These are the depths to which we will go for oil: 30,000 feet. Grist's Amanda Griscom Little describes the process: First drop that drill through two miles of water, then through 20,000 feet of rock and sediment to find that layer of oil. Finding it was tough enough; getting it out will cost billions. ::Wired
1) Stable platform
Giant engines at each corner of the drilling rig keep everything stable. When the ocean pulls one way, the thrusters push the other.
2) The 6-mile Drill
The drill is made up of hundreds of interlocking 90-foot sections of iron. Buoyant sidings reduce the weight burden on the rig.
3) Point of entry
The drill needs to enter the seafloor at exactly the right point, minimizing the risk of hitting an air pocket or a fault as it goes whirring down. Boiling-hot oil emerges here and collides with freezing water, which means that the underwater pipes pumping the oil back to shore must be heavily insulated.
4) Dangerous journey
The drill must traverse numerous pressure zones, any one of which could knock it off course.
5) X marks the spot
Bedrock mounds, formed by oil pushing upward, signal promising hot spots.
The oil is trapped in squishy, porous rock.