fluid is typically a slurry of water, proppant, and chemical additives. additionally, gels, foams, and compressed gases, including nitrogen, carbon dioxide and air can be injected. typically, 90% of the fluid is water and 9.5% is sand with chemical additives accounting to about 0.5%. however, fracturing fluids have been developed using liquefied petroleum gas (lpg) and propane in which water is unnecessary.