Here’s a pretty interesting description of an oil rig, used as an example in a technical writing tutorial.
I also found this terrific (but tiny) picture of a drilling platform on a frozen sea. It’s something called the Glomar Beaufort Sea I Concrete Island Drilling System in Alaska. Searching for that found an interesting press release (dated 1997) from GreenPeace about Arco’s Oil Exploration and Development Activities in the Arctic with some details about the platform. It’s part of an archived site about GreenPeace activities in the Arctic Frontier which includes diaries, press releases, writings as well as plenty of photos (a mobile drilling platform – the “Concrete Island” mentioned above, I guess, as well as boats, Arctic scenery and wildlife).