Williams, Mark C.¹, Qiang Sun¹, Scott Michell¹, John D. OldroydV, Ramsey R. Fisher¹, Ken H. Matson¹
(1) BP, Houston, TX

ABSTRACT: Atlantis Subsalt Imaging

The Atlantis Field, discovered in 1998, is located in the Western Atwater Foldbelt approximately 150 miles south of New Orleans, Louisiana in the Gulf of Mexico. Atlantis is located in water depths varying from 4,500 feet to greater than 6,800 feet with a full-field reserves range of 475 – 800 mmboe. BP is the operator with a 56% working interest. The project was sanctioned in November 2002 with first oil scheduled for July 2006. 
The Atlantis structure is an elongated faulted anticline with overall 4-way dip closure from the top of the Miocene down to the top of the autochthonous salt. Compartmentalization faults trend parallel, perpendicular, and radial to the long axis of the structure. Approximately 60% of the structure lies beneath salt and the Sigsbee Escarpment. 
Atlantis sub-salt seismic image quality ranges from poor to unreliable over 60% of the anticipated areal extent of the field. Initial field development will focus on the better-imaged southern segments. Development of sub-salt reserves will be contingent on additional appraisal drilling and early field performance. Seismic data quality is limited due to uncertainties in the following: multiple contamination by surface related multiples; the sediment and salt velocity model; complex illumination due to the overlying salt geometry and salt fingers and a steeply dipping water bottom associated with Sigsbee Escarpment. Recent seismic imaging efforts on Atlantis include the application of wavefield migration techniques, acquisition of a 3D VSP, enhanced velocity model building, raytrace illumination studies and the application of advanced demultiple techniques.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.