In recent years it has become increasingly important to develop a capability for monitoring enhanced oil recovery (EOR) processes as they are occurring within any reservoir. An amplitude - versus - angle (AVA) analysis over a steam injection location showed encouraging results and established that seismic reflection methods, when well designed and carefully processed, can be used to map the invaded steam zones in steam stimulation EOR operations. The results are imaged on a new type of display called ARPA (amplitude-ratio for partial angle), which illustrates reflection zones with low or high Poisson's ratio or equivalently high or low gas saturation with a CMP stack section plotted as the background. A seismic experiment consisting of three reflection lines was carried out by Esso Resources in February, 1984 over a steam injection site near Cold Lake, Alberta. Analysis of the field data showed that large variations in reflected scattered energy were a function of angle of incidence in areas affected by the steam zone.