Hurricane Energy has suffered another setback in its efforts to start production from the Lancaster field.
The company is struggling to hook up the Aoka Mizu production vessel to a buoy installed at the site, west of Shetland.
Last month, the rope for pulling in the buoy for the mooring system became snagged and the hook-up operation was postponed.
Another unsuccessful attempt was mounted on Saturday.
Hurricane said: “Immediately prior to engaging the latches in the turret to lock the buoy into position, the pull-in rope failed.
“There were no injuries to personnel or damage to the Aoka Mizu.
“A survey of the buoy by remotely operated underwater vehicle (ROV) confirmed that it has returned to its starting position and is not damaged.
“The Aoka Mizu is returning to the Cromarty Firth to await delivery of a new pull-in rope.”
Lancaster — 100%-owned by Hurricane — is thought to hold 523 million stock tank barrels of oil.
The company intends to develop the field in phases.
Initially, Hurricane will use an early production system (EPS) to assess whether it can progress to a full field development.
The EPS, which involves tying two wells back to Aoka Mizu, should produce 17,000 barrels of oil per day.
First oil is on the slate for the first half of this year.