Progress in rheological studies of W/O emulsion and its gel

In the process of crude oil exploitation and transportation, water and oil commonly coexist in the form of waterin- crude oil (W/O) emulsion. The rheological properties of this emulsion are the basic information for guaranteeing safe flow in multiphase transportation pipeline. In this paper, the W/O emulsion and its gel rheological properties were studied. Firstly, the effects of the volume fraction and size of dispersed droplets on the apparent viscosity of the emulsion were illustrated, and the existing viscosity prediction models were investigated. Secondly, the influences on the viscoelasticity of the emulsion from the dispersed droplet itself and the joint effect of droplet and wax crystal were analyzed with and without the existence of precipitated solid paraffin particles. Thirdly, the changes of the yield behavior of the emulsion gel caused by dispersed droplets were analyzed in detail from the aspects of yield process, yield stress, and yield strain. And finally, the effects of water content on thixotropic behaviors were discussed in terms of structural breakdown and recovery behaviors of the emulsion gel respectively.