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It is now possible to simulate the stationary multiphase wellbore flow and link the surface flow conditions (pressure, temperature and rates) to downhole flow conditions at any depth.

If flow is changing slowly over time the same solutions can be used with inputs as time functions which is called quasi-stationary flow conditions.

This model finds important applications in industry. 

If well production is varying in time slowly by operational the quazi-staytonary has been changed abruptly (for example opening or closing the flow) there will be a transition period towards the new quasi-stationary flow conditions (usually minutes or few hours).

The transition period for pressure and temperature is different and wellbore temperature takes much longer time to stabilize than pressure. 

Unlike single-phase flow the complexity of the multiphase flow during transition is so high and unstable that building a simple mathematical model does not make a practical sense.

Definition

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Mathematical model of Multiphase Wellbore Flow predicts the temperature, pressure and flow speed distribution along the wellbore trajectory with account for:

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