Study on Static Settling of Water-in-Oil Emulsion on the Basis of Statistical Analysis

The settling process of water droplets is significant in the processing technology of crude water-in-oil (W/O) emulsion. The process is complex because it is affected by various microforces on water droplets, which leads to difficulty in studying this issue comprehensively. A large amount of related work has been conducted, but with sparse emphasis being placed on the influence of Brownian motion on the settling process and the heterogeneous system of emulsion. This paper presents a method to study the effect of static settling of the heterogeneous W/O emulsion. A model for calculating water-droplet displacement is fundamentally established by constructing a momentum equation depending on the classical Langevin equation and Stokes formula. It considers dual influences of Stokes gravity settling and Brownian motion as well as microdistribution and interaction of water droplets. Statistical analysis is used to solve the problem of randomness. Combined with the water-cut model and the viscosity-prediction model, and according to the properties of oil phase and the heterogeneous size distribution of water droplets, the migration process of each water droplet can be calculated, and the variation of water cut and viscosity of each layer of the W/O emulsion system as well as the dehydration amount at the bottom can be predicted. In addition, an experiment was carried out to verify the accuracy and practicality of the method. The corresponding results displayed the dehydration amount at five different environment temperatures, and coincided well with the simulation results.