ABSTRACT In the last few years horizontal wells are becoming increasly important. This paper presents a hydrodynamic method for solving the flow problem of areal water–flooding systems of combinations of vertical and hprizontal wells( 5–spot well pattern and 7–spot well pattern). The potential function, production rate, breakthrough time, areal sweep efficiency and stream functions are derived respectively. Also, the flow resistance method is used for getting the equations of horizontal well production for all the areal floods. Finally, the equations of oil productions derived by the two methods are compared.