The penetration rate of the rotary drilling process can be increased greatly by lowering the hydrostatic pressure exerted against the hole bot- tom. In areas where formation pressures are con- trolled easily, the effective hydrostatic pressure sometimes is reduced by injecting gas with the well fluids. Calculate the volume of methane gas per volume of water (standard cubic feet per gallon) that must be injected at 5,000 ft to lower the effec- tive hydrostatic gradient of fresh water to 6.5 Ibm/gal. Assume ideal gas behavior and an average gas temperature of 174F. Neglect the slip velocity of the gas relative to the water velocity. Answer: 0.764 scf/gal.