China’s top two oil companies PetroChina and Sinopec are linking up to explore and develop oil and gas reserves in Xinjiang in the country’s far north-west and Sichuan in the south-west.

In an agreement signed last week, the two companies have agreed to carry out joint geological studies on 81 blocks covering 305,800 square kilometres in the Tarim, Jungar and Sichuan basins.