Subcircular features and autotracking artefacts in 3D seismic interpretation; a case study from the central North Sea

Abstract

Tertiary deep-water sandstones are major reservoirs in the North Sea, and display an upward gradation from sheet-like bodies to increasingly channelized units. 3D seismic horizon attribute maps at near Top Forties and Top Chalk levels within the Central North Sea portray peculiar textures, which were found to be genuine, and not the result of artefacts caused by the use of autotracking in seismic interpretation. The semi-circular fabric of the near Top Forties event is the result of pre-existing NW-SE structural trends, depositional processes and differential compaction. The pockmark pattern displayed by the Top Chalk horizon is associated with small-scale fractures related to reactivated shear zones and to episodic overpressure release. Use of attribute maps and time slices highlights elusive features, thus refining fairway delineation and understanding of fracture network properties, leading to improved reservoir description and management.