|Shell Oil has posted this graphic of the Perdido well compared to other|
wells in the Gulf of Mexico. Note the progression from shallow to deep over
the past 30 years.
A major part of the Perdido "spar" was constructed in Finland, and it took an 8,200 mile journey to Texas over a three month period in 2008. The spar is 555 feet long, attached to the sea floor. The drilling and production platform was constructed on top of the spar. About 270 people live on the platform and an "adjacent floating hotel (a flotel)." There are 22 vertical access wells from the spar.
Equally impressive is that the well is several miles away from the Perdido drilling and production that serves it, and other wells that are up to seven miles away. The oil has to flow along an incline on the sea floor before being pumped vertically to the platform. Shell says that the reservoir is a low-ressure reservoir which, I assume, means that it's mostly oil and not gas. The low pressure made it necessary for engineers to install a system of electrical pumps in the seabed to help get the oil to the surface, a technology that didn't exist when Shell purchased the lease in 1996.
A bit of an alarm bell went off when I got to the end of the article. According to Don Van Nieuwenhuise of the University of Houston, producing from this depth is pushing up against the limits of safety equipment which is designed, only recently, to be used in up to 10,000 feet of water. Well control equipment has been designed or redesigned for this limit in the aftermath of the Deepwater Horizon accident last year. Ven Nieuwenhuise says "They are getting real close to the limit of what we can do safely." To which, the shell spokesman, Jaryl Strong, replies "There are a number of safety innovations built into the Perdido platform to accomodate the environment it is in, in terms of the great depths and long distance from shore. Safety was the No. 1 priority."