National Oilwell Varco Inc , the largest U.S. oilfield equipment maker, struck a $1.5 billion deal to supply drilling equipment for seven drillships to Brazil's Estaleiro Atlantico Sul.

The supply agreement with the Brazilian shipyard company is the single largest order in National Oilwell's history, the company said.

In July, National Oilwell posted a higher than expected quarterly profit as its rig technology order backlog rose 26 percent, lifting its stock by as much as 5.3 percent.

The company is benefiting from a rig-building boom driven by the significant rise in oil prices in the past year, which is leading oil and gas companies to demand better performance from the equipment they use.

The company has been hoping to log more orders from Brazil, where large deepwater discoveries have led to significant demand for new drilling rigs and other equipment.

It said the supply packages for the new drillships include drilling risers and pressure control equipment.

Shares of National Oilwell closed at $66.78 on the New York Stock Exchange on Friday.

(Reporting by Michael Erman; Editing by Michael Urquhart)