Features of an experimental study of the stable and unstable displacement in the Hele-Shaw cell filled with glass balls

The paper presents the results of an experimental study of immiscible displacements: displacement of water by oil (stable) and displacement of oil by air or water (unstable) at constant pressure drop in the Hele-Shaw cell filled with glass balls, which is a physical model of a porous fracture in an oil reservoir. The presented data allows one to draw a logical conclusion: the higher the inlet pressure, the higher the displacement efficiency. With the same oil displacement time in the Hele-Shaw cell, the passed volume of the gas significantly exceeds that of the water. The displacement by water is more complete, though. Displacements are highly dependent on inhomogeneity of the model skeleton, most significantly for the flow at low pressure drop. At the edges of the model, where the volume of the dispersed medium is greater, the motion is faster. When displacement in the model with balls is stable, the flow spreads out towards the outlet and takes a “funnel” shape that gradually expands; the motion is directed through the channel passed. For unstable displacement at low pressure drop, the motion occurs along the edges of the cell; with an increase in the pressure drop, the motion becomes more uniform, and the " viscous fingers" begin to “branch” and grow even at a distance from the outlet.