In production wells, in line with the production time there is a decrease in reservoir pressure and this condition causes a reduction in the economic value of the well. The problem of wells that have decreased production capability caused by a decrease in reservoir pressure can be overcome by means of artificial lift methods. Water injection is a method of injecting by re-injecting water that is carried along with oil during the petroleum production process using an injection pump. Based on this, capacity planning is needed in relation to the need for injection pump engines in the operating area so that the petroleum production process can run smoothly. The method used is to perform formation water forecasting needed in each exploration wells based on historical data injection water formation to obtain a plan regarding the capacity of the pump engine to be used in the coming period. Based on the results of forecasting, it is known that 32 periods have the possibility to exceed WIP capacity by 2000 bwpd. From the observations, an additional 2000 bwpd is needed to increase WTP capacity to 4000 bwpd with the proposed cost needed for the procurement of injection water per month is Rp. 22.083.333 compared to the previous required cost of Rp. 32.129.400,- per month.