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Tahoe Subsea Development
The Tahoe Unit encompasses two OCS leases, acquired in April 1984 and May 1985, in the Viosca Knoll Area Blocks 783 and 827. The blocks are located in the Gulf of Mexico approximately 140 miles east, southeast of New Orleans and 105 miles south of Mobile, Alabama, in 1,500 foot water depth.
Shell Deepwater Production Inc. is the operator and has a 70 percent interest in wells and subsea systems. Murphy Exploration and Production Company has the remaining 30 percent interest. Shell has 100 percent interest in the platforms and surface facilities. The discovery well was drilled in 1984 on Viosca Knoll 783. Four wells and three sidetracks were drilled to evaluate the discovery.
Development and Production
Tahoe was developed initially using one subsea well tied back to SOI platform "Bud" at Main Pass 252, 12 miles away. The subsea tree was originally used on Placid’s Green Canyon 29 project and was refurbished for use at Tahoe. Oceaneering Production Systems provided engineering, procurement and installation services for the subsea system.
Beginning in January 1994, Phase I development was designed to produce about 30 million cubic feet of natural gas and 1,000 barrels of condensate per day.
The decision to proceed with Phase Two development was made in June 1995. Phase II development consists of three gas wells and one oil well. One of the gas wells is a single satellite well, Viosca Knoll 783 No. 5, with its own umbilical and two 6" flowlines.
The other two gas wells and the oil well are located in a central cluster and share electrohydraulic and chemical injection umbilicals via an umbilical termination structure and hydraulic distribution manifold. The two central cluster gas wells are daisy chained, sharing a pair of 6" flowlines and the oil well is served by two 4"x8 pipe in pipe insulated flowlines.
Drilling of the four Phase II wells began in September 1995, using Arethusa’s semisubmersible, "Concord". All of the wells are horizontal producers.
FMC | Wellheads and Christmas trees |
|---|---|
| Kvaerner FSSL | Subsea control system |
| Global Plus | Flowline |
| Coflexip/Stena/Duco | Umbilical fabrication and installation |
Phase Two wells are tied back to new facilities (Bud Lite) located at Main Pass 252. The Bud Lite facilities are located on a new jacket bridge connected to the existing Bud platform. Bud Lite is a hybrid of a new jacket and older deck and facilities taken from SOI’s Picaroon Field located at Brazos Block A19, C Platform.
McDermott was the contractor for the jacket fabrication and jacket and deck installation. The platform installation was completed in May 1996.
Production from Phase II began in August 1996 from the #5 well. The three other wells began production in April 1997.
Southeast Tahoe
Southeast Tahoe is a 100% Shell-owned field discovered in March 1996 and located in Block Viosca Knoll 784. Completed in June 1996, it is a single satellite well tied back to the Bud Lite facility, 13 miles away. First production began in October of 1996.