How do U wan´t to drive an Oil Rig??? 
Nothing funny about that. In fact most floating oil rigs got their own propulsion system, and they usually don't need any help from tugs, only sometimes when close to shore as a precaution. But they are not exactly fast, 6-8 knots max, and they are never on the move in bad weather. They are using the same propulsion system to stay in position, or anchored to the bottom if staying in the same position for a long period of time.
