KHOBAR, Saudi Arabia, July 10 (Reuters) - Oman will start operating a plant to process gas from the Khazzan gas field early September, the Oman news agency quoted an oil and gas ministry official as saying.

The first train has a capacity of 500 million cubic feet per day of gas, while the second train, which has a similar capacity, will be in operation in early 2018, Salim Al Aufi, Undersecretary at the Omani Ministry of Oil and Gas said.

BP said in November last year that the first phase of the project is more than 80 percent complete and remains on schedule to deliver first gas in late 2017, producing 1.0 billion cubic feet of gas a day (bcf/d).

BP Oman is lead partner in the project with a 60 percent interest. Oman Oil Company Exploration & Production holds 40 percent.

The two companies agreed last year to extend licensing agreements, paving the way for the development of a second phase of the giant Khazzan tight gas field, and increasing expected production by 50 pct.

Aufi expected oil to trade within $50-$55 for more than a year. He reaffirmed the sultanate's commitment to continue to deliver on its share of the cut agreed by global oil producers.

(Writing by Reem Shamseddine, editing by Louise Heavens) ((; +966503335202; Reuters Messaging: