In an operations update yesterday, Key said the well, located in the Nyuni Block of Tanzania, was at a depth of 2260m where the operator Ndovu Resources has run and cemented the 9 5/8-inch casing.

However, the company reported that multiple trips in and out of the hole were required to remove debris from a broken drill bit.

“The rig is currently cleaning the hole to remove that debris,” Key said.

“On completion of this operation, the well will cut around three metres of new hole and the well will be pressure tested prior to drilling ahead into the primary target.”

The primary objective, in Lower Cretaceous sands, is expected to be encountered at a depth of 2340m.

Spudded on November 19, the well was supposed to take 40 days to reach total depth.

However, by early January the joint venture had already been delayed by several shutdowns after mechanical and electrical problems, involving the mud pump and generator, on the rig.

Then yesterday, Key announced further hold-ups caused by the drill-bit failure.

The second well, Kiliwani North-1, will test the same reservoir system, as well as a shallower oil play with the potential to contain 10 million barrels of recoverable oil.

Key Petroleum, which listed on the Australian bourse in April, will have a 20% interest in the PSC by paying 30% of the cost to drill the two wells.

Fellow Australian junior Bounty will have a 6% stake, while operator Aminex has 39%, RAK Gas has 25% and East Africa Exploration has 10%.