PetroChina Company Limited recently inked a 22-year agreement with Qatargas Operating Company to purchase 3.4 million tons of liquified natural gas annually. The deal, which comes amid the brewing tension between United States and China, along with soaring Chinese LNG demand, marks PetroChina's biggest contract in terms of annual volumes. Per the deal, Qatargas will supply LNG from Qatargas 2 project, which is a joint venture between Qatar Petroleum, Exxon Mobil Corporation ( XOM - Free Report ) and Total S.A.. The first cargo is expected to be delivered later this month. Considering the secular shift to cleaner burning fuel for power generation, China has overtaken South Korea as the world's second-biggest buyer of LNG, being just behind Taiwan. The use of coal for heating purposes is expected to go down, per China's pollution control measures.