ASSESSMENT OF THE PERFORMANCE OF NATURAL POLYMER ASSISTED BY NANOPARTICLES

Abstract

With the increase in energy demand the natural resources like oil and gas are depleting steadily. Maximizing the potential of the old reservoir is an important, future oriented task. This task goes alone with the preservation of the environment. One of the EOR methods utilizes chemicals to inject into reservoir that helps to displace oil. Natural materials can very much be the material for chemical injections. Some byproducts of food or other organic plants have polysaccharides in their composition. These polysaccharides are considered as polymers, that in fact can increase the viscosity of the injective fluids and replace the synthetic polymers. However, biopolymers have drawbacks related to the vitality within harsh conditions of the reservoir and need assistance via other components. One of the new, promising methods is to combinate polymers with nanoparticles. Nanoparticles are particles with the scale of 1-100 nm that can alter wettability, reduce interfacial tension (IFT) and increase stability of other materials. Despite having evaluations of the nanoparticle effect on polymers, the literature lacks evaluation of nanoparticles in combination with biopolymers. Therefore, the aim of this thesis is to evaluate the effect of nanoparticles modification on biopolymer. Where nanoparticles were chosen to be SiO2 and ZnO metal oxide nanoparticles because they can improve rheological behavior under salinity and temperature. Natural polymer of Flaxseed gum previously evaluated under reservoir conditions in Nazarbayev University and Xanthan gum to compare results with established polymer. First, modified polymers were characterized to proof the adsorption and interaction with the polymer. FTIR, SEM and TEM were used to characterize modification. Samples undergone rheological tests such as analysis of concentration, temperature, salinity and stability. Then efficiency checked in core flooding experiments. Six experiments were done with Flaxseed and Xanthan gum modifications at ambient temperature and 35,000 ppm. Three core flooding experiments were conducted with Flaxseed gum and its modifications with silica and zinc oxide nanoparticles under close to reservoir conditions of 55oC and 35,000 ppm. Core flooding under harsh reservoir environment help to evaluate nanoparticles effect under worst salinity concentration and common Kazakhstan oil reservoir where the salinity and temperature were elevated. Silica nanoparticle modification worked best for both polymers especially in salinity. ZnO nanoparticle possibly was not dispersed in the medium well and showed aggregation. Moreover, ZnO nanoparticles showed negative impact on rheology at elevated temperature and salinity. Silica modified polymer showed the best results in the core flooding as incremental oil recovery of 4% and 7% was for, flaxseed and xanthan modifications. Zinc oxide showed less recovery at high temperature than Flaxseed.