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Llano Subsea Development
Llano is located in Garden Banks Blocks 385 and 386 in the Gulf of Mexico about 200 miles southeast of New Orleans in approximately 2,600 feet of water.
Effective August 7, 2002, the entities of Enterprise Oil Louisiana Inc. and Enterprise Oil Gulf of Mexico merged into Enterprise Oil Gulf of Mexico Inc. (25% owner in GB 385 and 30% owner in GB 386) and changed its name to Shell Gulf of Mexico Inc. Enterprise Oil had acquired the field from Enserch Exploration (EEX) in 1997. Enserch Exploration (EEX) originally acquired GB 385 in OCS Lease Sale 161 in 1996. Exxon and EP Operating acquired GB 386 in OCS Lease Sale 115 in 1988.
Working interests in the Llano Unit are Shell Gulf of Mexico Inc., operator, (27.5%), Hess Corporation (50%), and Mobil Producing Texas & New Mexico Inc. (22.5%).
After two sidetracks, the discovery well was drilled to measured depth of approximately 27,800 feet in 1998 using the Transocean Voyager & Omega. The target reserves are in turbidite sands at depths of approximately 24,000 feet subsea in the Pliocene layer and 26,000 feet subsea in the Miocene layer of the Gulf of Mexico. Located in two zones, the net thickness averages 150 feet in the Pliocene and 95 feet in the Miocene.
The reserves are both oil and gas.
Shell’s initial working interest in the Llano well LL3 is 35% subject to the terms of the joint venture agreement. The LL3 well drilling and completion campaign from the Ocean Baroness began on Sept. 3, 2009 and was completed to a depth of 27,410 feet into the Miocene layer.
Development Plans
Shell developed Llano utilizing a subsea system tied back 10.14 miles to its Auger tension leg platform on Garden Banks Block 426 in 2,860 feet of water.
The expandable subsea system initially consisted of two wells tied back to Auger via an 8 x 12-inch pipe-in-pipe looped flowline. Llano is SEPCo’s second project to utilize 15,000-psi subsea equipment.
Major contractors participating in this development are:
- FMC
- SIMRAD
- Sea Cat
- Tenaris
- V&M
In April 2010, LL3 installation and commissioning to the Llano subsea system was completed. LL3 was tied into the existing infrastructure by connecting a manifold into the existing flowline loop with two flowline jumpers. The LL3 subsea tree was then connected to that manifold using a well flowline jumper.
Production
Llano production began April 29, 2004 through one well. The second well came on stream May 25.
The LL3 well production began on April 6, 2010.
