Shell Alaska has corporate status in Alaska. Greenpeace is registered as a charity in the US that solicits donations in every state. Greenpeace boarded the rig which is bound for Alaska to protest drilling in Alaska. That is why Shell is suing Greenpeace in Alaska.
Alaska is much better choice for Shell than uber liberal greenie Seattle. If Shell were really smart, they would have changed course and taken the rig straight to Dutch Harbor so the Greenpeace pirates could be arrested by the USCG in Alaska.