Nitrogen gas fracking is used for water-sensitive and brittle shale formations because it prevents clay swelling that would otherwise be caused by water-based treatments. Therefore, nitrogen gas treatments produce the best results in brittle shale formations that have natural fractures and stay self-propped once pressure pumping is completed. Due to the low density of gaseous nitrogen, the main applications for nitrogen gas treatments are unconventional formations such as coal bed methane, tight sands, and shale formations.
“In certain shale plays, nitrogen-assisted treatments have offered superior performance when measured as the estimated ultimate recovery (EUR) of oil or gas compared to slick water treatments. This measure means that the cost of nitrogen-assisted treatments is lowered on a normalized production basis.”