Petrobras halted drilling at its largest oil discovery in deep waters, two people with knowledge of the matter said, underscoring the technical challenges facing the company’s new management team.

An unplanned procedure to retrieve equipment stopped work for more than a week at a well in Libra, the people said, asking not to be named because it hasn’t been made public. Rio de Janeiro-based Petrobras didn’t immediately respond to a request for comment on the incident and if it had been resolved. Commercial production is expected to start in 2020.

While Petrobras expanded output to a record in December at the so-called presalt region that holds Brazil’s largest deposits, it also has run into drilling disruptions in the past. In 2010, it abandoned the first well it started at Libra, citing mechanical issues. In 2011, it briefly halted production at the Sapinhoa Field in the same region after a pipe ruptured.

The snag shows that the challenges facing CEO Aldemir Bendine extend beyond finance and corruption as he chooses a new management team. The company is deploying the largest fleet of deepwater production vessels in the industry in an effort to boost output and pay down debt. All that as oil trades near six-year lows after an almost 50% drop.

Bendine started the job Feb. 6 after former CEO Maria das Gracas Foster and five of her executive managers quit amid difficulties reporting graft-related writedowns.

Government Auction

Petrobras took a 40% stake in a 35-year concession for Libra, the largest discovery in Brazil’s history, in a government auction in October 2013. It was the first auction of subsea prospects, known as presalt, using a production-sharing model. Petrobras drilled the first well in 2010 on behalf of oil regulator ANP as part of a project to gather data on the region before offering the areas.

Total and Shell each hold a 20% stake of the concession while China National Petroleum Corp. and Beijing-based Cnooc Ltd. have 10% apiece.

Libra is estimated by Brazil to hold as much as 12 Bbbl of recoverable crude, or 50% more than the proven reserves of OPEC member Ecuador. Schahin Petroleo & Gas SA, the owner of the Cerrado drillship Petrobras hired last year to drill two wells at Libra, didn’t immediately respond to an e- mail seeking comment on the rental fees.