Rheological Behavior of Nanofluids and their Application in Emulsion Inversion

Rheological behavior of nanofluids and their application in emulsion inversion D. Slavova, S. Pollak, M. Petermann Chair of Particle Technology, Ruhr-University Bochum The most common problem in crude oil production is the formation of water-in-oil (W/O) emulsions in reservoir rocks, which leads to an increase of viscosity compared to the oil itself. These types of emulsions are produced due to the simultaneous flow of oil and produced water, which increase the interfacial area of the oil and water phases. Chemical additives with functional groups such as naphthenic acids in oil form viscoelastic films at these surfaces resulting in stable water-in-oil (W/O) emulsions. By inducing a phase inversion into oil-in-water (O/W) emulsions, the viscosity can be reduced. Nanotechnology is an advanced technology that has proved its potential to cause phase inversion and to enhance oil recovery. The aim of this study is to investigate the effect of nanoparticles on the properties of emulsions. The use of new type of fluids called “nanofluid” has become an attractive tool to achieve emulsion inversion. However it is crucial to have a clear depiction of parameters that may influences the displacement process. Hydrophilic nanoparticles with single particle diameter range around 25 nm were employed and have been characterized under scanning electron microscope (SEM). The nanofluids are synthesized by the dispersion of different concentrations of nanoparticles Nanoclay to low salinity brines. The viscosity and density of the nanofluids have been investigated both as a function of nanoparticles concentration as well as temperature between 40°C and 80°C. As expected it was found, that the viscosity is increasing with the concentration of nanoparticles and decreasing with higher temperatures. In addition it could be demonstrated that the flow behavior of such nanofluids is strongly non-Newtonian in the range of the investigated shear rates from 100s-1. In addition to the investigation of the nanofluids, the phase inversion of different emulsions using these fluids was investigated. As model systems emulsions were formed with water, paraffin oil and different concentrations of naphthenic acid as surfactant. These emulsions were mixed with nanofluids of different viscosities and therefore different nanoparticle concentrations. The phase behavior and the viscosity of such mixtures was investigates in the range from 40°C and 80°C. The results clearly demonstrate that phase inversion could be achieved and that low viscous oil-in-water emulsions could be formed and therefore the high potential for EOR is illustrated.