Analytical techniques for prediction of waterfloods using homogeneous models are non-representative of behaviors observed for actual reservoirs. We have noted, however, that a scrutiny of such deviations can lead to estimation techniques for characterization of permeability contrast in a formation. This paper presents the results of studies conducted on the behavior of producing wells in a waterflood as affected by lateral variation in rock properties and formation stratification and crossflow. The purpose of the study was to derive useful reservoir characterization information from the embedded signals in waterflood performance data. Deviations from the predicted response for homogeneous reservoirs can serve to map the lateral reservoir properties.

For stratified reservoirs, we focused on the impact of a thief zone on the behavior of wells producing from sand-shale sequences. Using the theoretically predicted flood performance from analytical models for such systems, as calibrated by simulation studies, we developed the metrics for the estimation of a new parameter defined here as the thief zone heterogeneity index.

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