Russia's Energy Minister Alexander Novak, Saudi Arabia's Energy Minister and OPEC conference president Khalid al-Falih, and OPEC Secretary General Mohammad Barkindo attend a meeting of the Organization of the Petroleum Exporting Countries (OPEC) and non-OPEC producing countries in Vienna, Austria, May 25, 2017.

OPEC is expected to extend its agreement with Russia and other non-OPEC countries to curb production, even as U.S. shale production and exports continue to grow, according to a CNBC oil survey.

About 80 percent of the oil analysts and traders surveyed by CNBC also agree the market, which had been heavily oversupplied, is showing signs of rebalancing.

Forty-four percent say the rebalancing can continue if U.S. production, blamed for the glut, does not rise much more. Thirteen percent say if the U.S. output continues to grow, the rebalancing will end, as it will lead to oversupply.

The OPEC agreement, struck with Russia a year ago, is seen as a factor helping drive a turnaround in oil prices. Ninety-four percent of the 16 survey participants expect the price for West Texas Intermediate crude to end the year at about where it is now — $50 to $60 per barrel. But more than half, 56 percent, said there's a chance crude could fall back into the $40s in 2018.

OPEC meets in Vienna on Thursday, and the market has been expecting its deal with Russia and other producers to hold back 1.8 million barrels a day to be extended to the end of the year. Reuters reported Tuesday that sources said the technical committee of OPEC and the non-OPEC members recommended extending the agreement through the end of the year with a review in June.

Michael Cohen, head of commodities research at Barclays, said he had expected a six- or nine-month extension of the agreement, which is due to end in March, but he adds that the extension length is less important than the quota. He said the technical committee and Joint Ministerial Monitoring Committee can recommend changes at any time.

"Even if the deal ends, we would not expect an onslaught of new production from participants," Cohen wrote in his answer to the survey.

Russia has been a bit of a wild card. Russian companies had complained that U.S. shale was biting into market share, while they held to an agreement to keep their own production off the world market. Eighty-one percent of the survey participants expect Russia to be part of OPEC's deal Thursday.

The deal has been important to Saudi Arabia, as it needs a high oil price for its Vision 2030 program to transform the country's economy. In the survey, 81 percent said Saudi Arabia was "jawboning" the price of oil higher, ahead of its IPO of Saudi Aramco, the state-owned oil company.

The survey also focused on other factors that could impact oil prices. Forty-four percent said they expect the Trump administration's decertification of the Iran nuclear deal will result in reimposition of sanctions on Iran, but 31 percent do not believe it will, while 25 percent are unsure.

Sixty-nine percent expect to see Venezuelan oil supply to take a further hit next year.

A full 100 percent expect U.S. oil production to continue to rise and impact market dynamics.

"Increased U.S. production has taken away a significant portion of OPEC's power. As long as crude hovers near $60, I think that domestic production will continue to ramp," wrote Jim Iurio of TJM institutional Services.