Water coning and critical rates in vertical and horizontal wells

Most of the studies for horizontal wells present the critical rate as an increasing function of the anisotropy ratio. The present study shows that this is true only for 0.5<a<1. In fact, for 0.01<a<0.1, critical rate is a strongly decreasing function of anisotropy ratio. Also most of the studies describe the vertical well critical rate as a decreasing function of the anisotropy ratio, opposite in behavior to horizontal wells. Although the present study agrees with the general trend, it shows that there is a harmonious continuity between vertical and horizontal wells and short horizontal wells display a behavior in between.