Reconstruction of depocenter evolution through time using relative stratigraphic thickness

Abstract

In this article, we describe a new approach to seismic stratigraphic interpretation. We build on the concept of the relative geologic time attribute introduced by Stark (2004) to define a relative stratigraphic thickness attribute, which can then be interpreted to reconstruct depocenter migration from seismic data. The principles of seismic stratigraphy were established in the classic AAPG Memoir 26. At this time (1977), manual interpretation of 2D seismic was still typical in the E&P industry. Simple truncation geometries such as onlap, downlap, and toplap were used to characterize sequence boundaries and flooding surfaces. Recent work continues to emphasize these 2D concepts, for example, using them in introductory sequence stratigraphic exercises. The routine use of 3D seismic emerged in the 1980s and, with it, computer-assisted interpretation. The main focus of the industry was on large structural traps. Highly effective 3D structural interpretation workflows developed in the 1980s still form the core of current interpretation workflows. Given the time-consuming nature of seismic interpretation, most geoscientists are forced to limit their mapping to major unconformities and flooding surfaces. These correspond to first- and second-order sequences boundaries and occupy only a small fraction of the typical seismic volume. It was common then, and now, to infer stratigraphy by averaging attributes such as seismic amplitudes between structural picks.