--> ABSTRACT: Subsalt and Base-of-Salt Reflector Relationships and Hydrocarbon Trap Implications From a Large 3D, Depth Migrated, Seismic Volume, by George A. Jamieson; #91020 (1995).

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Subsalt and Base-of-Salt Reflector Relationships and Hydrocarbon Trap Implications From a Large 3D, Depth Migrated, Seismic Volume

George A. Jamieson

A large 3D seismic volume covering over 60 OCS Blocks of the Louisiana shelf edge had a poststack depth migration applied. The depth migration process has improved subsalt geological information, compared to 3D time data, by correctly positioning seismic events in depth such that a true depth representation of an allochthonous salt sheet has been produced. In addition, improved seismic resolution at depth has resulted in a clearer definition of the base-of-salt and subsalt reflectors which can be clearly seen under many parts of the salt sheet.

The base-of-salt reflector is generally a much smoother seismic event than that of the top-of-salt, which has been severely deformed by sediment loading and related faulting.

However, there are many examples of rapid dip changes of the base-of-salt, where large areas of gently undulating, low dip, base-of-salt abut steeply dipping salt keels. The flatter base-of-salt regions generally display parallel sediment reflectors beneath, such that their structural trends mimic those of the base-if-salt. This implies that in these regions salt was rapidly intruded laterally. High angle sediment truncations are often seen against the salt keels.

Two subsalt plays are immediately apparent: 4-way dip closures in regions where the base-of-salt reflector gently undulates and closures related to high angle truncation against steeply dipping salt faces.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995