The refinery will have a capacity of 20,000 barrel-per-day, Reuters reported citing CNOOC officials.
But the two companies have yet to push forward discussions on an earlier proposed refinery and petrochemical venture, concerned that the unattractive location of the plant may make it hard to win regulatory approval.
CNOOC will start up the Yingkou facility next month to process its heavy crude oil from Bohai Bay off north China and produce about 500,000 tonnes a year of bitumen.
Korean refining company SK Energy was in discussions with CNOOC about a year ago to build a 200,000 barrel-per-day refinery and a one million tonne-per-year ethylene plant in the coastal city of Yingkou, Liaoning province.
Reuters quoted a CNOOC official as saying that the Korean firm had the idea of supplying feedstock like naphtha from its plants.
State-controlled CNOOC is building itself into an integrated energy firm, involved in refining, petrochemicals and power sectors.
Early this month, the Chinese government granted CNOOC environmental clearance to double the capacity of its first major refining and petrochemical base in southern Guangdong province.
