| Summary: | 碩士 === 國立中央大學 === 地球物理研究所 === 91 === ABSTRACT
A differential delay time (DDT) concept is proposed for refraction static correction without picking first arrival times in the CDP reflection data processing. This new method is a modification of the ABCD method; it uses cross-correlation to measure the first arrival time difference between signals received at stations B and C, instead of directly computing them from their picked times. By taking advantage of multiple-fold CDP data, we apply the super trace measurement, which may alleviate the effect of data imperfections.
As alike as the ABC method, we fill the traveltime differences in a matrix with the reciprocal method concept in DDT method, then the matrix is inverted to solve for the refraction velocity and weathering depth by a inversion method. Finally, we can get the static correction value converted by the refractor model. A synthetic model and a real case with a severe weathered layer problem have been tested to evaluate the method. Stable and manageable computation processes have been explored to attain maximum performance. The results are quite satisfactory.
In the theory, the DDT method combines “delay time” concept of refraction with multiple fold of CDP data. In application, we can handle the data with DDT method automatically. This is very objective and convenient. Now we apply the DDT method to general shadow CDP seismic reflection cases and the results are very good. This method is worth using widely.
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