Biggest production semi headed for Brazil

Sept. 20, 1999
The world's largest semisubmersible drilling-production platform has been handed over to Petroleo Brasileiro SA, after 2 years of modifications in a shipyard at Davie, Que.
The P-36 semisubmersible drilling-production platform, claimed to be the largest of its kind in the world, is undergoing a revamp at a Davie, Que., shipyard, for operator Petroleo Brasileiro SA for installation in Roncador field in the Campos basin off Brazil. Petromec, a unit of Brazil's Mar!tima. Construcoes Navai, is handling the upgrade. Photo courtesy of Marítima.
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The world's largest semisubmersible drilling-production platform has been handed over to Petroleo Brasileiro SA, after 2 years of modifications in a shipyard at Davie, Que.

Petromec, a subsidiary of Brazilian offshore engineering and construction firm Maritima Construcoes Navai, handled the upgrade project.

A Petrobras official said that about $300 million was invested to upgrade the platform, which will arrive in Brazil in October.

The P-36 platform will be towed to Rio de Janeiro aboard a ship reinforced for this purpose. "This is the largest dry-tow operation ever undertaken by the petroleum industry," said Wagner Victer, Rio de Janeiro state's energy and shipping secretary and a former Petrobras engineer.

Platform upgrade

The P-36, formerly the Spirit of Columbus semisubmersible drilling rig, was modified for installation as a production facility in supergiant Roncador oil field, in more than 1,300 m of water in the Campos basin off Rio de Janeiro state. The original drilling facilities and most of the production equipment were stripped out. The original utility systems remained, but these required overhauls and some upgrades.

In order to accommodate larger production facilities, a new, 13-m long cantilever extension spanning all of the aft main deck was added. To comply with new stability and buoyancy criteria, modifications to the columns, pontoons, and central caisson were required, entailing expansion of blisters and addition of buoyancy boxes.

In addition, a spider deck was created 5 m below the lowest existing deck (with a tank top elevation of 35 m) , enabling pull-in operations to be craned out, say Petrobras officials. This added 2,400 tons of steel plus about 5,300 tons of piping and equipment to the unit.

Ninety steel catenary risers (SCRs), installed in 1,360 m of water and weighing more than a combined 5,200 tons, will be hung off the platform.

The P-36 has a displacement of 56,503 tons, weighs 32,400 dwt, has 60 rooms, a gym, a restaurant, and a hospital.

The platform will generate electricity for its own consumption, fired by the natural gas it produces. "The P-36 will be of great importance for Rio de Janeiro state's economy, because it will increase natural gas supply for the thermoelectric plants that will be built in the state," Victer said.

Roncador project

Roncador is a 132 sq km area that holds oil reserves estimated at 3 billion boe. It has the world's deepest offshore producing well-producing 20,000 b/d of crude oil-in 1,853 m of water. Discovered in October 1996 with the 1-RJS-436 wildcat, Roncador lies in 1,500-2,000 m of water northeast of Albacora and Frade fields.

Development plans comprise three phases, beyond the currently producing pilot producing system. Total investment for Roncador is estimated at $2 billion, for which Petrobras expects to secure outside project financing, say company officials.

Roncador's first-phase permanent production system will come on stream in early 2000. In this phase, the northern and eastern areas will be developed, with 21 wells producing 31° gravity oil. Phase 1 comprises the P-36 host unit, with a processing plant connected via flexible flow lines to the 21 subsea producers and 5 water injectors.

Oil production will be transferred to the P-47 floating storage and offloading unit via three export lines, two umbilicals, and one SCR.

The first phase is expected to go on stream in March 2000.

The second-phase development contract is to be awarded by the end of 2000, for producing the southwestern area, in water depths of 1,500-1,850 m. The third phase is for development of the deepest-water area, the southeast.

Roncador peak production of 180,000 b/d of crude oil and 7.6 million cu m/day of natural gas-which is equal to about 20% of current Campos basin output-is expected in 2001. This volume will contribute to the Petrobras target of reaching 1.3 million b/d by the end of 2000, up from the current level of 1.1 million b/d.