Pseudo-skin model for gravel-filled perforations

This paper discusses pressure losses due to flow in perforations filled with gravel or with formation material. These pressure losses are added to the pressure losses caused by convergence to perforations to obtain the pseudo-skin due to gravel-filled perforations. Calculation of the pressure loss due to convergence to perforation is discussed by Okonkwo (1995). The flow in the perforation tunnel could be turbulent or laminar. Therefore, we calculated the pressure losses in a gravel-filled perforation using Forchheimerʹs equation or Darcyʹs law. However, we expect that the flow in such tunnels will be turbulent. Results from our model agree with experimental data published by Penberthy and Cope (1980). Also, our results show that pressure losses during flow through gravel-filled perforations could be substantial. Therefore, productivities of gravel pack completions may differ significantly from perforated completions in competent formation without gravel pack.