China has achieved a significant milestone in shale oil exploration with the discovery of the Fuxing oilfield in the Sichuan Basin, the first shale oilfield in the country's southwestern region.

With initial proven reserves of 20.1 million metric tons of oil and 12.35 billion cubic meters of natural gas, the discovery is expected to boost domestic energy security and spur further exploration in the area, said its operator China Petroleum and Chemical Corp, also known as Sinopec.

Shale oil mainly refers to liquid hydrocarbons trapped in formations of shale rock that can be extracted for refining. It is often found in organic-rich shale and thin interlayers of carbonate rock, sandstone and siltstone.

The project is located in Chongqing on the southeastern edge of the Sichuan Basin, which has traditionally been characterized as "rich in gas but poor in oil", with exploration and development efforts historically focused on natural gas due to limited oil resources.

The Fuxing discovery thus signifies a breakthrough in shale oil exploration in Southwest China and opens up a new frontier for shale oil and gas resource expansion in the basin, it said.

Wei Xiangfeng, manager of the shale gas project department of Sinopec's exploration company, said the theoretical advancements and key technologies developed at the Fuxing oilfield are of great significance in supplementing and refining China's shale oil and gas exploration theories, technologies and standards.

Going forward, efforts will focus on deepening the understanding of enrichment patterns and strengthening the overall assessment and planning of terrestrial shale oil in the Sichuan Basin, with the aim of achieving another major breakthrough and establishing a second shale oil reserve base, Wei said.

China has been actively working to enhance its oil and natural gas production in recent years, including intensifying exploration and development of unconventional resources like shale oil and gas.

Wu Mouyuan, vice-president of the Economics and Technology Research Institute under China National Petroleum Corp, has said previously that China is making strides in expanding its energy resources by tapping into unconventional sources, notably with significant progress in shale gas exploration.

Resources like low-maturity shale oil and underground coal gasification, currently unexploited, hold the key to unlocking significant new opportunities in the decades ahead, Wu said.

Sinopec announced in March the discovery of two major shale oilfields — the Xinxing and Qintong oilfields — in the east of the country with combined proven reserves of 180 million tons, which have been approved by the Ministry of Natural Resources.