China\'s leading oil and gas producer PetroChina Co. has inked an agreement with Australian resources company BHP Billiton to purchase a stake in its two joint ventures for a cash consideration of USD 1.63 billion, the official Xinhua News Agency reported Wednesday. PetroChina announced on Wednesday that it will buy interests of 8.33 percent and 20 percent from the East Browse Joint Venture and the West Browse Joint Venture, respectively, through its subsidiary PetroChina International Investment (Australia) Pty Ltd., according to the report. \"This is an excellent opportunity for both companies. PetroChina has acquired an interest in a world-class gas resource and BHP Billiton has exited a non-strategic asset,\" said J Michael Yeager, chief executive of BHP Billiton\'s petroleum division. The transaction marks the first participation by the Chinese oil giant in natural gas exploitation on the northwestern continental shelf of Australia, according to PetroChina. The company expects the purchase to be completed in the first half of 2013, after it is approved by regulators and meets customary conditions. Participants in the two joint ventures, such as Woodside Petroleum Ltd. and Royal Dutch Shell Plc, hold a right to offer to match BHP Billiton\'s consideration for a customary period, the announcement added.