Consider a 2-km-deep gas well containing a gas mixture of methane and ethane at a uniform temperature of 30oC. The pressure at the top of the well is 14 MPa, and the composition on a mole basis is 90% methane, 10% ethane. Each component is in equilibrium (top to bottom) with dG + g dZ = 0 and assume ideal gas, so for each component Eq.15.10 applies. Determine the pressure and composition at the bottom of the well.