After leaving the Western company, Chevron's CEO saw a drop in Russian oil production

Russia still has buyers for its oil but will struggle to recover from Western technology and capital loss, Mike Wirth said. Russia still holds most of its oil despite the expanded sanctions, but its output is likely to fall after Western oil firm Chevron Corp. CVX 0.91%, said CEO Mike Wirth.

Speaking to reporters and editors in The Wall Street Journal this week, Wirth noted that many countries, along with the United States and Saudi Arabia, continue to buy crude from Russia, one of the world's largest oil producers.

But he said it would be difficult for Russia to cope with the loss of Western technology and capital, noting that other major oil producers had seen output drop following sanctions and withdrawals of international oil companies.

"If you look at Iran and Venezuela, two other examples of large producers that have been sanctioned and have done quite well with the same types of investment and technology, their production capacity has declined over time," Wirth said.

After decades of strengthening positions in the Russian oil business, BP PLC, Shell PLC, and Exxon Mobil Corp. said they would suspend operations once Russia's invasion of Ukraine began in late February. A few weeks later, Halliburton Co.'s oil giant Baker Hughes Co. and Schlumberger Ltd., which provides the equipment and workforce needed for oil production, all said they would suspend new investment in Russia.

The European Union plans to continue with a partial embargo on Russian oil, and many western refiners have stopped buying supplies from Russia. However, Wirth said Russian energy products would still find willing buyers worldwide at discounted prices. Therefore oil market participants were reacting to the prospect of a supply cut rather than a sharp drop in oil production. Russian oil is still running as some shippers and refiners remain silent about its origins.