Jackpot! Under miles of water and ancient rock lies oil

InTech, Oct 2006

The technology behind Chevron and partners' discovery of oil beneath 7,000 feet of Gulf of Mexico water and 29,000 feet of earth is beyond Jules Verne.

Satellite positioning, sensors on drilling templates, sound waves, acoustic data collection, computer processing, computer modeling, and visualization laboratories configured as some giant and complicated animal of automation.

The Sacramento Bee reported giant new drill ships and sophisticated computer technology made it all possible.

Drill ships more than seven football fields long have drilling platforms and derricks in their centers. They rely on electric motors beneath their hulls to maintain their positions over the drill sites or wells.

Their electric motors work in tandem with onboard computer systems that keep the vessels above the drill sites or wells by using satellite positioning technology and sensors.

The drilling itself uses heavy, massive diamond bits. Giant pumps circulate the drilling mud as layers of drill pipe force their way down via top drives that rotate the drill pipes as heavy additional pipe adds on.

Visualize the process as giant drinking straws connected one to another in a long chain. Those that stretch down almost 6 miles apply more than a million pounds of pressure.

The next generation of gargantuan ultra-deep-water drill ships, two of which Chevron ordered this year for deployment in 2010, will be able to drill below 12,000 feet of water to a depth of about 7.6 miles from the ocean's surface to the bottom of the well.

Complementing the new ships and rigs are advances in computer modeling and seismic imaging that allow geologists to estimate accurately what lies miles below the ocean floor.

As far as the search science goes, tow vessels drag up to nine cables, each stretching as much as 33,000 feet that shoot sound waves along the ocean floor.

Computers process and generate threedimensional images for geologists and engineers to examine in "visualization" laboratories.

What had long stymied ultra-deep exploration were thick layers of salt below the ocean floor that distorted the sound waves geologists use to gauge density. That made it difficult to assess the rock formations below the salt layers to determine whether they held trapped hydrocarbons.

More powerful computers and software advances helped overcome salt layer-imaging problems, allowing for remarkably accurate computer modeling.

Devon Energy, which holds many exploration leases in the Gulf of Mexico, boasts four strikes in six drills. The usual success ratio is closer to 10%.