China National Offshore Oil Corporation (CNOOC) has achieved a milestone in ultra-deepwater natural gas exploration by drilling a well in the Liwan 4-1 structure within the Pearl River Mouth Basin.
The company said this well represents the first substantial exploration success in ultra-deepwater carbonate rocks offshore China.
Situated in the hydrocarbon-rich Baiyun Sag, approximately 300km south-east of Shenzhen, the well reached a water depth of nearly 1,640m.
It was drilled to a vertical depth of nearly 3,000m and finished at a depth of almost 4,400m, revealing a gas pay zone of around 650m in the horizontal section.
Testing of the well yielded an absolute open flow natural gas production rate of 430,000m³ per day.
The energy company noted that the discovery has unveiled promising exploration prospects in the ultra-deepwater Globigerinid limestone in China and is set to advance the natural gas exploration efforts in Baiyun Sag.
CNOOC chief geologist Xu Changgui said: “Previously, exploration in China's ultra-deepwater areas mainly focused on clastic rocks. The success of this well has, for the first time, revealed the enormous potential of carbonate rocks in China’s ultra-deep waters, marking significant breakthroughs in both exploration understanding and operational techniques.
“In addition, this discovery is close to the existing production facilities of Liwan3-1 gas field, which could be utilised to develop the new discovery, thereby enabling economic and efficient development of natural gas resources in the deep waters of the Pearl River Mouth Basin.”
Earlier in the month, CNOOC commenced production at the Wushi 17-2 Oilfields Development Project in the Beibu Gulf, with an average water depth of around 28m.
By 2026, the project is expected to reach peak production of roughly 9,900 barrels of oil equivalent per day, with the oil being classified as light crude.
Last month, CNOOC received official approval for a proved gas in-place volume exceeding 100 billion cubic metres at the Lingshui 36-1 field in the South China Sea.
With this approval, the total proved gas in-place in the South China Sea has now exceeded one trillion cubic metres.
