Libra Consortium operator Petrobras has concluded on Tuesday, Oct. 2, the extended well test (EWT) in the Mero field, located in the block of Libra, in Santos Basin’s pre-salt layer. Launched in November 2017, production was carried out by FPSO Pioneiro de Libra, the first Petrobras extended well testing dedicated unit equipped to inject the gas produced. FPSO is the English acronym for the vessel that produces, stores and offloads oil.
During the tests, the producer well connected to the platform achieved 58 thousand barrels of oil equivalent per day (boed) in production, which is a great result in ultra-deep waters. The technological achievements attained during this period were fundamental to obtaining high-quality data and reduce uncertainties about the reservoir, which will enable the accelerated deployment of up to 4 final production systems in Libra in the coming years. Each system will be capable of producing up to 180 thousand barrels of oil per day. In addition, these technologies will contribute to the safe and efficient development of upcoming projects in the global ultra-deep water oil and gas industry.
With the completion of the tests, the FPSO Pioneiro de Libra will operate the subsequent Early Production Systems (EPS) in other Mero wells. The next step consists in the replacement of the current gas injector well by another one located closer to the producer well. After this step, the vessel will be unanchored and displaced to a new location in the Mero field, to move forward with the EPS program. Pioneiro de Libra is capable of processing up to 50 thousand barrels of oil and 4 million cubic meters of associated gas on a daily basis.
Located in the Southeastern region of Brazil, Libra is one of the most robust oil and gas production projects ever developed by the offshore industry worldwide. The area features reservoirs that are among the most productive in the country, with oil columns that reach up to 400 meters in thickness – the equivalent to the height of the Sugar Loaf mountain.
The high flow rates and pressures, the significant presence of gas associated to oil, in addition to the high content of CO2 in the area have demanded the development of latest-generation solutions to facilitate production. As such, Petrobras and its partners have developed new technologies designed to operate in these environments, with water depths ranging from 1700 to 2400 meters, and total depths that reach up to 6 thousand meters.
One of the pioneering solutions was to install in the area the first FPSO dedicated exclusively to Extended Well Tests capable of reinjecting the gas produced. This innovation brings better results to the consortium and the environment, because it allows the elimination of continuous burning of gas, thus minimizing CO2 emissions into the atmosphere and enabling the production of wells at their maximum potential. To produce during EWT without restrictions allowed to optimize the acquisition of dynamic data from the reservoir.
In the deployment of the EWT, the first pre-launch of flexible lines with floats in ultra-deep waters was carried out. This method anticipated the start of well production by 43 days, compared to a scenario without the pre-release of the lines.
The use of flexible ducts for the production measuring 8 inches in diameter, in ultra-deep waters and in a setting known as lazy wave, allowed to obtain large production at such a depth. Due to the loads imposed to the 8-inch lines, the FPSO Pioneiro de Libra has an external turret anchoring scheme with the greatest support of the vertical load in the world’s industry, with a capacity of 700 tons per underwater line (riser), the equivalent to the weight of 4 Boeing 747 aircrafts. This equipment is responsible for supporting the load of nine lines at water depths of up to 2,400 meters.
The Libra consortium also used a robust swivel, which is an equipment that allows the ship to rotate in relation to the turret, which is fixed to the bottom of the sea through mooring lines. This installed model supports the largest operating (550 bar) and design (605 bar) pressure of gas injection in the global oil industry.
The consortium is led by Petrobras – with 40% stake – in partnership with Shell (20%); Total (20%); and the Chinese companies CNPC (10%) and CNOOC Limited (10%). The consortium also has the participation of the state-owned enterprise Pré-Sal Petróleo - PPSA, which operates as contract manager.