South Korea’s state-owned Korea Gas Corporation, Kogas, said in a stock-exchange filing that it would invest 5.87 trillion won ($4.91 billion) in development and production at Iraq’s Zubair oil field. Kogas said the investment was part of the total $19.4 billion expenditure required to complete the project. It added that it had invested $370 million in the project in the first half of 2015.