PetroChina Co. Ltd. engages in the exploration, development, production and sale of crude oil and natural gas. The company also involves in the refining of crude oil and petroleum products, production and marketing of primary petrochemical products, derivative chemical products and other chemical products. it operates its business through five segments: exploration and production, refining and chemicals, marketing, natural gas and pipeline, and other. The exploration and production segment is engaged in the exploration, development, production and marketing of crude oil and natural gas. The refining and chemicals segment is engaged in the refining of crude oil and petroleum products, production and marketing of primary petrochemical products, and derivative petrochemical products and other chemical products. The marketing segment is engaged in the marketing of refined products and the trading of crude oil and petrochemical products. The natural gas and pipeline segment is engaged in th