Low oil prices are just the tip of what ails Russia, according to Moody’s Investors Service.

With its dependence on commodities and a slump in investment, Russia will have a hard time recovering from its record economic slump as global oil prices are bound to remain lower for a long time, Yves Lemay, managing director in the sovereign risk group at Moody’s in London, said in an interview on Wednesday. As much as a quarter of Russia’s gross domestic product and two-thirds of its exports are linked to the energy industry, according to the rating company.

“Our assessment is that low oil prices are here to stay,” Lemay said. “Without major investment in the infrastructure, modernizing the equipment, oil production in Russia is unlikely to rise and may slowly decline in the coming years.”

Crippled by its first recession since 2009, Russia is starved of investment as U.S. and European Union sanctions over the conflict in Ukraine limit access to international capital markets and curb imports of drilling technology. Fixed-capital investment has fallen for 18 months, and the Economy Ministry predicts capital outflows may reach $90 billion in 2015 after last year’s record of more than $150 billion.

While Russia’s oil output has remained above 10 million barrels a day for almost six years and reached a post-Soviet record in January, sanctions have raised the cost of borrowing and barred technology exports needed for new, more complex oil projects. OAO Rosneft, the world’s biggest publicly traded oil company by volume, and gas producer OAO Novatek are among firms targetedfor Russia’s actions in Ukraine.