* Judge asks for bond of about $275,000 from rig employee
* Employee said to have accepted new job in U.S.
* Employee agreed to cooperate, return to Brazil-judge
* Two other accused workers previously allowed to leave
RIO DE JANEIRO, April 4 (Reuters) - A judge in Brazil gave permission to one of the 17 Chevron and Transocean employees facing criminal charges over a November offshore oil spill to leave the country, documents released by a federal court on W edn esday showed.
The permission is conditional on the payment of a 500,000 real ($275,000) bond, the court said.
Jason Warren Clendenen, who for Chevron helped manage the use of drilling mud on Transocean's Sedco 706 rig in the Chevron-operated Frade field northeast of Rio de Janeiro, accepted a new job in the United States during the investigation, judge Claudio Gerão Barreto of Brazil's Federal Court in Campos wrote in his ruling.
Clendenen has shown willingness to cooperate with Brazilian authorities, and pending the payment of the bond and signing of an agreement to return to face proceedings, his absence from Brazil will be permitted, the judge wrote.
The bond payment was needed because Clendenen does not have work reasons to return to Brazil and because a judicial treaty between the United States and Brazil is not sufficient to ensure his return, the judge wrote.
On March 16, several days before the filing of criminal charges, Clendenen and 16 others, including Transocean and Chevron's Brazil chiefs, were ordered to turn in their passports and remain in the country.
Ahead of the filing, the judge gave two of the 17 employees, Gary Marcel Slaney and Brian Mara, permission to leave Brazil without posting bonds. Both are expected to return to work on the Sedco 706 after visits with their families abroad.
The 17 Transocean and Chevron employees face prison terms of up to 31 years if convicted. The prosecutor who filed the charges has also filed two 20 billion real ($10.9 billion) lawsuits against the companies, one for the November spill and another for a leak in March.
The November discharge leaked an estimated 3,000 barrels. By comparison, BP's 2010 Macondo disaster in the Gulf of Mexico spilled 4.9 million barrels.
The March leak, which remains unexplained, spilled less than two barrels, Chevron said. No oil from either spill reached Brazil's coast.
Brazilian prosecutor Eduardo Santos de Oliveira, who filed the initial civil and criminal cases, considers the November spill one of the worst-ever ecological disasters in Brazil.
Chevron and Transocean have said they committed no crimes, consider the charges excessive, that their employees acted properly, and that they will cooperate with authorities and defend themselves and their employees from all charges and claims.