A huge Petrobras rig tender has attracted heated competition for a prize of potentially $2 billion in contracts to charter up to four deep-water drilling units offshore Brazil.

The state-controlled company is seeking to replenish its fleet as demand for rigs rapidly rises, lifting dayrates and tightening the supply of the vessels.

The contest has enticed nine contractors to submit more than 40 commercial bids for the long-term contracts.

Competition for the contracts reflects the recent positive outlook for the drilling sector, with most dayrates ranging from just over $400,000 to about $600,000 in the bids submitted.