Illuminating Asset Value at Mad Dog through New Seismic Technology

Michael J. Staines¹, Scott Michell¹, Dean Chergotis², and John Sharp^1
1Houston, TX
²Anchorage, AK

The ability to reduce risk and uncertainty across the full life cycle of an asset is directly correlated to creating an accurate subsurface image to enhance our understanding of the geology. This presentation focuses on the objective of imaging below salt for development of the BP operated Mad Dog field in deepwater GoM. As the industry has moved into more complicated geologic settings conventional narrow azimuth surveys no longer meet the subsurface imaging objectives for well informed field development and production decisions. We have developed and applied new breakthrough wide azimuth seismic acquisition and processing technology for subsalt imaging.

The Mad Dog field is located approximately 140 miles south of the Louisiana coastline in the southern Green Canyon area in water depths between 4100 feet to 6000 feet. The complex salt canopy overlying a large portion of the field results in generally poor seismic data quality on narrow azimuth seismic data. Advanced processing techniques improved the image, but gaps still remained even after several years of technology development and application effort. We concluded that wide azimuth acquisition was required to illuminate the field in a new way and conducted the industry's first at-scale Wide Azimuth Towed Streamer (WATS) survey over Mad Dog in 2004/2005. The initial results provided significant enhancement over the narrow azimuth data, immediately impacting well decisions. Subsequent reprocessing using new and emerging wide azimuth techniques and a complete rebuild of the salt velocity model provided further enhancements in data quality with the products being fully utilised in subsurface decisions on the field. The need to mitigate business risks in highly material subsalt plays led BP to explore the technical limits of the seismic method, testing novel acquisition techniques to improve illumination and signal to noise ratio. These were successful in illuminating previously hidden parts of the field.

AAPG Search and Discover Article #90085 © 2008 GCAGS 58th Annual Meeting, Houston, Texas