A oil field worker works at a pump jack in PetroChina’s Daqing oil field in China’s northeastern Heilongjiang province November 5, 2007. Chinese oil majors will push back maintenance work and curb exports to guarantee diesel supplies after the country’s worst fuel crunch in four years, the country’s top economic planner said on Tuesday. Picture taken November 5, 2007. REUTERS/Stringer (CHINA) CHINA OUT