A high-tech effort by BP, to slow the oil gushing from its ruptured wellhead, led to a large accident yesterday that forced the company to remove a vital containment cap for 10 hours.

Robots, known as remote operated vehicles, were performing multiple operations at the disaster site when one bumped into the ‘top hat’ cap and damaged one of the vents that removes excess fluid, according to the US coastguard.

The robots weigh around four tonnes, and are controlled from vessels on the surface using advanced IT systems with both manual and automated functions.

CIO 100 ranked BP removed the cap for nearly 10 hours, until 0845 CDT (1445 BST) yesterday, in order to assess it after a discharge of liquids was noted from a key valve. The cap’s removal left the oil gushing out of the wellhead, largely uninterrupted.

Admiral Thad Allen, US National Incident Commander for the response, told the media that part of the problem was the number of robots conducting simultaneous operations at an immense depth. A dozen robots are circulating the wellhead.

“There are an unbelievable amount of ROVs operating down there,” he said. “One of the risks inherent in everything we’re doing out there is simultaneous operations, or what they would call SimOps.”

“It’s never going to be risk-free out there.”

Allen said the clear “assumption” was that the robot had damaged the cap. A BP spokesperson told Computerworld UK it was still too early for exact details of the events.

BP has now fixed the cap and placed it back on the site, allowing a surface vessel to resume the capture of oil. In the 24 hours before the accident, the vessels recovered more than 27,000 barrels of oil – the largest daily collection amount to date but only a portion of the 30,000 to 60,000 barrels estimated by US scientists to be spewing daily.

Last week, as US president Barack Obama piled pressure on BP to speed up efforts to clear up the problem, the company committed to a $20 billion payment for an independent claims fund to support the individuals and businesses affected by the disaster.

Yesterday's ROV incident is not BP's first. In April, the robots failed to activate the blow out preventer device, a step that early investigations said played a part in the disaster. Subsequent efforts to cut off the damaged riser pipe also initially failed.

Failures of other electronic systems are also being investigated. The emergency disconnect system should have kicked in to stop the oil from flowing to the well head, but signals may not have reached the blowout preventer because of the explosion. There were also problems with a further automatic closure system, or deadman switch, that did not close off the preventer when the connections were lost.

The testing and maintenance of systems is being examined, as are the quality of cementing and casing around the well and the processes taken before the explosion. All the factors are subject to ongoing investigations by BP and the US authorities.