Norsk Hydro first with wellbore innovation

Norsk Hydro AS has put innovative lateral wellbore technology to work in Oseberg oil field in the Norwegian North Sea. Hydro's C-12 well on Oseberg Platform C employs the Multilateral System 3000 developed by Halliburton Co., Dallas. Halliburton said while industry has completed hundreds of multilateral wells, including duals and quads with separated production, this is the first use of equipment that provides full bore reentry access to a lateral while maintaining integrity of the main

May 20, 1996

3 min read

Norsk Hydro AS has put innovative lateral wellbore technology to work in Oseberg oil field in the Norwegian North Sea.

Hydro's C-12 well on Oseberg Platform C employs the Multilateral System 3000 developed by Halliburton Co., Dallas.

Halliburton said while industry has completed hundreds of multilateral wells, including duals and quads with separated production, this is the first use of equipment that provides full bore reentry access to a lateral while maintaining integrity of the main wellbore. The system allows commingling of production streams.

Hydro does not plan to produce through both C-12 wellbores at first because of pressure differences between formations. However, as pressure differences decrease with production from one formation, the second wellbore will be placed on production and the streams commingled.

Hydro chose lateral drilling because of the small number of well slots on Platform C and the need to reach remote portions of the field's reservoirs.

System capability

Halliburton said Hydro set a specific goal to increase Oseberg oil recovery and saw multilateral technology as the way to achieve its goal.

"The multilateral system needed the capability to commingle production from primary and secondary formations," Halliburton said. "Due to pressure differentials, each formation would also need to be isolated at various times.

"Additionally, the secondary formation would likely require reperforation during its producing life, so selective reentry to the main and secondary wellbores for running perforating guns and production logs and installing production control devices was a required feature."

The C-12 system uses 95/8 in. casing with a 7 in. liner connected mechanically and isolated at the junction with Halliburton's M-Seal high impact sealant.

A 7 in. production tubing string allows maximum flow in a monobore configuration and full bore reentry access to the lateral.

Halliburton Energy Services, Houston, said its installation of Multilateral System 3000 as "a fully integrated technical solution" combines its project design and management, directional drilling, reservoir description, cementing, and completion capabilities with Brown & Root surface facilities. Weatherford Enterra Inc. worked with Halliburton in development of the system.

Johan Mikkelsen, assistant director of Hydro exploration and production, said, "This multilateral system will allow us to increase recoverable reserves economically. Using this technology, Hydro will produce considerably more oil in certain fields at far lower prices than in the past. This is a milestone for us."

Hydro said three wells in Oseberg field will be multilaterals. The company intends to use the technology in other fields.

The field

Hydro developed Oseberg field, on Blocks 30/6 and 30/9, with bridge-linked Platforms A and B over the southern part of the reservoir and Platform C over the north.

Oseberg held estimated oil reserves of almost 2 billion bbl when production began in December 1988. By the end of 1994, reserves were estimated at more than 1 billion bbl. Production averaged 500,000 b/d last year.

The field's gas reserves of 89 billion cu m have not been tapped. Norway's Ministry of Industry & Energy recently sanctioned a plan to begin Oseberg gas production in 2000 (OGJ, Apr. 1, Newsletter).