SINGAPORE, July 31 (Reuters) - China's Sinopec Corp 600028.SS0386.HK said on Thursday the Chinese government has certified geological oil reserves of 20.1 million metric tons, or 147 million barrels, in a new shale play the company operates in southwest China.

The Ministry of Natural Resources also certified 12.35 billion cubic metres of geological gas reserves in Fuxing field, located in the municipality of Chongqing, Sinopec said in a statement.

The Fuxing discovery - located in the southeastern rim of the Sichuan basin and with the first successful exploration well drilled in 2021 - marked a breakthrough in shale oil exploration in a traditionally gas-rich zone.

Sinopec said it would further expand exploration and evaluation of similar deposits in the Sichuan basin, building on a new understanding of the geology and improved technology.

Sinopec, which operates China's first major commercial shale gas field, has in recent years been expanding exploration and production of shale oil.

Besides Fuxing, Sinopec has tapped two other shale oil plays, Xinxing in the Jiyang trough of the Bohai Bay basin and the Qintong field in the Subei basin in east China. Those two finds have combined geological reserves of 1.3 billion barrels.

Despite the huge resource potential, shale oil remains among the most geologically challenging and costly types of oil to explore and produce, and production remained miniscule.

Sinopec last year produced 705,000 metric tons, or 5.15 million barrels, of shale oil. It is aiming for 2 million tons a year or 40,000 barrels per day of output by 2030, which would be less than 1% of total national oil production.

(Reporting by Chen Aizhu; Editing by Tom Hogue)

((aizhu.chen@thomsonreuters.com; Reuters Messaging: aizhu.chen.reuters.com@reuters.net))