South Korean refiners are expected to have racked up robust earnings in the second quarter on the back of higher cracking margins and stable oil prices, industry data showed Friday.
  

The nation's three refiners posted their worst-ever performance last year as a freefall in oil prices hurt the value of their crude inventories with the combined operating reaching 2.6 trillion won.
  

But they swung to the black in the first quarter as cracking margins climbed and crude prices remained at stable levels. For the second quarter, their performances are estimated to have further improved, the data showed.
  

SK Innovation Co., the nation's biggest refiner, was expected to have logged 661.6 billion ($591.4 million) in operating profit in the second quarter, about double the amount from the previous quarter, according to the estimate by 11 local brokerage houses.
  

GS Caltex Co., the No. 2 player, was estimated to have posted 621.9 billion won in operating profit, also double the amount in the first three months of this year, a survey by four securities firms showed.
  

No. 3 S-Oil Co.'s profit was expected to rise 80 percent to 445 billion won over the cited period, the median estimate by eight brokerage firms noted.
  

The Singapore cracking margins have remained over $8 per barrel this year, sharply up from $4.30 and $6.30 in the third and fourth quarter of last year, driven by strong demand and limited facility expansion in other countries.
  

In early June, the Organization of Petroleum Exporting Countries agreed to maintain the current policy of unconstrained output for another six months, leaving crude oil in a "buyer's market" driven by ample supplies.
  

As refiners are swayed by external factors, market watchers kept their eye on Iran, which looks to ramp up supply once sanctions on its oil exports are lifted. The Middle Eastern country has the world's fourth-largest reserves of oil. (Yonhap)