Abstract-- This paper presents a method which uses boundary control to increase the oil production in the subcritical phase of a thin oil rim reservoir which is drained via horizontal wells. The problem of finding an optimal well rate is considered using the backstepping method. The feedback control law is constructed explicitly and together with a reservoir-well simulator are used to generate a time varying production plan. The simulation result shows that the performance of the active control law is much better than conventional production strategies using constant oil rates until gas breakthrough.