Transco slates pipeline expansion in gulf

Proposed Deepwater Gulf Gas Pipelines [39992 bytes]

Transcontinental Gas Pipe Line Corp. (Transco), Houston, is planning a big expansion of an offshore gas pipeline to support deepwater development in the Gulf of Mexico.

The two-phase, $129 million project will add 660 MMcfd of capacity to the Southeast Louisiana Gathering System (Selags) off Louisiana in the central gulf. Selags' total capacity after completion of phase two facilities will total about 1.935 bcfd.

Transco's expansion plans mark the fifth disclosure since May of offshore pipeline projects aimed at boosting gas transportation capacity in the Gulf of Mexico, mostly for deepwater fields. The five projects together will add more than 3.5 bcfd of new transportation capacity in the central Gulf of Mexico by January 1999. Earlier:

Texaco Natural Gas (TNG) unit of Texaco Inc. in May unveiled a $300 million program to construct Discovery gas gathering, transmission, and processing system to provide 600-750 MMcfd of capacity mostly for fields coming on line in the central gulf (OGJ, May 27, p. 24). Discovery Gas Transmission LLC Sept. 5 disclosed an open season through Sept. 24 for shippers seeking firm transportation capacity on the system.
Marathon Oil Co., Shell Oil Co., and a unit of DeepTech International Inc., Houston, in July said they will build Nautilus offshore pipeline and expand Manta Ray gathering system at a cost of about $220 million to add as much as 600 MMcfd of gas transportation capacity in the gulf's Eugene Island, Ship Shoal, South Timbalier, Ewing Bank, and Green Canyon areas (OGJ, July 15, p. 23).
Destin Pipeline Co. unit of Southern Natural Gas Co., Birmingham, Ala., in late July said it is planning a $294 million program to add as much as 1 bcfd of gas transportation capacity off Mississippi in the east-central gulf's Mobile, Viosca Knoll, and Main Pass-East Addition planning areas (OGJ, Aug. 5, p. 21).
Dauphin Island Gathering Partners, Houston-a general partnership of MCN Corp., Detroit, PanEnergy Corp., Houston, and Offshore Energy Development Corp., The Woodlands, Tex.-last month said it plans to boost capacity of Dauphin Island Gathering System 450-550 MMcfd off Alabama in the Mobile, Viosca Knoll, and Main Pass East areas (OGJ, Aug. 19, p. 32).

Selags expansion details

Transco in phase one of the Selags expansion plans to lay a 50.7 mile, 30 in. pipeline loop from Ship Shoal Block 14 to Ship Shoal Block 214, increasing Selags capacity by about 380 MMcfd.

Phase one facilities, which include piping and related modifications on the Block 14 platform, are to be in service by November 1997.

Phase two of the project calls for installation of 26.9 miles of 30 in. loop from Ship Shoal 214 to a platform to be installed on South Timbalier-South Addition Block 301, at the edge of the gulf's Outer Continental Shelf. Second phase work is to add 280 MMcfd of capacity by November 1998.

In a related project, Transco and Texas Gas Transmission Corp. (TGT), Houston, plan to construct an interconnect at the point near Bayou Piquant in Terrebonne Parish, La., where the two pipeline systems cross. The interconnection is to begin service in 1997. Transco and TGT are units of Williams Cos. Inc., Tulsa.

Another Williams company, Williams Field Services Group (WFS) operates Selags as an agent for Transco.

Transco in February asked the Federal Energy Regulatory Commission for permission to transfer all its gathering facilities to an unregulated unit of WFS. Transco will continue to seek FERC approval of both the transfer and Selags expansions, the latter to avoid delays in meeting the transportation needs of producers of deepwater gas in the central gulf.

Transco's rates on the Selags expansion will be incremental and not affect the rates of current shippers on the system. Transco beginning in mid-September is to conduct a month-long open season for shippers seeking firm transportation capacity on the expanded facilities.

Discovery open season

The 30 in. main line of TNG's Discovery gas pipeline is to extend 105 miles from a gas plant at Larose in Lafourche Parish, La., to a meter station at a platform on Ewing Bank Block 873.

First phase development of the system is to create capacity for as much as 600 MMcfd of gas. But TNG expects capacity will increase as partners lay several laterals off the main line to tie in gas fields along Discovery's route.

Two meter station laterals are planned presently: an 18 in. line to a Texaco platform on South Timbalier Block 200 and a 20 in. line to a platform on Grand Isle-South Addition Block 115 owned by British-Borneo Exploration Inc., Houston.

Discovery gas pipeline system is to serve projects coming on line in the central gulf, mostly in the deepwater parts of South Timbalier, Grand Isle, Ewing Bank, Green Canyon, Mississippi Canyon, and Atwater Valley federal planning areas.

TNG expects to complete Discovery gas pipeline in time to begin operations in third quarter 1997.