As low oil prices remain steady, many oil companies have been forced to write down the value of their reserves.
It's something oil giant ExxonMobil has resisted, even as its revenues have dropped.
But the company is now expected to reassess the value of 3.6 billion barrels of oil-sand reserves, and 1 billion barrels of other North American oil reserves.
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This could represent the the biggest accounting revision of reserves in ExxonMobil's history, according to The New York Times (subscription required).
The move comes as a result of regulatory as well as market pressures.
ExxonMobil's accounting practices have attracted the scrutiny of the Securities and Exchange Commission (SEC) and New York state attorney general Eric T. Schneiderman.
Offshore Oil Rig
He also accused ExxonMobil of misleading the public on the impact of greenhouse-gas emissions from fossil fuels.
New York is one of multiple states investigating whether ExxonMobil—in its former incarnation as Exxon—suppressed research from its own scientists confirming the occurrence of climate change.
In August, the SEC requested documents related to the valuation of ExxonMobil's reserves, but has not publicly commented on the nature of the inquiry.
ExxonMobil's discussion of writing down the value of oil in the ground is a reversal of the company's recent policy.
Other oil companies—including Chevron and Shell—have lowered valuations by more than $50 billion since 2014, The New York Times notes.
Oil well (photo by John Hill)
The likely first targets for write downs are ExxonMobil's oil-sand reserves in Canada's Alberta province, because they particularly expensive to mine and process.
The announcement of the potential accounting revision for these assets came as ExxonMobil reported third-quarter earnings of $2.7 billion.
That's a 38-percent decline from the same period last year, meaning ExxonMobil has now reported two full years of quarterly declines.