Seismic velocity and attribute study based on well interpolated data

Douglas Gratwick and Daniel Rosales

doug@sep.stanford.edu, daniel@sep.stanford.edu

ABSTRACT

This paper studies the effects of fluid type in pore space for a channel sand in the Stanford V dataset. The model used was created by interpolation of 3D well data using ordinary kriging. V_p, V_s, density, and porosity were all kriged into 3D volumes, and then a slice was extracted, which contained a sand body surrounded by a shale. Elastic modeling was run on this slice, and the data were processed into CMP gathers for AVO study. Subsequent modeling was done for fluid substitution of both oil and gas. It was found that the hydrocarbons yielded higher amplitude reflections, and that the gas model showed an increased amplitude with offset.

A velocity slice containing well information was used for modeling and subsequent velocity analysis. This velocity analysis shows the difference between seismic and well velocities due to the frequency content of the source.