Australian independent Roc Oil has completed its latest disappointing oil exploration well offshore China after failing to discover hydrocarbons in the basement target.

The Weizhou WZ12-8E A8 exploration well in the Beibu Gulf was drilled to a total measured depth of 3597 metres and intersected both the targeted Tertiary stacked sandstones and the basement.

However, while the probe encountered two minor oil columns of approximately two metres and 3.6 metres true vertical depth, the fractured basement target came up dry, confirmed co-venturer Horizon Oil.

The exploration well was targeting an unrisked best estimate gross prospective resource of 5.1 million barrels of oil.

If it had delivered as hoped, the A8 well could have been brought into production within a few days of discovery via the WZ12-8E infrastructure.

However, the well instead has been plugged and abandoned, which frees up a rig slot on the WZ12-8E platform for a possible phase two development well.

Meanwhile, Roc and its partners are continuing to assess the geological and commercial implications of the WZ12-8E A8 well results.

The COSL Strike rig now is completing the WZ12-8E A7 water disposal well — an operation that will conclude the WZ12-8E phase one drilling programme.

Participants in the unsuccessful WZ12-8E A8 exploration well were operator Roc on 40%, Horizon with 55% and Oil Australia having 5%.