Partners and development schedule
Pawnee is designed to take carbon dioxide from a StarTex Field Services natural gas treating plant, compress it and transport it for permanent underground storage. According to Decarbonfuse, the project is about 90 miles southeast of San Antonio, while the supplying plant is about 2 miles south of Pawnee, Texas.
Responsibility for construction and operations rests with Ozona. Marubeni will lead the marketing and commercialization of the project's carbon credits. San Antonio-based Ozona is a carbon management company founded in 2021; it says its management team has raised and deployed more than $7 billion for large capital projects over their careers. Marubeni, a global trading and investment company headquartered in Tokyo, already has upstream shale interests in Texas.
The current schedule follows earlier targets set when the joint venture was announced in September 2024. The partners initially sought an investment decision in 2025 and the start of operations in the first quarter of 2026.
"Pawnee moves our strategy from development into construction and ultimately operations," Ozona CEO Rich Adams said. He said connecting additional CO2 sources could allow the project to expand. Both companies are also assessing other carbon capture and storage opportunities in Texas.
Initial volumes and storage potential
The partners plan to repurpose O'Neal Gas Unit No. 4 as the injection well. Ozona puts the potential capacity of the well and surrounding storage area at about 400,000 metric tons of CO2 a year and has reported a successful injection test in the Sligo formation. The storage design uses the overlying Pearsall Formation as an upper seal, according to Decarbonfuse.
That potential capacity is substantially larger than the planned opening phase. Decarbonfuse's analysis describes the initial phase as sized to the StarTex supply: the requested injection limit of 1.5 million standard cubic feet per day corresponds to an estimated 27,500 metric tons of CO2 annually over about 12 years.
Monitoring plan and pending injection permit
The US Environmental Protection Agency approved the well's monitoring, reporting and verification plan in 2024. Under that plan, the Sligo injection interval would lie approximately 14,924 feet below the base of the underground source of drinking water. The planned injection stream consists of 98.2% CO2, 0.4% H2S, 1.03% hydrocarbons and 0.37% nitrogen.
A separate Class II disposal permit remains pending with the Texas Railroad Commission, which regulates the state's oil and gas industry and wells. Submitted in September 2023, the application seeks authorization to inject treated acid gas into the Sligo formation for approximately 12 years.
The requested operating limits are up to 1.5 million standard cubic feet per day at depths of 15,874 to 16,056 feet, with a maximum allowable surface pressure of 7,920 psig.
