Pioneering in the Gulf
Pioneering in the Gulf
Reprinted with kind permission from Petrobras Magazine.
Petrobras takes the fi rst FPSO and widely recognized technologies in which it has know-how to the U.S. sector of the Gulf of Mexico and alters the modus operandi in the region.
The largest operator of Floating Production, Storage, and Offl oading oil systems (FPSOs) in the world, with almost three decades of experience, and also internationally renowned for the technology employed in association with its platform ships, Petrobras is exporting this know-how on a pioneering basis to the oil industry shopwindow of the world. It is taking its expertise to the U.S. sector of the Gulf of Mexico, where the largest companies in the energy industry are working, and where the company is going to explore for and produce oil and gas in the Cascade and Chinook fi elds. Accordingly, it will become the fi rst operator in the region to have an FPSO, a disconnectable buoyant turret mooring system, self-sustainable hybrid risers, multiphase submarine pumping, and oil transportation using shuttle tankers. Th is will completely change the methods of operating presently being used there.
Th e use of FPSO units in the region had not previously been allowed by the regulatory agency for activities related to oil, gas, and mineral resources – the Mineral Management Service (MMS) – because all of the active oil fi elds were connected to the land by pipelines. As the Cascade and Chinook fi elds, which are 24km apart and some 250km off the Louisiana coast, are situated in ultra- deep waters, they will be developed simultaneously. Since no constructed oil pipelines are yet available at this distance and such depth, the arrangement is justifi ed. To build such an infrastructure would demand more time and money, which would not be advantageous in the beginning.
The FPSO that Petrobras will operate in the Gulf waters, named BW Pioneer, is 241m long, 42m wide and 20.4m high. It is capable of processing 80,000 barrels of oil per day and will be installed in the fi rst half of 2010, at a water depth of 2,500m, a record for any type of platform. "Th e unit will be used in the fi rst phase of developing the Cascade and Chinook fi elds, in which the objective will be to analyze the performance of the reservoirs so as to optimize the subsequent phases. Petrobras will be the operator in both fi elds, which are situated in the Walker Ridge area," says the Petrobras America vicepresident of Upstream, Gustavo Amaral.
The platform ship is equipped with an internal mooring system using a disconnectable turret buoy. Th is makes the equipment ideal for the region, where there are often very strong currents and winds, gigantic waves, and hurricanes. For example, in the 2009 hurricane season, Hurricane Ida caused the suspension of 29.6% of the oil production and 27.5% of the natural gas extraction. In 2008, Hurricane Ike devastated at least 49 platforms off shore. And in 2005, Hurricane Katrina destroyed 44 platforms in the Gulf, while Hurricane Rita damaged a further 64. In the Gulf as a whole, there are thousands of platforms in operation.
Within this context, the disconnectable turret buoy will function as a piece of safety equipment. "Th e equipment will enable the FPSO to revolve around an axis to position itself according to the most favorable current and wind conditions. Because it is disconnectable, with risers*, umbilicals**, and systems for monitoring the fl oating unit coupled to the buoy, it will become possible, as a hurricane approaches, to disconnect the platform ship from the wells to which it is connected so that it can navigate to calmer waters, where it can remain in safety, returning to the working location when the situation is normalized. Th e rest of the structure will remain below sea level, protected against inclement weather. Accordingly, it will be possible to ensure the safety of the personnel on board, preserve the equipment, and reduce interruptions in operations," explains the manager of Walker Ridge production assets, César Palagi.
When dealing with very deep waters and high pressures, conditions that could lead to the cooling of fl uids and the formation of hydrates or solid elements in the pipelines transporting hydrocarbons, the production lines utilized will be the pipe-in pipe design.
Th e FPSO will remain connected to two wells in the Cascade fi eld and one in the Chinook fi eld during the fi rst phase of the development of the fi elds. In the second phase, more wells from both fi elds will be connected to the fl oating unit.
Regarding the technologies exported to the Gulf, an external mooring system using the more elastic polyester cables will cushion the movements of the FPSO, an advantageous solution in an area subject to stormy weather. It will also avoid the weight of critical loads on the fl oating unit.
Two subsea electric pumping systems will be used to lift the production from the seabed to the FPSO. Th is solution will bring logistical and economic advantages. "Since the pumps will be placed outside the wells, repairs or possible exchanges may be made more easily. Since it will no longer be necessary to intervene in the wells, the production interruption time will be less, as will the costs, even though the initial investment in installing pumps outside the wells is greater than installing them inside," says Palagi.
Th e tubing adopted to transport the oil and gas from the outfl ow lines to the FPSO and the gas from the unit to the export gas pipeline will be self-sustainable hybrid risers. In this system, rigid vertical risers suspended by fl oating elements are extended from the seabed to around 100m below sea level, with the connection to the FPSO being made through fl exible lines. In all, fi ve risers will be used in the fi rst phase of the development of the Cascade and Chinook fi elds. "Th e use of these risers will reduce the weight in the mooring system of the FPSO and ensure the unit greater security in the case of hurricanes," justifi es Palagi.
When dealing with very deep waters and high pressures, conditions that could lead to the cooling of fl uids and the formation of hydrates or solid elements in the pipelines transporting hydrocarbons, the production lines utilized will be the pipe-in pipe design. Th ey will be among the deepest in the world. "We are dealing with a system in which the lines transporting the fl uids are inserted into other lines and the internal lines are thermally insulated with material developed by nanotechnology and put around the ring that connects one tube to another. With this technology, it is possible to operate without constant interruptions despite the cooling of the lines," he goes on to clarify
As for the shuttle tankers, they will constitute the best alternative for the outfl ow of the oil produced in the Cascade and Chinook fi elds, far from the coast of the Gulf, where it will be marketed in the USA to be refi ned. After all, in the event of hurricanes, the measure will prevent damage to the infrastructure of oil pipelines.
From what can be seen, it is possible to conclude that the project of developing the Cascade and Chinook fi elds marks history for Petrobras. "For the fi rst time, the company has the opportunity to take out of Brazil its off - shore technology that has been developed and applied successfully for decades. Th e result of doing this in the U.S. Sector of the Gulf of Mexico will be to give higher visibility for Petrobras, to crown its strategy in the region, and to consolidate its position in the USA," concludes the president of Petrobras America, José Orlando Melo de Azevedo.
No wonder the actions of Petrobras in the Gulf have been widely divulged in speeches and seminars, and the progress achieved has been closely monitored by the U.S. industry, by the government, and by society.
*risers – pipelines that connect the platform to the wells. **umbilicals – multifunctional systems comprising tubes, energy cables, and optic cables that, when connected, enable communication between the oil wellheads on the seabed and the platforms.
*** hydrocarbons – chemical compounds formed by atoms of carbon and hydrogen. Oil and natural gas are natural hydrocarbons.
