KIEV, June 25 - The second sea-based natural gas and oil drilling rig, purchased by state-owned ChornomorNaftoGaz last year, is expected to arrive and to start operation in the fourth quarter of 2012, ChornomorNaftoGaz reported Monday.

The rig was originally expected to arrive early next year, but the timeframe was adjusted after Keppel FELS of Singapore last week had completed construction of the rig ahead of schedule.

“The second rig will start drilling offshore the Black Sea in the fourth quarter of the current year,” the company said in a statement.