A quantitative study of immiscible and miscible displacement flows in a rotating pipe

Abstract

Displacements of oil-based and water-based fluids, corresponding to miscible and immiscible fluids, exist widely in well cementing processes in the oil & gas industry. In this paper, we experimentally investigate the density-unstable miscible and immiscible displacement flows in an axially rotating pipe. The density of displacing fluid is larger than that of the displaced fluid (𝜌 ̂𝐻 > 𝜌 ̂𝐿). In our experiments, the density difference (quantified via 𝐴𝑡 = 0.041 ), the viscosity ratio ( 𝑀 = 0.22 ), and the inclination angle ( 𝛽 = 83°) are kept constant. The pipe rotating speed (𝜔 ̂) and imposed flow velocity ( 𝑈 ̂0 ) are the most critical parameters in this study.Correspondingly, the effects of the imposed flow inertia and rotating inertia are investigated. Sequences of images are captured by a high-speed camera and their spatiotemporal concentration profiles are analyzed. The immiscible displacement flows are quantitatively analyzed and compared with miscible displacement flows. Based on our results, two kinds of downstream interfacial fronts are found in the immiscible displacement flow, but only one is witnessed in the miscible displacement flow. Also, our results show that, by increasing the imposed flow velocity, the interfacial front moves faster. On the other hand, when increasing the rotating speed, the first front velocities are slower. For displacement flows without a rotation, the first front velocities of the miscible displacement flows are smaller than those of the immiscible conditions. Nevertheless, for the displacement flows with a rotation, the first front velocities of the miscible displacement flows are larger than those of the immiscible conditions.