SINGAPORE, March 3 (Reuters) - Sinopec Corp said on Monday the Chinese government has certified about 180 million metric tons, or about 1.3 billion barrels, of new geological reserves at two of its shale oil plays.

The new reserves were tapped at the Xinxing field in the Jiyang trough of the Bohai Bay basin and the Qintong field in the Subei basin, Sinopec said in a statement.

Xinxing's shale formations are buried 2,900 metres to 4,000 metres below the surface and those of Qintong, 3,430 metres to 4,560 metres deep.

Both fields tested high single-well production with long, stable output, Sinopec added.

Sinopec aims to prove more than 100 million tons (730 million barrels) of new reserves every year during the 2026-2030 period, with a goal to pump 2 million tons, or 40,000 barrels per day of shale oil by 2030.

Last year the state oil giant produced 705,000 tons, or 5.15 million barrels of shale oil.

Following a call from the central government to boost domestic energy security, China's national oil companies are making greater efforts to tap hard-to-extract shale deposits to help compensate for older, fast-depleting conventional oilfields.

Despite the huge resource size, shale oil remains among the geologically most challenging and costly types of oil to explore and produce, with output making up only 1% of China's total crude oil production.

(Reporting by Chen Aizhu, Editing by Louise Heavens)

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