In immiscible displacements processes such as water flooding, an important consideration is how to maximize the areal sweep efficiency. Limited numbers of tools exist to map oil-water interface movement. It is our expectation that the extended and repeated application of interwell pulse tests can provide some insight in tracking the fluid front approaching the producing wells. The improvement of sensor technology and data mining has opened up new opportunities to obtain continuous recording of rate and pressure data at the observation/producing and injection wells. In reality, each injection well can be subjected to pre-scheduled or unsupervised rate changes. These rate changes create pulsation and observation wells detect the pulse after a time lag. The delay is a function of interwell distance and the effective interwell formation and fluid properties. In this study we focus on both flowing wells and observation wells. We propose that the monitoring of the time lags can help in tracking fluid front plus indigenous reservoir properties. To separate the two effects, we postulate that a comparison of time lags with the first available time lag can lead to the estimation of front location. The differences between displacing and displaced fluid properties on the two sides of the interface impacts the observed time lag. We focus also on the sensitivity of this relationship to the strength of pulsation caused by rate changes rather than shutting-in the injection well. Our approach to examine this problem is with using a combination of analytical and numerical solutions. Analytical solutions to calibrate numerical test cases for radial and linear flow geometries are presented for homogeneous and composite reservoirs. We also present the result of this study for some 2-dimensional reservoir cases. From the studies of these systems, we have demonstrated the definite potential of monitoring repeated pulses for front tracking in immiscible fluid displacement processes. From the sensitivity studies of the effect of static and dynamic reservoir and fluid properties between observation and the pulsing wells, we note progressive changes in the measured time lags with the movement of interface between the displacing and displaced fluid.
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