Nanocellulose serve as a potential new water additive for enhanced oil recovery (EOR) applications. Several advantages gives nanocellulose promising potential for EOR, as e.g. excellent viscosifying and shear thinning properties, hydrophilic particles, excellent possibilities for chemical modification and particle character instead of dissolved polymers. Additionally, the material is biodegradable, non-toxic and obtained from an environmental-friendly resource. Also, the nanocellulose particles are different from traditional nanoparticles, such as silica, since they are rod-shaped instead of spherical. This adds a new element of complexity to their flow behavior. The most likely mechanisms for EOR from injection of nanocellulose dispersions are increased viscosity, decreased interfacial tension and wettability alteration. However, the retention characteristics are the main concern initially and are investigated in this study. The objective of this study was to identify the main retention mechanism affecting the transport of cellulose nanocrystals (CNC) through porous media. The experiments consisted of single phase flow through unconsolidated sandpacks and consolidated core plugs. Two floods were performed for each experiment – a tracerflood and a nanoflood. An ultraviolet (UV)-visible (VIS) spectrometer was used to measure the CNC concentration, and pressure data gave information about permeability alterations. For the sandpacks the effects of varying the salinity, grain size, particle size and velocity were examined. From these experiments it is clear that CNC particles, suspended in aqueous phase, have the ability to flow through porous media. As a general trend, it was observed that larger particles or aggregates resulted in higher retention and permeability impairment. By increasing the salinity, particles started to aggregate more, which resulted in blocking and log-jamming. Thus, salinity was found to be the most important parameter affecting transport. The core plugs had a permeability that was over three times smaller than the smallest grain size tested in the sandpacks. From these experiments there seem to be inaccessible pore volume present in the rock, meaning that some pores are too small for the nanocellulose particles to transport through. Thus, this resulted in different transport behavior where nanocellulose fluid breaks through earlier than the tracercurve.

Nanocellulose for use in enhanced oil recovery: Transportation of nanocellulose dispersions through porous media

255th National Meeting (2018)

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