Hong Kong-listed oil and gas production stocks fell in early trading, with Shandong Molong (00568.HK) down nearly 8%, CNOOC (00883.HK) down more than 5.5%, PetroChina (00857.HK) down more than 2.5%, and CITIC Resources (01205.HK) and PetroChina (00857.HK) following suit.