The Organization of the Petroleum Exporting Countries is reducing output by about 1.2 million barrels per day as part of a deal with Russia and other non-OPEC producers. The pact will run until the end of 2018. He said the OPEC and non-OPEC members were committed to bringing stability and to balancing the market. "The next step may be easing of the production constraints. My estimation is that it will happen sometime in 2019. But we don't know when and we don't know how," he said.