Royal Dutch Shell plc expects to write down between $3.5 billion to $4.5 billion during the fourth quarter because of impairments, asset restructuring and onerous contracts. It would be the third time this year the Anglo-Dutch supermajor has written down assets.

In a fourth quarter update, Shell said it expects to take a partial impairment on the Appomattox asset in the U.S. Gulf of Mexico (GOM) because of sub-surface updates. The project, located about 80 miles south of New Orleans, began production in May 2019. It was the first commercial discovery to ramp up in the Norphlet formation.

It also expects charges on oil products related to the previously announced transformation of the refinery portfolio, as well as on onerous contracts in the Integrated Gas (IG) segment.

Shell...