Tā zài yìjiā shíyóu huàgōng gōngsī dāng gōngchéngshī.
He works as an engineer at a petrochemical company.
Tips
usage
化工 is the standard short form of 化学工业 (chemical industry). So 石油化工 = petroleum (石油) + chemical industry (化工) = petrochemicals. You will see it most in the name 中石化 (Sinopec, 中国石油化工集团).
