Deterministic and stochastic models based on the previous analysis of porosity variograms range distribution across the Romashkinskoye oil field were used to assess the effect. The variograms’ range in the geologic stochastic models changed from 100 to 1000 m in 50-m increments. For each model version, 10 equiprobable model options were built; for each model option, 20 modes of well operation and 2 modes of oil flow, Newtonian and non-Newtonian, were generated. All in all, 7640 reservoir models were built.
The generated models were used to assess the effect of non-Newtonian oil properties on the effectiveness of reservoir performance. Deterministic and stochastic geologic and reservoir models with various input parameters were used to determine the effectiveness of cyclic waterflooding.
The analysis made suggests that the physical characteristics of flow have a significant effect on the forecast reservoir performance. A slight deviation from the linear flow results in a substantial deviation from the forecast data – the ultimate recovery decreases, the effectiveness of cyclic waterflooding increases; the effect of reservoir heterogeneity on cyclic waterflooding performance is more or less similar for Newtonian and non-Newtonian flows. The analysis of models differing in the number of injection wells that are simultaneously shut down shows that for the cyclic waterflooding providing for wells shutdown in a circle, the maximum effect is noted in case of the maximum number of shutdown wells (six well), when the number of active and inactive wells is the same. Nonlinear behavior of the production increment vs. shutdown period curve is characteristic for the case providing for six wells shutdown for less than two weeks’ period. The effect is even more salient for non-Newtonian flow – a sharp increase of oil production is noted following shutdown of injection wells for the period of 1 to 5 days, in particular, one-day shutdown yields 50% increase in the incremental oil production vs. 1-month shutdown.
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