What is "oilrigs"

Usage examples of "oilrigs".

Instead they used it to haul oilrigs through twenty-foot swells in the North Atlantic.

There was a vein of murder snaking across the continent beneath highways, smokestacks, oilrigs and gasworks, a casual savagery fed by the mute cities, and I wondered what impossible distance must be traveled to get from there to here, what language crossed, how many levels of being.