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Dykstra and Parsons presented a correlation for predicting waterflood oil recovery that uses the mobility ratio, permeability variation, and producing water–oil ratio as correlating parameters.
Johnson developed a simplified graphical approach for the Dykstra and Parsons method that is based on predicting the overall oil recovery at water–oil ratios (WOR) of 1, 5, 25, and 100 bbl/bbl.
The technique of calculating the simplified Dykstra and Parsons method is presented below :
| 1. | Calculate the permeability variation and mobility ratio. |
| 2. | The overall oil recovery factor is calculated from four WOR values of 1, 5, 25, 100 bbl/bbl. The original curves of Johnson have been digitised and input into this routine to permit interpolation between permeability variation and mobility ratio. The oil recovery factor at water breakthrough is calculated by extrapolating back to a WOR of zero. |
| 3. | Calculate the cumulative oil production at each of the four WOR values, and the cumulative oil production at water breakthrough for a WOR = 0, from the following : |
| 4. | For a constant injection rate, adding the fill-up volume Wif to the cumulative oil produced at breakthrough and dividing by the injection rate will estimate the time to breakthrough. |
| 5. | The equation to link water injection to oil and water production and fillup volume is presented below. This equation is used together with the relationship of WOR v's overall oil recovery factor to derive the oil and water production rates versus time. |
References:
Dykstra, H., Parsons, R., "The Prediction of Oil Recovery by Water Flood", Secondary Recovery of Oil in the United States, 2nd ed. American Petroleum Institute, 1950
Johnson, C., “Prediction of Oil Recovery by Waterflood - A Simplified Graphical Treatment of the Dykstra-Parsons Method” AIME, 1956
Ahmed, T., “Reservoir Engineering Handbook”, Elsevier, 2006
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