Australian natural resources company BHP Billiton said Wednesday onshore operations in the United States helped boost its oil production by 4 percent.

BHP said total petroleum production for the fiscal year ending June 30 was up 4 percent year-on-year to 246 million barrels of oil equivalent per day. The Australian company said in a financial report operations in U.S. shale helped boost the output.

"Onshore U.S. liquids production increased by 23 percent in the June 2014 quarter and we expect to carry strong momentum into the 2015 financial year as shale liquids volumes are forecast to increase by over 17 million boe in the period," the report said.

The company said the bulk of its onshore investments targeted the Eagle Ford shale play in the southern part of the United States. Roughly 75 percent of the $4.2 billion in drilling expenses targeted that play. Eagle Ford output during the 2014 financial year was mostly in the form of crude oil.

The company's natural gas focus in the United States was in the Haynesville and Fayetteville reserve areas, where the company spent about $600 million in capital expenses, down more than 30 percent year-on-year.