Factbox: Oil companies rally to help in Gulf cleanup

(Reuters) - The spread of a huge oil spill in the Gulf of Mexico has rallied energy companies to work together in the cleanup effort.

A blown out undersea oil well owned by BP Plc is spilling about 5,000 barrels a day, creating a slick measuring at least 130 miles (208km) by 70 miles.

Below is a list of what oil companies have done to assist in the cleanup effort:

Royal Dutch Shell:

- Given BP use of Shell's Robert Training and Conference center in Robert, Louisiana, for use as headquarters for coordinating cleanup efforts.

- Following BP's request, given the company access to Shell's ocean cleanup experts. Shell could not say how many are currently assisting BP.

ExxonMobil:

- Given use of a drilling rig as a staging base, two supply vessels, an underwater vehicle and support vessel.

- It has provided experts to respond to BP's request for technical advice on blowout preventers, dispersant injection, well construction and containment options.

- Is supporting Tier 3 spill response and cleanup cooperatives, such as Marine Spill Response Corporation, Clean Gulf, and Oil Spill Response Ltd., to provide personnel and equipment, such as dispersants, fire boom and radios.

- Procuring and manufacturing additional supplies of dispersant for potential use.

Chevron Corp

- Assigned personnel with expertise in subsea blowout preventer intervention and subsea construction to support BP.

- Personnel from Chevron's 330,000 barrel-per-day Pascagoula, Mississippi, refinery joined the U.S. Coast Guard's local incident command response team in Mobile, Alabama.

- BP contracted the Pascagoula refinery's marine wildlife rescue portable trailer.

(Reporting by Steve James in New York and Kristen Hays in Houston; Editing by David Gregorio)