Offshore Activity

USE OF STEEL UMBILICALS STUMBLES ON THE TECHNOLOGY AGAINST THE HIGH CORROSION IN LIBRA

 

Sep 12, 2017

Petrobrás can only use steel umbilicals in the operations of the pilot in Libra. The imperative reason is the corrosive result caused by H2S and CO2 found in the oil, extremely corrosive not only for flexible risers but also for umbilicals.

This will also require an adaptation of the possible suppliers, who are accustomed to thermoplastic lines. The technology is not new to Petrobras. Overcoming the high corrosion rate is. Mainly for the supplier companies. Some of them unable to invest in new technologies.

In general the umbilicals use polyethylene plastic cables and inside control lines with hydraulic fluid that by pressure move the submersed valves. There is also the depth and pressure component at these locations that can exceed 15,000 psi. Neither the thin hose, nor the fluids, can withstand. Steel is the only alternative known so far. But even with that steel there are problems. How to overcome the extremely high corrosion rate? There are still no definitive answers, despite the studies being done by several universities and institutions. Nobody has a definitive answer.

The strategy of using steel lines in Libra aims to increase the availability of the control system and chemical injection of the underwater production system. Petrobras says it uses it in the Campos, Santos, Espírito Santo and Gulf of Mexico basins. But in none of these places have H2S and CO2 as intense as in Libra.

The challenges of pre-salt are really immense. There have already been long meetings with suppliers on this problem, which began with the disruption of the flexible risers lines well before their estimated life time. Petrobras and its partners in Libra’s exploration want to avoid setbacks, delays and losses.

The market says that at least two of the traditional suppliers are financially raising a yellow flag. MFX, for example, after good international sales to Shell, Saudi Aramco to Ireland, the United States, India, Singapore and Italy, is suffering including the likes Oceaneering and Prysmian. There are other experienced suppliers that are being heard and already produce umbilicals with steel: JDR, Nexans and Aker. So far, however, there is no date for testing or even for bidding. Before supplying they need to show that they are capable of overcoming corrosion. The fight is for technology and against time.

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