A commitment to expand operations at one of the largest oil fields in Central Asia is a testament to investor confidence, the Kazakh oil minister said.

Chevron, its consortium partners and the government of Kazakhstan announced support for a $36.8 billion plan to expand production at the Tengiz oil field. One of the largest fields in the region, the investment could boost production by around 40 percent to 850,000 barrels per day by the start of the next decade.

Kazakh Energy Minister Kanat Bozumbayev said the spending agreement on Tengiz is a testament to investor confidence in his country.

"This decision made by major international companies re-affirms that the Republic of Kazakhstan is a country with favorable business-climate where long-term investments can be made with confidence," he said in a statement.

A year ago, the government said total crude oil output would reach 630 million barrels in 2017 and 760 million barrels in 2020 thanks in part to the expansion program planned for the Tengiz field.

In 2014, when crude oil prices were above $100 per barrel, Kazakhstan produced around 590 million barrels of oil. Part of Kazakhstan's oil production gains are expected to come from the Kashagan oil field in the Caspian Sea, one of the largest in the world. Pipeline issues at Kashagan, which disrupted production in 2013, may cost as much as 15 times more than initially expected.

According to the latest report from the Organization of Petroleum Exporting Countries, Kazakh oil production is in decline because of ongoing field maintenance. On a country-by-country basis, OPEC said Kazakhstan was one of those experiencing the strongest declines in production for 2016.

The International Monetary Fund said economic growth for Kazakhstan is expected to be "subdued." IMF Managing Director Christine Lagarde said in May low oil prices, as well as weaker growth with key regional trading partners, were having a profound impact on the economy.

"Unfortunately, some of these changes are likely to be lasting," she said.