ONEOK, Inc. engages in gathering, processing, fractionation, storage, transportation, and marketing of natural gas and natural gas liquids (NGL) in the United States. It operates through 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 and Rocky Mountain regions; and provides midstream services to producers of NGLs. It also owns NGL gathering and distribution pipelines in Oklahoma, Kansas, Texas, New Mexico, Montana, North Dakota, Wyoming, and Colorado; terminal and storage facilities in Kansas, Nebraska, Iowa, and Illinois; NGL distribution pipelines in Kansas, Nebraska, Iowa, Illinois, and Indiana; transports refined petroleum products, including unleaded gasoline and diesel; and owns and operates truck- and rail-loading, and -unloading facilities connected to NGL fractionation, storage, and pipeline assets. In addition, the company transports and stores natural gas through regulated interstate and intrastate natural gas transmission pipelines, and natural gas storage facilities. Further, it owns and operates a parking garage in downtown Tulsa, Oklahoma; and leases excess office space and rail cars. Additionally, the company transports, stores, and distributes refined products, NGLs, and crude oil, as well as conducts commodity-related activities, including liquids blending and marketing activities. It serves integrated and independent exploration and production companies; other NGL and natural gas gathering and processing companies; crude oil and natural gas production companies; utilities; industrial companies; natural gasoline distributors; propane distributors; municipalities; ethanol producers; petrochemical, refining, and marketing companies; and heating fuel users, refineries, and exporters. ONEOK, Inc. was founded in 1906 and is headquartered in Tulsa, Oklahoma.

Devon Energy Corporation, an independent energy company, engages in the exploration, development, and production of oil, natural gas, and natural gas liquids in the United States. It operates in Delaware, Eagle Ford, Anadarko, Williston, and Powder River Basins. The company was founded in 1971 and is headquartered in Oklahoma City, Oklahoma.

Gulfport Energy Corporation engages in the acquisition, exploration, development, and production of natural gas, crude oil, and natural gas liquids in the United States. Its principal properties include Utica and Marcellus in eastern Ohio; and the SCOOP Woodford and Springer formations in central Oklahoma. The company was incorporated in 1997 and is headquartered in Oklahoma City, Oklahoma.

Mach Natural Resources LP, an independent upstream oil and gas company, focuses on the acquisition, development, and production of oil, natural gas, and natural gas liquids reserves in the Anadarko Basin region of Western Oklahoma, Southern Kansas, and the panhandle of Texas. It also owns a portfolio of midstream assets, as well as owns plants and water infrastructure. The company was incorporated in 2023 and is headquartered in Oklahoma City, Oklahoma.

Vital Energy, Inc., an independent energy company, engages in the acquisition, exploration, and development of oil and natural gas properties in the Permian Basin of West Texas, the United States. The company was formerly known as Laredo Petroleum, Inc. and changed its name to Vital Energy, Inc. in January 2023. Vital Energy, Inc. was founded in 2006 and is headquartered in Tulsa, Oklahoma.

Amplify Energy Corp., together with its subsidiaries, engages in the acquisition, development, exploitation, and production of oil and natural gas properties in the United States. The company's properties consist of operated and non-operated working interests in producing and undeveloped leasehold acreage, as well as working interests in identified producing wells located in Oklahoma, the Rockies, federal waters offshore Southern California, East Texas/North Louisiana, and Eagle Ford. The company is based in Houston, Texas.

U.S. Energy Corp., an independent energy company, focuses on the acquisition, exploration, and development of oil and natural gas properties in the United States. It holds interests in various oil and gas properties located in the Rockies region, including Montana, Wyoming, and North Dakota; the Mid-Continent region comprising Oklahoma, Kansas, and North and East Texas; West Texas; South Texas; and the Gulf Coast regions. The company was incorporated in 1966 and is headquartered in Houston, Texas.

Mexco Energy Corporation, an independent oil and gas company, engages in the acquisition, exploration, development, and production of natural gas, crude oil, condensate, and natural gas liquids in the United States. It owns partial interests in wells located in the states of Texas, New Mexico, Oklahoma, Louisiana, Alabama, Mississippi, Arkansas, Wyoming, Kansas, Colorado, Montana, Virginia, North Dakota, and Ohio. It also owns leasehold mineral, royalty, and other interests. The company was formerly known as Miller Oil Company and changed its name to Mexco Energy Corporation in April 1980. Mexco Energy Corporation was incorporated in 1972 and is based in Midland, Texas.