PetroChina had initially planned to shut down the largest refinery in northwestern Xinjiang in June or July, but it postponed the 50-day overhaul to begin in early August, as its 210,000-bpd Lanzhou refinery in neighbouring Gansu province started a partial turnaround from June 20. The overhaul in Lanzhou was completed in late July.

Staggering the maintenance time of PetroChina's two major refineries in west China will help smooth out possible fuel supply hiccups. Dushanzi, processing mainly Kazakhstan crude oil, was fully commissioned in September 2009 after replacing several old crude oil units with a new 200,000-bpd unit and adding a 1-million-tonne-per-year ethylene cracking unit.

Copyright Reuters, 2011