Oil producers that operate in U.S. shale fields and OPEC member nations should do more to help stabilize crude prices, Nigerian Oil Minister Emmanuel Ibe Kachikwu said on Monday. The Organization of the Petroleum Exporting Countries plans a“company-based workshop” with companies that operate in both areas, Kachikwu said on the sidelines of the CERAWeek energy conference in Houston. Exxon Mobil Corp, Chevron Corp and Royal Dutch Shell Plc have large U.S. shale operations and also operate in Nigeria. “Some of the same companies that are working in shale are the same companies working in OPEC,” Kachikwu said.“We need to begin to look at companies that are very active in these areas and begin to get them to take some responsibilities in terms of stability of oil prices.”