Well testing data is usually affected by different wellbore effects. Phase redistribution is one of the most important in gas wells with high liquid production (condensate or water) and volatile oil wells. The longer the wellbore phenomena, the higher the probability to distort reservoir pressure behavior (infinite acting flow regime, linear flow, etc.).

In this situation, the conventional pressure transient analysis would be hard to perform, increasing the probability to obtain erroneous values of permeability and skin factor. Nevertheless, in the last years, the use of primary and secondary pressure derivative as a diagnostic plots (Semilog and Log-Log plots), demonstrated to be very useful in low permeability gas wells and weak phase redistribution gas wells.

This paper evaluates of the second semilog pressure derivative technique for different types of phase redistribution. It also presents the application of this diagnostic plot in the interpretation of two gas-condensate well test with strong phase redistribution phenomena. Results highlight the applicability of second semilog pressure derivative over other similar techniques.

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