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STANCLIFFE, RICHARD J., and MICHAEL C. JACOBI, Shell Deepwater Production Inc., New Orleans, Louisiana

Abstract: The Ursa Project, A Geologic and Developmental Overview of a Giant Oilfield in the Deepwater, Gulf of Mexico

The Ursa project (Mississippi Canyon block 809 field) is located within an intraslope, salt-bounded minibasin approximately 26 miles downdip of the current shelf-slope break and 95 miles south of the city of New Orleans in the deepwater Gulf of Mexico. Located seven miles northeast, and in the same minibasin, is the Mars field currently on production by Shell and BP. Shell with partners BP, Conoco, and Exxon are developing Ursa from a TLP located in approximately 3,800 feet of water.

Since the discovery well in 1990, two appraisal wells and two extended sidetracks have been drilled at project Ursa.These wells, combined with 3D seismic mapping and pressure data, have documented ten sands and 20 reservoirs bearing hydrocarbons of economic importance. At Ursa, as is the case with most Gulf of Mexico fields, amplitude supported pay is the norm.

All hydrocarbon accumulations at Ursa are located in fault and/or salt bounded anticlinal closure, yet each display significant stratigraphic bounding elements. Pay horizons range in depth from 12,000 feet subsea to below 19,000 feet subsea and are late Miocene to early Pliocene in age. The reservoirs are typically comprised of thick, high quality, turbidite sands with porosities ranging between 24% and 30% and permeabilities between 200 and 800 md.

Total reserves of 400 MMBEQ will be developed from an 11 slot TLP installed in December of 1998.The Yellow sand horizon contains approximately 50% of field reserves, and is the objective of the first three development wells at Ursa. Initial flow rates of up to 30,000 BOPD are anticipated per well, while daily facility capacity is 150 MBO and 400 MMCF. Significant learnings related to continuity and reservoir performances are expected after initial production in early 1999.

AAPG Search and Discovery Article #[email protected] International Conference and Exhibition, Birmingham, England