The eight hostages were released six hours after being abducted on Thursday from the facility, a stationary vessel that produces, stores and exports crude oil, located 34 miles off the coast of the Niger Delta.

Africa"s largest oil producer has been plagued by supply disruptions for more than a year.

Companies have detailed around 652,000 bpd of lost oil, about 25 percent of Nigeria"s three million bpd production capacity.

FORCADOS AND EA - Shell

- Nigeria"s biggest foreign operator Royal Dutch Shell <RDSa.L> has kept its Forcados and EA oilfields shut for nearly a year after they were attacked by the Movement for the Emancipation of the Niger Delta (MEND).

The February 2006 attacks wiped out 477,000 bpd of Shell-operated output.

Nigeria"s oil minister Edmund Daukoru has said another 100,000 bpd of output is believed shut from other producers that use the Shell infrastructure to transport and export oil. But company officials could not confirm this.

Daukoru said the Forcados oilfields will resume production by the end of the month. Shell officials have declined to specify a time, saying only it may resume in June.

BRASS - Eni

- Eni <ENI.MI> suspended some 40,000 bpd of oil production at its Tebidaba flow station, which is connected to the Brass River terminal, after repeated attacks on the facility in the last two months.

ESCRAVOS - Chevron

- About 70,000 bpd of Chevron"s <CVX.N> Escravos production remained shut-in since inter-ethnic fighting disrupted output in 2003.

PENNINGTON - Chevron

- About 15,000 bpd of Chevron"s Pennington output was shut down this week after it closed the offshore Funiwa oilfield due to security concerns.

OKONO - Saipem <SPMI.MI> and SBM Offshore <SBMO.AS>

-         The abduction of eight foreign workers from the Okono/Okpoho offshore oilfield on Thursday prompted the shutdown of 50,000 barrels per day of production.

PIN/REUTERS