Formation damage along well axis may be distributed unevenly. Especially in horizontal wells, the damage around the wellbore is highly non-uniform. The literature hosts many studies focusing on the effect of non-uniform skin distribution on the transient pressure behavior of horizontal wells. There are few studies concentrating on how the uneven distribution of the skin factor affects well productivity. Furui et al. and Frick and Economides presented simple models accounting for the non-uniform formation damage around horizontal wells.
In this study, we compare the simple heterogeneous skin distribution models against the results from a 3D multisegment model. We show that the non-uniform skin models proposed by Furui et al. and Frick and Economides for horizontal wells are incorrect although the methods are simple and easy to use. Additionally, we demonstrate that the horizontal well skin formulation suggested by Malekzadeh and Tiab is inaccurate.