Hercules Offshore Inc. (HERO) on Thursday said in a securities filing that it has received approval from U.S. antitrust regulators to proceed with purchasing the assets of smaller rival Seahawk Drilling Inc. (HAWKQ).

Hercules agreed in February to acquire Seahawk's 20 shallow-water drilling rigs and other assets for about $100 million in cash and stock. Seahawk, which says it was hurt in large part by a slowdown in Gulf of Mexico drilling activity following the Deepwater Horizon disaster, filed for Chapter 11 bankruptcy protection simultaneously with announcing the asset sale.

The two companies are the leaders in drilling at depths of less than 500 feet in the Gulf of Mexico.

With the blessing of federal regulators, the acquisition now must win the approval of a federal bankruptcy judge in Corpus Christi, Texas.

Hercules said it expects the transaction to close during the second quarter.

Shares of Hercules recently traded 5.2% higher at $6.65.

-By Ryan Dezember, Dow Jones Newswires; 713-547-9208; ryan.dezember@dowjones.com