Oil rigs are, originally, wells that drill for and collect oil on a planet. In the 40th century, the Oil Corp devised large, insectoid oil rig vehicles that could move and drain oil on other planets after Earth's wells had dried up. Rigs were in use on Boukon, since the planet was full of oil.
As Oil Corp had to deal with pirates, Rigs had inbuilt laser weoponry to deter them, but they were often keel-halled by pirates in such ships as the Black Gold, captained by Kaliko. (DW: The Infinite Quest)
