The China National Offshore Oil Corporation (CNOOC) has discovered an oilfield in the South China Sea with proven reserves exceeding 100 million tonnes, Xinhua news agency reported on Monday.

The newly-found Huizhou 19-6 oilfield is around 170 km off the coast of Shenzhen and sits at an average water depth of 100 metres, the report said, adding that test drilling has yielded a daily production of 413 barrels of crude oil and 68,000 cubic metres of natural gas.

Huizhou 19-6 is China's first large-scale integrated clastic oilfield in the deep to ultra-deep layers, the report said.

According to CNOOC, offshore oil and gas exploration in deep to ultra-deep layers face multiple challenges, including high temperatures, high pressures, and complex conditions.

Meanwhile, clastic reservoirs, an important component of deep-sea hydrocarbon deposits, generally have low permeability, making the identification of large oil and gas fields more difficult.

Peng Guangrong, a geologist at CNOOC's Shenzhen branch, noted that 60 percent of the world's newly-discovered oil and gas reserves have come from deep layers. With abundant resources and a low level of exploration, deep to ultra-deep layers are expected to drive future growth in oil and gas reserves and production.

CNOOC's CEO says China's oil and gas exploration in the eastern South China Sea has seen consecutive breakthroughs, with oilfields exceeding 100 million tonnes in reserves discovered for two straight years. (Xinhua)