Exxon CEO says hopes Mexico extends oil reforms NEW YORK (Reuters) - Exxon Mobil (XOM.N) would be interested in investing in Mexico's oil and gas sector, but only if the Mexican government allows the company to own some energy reserves, its chief executive said on Wednesday. We're not real keen on service contracts, we're not real keen on fixed margin contracts. Although we have some of those, they're not particularly great for us," Exxon Mobil CEO Rex Tillerson told reporters after a speech. Mexico's constitution bars outside exploitation of the country's oil resources, making joint ventures or profit sharing with private companies difficult. But the country has been seeking to open the door to attract investment from foreign oil and gas producers to help tap the vast reserves there. Mexico's state oil monopoly Pemex PEMX.UL awarded contracts to some foreign companies earlier this month to help develop offshore fields, but those contracts pay bonuses based on performance and do not allow for ownership of oil and gas. Tillerson said he was encouraged by the initial moves to open the Mexican energy sector, which could eventually attract financing and technology from the global industry. I think it's going to be a long process. And what we're advocating is just for Mexico to take the next step," he said. In addition to its offshore oil fields, Mexico has the world's fourth-largest reserves of shale gas, according to the U.S. Energy Information Administration. But so far, Pemex has drilled relatively few wells in the those fields near the Rio Grande because it has little capital to develop those areas. Tillerson also said the United States, Canada and Mexico should work together to develop energy supplies and promote "energy security" that would keep a flow of oil and gas to North America. Currently, North America produces about 15 million barrels of oil per day, he said, and Exxon expects that figure to grow to 18 million barrels a day by 2020. "That is a force to be dealt with in global oil markets," he said. "It's my hope that at some point energy security can become a policy issue in our foreign policy discussion with Mexico, Canada and the United States," he said. Reporting by Matt Daily; Editing by Leslie Gevirtz