channels arranged is 2N (N is a positive integer) of the number of rolling channels. The coverage times are completely uniform; On the horizontal side, it is more complex and the discussion result is more complex; Thirdly, the global optimization calculation of CMP surface element is very large. Under the condition of strong constraint, the global optimization of coverage number attribute is realized, and the optimal selection of offset and azimuth attributes is carried out. The optimal parameters of observation system based on the theory of CMP surface element attributes are obtained. Fourth, the ray path of the traditional CRP panel covering times illumination analysis is unitary. For the undulating model, it is easy to appear the strong oscillation of the illumination curve. Increasing the sampling density or increasing the size of the surface element can improve the lighting results. Fifthly, the author has realized the illumination analysis method based on multi-path ray tracing. This method can significantly reduce the distortion of lighting curve caused by stratum undulation, and the lighting result is more reasonable.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4

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