Total is understood to have given investment approval for the refinery on 6 May following the release of its first-quarter results in Paris, while Aramco held a board meeting the following day to finalise its involvement.
One executive close to the joint venture says the agreement follows detailed talks between the two sides over the past few weeks.
"The deal has been done and is just awaiting final sign-off from the Saudi Oil Ministry," says the executive.
The move comes despite costs on the Jubail complex soaring above $10bn from an initial budget of $6bn. There has also been doubt over Total's involvement after the French oil major pulled out of a gas exploration agreement with Aramco and the UK/Dutch Shell Group in the Rub al-Khali (Empty Quarter) (MEED 7:2:08).
The Jubail refinery is expected to be prioritised ahead of a second export refinery being developed at Yanbu. "The Jubail refinery project in Saudi Arabia in partnership with Saudi Aramco should be pro-posed for approval soon," Total said as part of its results statement.
Saudi Aramco was unavailable for comment.