Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Reducing Structural Uncertainty at Tahiti Field Using TTI WAZ Imaging
(1) Chevron North America Exploration and Production Company, Houston, TX.
(2) Chevron North America Exploration and Production Company, Houston, TX.
(3) Chevron North America Exploration and Production Company, Houston, TX.
The Tahiti field is a major Chevron asset in the deepwater Gulf of Mexico, located 190 miles south of New Orleans in 4,100 feet of water. Discovered in 2002, the field started production in May 2009 from the primary Miocene reservoir, reaching facility capacity within three months of start-up. The reservoir section is at a depth of 23,000 to 28,000 feet subsea, below a thick salt canopy and trapped against a near-vertical salt face with structural dips approaching 80 degrees. The imaging challenges associated with this type of geometry required the latest technology in seismic acquisition, velocity model definition and pre-stack depth migration to reduce the structural uncertainty.
Over the past decade Chevron has re-imaged the Tahiti field with multiple iterations of proprietary earth modeling and depth imaging on narrow azimuth seismic data. These surveys were used to successfully position wells for the first phase of the Tahiti development. However, reservoir scale mapping and fault definition remained challenging, and a certain degree of structural uncertainty remained. In 2009-10, the Tahiti partners, led by Chevron, initiated a re-imaging project incorporating the multi client wide azimuth (WAZ) seismic data acquired by WesternGeco and the latest technologies in multiple attenuation, tilted transverse isotropy (TTI), Reverse Time Migration and Beam imaging.
The Tahiti TTI WAZ re-imaging project delivered significantly enhanced structural imaging for future field development. The project benefited from all the positive attributes of WAZ acquisition including increased azimuth, fold, inherent multiple attenuation and increased offset. The latest noise and multiple attenuation, including WesternGeco’s GSMP-SRME, provided cleaner data with enhanced signal-to-noise, especially subsalt. Earth models representing multi-azimuth subsurface velocities, TTI parameters, ties to well data, and detailed salt interpretation resulted in a higher confidence structural image. Advanced imaging routines including Gaussian Beam and Reverse Time Migration provided final images that are reducing uncertainty in the current development phase as well as impacting decisions in the next Phase of development.
This talk will showcase the power of the latest seismic acquisition and imaging technologies on a major deepwater Gulf of Mexico subsalt field development.