Brazilian oil giant Petrobras has invited a quartet of companies to battle it out in a multi-million-dollar tender to provide a rigid riser-based solution for the development of its flagship Mero (Libra) field in the Santos basin pre-salt province.

Petrobras has called Subsea 7, McDermott International, Allseas and Heerema Marine Contractors to submit bids on 4 June, asking for the supply of subsea umbilicals, risers and flowlines to serve Mero, according to well-informed sources.

It is understood that the Surf package will cover engineering, procurement, construction and installation work on rigid production and injection lines and flexible connectors that will be linked to the Modec-owned Guanabara floating production, storage and offloading vessel.

Petrobras and its partners on Mero had considered allowing a riser tower solution for the injectors, but Upstream understands the partners are favouring a hybrid system with a lazy-wave configuration that use risers with cladded steel and flexible jumpers.

The FPSO will be the first full-scale production unit at Mero, which is so far estimated to hold recoverable volumes of 3.3 billion barrels of oil, and is due to enter operations in late 2021.

Petrobras did not extend the tender invitation to contractors such as Sapura Navegacao, Saipem and TechnipFMC due, sources said, to a mixture of technical qualification issues and compliance matters. Upstream understands the three companies are appealing against their exclusion.

Ocyan, which is developing its own rigid riser tower project in partnership with Oil States and at least two other service providers, was not invited, as the company — formerly known as Odebrecht Oil & Gas — remains blacklisted by Petrobras in the wake of the Car Wash corruption scandal.

After years of using flexible risers as the default solution for many of its groundbreaking pre-salt projects in the Santos basin, Petrobras discarded that option for the Mero development, leaving players such as Baker Hughes, NOV Flexibles and Prysmian out of the race.

The company has become more open to rigid riser-based solutions since inspections at the Lula and Sapinhoa fields, carried out in 2016 and 2017, found two ruptures in flexible gas risers that had been subjected to stress and high carbon dioxide levels characteristic of such pre-salt reservoirs.

Analysis revealed that the riser failure occurred in conditions where flexible pipe was being subjected to strong tension and suffered a breach of the external armour, allowing seawater to infiltrate the annular sections, mixing with CO2. The powerful corrosive effect of this seawater influx compromised the annular, causing the pipe structure to rupture after only two or three years of service.

Petrobras initially said that mitigation efforts have contained the problem, but Upstream understands that inspections have found additional cases of seawater infiltration in annular sections.

Industry sources suggested European oil majors Shell and Total have also brought their

own experience on overseas projects to the table, influencing Petrobras’ decision to switch to a rigid-riser-based solution for Mero.

Shell, like Petrobras, already has experience of deploying a steel lazy-wave riser solution in Brazil. The requirement for cladding may offer a competitive advantage to Subsea 7, as the Oslo-listed company has already supplied a similar solution on the Petrobras-operated Sapinhoa-Lula North East project.

However, even though Petrobras has picked a rigid riser solution for the Mero-1 floater, the company said the scale of Mero and other pre-salt developments will likely allow the use of both flexible and rigid risers in the future.

“The decision regarding the configuration of the subsea production system is based on technical and economic analysis to optimise results, considering the specifics of the Mero field and the production sharing contract,” Petrobras told Upstream in an emailed reply.

Petrobras operates the Libra consortium, which includes the now renamed Mero field, with a 40% stake. Anglo-Dutch supermajor Shell and France’s Total have 20% each, while China National Petroleum Corporation and China National Offshore Oil Corporation hold 10% each.

Upstream understands that the partners are also mulling the possibility of bringing composite riser solutions into the frame for the Mero-2 floater’s surf project.

On its own portfolio of projects, Petrobras is aiming to get to the situation where suppliers can be given the opportunity to present competing rigid and flexible riser-based solutions in the same tender, with sources suggesting that this may be the case for the Buzios-5 FPSO project. The tenders for the Mero-2 and Buzios-5 FPSOs are in the market right now.

Petrobras is expected to approach the market again as soon as the Libra-1 job is awarded to contract the surf package for the Carioca FPSO to be installed on Sepia, and, like Mero-1, contracted to Modec International.

Petrobras told Upstream it is still analysing which riser solution to use on the Sepia pre-salt development, where the Carioca unit is due to enter operations in 2021.

Petrobras is conducting a closely-watched extended well test at Mero with the Pioneiro de Libra FPSO using flexible risers. The single-well test produced 16,300 barrels per day of oil in February, and output is on the rise.

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