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| Application of non ray-tracing tomography static correction technique in Loess Plateau |
| Hu Zi-duo1,2, He Zhen-hua1, Wang Xi-wen2, Wang Yu-chao2, Wang Shu-jiang2, Liu Qiu-liang2 |
1. Chengdu University of Technology,Chengdu City,Sichuan Province,610059,China;
2. Northwest Branch,Research Institute of Petroleum Exploration&Development of Petrochina,Lanzhou City,Gansu Province,730020,China |
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Abstract Based on the assumption of the 1D continuous medium model,the non ray-tracing tomography static correction technique implicitly utilizes the propagation law and the dynamic characteristics of the horizontal surface turning wave to conduct tomography inversion for the surface model.The loess layer in the Loess Plateau,Ordos Basin is very thick with server relief surface,however lateral velocity change in the weathered layer is relatively stable and the velocity showed a continuous variation in vertical direction,so it matches the assumption of the 1D continuous medium model.Due to its relief surface,the time-distance curve characteristics of the turning wave for the horizontal surface can not be established,so the non ray-tracing tomography static correction technique can not be directly utilized.In this paper the basic fundamental of the non ray-tracing tomography static correction technique,its algorithm and suitable conditions were firstly discussed,then regarding the relief surface in the Loess Plateau,the time-distance curve equation of the relief surface in the continuous medium was derived,by integration of the micro-logging method,the polynomial fitting for time-depth curve of the shallow refraction data,and the first arrival time-distance curve exponential fitting for the field single shot,the influence of the relief surface to the first arrival propagation time was removed,then by application of the non ray-tracing tomography static correction technique the static correction problem in the Loess Plateau was successfully solved.
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Received: 25 May 2010
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2010, Vol. 45 
