CIMC Delivers Semisubs OOS Gretha, OOS Prometheus

China's Yantai CIMC Raffles Shipyard Limited (CIMC Raffles) announced Monday that a naming and delivery ceremony for OOS Gretha and OOS Prometheus was held at its yard in Yantai, China Nov. 25. These two semisubmersible drilling rigs were designed and built by the company, which reserves the complete intellectual property.

The OOS Gretha measures 451 feet (137.5 meters) in length, beam 265 feet (81 meters), depth (base line to main deck) 127 feet or 39 meters. It has a maximum variable load of 7,070 tons and can accommodate 618 people. The semisub is also equipped with dynamic positioning 3 (DP3) system, which was classed by ABS. It is the first asymmetric semisubmersible unit without bracing in the world, which reduced the towing resistance and dynamic positioning load, improved the sailing speed greatly and made its average transit speed from about 8 knots to more than 12 knots. Asymmetric pontoon outline with pneumatic de-ballast system is very useful for quick ballast adjustment to suit heavy lifting operation. The vessel is designed and equipped with 2 sets of 1,800 tons offshore mast crane which can perform tandem lifting. The improved movement performance can withstand over 72 feet (22 meters) high sea wave. All of the features enable this vessel to serve in West Africa, Brazil, Gulf of Mexico and the North Sea, as well as to meet the quality specification of UK HSE. We have independent intellectual property rights in 12 areas (2 overseas and 10 in China).

The sister semisub OOS Prometheus measures 387 feet (118 meters) in length, width 229 feet (70 meters) and depth 124 feet (38 meters). It has a maximum variable load 5,000 tones and can accommodate 500 people. The ABS-classed semisub can operate at a maximum depth of 3,281 feet (1,000 meters). It is equipped with a set of 1,100 ton deck crane and has clear space of 32,291 square feet (3,000 square meters), which provide plenty of storage room for large sized offshore equipments.

The two boats were designed and constructed by CIMC Raffles in-house, from basic design, detail design to shop design. CSIC 702 institute and Harbin Engineering University participated into the basic design, for seakeeping test, towing basin test and wind tunnel experiment.

Brazil is rich in oil and gas resources in deep sea, which is the main market for deepwater drilling rigs to operate. At present, over 25 percent drilling rigs of the world are serving in Brazil. CIMC Raffles delivered two deepwater semisubmersibles - SS Pantanal and SS Amazonia - in October 2010 and April 2011, respectively. Now the SS Pantanal is wildcatting the 14th oil well in Campos Basin, and the SS Amazonia, the 4th in Santos Basin, both of them working for Petrobras, and so will the OOS Gretha and OOS Prometheus.