The effect of pressure gauge placement on well testing analysis accuracy

The main assumption in well test analysis is that the pressure at the perforation zone is known, although transient pressure data may often be recorded at points above the perforation zone in the wellbore. Conversion of recorded data to bottomhole pressure can be affected by wellbore-related phenomena. In this article we develop a nonisothermal transient multiphase wellbore simulator, coupled to a compositional reservoir simulator, to model fluid flow and pressure during well testing. We show that neglecting multiphase flow effects in wellbores for the calculation of bottomhole pressure may make well test results unreliable. We also develop a method to use our simulator to calculate bottomhole pressure from measured pressure data when gauges are placed far from the perforations due to downhole restrictions.