Gas condensate flow around hydraulically fractured/perforated wells
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Gas condensate flow, which is very different from the conventional two-phase (oil and gas) flow, shows more complicated behaviour around the wellbore owing to condensate buildup and the different velocity effects on relative permeability (kr) of these low IFT fluid systems. This is especially true for complex wellbore completions, such as hydraulically fractured or perforated wells. This research programme has two separate parts. The first part is about gas condensate flow around hydraulically fractured wells (HFWs). In this part of the study, different inhouse simulators have been developed by the author. These simulators account for the changes in fluid properties with pressure, phase change, coupling (increase in kr as IFT decreases or velocity increases) and inertia (decrease in kr when velocity increases) when it is required to do so. The simulators have been used to investigate the effect of different important geometrical and flow parameters on the performance of a HFW. The new developed formulae for accurate estimation of effective fracture conductivity, fracture skin factors (mechanical and flow) and effective wellbore radius are the main practical outcomes of this part of the study. The author has also provided a new convenient method for the optimization of fracture dimensions for a given fracture volume, in gas condensate reservoirs. The second part of this research is about the study of gas condensate flow around perforated wells. Here the previously developed simulators by the Gas Condensate Research group have been used to develop a new method for estimation of mechanical perforation skin. The introduction of a method for calculation of effective wellbore radius of a perforated well by which the flow skin is negligible is another important result of this part. The new formulae introduced in this work can be used as a useful tool for estimation of well productivity/injectivity. They are also very useful in reservoir simulation, because having the effective wellbore radius for a complex wellbore geometry- such as a perforated well or hydraulically fractured well - provides an opportunity to define a simple open-hole system instead of the real wellbore. This eliminates the need for a costly and cumbersome fine grid exercise, which otherwise would be required to capture accurately the variation of flow parameters around these types of wellbores.