Just take a second to fathom what 10,000 feet of water actually is. That’s nearly two miles. It would take an average runner 15-20 minutes to run from the top of the offshore rig down to the bottom of the ocean where it’s extracting petroleum.
Furthermore, it’s mind-boggling to compare this 10,000-foot feat to the deepest part of the world–the Mariana Trench off the coast of Guam. This trench is just over 36,000 feet in depth, compared to the average ocean depth of about 12,000 feet. When stacked up against these figures, it’s clear that humans have managed to basically tame the ocean and drill wherever they want.
It takes a great amount of engineering to accomplish this, however. The first offshore rigs of the 1960’s operated in about 600 feet of water. It wasn’t until the 1990’s that we started to drill in 3,000 feet of water, which still isn’t all that close to 10,000 feet.
So, how do we do it?
Well, the reality is we have to use floating vessels at this particular depth.
Two types of rigs are used for this: A deepwater semi-submersible vessel, or what’s known as a drillship.
The semi-submersible has a system of anchors and mooring lines that take time to deploy at each new location. They have four large vertical columns and submerged pontoons that hold it in place, making them extremely stable in rough seas–even more stable than ships.
Drillships have a different function since they’re designed like ships. They’re used more for well exploration and completion than anything else. And since they’re basically a ship, they have high mobility and can move to new locations much easier than a semi-submersible.