At a shipyard in São Roque do Paraguaçu, in Maragojipe county, Bahia, 1,700 workers since September 2008 have been building two self-raising jack-up platforms for Petrobras, christened P-59 and P-60. The project is the responsibility of Consórcio Rio Paraguaçu, a joint venture of Odebrecht, Queiroz Galvão and UTC Engenharia. Each rig will cost BRL 370 million. As construction moves ahead at the jobsite, some important procedures are being carried out far away, including tests of scale models in Rio de Janeiro, which will enable the joint venture to implement an engineering solution that is unprecedented anywhere in the world.

From June 2009 to March of this year, Mario Moura and Jacques Raigorodsky, respectively the project’s Field Engineer and Technical Consultant, headed up studies of methods that could be used to launch offshore oil platforms. The three main methods currently employed are fixed ramps, using a sloping structure at the yard to slide the rigs into the water; building the rigs in dry dock, also at the yard, where the platform is built (in the end, the dry dock is filled with water and the platform floats through the main sluice) and, finally, a submersible barge, which docks at the yard where the platform is loaded onto it. Then the raft sinks until the structure floats free.

As there is neither a fixed ramp nor a dry dock at the São Roque do Paraguaçu yard, and nobody in Brazil owns a submersible barge, the solution would be to build the ramp or dry dock, or even import a barge. None of these solutions would cost less than USD 6 million. Therefore, the joint venture proposed an alternative method to Petrobras: launching the rigs with the BGL-2, the state-owned oil company’s non-submersible barge. “The point is that nobody in the world has never launched a jack-up platform from a floating structure,” says Jacques. “We will carry out an operation that is unprecedented worldwide,” he adds. To prove the feasibility of using the BGL-2, tests were performed with scale models at LabOceano, a laboratory specializing in ocean engineering in Rio de Janeiro.

First, a miniature version of a rig was launched from a fixed ramp. The goal was to obtain data on the platform. Then the rig was tested with a scale model of the BGL-2. It was time to get to know every inch and detail of the relationship between platform and barge. The resulting information was conveyed to the appropriate software. After comparing data from the scale models with the computer program the team started the third phase of tests, which aimed to achieve the most ideal launch possible, with maximum safety.

“When the tests were completed, we found that the closer we can position the platform to the stern of the barge, the lower the risk of damage to the hull of the BGL-2 and the rig,” says Mario Moura. “Now that the testing has been done, everyone feels confident," he stresses. “We are proud to be a part of this landmark moment,” says LabOceano Engineer Cláudio Rodriguez.

Because of their weight (7,700 metric tons each), P-59 and P-60 will be released half-finished into the Paraguaçu River and towed back to the shipyard’s dock to complete their assembly. They are slated for launch in December 2010 and April 2011. The units will be completed in June and October 2011.