W Waterflooding is the most common secondary recovery method used to improve oil recovery from the reservoirs. The way to increase the reserves is by injecting water to increase energy and increase oil recovery. Reservoir management for surveillance waterflood is carried out to consider systems from reservoir characteristics such as fluid and reservoir behavior, wells manufacture and operation, and fluid processing facilities. Waterflood analysis is intended to find out how the state of the formation around the injection well during waterflooding. In any waterflooding project, the available data is the rate of production and injection carried out on a monthly well test. Usually, the description and characterization of the reservoir along with observation of injection and production rates is used to determine the effect of each injector on producers.There are four methods that will be used in this waterflood analysis. Evaluation of connectivity is an attempt to understand how effectively two wells are connected to each other. Hall Plot is used to analyze injection well data, based on a plot of cumulative pressure vs cumulative injection where can provide a lot of information about the characteristics of injection wells. The Chan's Diagnostic is log-log plots of the WOR vs time were found to be more effective in identifying the production trends and. problem mechanisms. It was discovered that derivatives of the WOR versus time can be used for differentiating whether the excessive water production problem as seen in a well is due to water coning or multilayer channeling. Effective pressure management and surveillance are essential to maintaining successful waterflood operations. One needs to properly manage is voidage replacement ratio (VRR) for pressure maintenance purposes. This will help to avoid the production of excessive solution gas and prevent reservoir subsidence for poorly consolidated systems.Pattern X is one of the Z Field Patterns in 60 km west of Prabumulih, South Sumatra which is at the stage of implementing full scale waterflood. In general, the pattern scenario used is an inverted 5-spot. Pattern X has six production monitor wells, namely Z-091, Z-098, Z-110, Z-157, Z-195, and Z-233, and one Z-227 injection well. Analysis of surveillance waterflood on a field is very important to be done as a benchmark for the success of waterflood activities that have been carried out. Analysis of connectivity is carried out to determine the water injection response that has been made to surrounding production wells, namely by using a plot of gross rates, oil rates, dynamic fluid level (DFL), and water cut against time. From the analysis carried out on one Z-227 injection well it was found that the slope moved upwards which indicated that the injection was normal or injection stable. However, over time there is an increase in the slope that indicates the occurrence of skin. In fact, the increase in slope occurs due to the installation of Multilayer Packer which is used to adjust the planned injection rate. the analysis that the Hall Plots in this injection well which have no problems and the injection runs stably in accordance with the Z-227 well injection planning plan. For Chan’s Diagnostic Z-091, Z-098, Z-195 Well, the distribution of WOR and WOR derivatives in each production well, have a problem, namely the near wellbore water channeling. Through a comparison with the Chan method for Z-110, Z-157, Z-233 Well have a problem, namely the multilayer channeling with production changes. From the analysis of Voidage Replacement Ratio in Pattern X, it was found that the VRR value increased to 0.84, but because the injection system was not good (there was no regulating rate for each injection well) there was a decrease in VRR value. In January 2017 there was a decline until the VRR value was 0.78 after MLP was installed to adjust the injection rate target.The good connectivity is found in well pairs Z-227 with Z-091, Z-195, and Z-233. Wells with poor connection is Z-227 with Z-098. While further observations are needed on Z-227 with Z-110 and Z-157 because there are no significant results. Hall analysis for Z-227 injection well plot found that the injection is normal or stable. Analysis of Chan's in Pattern X where production wells have two problems, namely 3 wells with near wellbore water channeling wells and 3 wells with multilayer channeling with production changes. From the Voidage Replacement Ratio analysis it was found that the VRR value increased to 0.84 but then decline until 0.78. So that the injection is concluded it is still not optimal because the VRR value is still below the value of 1.