Forecasting volumetric sweep efficiency and oil recovery of a miscible flood is difficult, yet reliable production forecasts are required for economic analysis. Conventional decline curve analysis cannot be applied until well after the miscible flood is underway, and may be inapplicable if oil production rates are constant or increasing. Numerical simulation can usually give reliable estimates of oil recovery but only after a time consuming history match. In addition, computer resources and manpower constraints can often limit the areal extent of a simulation model, and therefore limit the model＇s applicability for full field forecasts. In this study, simple methods based on waterflood surveillance techniques were developed for estimating miscible flood volumetric sweep efficiency. These methods can be used to predict ultimate recovery and volumetric sweep for horizontal miscible floods in either strongly gravity-dominated systems, heterogeneous systems or viscous fingering dominated systems. Miscible flood simulation studies and results from actual field projects show that a plot of gas-oil ratio (GOR) correlates well with cumulative incremental oil production. Such a plot can be used to estimate miscible flood incremental recovery. If the log GOR vs. cumulative oil is a straight line, this implies that the late oil rate decline will be either harmonic or hyperbolic depending upon total fluid production rate. These surveillance techniques can identify areas in which volumetric sweep and oil recovery is performing below expectations. These techniques allow an operator to continuously monitor performance and to make timely operational changes to maximize oil recovery.