AVERAGE GRADIENT METHOD WITH VARIABLE V₀

In areas of complex geology, the ture velocity of the strata doesn't variate linearly in accordance with the formula V(z) = V₀(1 + βZ) but it variates non-linearly and presents to be a curve of higher degree. Hence, if the seismic section is mapped by conventional method, the distortion would be easily caused in the procedure of constructing the deep reflectors with steep occurrence. Similarly, the average velocity fitted by the constant V₀ and the parameter β do often deviate obviously from the average velocity measured. Fortunately, there is a remedy for such a defect by adopting the technique of average gradient with variable V₀ and the realistic situation about the medium underground could be reflected more objectively. In this paper, the basic theory of the average gradient technique with variable V₀ was described and the approximate resolution for extracting V₀(t₀), β(t₀) and α(t₀) from curves of average velocity or root mean square velocity was found. The program flowchart and the computing procedure were given. At the end of this paper, the effects of the technique recommended were discussed and examined.