Heritage Oil plc, the independent British exploration company, said it has made a major gas discovery in the Kurdistan region of Iraq.

The gas field may have up to 12.3 trillion cubic feet of gas, with a flow rate of 75-million cubic feet per day when the field is operational, the company said. It is believed to be the largest gas field found in Iraq in more than 30 years and might be worth $2.7-billion to Heritage, the company stated.

The discovery of a major gas field with exceptional flow rates makes this one of the largest gas fields to be discovered in Iraq, said Heritage chief executive Tony Buckingham.

However, Heritage shares are falling on the FTSE because investors had expected the company to find oil on the property. Moving gas to its final markets is much more difficult in this region of Iraq than it is with oil.

“We are considering various development options including a tie-in to planned infrastructure that will achieve first production for both oil and gas in 2015,” Buckingham added. “This discovery has the potential to generate substantial further value for our shareholders and benefit the people of Kurdistan and Iraq.”