Oman's Duqm refinery has completed its start-up processes and its operator OQ aims to begin commercial operations by year-end, it said on Thursday.

"Significant progress has been made in the project's execution, with the start-up phase of the refinery now completed, marked by the production of high sulphur fuel oil (HSFO)," OQ said in a written statement in response to a Reuters email.

A first shipment of HSFO has already been exported to the U.S., it said, after ongoing trial runs prior to the plant entering full commercial operations. Naphtha production has also been achieved, OQ added.

Around 95,000 metric tons of HSFO shipped from Duqm is heading to Corpus Christi, Texas, Kpler ship tracking data showed.

The refinery also exported its first diesel shipment in September, said OQ.

"Additionally, Omani and Kuwaiti crude oil has been successfully shipped to Ras Markaz and subsequently pumped to the refinery complex in Duqm via pipelines."

The refinery's construction is 99% complete, with 81% of the commissioning process done, OQ said.

The commissioning activities will span the refinery's entire supply chain, from its crude storage tanks at Ras Markaz to the product export systems from the refinery to the Duqm export terminal jetty, they added.

The Duqm refinery, which has a crude processing capacity of 230,000 barrels per day, is a 50:50 joint venture between OQ Group and Kuwait Petroleum International.

(Reporting by Trixie Yap in Singapore and Maha El Dahan in Dubai; Editing by Jason Neely and Jan Harvey)