Self-elevating Offshore Drilling Rig

One of the most striking (and larger) models on display at the Houston Maritime Museum in the Energy Industry exhibit is the self-elevating offshore drilling rig “OFFSHORE MISCHIEF”. Properly referred to in the offshore industry as a mobile offshore drilling unit or “MODU”. This enormous machine is among the largest of its kind in service today designed by an American engineering company LeTourneau.

This MODU was constructed by Lamprell-Sharjah shipbuilding in the UAE, and delivered to its owner/operator SEADRILL in 2010. Subsequent to delivery, the unit commenced to drill for an oil and gas exploration company on a day rate (daily rental) basis. This MODU is designed primarily for exploratory drilling in the deeper waters of the continental shelf. The
OFFSHORE MISCHIEF is capable of drilling in waters up to 350′ deep (about the depth or a 30 story building) by lowering its three steel truss legs (each about 477′ long) by means of large jacking gears located in each corner of the rig hull where the legs are located. The lower end of the legs (cans) are firmly planted on the ocean floor to support the massive weight of the rig itself and up to another 750 tons comprised of 25,000 feet of 5 1/2′ steel drill pipe when in the hole.

Jack-up rigs of this type are generally not self-propelled and must be towed to the next drilling location by ocean-going tugs. Statistically, the rig is 243′ long, 206′ wide, incorporates a derrick 170′ tall, is powered by a total of
10,750 diesel-electric horsepower and supports a crew of 105 soles.

By: Tom Johnson, Docent

Excerpt taken from The Anchor Newsletter, July, 2014.