A BP scientist identified a previously unreported deposit of flammable gas that could have played a role in the Gulf of Mexico oil spill, it has emerged.
But the oil giant failed to divulge the finding to US government investigators for as long as a year, according to interviews and documents obtained by The Associated Press.
While engineering experts differ on the extent to which the 2ft-wide swathe of gas-bearing sands helped cause the disaster, the finding raises the spectre of further legal and financial troubles for BP. It could also raise the stakes in the multi-billion court battle between the companies involved.
A key government report into what caused the worst offshore oil spill in US history is due to be released.
"This is a critical factor, where the hydrocarbons are found," said Rice University engineering professor Satish Nagarajaiah. "I think further studies are needed to determine where this exactly was and what response was initiated by BP if they knew this fact."
In a closed-door deposition two months ago, BP petrophysicist Galina Skripnikova told lawyers involved in the oil spill litigation that there appeared to be a zone of gas more than 300ft above where BP told its contractors and regulators with the then-Minerals Management Service the shallowest zone was located.
The depth of the oil and gas is a critical parameter in drilling because it determines how much cement a company needs to pump to adequately seal a well. Government regulations require the top of the cement to be 500ft above the shallowest zone holding hydrocarbons, meaning BP's cement job was potentially well below where it should have been.
Cement contractor Halliburton recently filed a lawsuit against BP asserting that Ms Skripnikova's statements prove the oil giant knew about the shallower gas before the explosion and should have sought a new cement and well design. BP has denied the claims.
Early on Wednesday BP provided a letter it said it sent the oil spill commission on October 30 2010, six months after the explosion. The letter said BP would be sending the commission draft reports the company prepared and more detailed studies to help inform its efforts to stop the flow of oil to the sea. The letter does not detail what the reports said, what data was provided, or whether the data was the same as that which Ms Skripnikova discussed in her deposition.
And an investigator with the presidential oil spill commission, which released a report on the disaster months ago and disbanded in January, told AP that BP did not specifically reveal the higher probable gas zone during the course of the panel's investigation. The investigator, who spoke anonymously, said an independent petrophysicist reviewed the data available to the panel and did not express concern about gas being at a shallower depth.