1-how do you know there is no interflow between layers? 2-Isn't it possible for you to adjust the program in a way that he considers the layers non-communicating? 3-may be the sandface pressures of 3 black zones are at higher pressures than upper condensate zone so that the 40% of each lower layer oil is pushed throuh condensate layer [I]at the sandface of condensate layer [/I]