Reliable predictions of productivity decline of gas condensate wells require a proper description of complex flow behaviour in the near-wellbore region. In that region high pressure gradient induces both large condensate saturation and high gas velocities which may lead to significant deviation from Darcy's law for gas permeability. At the present time, no physically relevant model exists which takes into account these non-Darcian two-phase region.
During the exploitation of gas condensate reservoirs, the bottom hole flowing pressure decreases gradually. Below the dew point pressure, retrograde condensation occurs leading to the segregation and then the mobilisation of the condensate phase (above the critical condensate saturation) towards the producing wells. The liquid phase accumulates in the near-wellbore region, forming a ring which impairs progressively the gas deliverability. On the other hand, steadily, the produced gas become lighter and therefore less marketable.
Predicting reservoir gas Performance and Economy thus requires an accurate modelling of the flow behaviour in the near wellbore.
Much research has been conducted to understand the failure of Darcy's law when gas flow rate is gradually increased. The most commonly used flow equation is the so-called Forcheimer Equation (1914).
In this work few parameters will be investigate to understand productivity impairment in gas reservoirs.
A reservoir numerical model will be built on a simulator to predict the effect of these parameters on well productivity in order to increase deliverability.