Marathon filed its quarterly report Thursday. The company posted an 8.4 percent increase in net income for the second quarter of 2013.
Overseas, the company said it was planning further development of the Atrush reserve area in the Kurdish region of Iraq. The company said it notified the Kurdish government in May the prospect had commercial potential.
"The development plan is currently under review with final approval expected in the third quarter of 2013," the report stated. "We anticipate first production in 2015."
ShaMaran Petroleum, a Canadian oil and gas company holding an interest in the Atrush area, said in a quarterly update there may be more than 627 million barrels of oil equivalent in the block.
Marathon holds a 15 percent stake in the Atrush area. It said it was working on testing programs at other assets in the Kurdish region. It started exploratory drilling campaigns in a well in March.
The semi-autonomous Kurdish north has been shielded from much of the violence plaguing Iraq. Its government, however, is at odds with the national government over who controls the country's oil sector.