REFILE-Petrobras asks court to suspend injunction banning Transocean

* Transocean ban could take place by Oct. 27

* Petrobras stands to lose seven drill rigs

* Rigs are key to Petrobras oil expansion plans

* Petrobras may need to lease new drill ships

SAO PAULO, Sept 28 (Reuters) - Brazilian state-led oil company Petrobras said on Friday it filed suit to suspend an injunction banning drill-rig operator Transocean from operating in the country, a ban that could seriously disrupt Petrobras' exploration activities.

If the ban is not overturned or suspended, work on 10 Transocean rigs in Brazil, seven of them working for Petrobras, will stop by Oct. 27, Petrobras said in a statement.

The motion by Petrobras follows a request by the national oil regulator ANP in a Rio de Janeiro federal courts on Sept. 17 to overturn the injunction, the filing said.

A lack of drilling rigs able to drill in waters more than 2,000 meters deep is one of the main problems that has helped Petrobras production stagnate in recently despite a $237 billion five-year expansion plan, Chief Executive Maria das Gracas Foster said earlier this month.

The Transocean ban is related to a lawsuit seeking nearly $20 billion from the rig operator and Chevron Corp. for a November oil spill in the Frade offshore field northeast of Rio de Janeiro. If not overturned the ban will stay in effect until the legal issues related to the spill are settled.

Chevron had contracted Transocean's Sedco 706 rig to drill in Frade. Chevron and Transocean say they were not negligent in the spill and are fighting the lawsuits, related criminal charges and the ban in the courts.

Brazil's oil regulator ANP said in a July report that Transocean had no responsibility for the spill.

Petrobras said it is also analyzing other legal and operational actions in case the injunction goes into force next month and suspends Transocean's operations in Brazil.

These actions include the possibility of leasing oil rigs to replace the Transocean equipment.