Most of the studies in literature show that there is an improvement in sweep efficiency from infill drilling and from drilling horizontal producers and horizontal injectors. The purpose of this study is to improve the sweep efficiency and accelerating oil production in Field A in Middle East. Production in Field A is not as expected because of having vertical injectors commingled to three zones and completed with limited entry perforations that could not provide good vertical steam distribution. This is because of steam quality drops dramatically before it reaches the zones of interest especially the lower one. This issue can be resolved by installing special and expensive completion for each injector that can solve segregation problem or by drilling horizontal injectors for each zone. In this study horizontal injectors with steam control along the lateral is simulated and compared with the vertical injectors with the same control but with zonal device. This work show that horizontal injectors and vertical injectors cases give almost similar results in terms of oil productionimprovement. However, it was difficult to know which of the 12 vertical injectors is affecting the three offending producers but with horizontal ones, it is only 2 injectors affecting each producer. Additionally, the horizontal injectors option will save cost of flow lines and wellheads over the vertical injectors option, Converting injectors to producers is one of the strategies we examined for improving sweep efficiency but the results show that there is no benefit to do that because of the steam lose and hence pressure support reduction.. This study results reveal that drilling infill wells will improve oil production. The most preferable case is drilling vertical injectors at the four corners of the sector to displace the remaining oil in that area. Each sector will need only one injector, Also, 2 half vertical producers can be drilled along with 4 quarter injectors and can give good production and sweeping the trapped oil but with increase in cost