Saltwater found in underground formations in which the pressure is much higher than commonly exists at such depths (primarily in the Gulf Coast states and under the Gulf of Mexico). Gas is soluble in water, just as it is in crude oil, but in much lower amounts. Solubility increases with pressure. Geopressured brines (with formation pressures of 10,000 psi or higher) contain sufficient gas in solution that were the pressure reduced (by producing the saltwater) significant quantities of gas could be produced. The total amount of gas held in geopressured brines is quite large and represents a potential energy resource for the U.S. However, the production of such gas is currently not economic.