FIG. H-11. Hydrocarbon pressure-temperature relations for multicomponent hydrocarbons. (a) The line indicates isothermal changes (as might happen in a reservoir) as pressure falls in the case of retrograde condensation. The percentages indicate hydrocarbon saturation. For initial condition A, from A to B gas goes into solution as pressure is lowered and from B to C gas comes out of solution. To the left of the critical point, as pressure is lowered, gas comes out of solution. Fluid volumes also change as pressure and temperature change. (After Dickey, 1979, 192.) (b) Schematic diagram for natural gas and (c) for oil.