FOTO ANDRÉ RIBEIRO / AGÊNCIA PETROBRAS
Well is among those with the highest production in ultra-deep waters
Petrobras, operator of the Libra Consortium, concluded the long-term test (TLD) at the Mero field, located in the Libra block, in the Santos Basin pre-salt. Started in November 2017, production was carried out by FPSO Pioneiro de Libra, the first Petrobras unit dedicated to long-term tests equipped to inject the gas produced.
During the tests, the producing well linked to the platform reached the production of 58 thousand barrels of oil equivalent per day (boed). The results achieved in this period were instrumental in obtaining high quality data and reducing uncertainties about the reservoir, which will allow the accelerated implementation of up to 4 definitive PPS production systems in the coming years. Each system will have the capacity to produce up to 180,000 barrels of oil per day.
Upon completion of the tests, the Pioneer Libra FPSO will operate the Subsequent Production Systems (SPAs) in other Mero wells. The next step is to replace the current gas injector well with another one located closer to the producer well. After this stage, the vessel will be undocked and transported to a new location in the field of Mero, giving continuity to the SPAs program. The Libra Pioneer has a daily capacity of up to 50,000 barrels of oil and 4 million cubic meters of associated gas.
Located in the Southeastern region of Brazil, the Libra area has reservoirs with oil columns that reach up to 400 meters thick – equivalent to the height of the Sugar Loaf.
The high flow rates and pressures, the significant presence of gas associated with the oil, and the high CO2 content in the area required that solutions be developed to make production feasible. In this way, Petrobras and its partners have developed technologies designed to operate in these environments, with water depths ranging from 1700 to 2400 meters, and total depths of up to 6,000 meters.
One of the solutions was to install in the area the first FPSO dedicated exclusively to Long-term Tests able to re-inject the gas produced. This innovation brings better results to the consortium and to the environment, as it allows the elimination of continuous burning of gas, minimizing the emission of CO2 into the atmosphere and making possible the production of the wells at their maximum potential. Producing during the TLD without restrictions allowed to optimize the acquisition of dynamic data of the reservoir.
In the implementation of the TLD, the first pre-launch of flexible lines with floats in ultra-deep waters was carried out. This method anticipated in 43 days from the production of the well, when compared to a scenario without pre-launch of the lines.
The use of flexible production ducts 8 inches in diameter, in ultra-deep water depth and in a configuration known as lazy-wave, allowed to obtain a large production at that depth. Due to the loads imposed on the 8-inch lines, the Pioneiro de Libra FPSO has an external turret with the highest vertical load rating of the industry worldwide, with a capacity of 700 tons per submarine line (riser), the equivalent of the weight of 4 Boeings 747. This equipment is responsible for the load support of nine deep water lines of up to 2,400 meters.
The Libra consortium also used a swivel, which allows the ship to rotate in relation to the turret, which is fixed to the seabed by means of anchor lines. This installed model supports the highest operating pressure (550 bar) and gas injection design (605 bar) of the global oil industry.
The Consortium is led by Petrobras – with a 40% stake – in partnership with Shell (20%); Total (20%) and the Chinese CNPC (10%) and CNOOC Limited (10%). The consortium also has the participation of the state company Pre-Sal Petróleo – PPSA, which performs the role of contract manager.