What are Oil rigs?

Answer 1

The Offshore Oil Rig is a large platform constructed and anchored in the ocean waters designed to drill into the ocean bottom and extract fossil fuels like gas and oil. It contains a drilling tower, cranes for laying pipes, a helicopter landing platform, emergency evacuation lifeboats or other safety devices, several story buildings containing everything from crew quarters, kitchen, recreation, maintenance, storage. It can be a hazardous place to work and often the crew must live there for long periods of time. The oil that is pulled up must then be either piped ashore or offloaded onto large oil tanker ships for eventual storage and refining.
An oil rig can be a platform out at sea where oil is brought up from deep under the ground to the rig.

Alternatively OIL RIG can be a handy way to remember the effects of oxidation and reduction.

i.e Oxidation Is Loss. OIL

Reduction Is Gain RIG