4D Wheeler diagrams: concept and applications

Abstract

Abstract The conventional Wheeler diagram aids the construction of a spatiotemporal framework of strata. The diagrams are created manually by studying outcrops, wells, or seismic data. For the latter case, automated methods now exist, which support the construction of 2D, as well as 3D Wheeler diagrams. Seismic data contains information in three dimensions, X , Y and Z , where ‘ Z ’ is either two-way time or depth. Seismic horizons are correlated surfaces that often follow geological time lines. In this case, a set of interpreted seismic horizons contains information in four dimensions ( X , Y , Z , and Geological Time). In the mapping from the structural domain to Wheeler space, information about Z (thickness) is lost. This means that one dimension is missing in the conventional Wheeler diagram. This paper describes a method to add information from the Z dimension to the Wheeler domain. It is done by computing stratigraphic thicknesses per sequence stratigraphic unit and displaying these as colour-coded overlays in the Wheeler domain. Thus displayed, thickness variations help in understanding changes in accommodation, sedimentation rate, and depositional trends. 3D Wheeler displays with colour-coded thickness information are referred to as 4D Wheeler diagrams. In this article, the method is described and applied to a case study from the southern North Sea.