In some micellar/polymer flooding pilots, severe problems associated with polymer stability and/or polymer injectivity have been experienced. These problems have contributed to less than optimal pilot performances. As a result, process strategies which do not employ polymer have been actively considered.

The strategy evaluated in this paper consists of a low concentration (<2 wt% active) micellar fluid which is injected as a large bank (>20% PV) and which forms a lower phase microemulsion under prevailing reservoir conditions. This micellar bank is in turn displaced by a water drive with no provisions for mobility control. Such a process was deemed to be simplified in application and to be potentially of low economic risk in that a large bank, lower phase displacement was assumed to be less susceptible to the deleterious effects of reservoir heterogeneity in the absence of mobility control agents.

Performance predictions were based first upon the successful simulation of laboratory field core tests for which fluid physical properties, phase behavior, chemical retention, and oil recovery were well-quantified for a commercially available surfactant system. Simulation matches were obtained with a nonproprietary chemical flooding simulator. Once suitably calibrated, the simulator was then applied in a predictive mode to a field scale displacement in a typical 21-acre, four-layered five spot in the target reservoir.

The sensitivity of the process to slug size, chemical concentration, capillary desaturation characteristics, injection rate, microemulsion viscosity, and other design strategies was determined.

The results suggest that the current laboratory system is unacceptable for field testing because the system fails to produce sufficiently low interfacial tensions to significantly desaturate waterflood residual oil in the lower phase environment. The study does, however, point out useful goals, guidelines, and evaluation strategies by which the economic potential of future process designs can be assessed.

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