Adsorptive Nitrogen Rejection from Natural Gas

Low permeability natural gas reservoirs are being developed across the world using fracturing technologies. The most common approach for fracturing uses water with friction-reducing agents and thickening polymers. However, this approach requires approximately 400 tanker trucks to bring millions of gallons of water to a wellhead and results in millions of gallons of contaminated water that must be treated before going back into the natural water cycle. A second approach to fracturing uses high-pressure gases such as nitrogen or carbon dioxide. The use of energized fluids such as N2 or CO2 offers the potential to carry out fracturing without the negative aspects associated with water-based fracturing. This approach, however, often requires producers to divert initial gas production to a flare until N2 / CO2 gas concentrations in the “flow-back” drop below allowable limits for feeding into the natural gas pipeline network. This project aims to address the loss of hydrocarbon energy and the associated CO2 emissions related to N2 fracture operations by utilizing a new adsorbent developed by Praxair in a modular Pressure Swing Adsorption (PSA) system capable of recovering N2 from produced gas at wellhead locations. Technology development in this area will address the specific problem described above and will shed light on the challenges of modular processing of distributed resources in general.