Robust estimates of 3D reflector dip and azimuth

Abstract

Much of seismic stratigraphy is based on the morphology of seismic textures. The identification of reflector terminations and subtle changes in dip and azimuth allows us to infer coherent progradational and transgressive packages as well as more chaotic slumps, fans, and braided-stream complexes; infill of karsted terrains; gas seeps; and, of course, faults and angular unconformities. A major difficulty in estimating reflector dip and azimuth arises at discrete lateral and vertical discontinuities across which reflector dip and azimuth change. The smearing across these boundaries produced by traditional dip and azimuth estimations is avoided by using temporally and spatially shifted multiple windows that contain each analysis point. This more robust estimation of dip and azimuth leads to increased resolution of well-established algorithms such as coherence, coherent amplitude gradients, and structurally oriented filtering. More promising still is the analysis of high-resolution dip and azimuth through volumetric estimates of reflector curvature and angular unconformities. This new technique is demonstrated using two land data volumes, one from the Louisiana salt province and the other from the fractured Fort Worth basin.

From mechanical modeling to seismic imaging of faults: A synthetic workflow to study the impact of faults on seismic

“…These are called volume-based attributes Several methods have been developed to calculate volumetric attributes of dip, azimuth and curvature (e.g. Chopra and Marfurt, 2005;Marfurt, 2006;Chopra and Marfurt, 2007). Attributes that deal with the continuity of seismic reflectors throughout the volume, such as the semblance or coherence, are typically used for fault characterisation.…”

Application of Cutting-Edge 3D Seismic Attribute Technology to the Assessment of Geological Reservoirs for CO2 Sequestration

“…Much like coherence, curvature attributes (Marfurt, 2006) are computed with an extended operator, while SPICE is a point-wise computation localized in both space and time. In this case, curvatures were computed with a 20 ms time window (red bar).…”

Seismic characterization of a carbonate reservoir in Tarim Basin

“…The information input to the coherence algorithm consists of seismic data dðt; x; yÞ, apparent dips along the inline direction pðt; x; yÞ, and apparent dips along crossline direction qðt; x; yÞ, where x is the crossline index, y is the inline index, and t is the time (Figure 3a). The apparent dips are estimated from seismic data based on the dip estimation algorithm by Marfurt (2006). The local analysis window is adjusted using preestimated reflector dips to flatten seismic data along local reflections (to eliminate the potential impact of dipping reflections on the coherence calculation).…”