Mapping Overpressure Features With Broadband Multimeasurement Seismic Data

Abstract

The mapping and reconstruction of overpressure processes, in context with the bounding strata, is made possible from the interpretation of broadband and equi-sampled multimeasurement data using a color-domain processing technique. The depositional environment of a shelf edge with slope channels and fan deltas is mapped from seismic data. After deposition of the seal and compaction, pressurized fluids re-use slope to communicate the pressure from the abyss up to the shelf, if the channels remained intact and have not been destroyed by slumping on unstable slopes. Overpressure features, such as sand injectites, along these channels support this interpretation. The migration of gas appears to follow faults thus creating gas chimneys, which in turn can also trigger sand injectites above, if sufficient fluids are available and the sediments are still unconsolidated. The comparison of broadband multimeasurement data with legacy seismic data, acquired with conventional inline hydrophone streamers and interpolation, demonstrates the improvement provided by the advanced acquisition technique for the interpretation of complex slope deposition and overpressure environments. Interpolation is commonly used after conventional seismic data acquisition degrades the representation of channels, in the direction perpendicular to the streamers to a degree that the connectivity of these channels can no longer be determined. The advanced acquisition technique combined with color-domain processing provides a new route for mapping both present and fossil deepwater slope processes to better understand pressure communication from a reservoir and from a drilling hazard point of view.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016