Shell is preserving its options to drill for oil in Arctic waters next year by filing a revised exploration plan with federal officials.

A subsidiary of Royal Dutch Shell PLC filed the revised plan Thursday with the Bureau of Ocean Energy Management in Anchorage.

Shell Alaska spokesman Curtis Smith says in an email that the plan calls for two drilling vessels to operate in the Chukchi (chuk-CHEE') Sea.

Smith says the filing of the plan is not a final decision to drill in 2015 but it lets Shell keep its options open.

The last time Shell drilled in Arctic waters was in 2012.

Smith says drilling would require a successful resolution to federal supplemental environmental work. That's required after an appeals court concluded that an environmental review preceding the 2008 Chukchi lease sale was flawed.