Abstract: Integrated Structural-Stratigraphic Interpretation and Analysis of 3-D "Seismic Horizon Surface Maps," Brae Area, South Viking Graben, North Sea

Thomas A. Mazza, Phil J. Allen, Branch J. Russell

Interpretation and analysis of 3-D seismic data volumes on interactive geophysical workstations can result in a fundamentally new data type, the "seismic horizon surface map." A seismic horizon surface map is created using automatic event picking software, and is an exact spatial representation of a seismic reflection event sampled at the intrinsic limits of the 3-D seismic grid. Seismic horizon surface maps offer a plan-view perspective of seismic horizons that, for the first time, are devoid of the 2-D "artifacts" resulting from under-sampling sideswipe, improper migration and interpreter error.

Workstation-based interpretations of three large 3-D seismic data volumes were integrated with an extensive subsurface database for the Upper Jurassic of the Brae area in the South Viking Graben of the North Sea. The Kimmeridge Clay in the Brae area forms a ubiquitous shale drape over the coarse-grained submarine fan deposits of the Brae Formation. This stratigraphic relationship results in a high-amplitude, laterally continuous seismic reflection that is ideal for workstation autopicking. A seismic horizon surface map creed from the Top Kimmeridge Clay reflection should contain features that are the result of both syn-sedimentary phenomena (such as differential compaction) and post-depositional tectonic deformation.

Map attribute analyses (dip magnitude and azimuth) of the Top Kimmeridge Clay seismic horizon surface yields a wide variety of otherwise undetected structural and stratigraphic details. When calibrated and correlated with vertical seismic facies and lithofacies from well control, the seismic horizon surface maps provide important new geologic insight into reservoir and trap distribution in the Brae area.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada