Print this pageRegional Salt Distribution from 3-D Data Across the South Additions, Offshore Louisiana
George A. Jamieson
A contiguous 3-D dataset comprising 20 surveys covering over 800 OCS blocks
in the offshore Louisiana South Additions region formed the primary database for
a regional interpretation of top and 
base
salt surfaces. The interpretation was
performed on a 800 m by 800 m grid of 3-D time migrated lines extracted from
each survey and loaded into a single project on a workstation. After completing
the interpretation the top and base salt horizons were depth converted,
incorporating representative well velocity information across the study area.
The use of 3-D data has significantly improved interpretation confidence,
particularly of the base salt, compared to 2-D data, which, to date, has been
the most commonly utilized regional tool. However, 2-D data suffers from
out-of-plane effects which can lead to erroneous interpretations of the base of
salt and deep welds. A number of significant regional salt-related features and
trends have been identified from the top and base salt time and depth maps.
Significant identified features on the base
of salt and below include keels,
welds, fault zones and possible ramps which, in places, display significantly
differing trends to those of the suprasalt section. The 3-D data allows the
mapping of feeders associated with large counter-regional fault systems down to
extreme depths, in plac s to over 7 kms, as well as the location of feeder stock
and wall locations beneath salt canopies. This has shown that many large sheets
comprise several salt masses which have coalesced along suture zones, for
example in the Vermilion and Ship Shoal regions.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California