• S&P Global's base case forecast for oil prices is $90 a barrel for 2023, but Dan Yergin warns there are major uncertainties looming over markets.
• For example, he said there's a chance prices could retake $120 when China fully reopens — that would be around the same level as March highs after Russia invaded Ukraine.

While S&P's Dan Yergin expects the base case for oil prices to stand at $90 in 2023, there remains a chance it could go as high as $121 when China fully reopens, he said, adding that there are three major uncertainties looming over the market.

"Our base case for 2023 is $90 for Brent but you have to look at other cases," the S&P Global vice chairman said, adding there are three major uncertainties: the Federal Reserve's decisions, China demand and Moscow's reaction to the price caps.

"If China gets over Covid ... then you add a lot of demand to the market," Yergin told CNBC's "Street Signs Asia" on Tuesday.

That could be "one big boost" and push prices to $121 a barrel, building on strains caused by underinvestment in oil and gas, Yergin said. That would be near highs set in March after Russia invaded Ukraine.

On the flipside, Yergin said prices could fall to around $70 per barrel in a recession.

In the past three weeks, local and central government authorities in China loosened several strict Covid measures that had required people to stay home and businesses to operate mostly remotely.

Oil demand from the world's top importer could reach 15.7 million barrels per day in 2023, which is around 700,000 barrels higher than 2022, S&P said in its most recent forecast.

Other considerations include Russian President Vladimir Putin's response to the price caps imposed by the European Union, as well as further rate hikes undertaken by the Fed.

EU energy ministers on Monday agreed to cap natural gas prices at 180 euros per megawatt hour, but the European Commission cautioned that the measure could be suspended if the "risks outweigh the benefits." The decision came on the heels of an oil price cap of $60 per barrel at the start of December.

Yergin said he thinks the recently imposed gas price cap "probably will work. He said it also acts as an anticipation of higher gas prices in subsequent winters due to a lack of Russian gas and competing demand between Europe and Asia for LNG.

In Asia's Wednesday morning trade, Brent crude futures added 0.40% to $80.31 a barrel, while U.S. marker West Texas Intermediate futures traded up 0.33% at $76.48 per barrel.

Clarification: This story has been updated to clarify that Dan Yergin expects oil at $90 in 2023 but says there's a chance it could go as high as $121 when China fully reopens.