Velocity Interpretation: Southern North Sea Gas Basin

Mel D. Carter, J. S. Fisher, S. W. Thomas

A data set including both seismic and well data from the Southern North Sea gas basin illustrates several techniques for integrated velocity interpretation and depth conversion. The most important technique is the depth-normalized interval velocity method. This approach is founded on an analysis of the compaction characteristics of the geologic section and makes possible more accurate velocity estimates from both well and seismic data.

The data set itself reveals several interesting phenomena. Unusually large velocity increases with depth of burial are present and these data are typically available. Significant horizontal vs. vertical p-wave anisotropy is present in the Tertiary layer. Velocity within the Zechstein Formation varies systematically because of variable anhydrite content. Examples illustrate the exploration significance of these phenomena.

AAPG Search and Discovery Article #91035©1988 AAPG-SEPM-SEG Pacific Sections and SPWLA Annual Convention, Santa Barbara, California, 17-19 April 1988.