China National Petroleum Corporation announced on June 20 the discovery of a shale oil field with geological reserves of 1 billion metric tons in Northwest China's Ordos Basin, making it the largest in the country.

The leading energy company said the accumulated proven geological reserves of its Changqing Oilfield reached 1.052 billion tons thanks to breakthroughs in core technologies like horizontal drilling.

Proven reserves — resources that can be recovered with existing technology after detection — of 359 million tons were found in 2019, 143 million tons in 2020 and another 550 million tons in the first five months of this year.

It is estimated that by the end of the 14th Five-Year Plan period (2021-25), the shale oil capacity in the Changqing Oilfield will exceed 5 million tons with output exceeding 3 million tons.

Shale oil is a type of unconventional oil found in sedimentary rock that requires fractional extraction. The heavier, waxy oil is more difficult and costly to recover than traditional crude.

Top global holders of technically recoverable shale oil resources include the United States, Russia and China.