ONEOK, Inc. operates as a midstream service provider of gathering, processing, fractionation, transportation, storage, and marine export services in the United States. It operates in four segments: Natural Gas Gathering and Processing; Natural Gas Liquids; Natural Gas Pipelines; and Refined Products and Crude. The company owns natural gas gathering pipelines and processing plants in the Mid-Continent, Permian Basin, North Texas, Gulf Coast region, and Rocky Mountain regions; and provides midstream services to producers of NGLs.