"Shaikan cumulative production reached our record maximum daily rate to date of 25,000 gross bpd," CEO Todd Kozel said in a statement. "We look forward to exiting 2014 with 40,000 gross bpd of production."
The company, which has headquarters in London, estimates Shaikan could hold as much as 10.5 billion barrels of oil. The semiautonomous Kurdistan Regional Government has said production could reach 250,000 bpd by 2018.
Gulf Keystone says most of the oil from Shaikan is shipped across the border to the Turkish port of Dortyol, where it's sold on the international market.
Kurdish oil sales are a source of contention for the central government in Baghdad, which views them as illegal. Nevertheless, the British company said 1.85 million barrels of Shaikan crude have been sold to date.
The announcement comes as ISIS militants have seized Mosul and Tikrit in northern Iraq. Kozel said much of the conflict lies outside the Kurdish region.