Study of Rheological Properties and Micro-mechanism of Heavy Oil Emulsion Prepared via Ultrasonic Dispersion

Abstract

An emulsion is a dispersion with a complex mechanism of formation and a poor stability. In the preparation of emulsions, the used surfactant concentration, oil−water ratio, and kinetic conditions affect the type, microscopic characteristics, and rheological properties of the emulsions. As a result of its high viscosity, it is difficult to disperse the heavy oil with mechanical agitation, and the stability of the emulsion system formed is poor; hence, it is challenging to study its rheological properties. Therefore, herein, the ultrasonic dispersion method was employed to prepare the emulsion, and the microscopic characteristics of the emulsion were observed using an optical microscope and nanoparticle size analyzer. The conductivity of the emulsion system was studied by a conductivity meter. The effects of different surfactant concentrations, oil−water ratios, and kinetic conditions on the emulsion type and micro-characteristics were obtained. The experiments were performed to study the rheological properties of oilin-water (O/W) and water-in-oil (W/O) emulsions. The results indicate that the emulsion prepared using an ultrasonic dispersion method was O/W-type when the mass percentage of a surfactant solution was higher than 0.1 wt % and the oil−water ratio was less than 1:3. The droplet size reaches a nanometer level and increases with a higher surfactant concentration. The particle size no longer decreases when the critical micelle concentration of the surfactant is reached. The droplet size corresponding to the peak of size frequency distribution was 70 nm, and the rheological curve was a shear-thickening dilatant fluid. When the mass percentage of a surfactant solution was lower than 0.1 wt % and the oil−water ratio was higher than 1, a W/O emulsion was formed with the droplet size of 10 μm. When the shear rate was less than 50 s −1 , the emulsion was a pseudo-plastic fluid with shear-thinning behavior. As the shear rate increased, the emulsion gradually exhibited Newtonian fluid behavior.

Experimental Study on Water-in-Heavy-Oil Droplets Stability and Viscosity Variations in the Dilution Process of Water-in-Heavy-Oil Emulsions by Light Crude Oil

“…In the case of the bitumen-aqueous interface, optimal primary recovery efficiency was found to be associated with a maximum in interfacial electric charge and a minimum in interfacial tension [39]. However, Jamin's effect still occur when emulsified O/W droplets flow through small throats of porous media [40]. Furthermore, the pollution problems and the cost resulted by alkali's serious adsorption or caused by the produced water process and a large amount of the chemical agents injected inspired us to put forward a more environmentally scheme.…”

Influence of Emulsification Characteristics on the Pressure Dynamics during Chemical Flooding for Oil Recovery

“…The emulsification flooding agent would act with the rock surface and make it gradually become water wet so that crude oil would easily peel off from the rock surface to form the O/W emulsion. − Jamin effect would occur when emulsified oil droplets flow through small throats of porous media. The swept area would increase for the temporary plugging effect of the oil droplet. − Soo et al found that the retention and trapping effects of oil droplets can lead to droplet fluidity decrease in porous media . Therefore, Arhuma et al proposed to use the apparent viscosity of O/W emulsions when flowing in porous media to characterize its fluidity .…”

Synthesis, Performance, Mechanism: A Hyperbranched Phase Reverse Nano-Demulsifier for Condensate Emulsion

“…The development of gas fields is often accompanied by the production of condensate oil [1][2][3]. It is highly challenging to separate the condensate oil from the emulsion [4,5]. During the production process, a significant amount of surfactant liquid is injected into the gas well [6,7].…”