Analytical study of capture zone of a horizontal well in a confined aquifer

We have presented analytical solutions for the capture zones of infinitely long horizontal wells in a homogeneous, confined aquifer with uniform flow. We find that the capture width enlarges and the bisector line of the capture zone moves toward the centerline of the aquifer when moving away from the well in the upstream direction for an arbitrary well location. The capture width and bisector line approach their ultimate width and position, respectively, after a distance of about 1.5 times the aquifer thickness. The ultimate capture width depends on the well discharge but not on the well location. We have plotted the ultimate bisector line position versus discharge for different well locations. Compared to the capture zone of a fully penetrating vertical well in an isotropic and laterally infinite aquifer, the ultimate capture width of a horizontal well is smaller than that of a vertical well given the same discharge rate per unit length. Furthermore, the relationship between the ultimate capture width and the well discharge rate is non-linear, in contrast to the linear behavior often observed in the vertical well capture zone.