PetroChina Co., the country’s biggest oil and gas producer, and China’s largest offshore explorer Cnooc Ltd., may write down assets following crude’s plunge, analysts say. Analysts from Macquarie Capital Securities Ltd. to Jefferies Group LLC are predicting impairments when the companies report 2015 earnings this week. PetroChina may take a charge of about 28 billion yuan ($4.3 billion), which may push it to its first ever quarterly loss, according to Gordon Kwan, head of Asia oil and gas research at Nomura Holdings Inc. in Hong Hong. Cnooc, which undertook some asset impairments in 2014, may write down more for 2015, according to Lu Wang, an analyst at Bloomberg Intelligence. PetroChina, Cnooc and China Petroleum & Chemical Corp., Asia’s biggest refiner “will unveil sizable impairment writedowns for 2015,” Nomura’s Kwan said by phone. “These impairment charges are non-cash in nature and there could be write-backs if oil prices surge in […]