The influence of water droplet packing on crude oil emulsion

To assure a smooth and cost-efficient flow of crude oil emulsion from wells to a production facility, the oil industry relies heavily on the prediction of viscosity in pipe. The physical expression of this viscosity depends on a subjective estimate of a maximum packing volume fraction (compacity), ranging between 58 and 74 vol%. This inaccurate practice can lead to catastrophic loss of pump efficiency. Two new concepts were defined to describe the emulsion: its compacity; and the occupancy of water droplets at the oil–water interface. This development leads to a better understanding of the formation and disappearance of a suspension, and can assist in building a reliable phenomenological model of the sedimentation and coalescence of an emulsion. Theoretical and experimental approaches were conducted to investigate the packing of water droplets in emulsions. A 3D packing model was developed to explain the observations made during emulsification experiments. It was found that below a water volume fraction of 34 vol%, water droplets settle, under the effect of gravity, in a loose-packed zone; and then sediment in a dense-packed zone (DPZ). The DPZ exists between a water volume fraction of 34 vol% and 60 vol%. The maximum compacity is the upper limit of this zone; and has a value of 60.46%. Knowing this objective value, other parameters affecting the viscosity can be better studied. Graphical abstract