This model is slightly more complicated than the conventional block model of a steam zone, a hot condensate zone, and a cold oil zone, but does not try to incorporate the complexity of mixed fluid phases, emulsions, fingering, gravity overrides, etc., as described by Lake 1989 for example. As a point of interest, the seismic images show no evidence of gravity override at the top of the P formation. If a thin steam zone existed along the formation top, it would show up as a bright reflection, and possibly cause some time delay below, depending on its thickness. The reason that gravity override is not visible may be because the permeability and absence of clay is much higher at the base of the P formation than at the top. This would inhibit steam from racing along the top of the formation, and favor it spreading slowly along the base of the unit instead.