The oil and natural gas industries require sprawling, complex infrastructure that can be extremely difficult to monitor. Launch a drone, though, and suddenly these chores become much more efficient.
For example, offshore oil rigs are notoriously hard to access. They're miles out at sea, and there are a whole lot of them -- thousands are in the Gulf of Mexico alone. With drones, engineers on shore can look for safety problems, detect oil leaks, and patrol their rigs for any sign of trespassing.
Both natural gas and oil require many miles of pipeline, and it's tough for companies to keep tabs on these investments. Program a few drones to fly along a pipeline route, though, and the automated camera can send back a stream of images that can detect problems, whether they are nearby or in extremely remote locations.
Drones aren't just about safety, though. Companies also use them to explore the Earth for new sources of oil and gas. With the right kind of laser and infrared sensors attached to a drone, they can conduct surveys of terrain and get a better idea of where they might find deposits of energy sources.