Phases re-distribution during build up test.

[reservoir_engineer]

dear all,
i am doing PBU test interpretation for well in gas cab reservoir, you can consider it as thin oil rime reservoir. during the production period GOR was high. the BU exihibit phases re-distribution pheonomena resulting in gas hump as you see.
iam using saphir, how i can include this pheonomena to be modeled and enhance my match.
regards,,,,