SEOUL, July 28 (Reuters) - South Korea's S-Oil Corp said on Thursday that profits in the second quarter rose more than 200%, while expecting regional refining margins to correct downward in the third quarter.

Regional refining margins are expected to correct downward in the third quarter but stay elevated more than in previous cycles supported by the tight supply situation in the global refining system, the company said in its earnings statement.

The company's second-quarter operating profit rose 201.6% to 1.72 trillion won ($1.31 billion) over the same period a year ago, according to the statement.

In the April-June period, the refiner operated the crude distillation units at its 669,000-barrel-per-day (bpd) refinery in the southeastern city of Ulsan at 93.8% of capacity, down from 98.4% percent in the previous quarter.

The refiner said it plans to carry out maintenance for its No.1 residue fluidized catalytic cracker (RFCC) in the second half of this year.

S-Oil shares were down 2.4% as of 0028 GMT, compared with the wider market that rose 0.8%.

S-Oil's largest shareholder is Saudi Aramco. ($1 = 1,308.9400 won) (Reporting by Jihoon Lee; Editing by Christian Schmollinger)