The coefficient of oil displacement by water at variable values of capillary number

UDK: 622.276.031:532.5:550.822.3
DOI: 10.24887/0028-2448-2021-4-62-66
Key words: displacement coefficient, residual oil saturation, the curves of capillary displacement, the threshold of mobilization, capillary number
Authors: N.N. Mikhailov (Gubkin University, RF, Moscow; Oil and Gas Research Institute of RAS, RF, Moscow), S.V. Melekhin (PermNIPIneft Branch of LUKOIL-Engineering LLC in Perm, RF, Perm)

Standard procedures for determining the displacement coefficient assume a single value of this parameter for reservoirs with fixed filtration-capacity properties. For inhomogeneous formations, petrophysical relationships are usually constructed between the values of the displacement coefficients and the filtration and reservoir properties of the formation. However, the generally accepted standard approach does not take into account the structure and mobility of the residual oil. In the proposed article, the authors present the results of experiments showing significant changes in the oil displacement coefficient by water when the displacement conditions change, characterized by different values of the capillary number. Experimental dependences of the displacement coefficients on the capillary number are obtained. It is shown that the standard values of the displacement coefficients, at the maximum values of the capillary numbers, can change multiple times with varying values of the capillary number. This leads to changes in the values of displacement coefficients in the near-well and inter-well areas of the developed formations. Examples of the distribution of displacement coefficients in development elements with the same filtration and reservoir properties, but with changing well placement systems, are given. The influence of well placement systems on changes in the displacement coefficient is shown.


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