The numerical investigation of the oil displacing efficiency from the pore in the rock formation depending on the width and height of the pore

The calculated study of the oil displacing by the water from straight microchannels, which simulate a pore in the rock formation, was carried out. The Reynolds numbers were varied in the range from one to 1000. The channel’s width and height were in the range of 100 μm to 800 μm. The «Volume of Fluid» (VOF) numerical method with the «Continuum Surface Force» (CSF) algorithm was used. It was found that the oil recovery coefficient increases with a decrease in the height of the pore microchannel and with an increase of its width. In case of constant channel width, the oil recovery coefficient: increases in the ranges of Reynolds numbers from 1 to 50 and from 100 to 400 and decreases in the ranges of Reynolds numbers from 50 to 100 and from 400 to 1000. In case of constant channel height, the oil recovery factor behaves as follows: at h = 100 μm it slightly increases in a whole range of Reynolds numbers; at h = 200 μm its behaviour is the same the in case of constant channel width; at h = 400 μm it sharply increases in the ranges of Reynolds numbers from one to 50 and slightly decreases in the ranges of Reynolds numbers from 50 to 1000; at h = 800 μm it sharply increases in the ranges of Reynolds numbers from one to 100 and sharply decreases in the ranges of Reynolds numbers from 100 to 1000. Such behaviour in both cases can be explained by the competition between the forces of inertia and capillary, but further research is needed for a more complete understanding. It was also found that, in almost all cases, the oil recovery coefficient does not exceed 10%. It follows that water is a poor washing agent in terms of oil recovery from reservoirs.