Polymeric Additives For Petroleum Industry: The Demulsification Process E. F. Lucas* 1 F. C. Lechuga 1 , J. B. V. S. Ramalho 2 1 Macromolecules Institute, Federal University of Rio de Janeiro, CT Bl. J, Cidade Universitária, Ilha do Fundão, 21945970, Rio de Janeiro, Brazil. 2 Brazilian Petroleum Company (Petrobras), Research Center (CENPES), Cidade Universitária, Ilha do Fundão, 21940000, Rio de Janeiro, Brazil Polymeric additives are generally used by adding them to fluids, with the aim of enabling or optimizing a specific operation. They can also be one of the constituents of a formulation added to the crude oil to solve production problems. Polymers are used in all steps of oil extraction: drilling, cementation, completion, production (acidification, hydraulic fracturing, water injection, divergence, elimination/prevention of sludge and incrustations) and treatment of oil and oily water. During the well drilling operations, the polymer is dispersed in the moiety, producing, together other constituents, the drilling fluid. Among the polymeric agents that can be used in drilling are xanthan gum (XC), partially hydrolyzed polyacrylamide (PHPA), starch or carboxymethyl cellulose (CMC), which perform functions such as viscosifiers, filtrate reducers, drag reducers and clay swelling inhibitors. PHPA is used in cement pastes for filtrate control and hydroxyethyl cellulose (HEC) with low molar mass is used as thinning agent. CMC, HEC and guar gum are used as thickening agents for spacers. During the oil production several operations are involved: all of them aiming increasing the oil production. Acidification, hydraulic fracturing and enhanced oil recovery (EOR) are some examples of such kind of operation. In acidification, polymers such as XC, CMC and poly(propylene glycol) are used to control viscosity and foam formation, besides filtrate control and friction. Since hydroxypropyl guar (HPG) can form reversible crosslinked structures, it is very suitable for use in hydraulic fracturing operations. In many cases, in order to increase oil production it is necessary to inject aqueous fluids in water wells, located at adjacent position to the oil one. The performance of this kind of operation depends on the fluid mobility, which can be controlled by polymer addition. PHPA, XC, CMC and HEC are employed in these cases. Also during production, the formation of organic and inorganic solid deposits is the responsible by oil production decreasing, or even by the production interruption. Polymers such as poly(ethylene-co-vinyl acetate) or long-chain polyacrylates are used to inhibit the formation of organic deposits, while additives containing poly (sodium acrylate) or poly(vinyl sodium sulfate) are used to inhibit incrustation. Demulsification of crude oil is carried out with polyoxide-base and other polymers, while oily water treatment uses flocculants polymers. As important as knowing the operation and the polymer normally used is to understand the mechanism of polymer action in order to predict the most suitable polymer to the same operation under different conditions. Very recently results have been obtained by researching the influence of demulsifiers on asphaltenes aggregation, since that the asphaltenes play an important role on the water in oil emulsion stabilization. Asphaltenes particle size analyses showed that the demulsifiers do not improve the asphaltenes solubilization; on the opposite, bigger asphaltenes particle sizes are observed for the best demulsifier performance system. Figure 1 –Effect of the demulsifier base on asphaltene aggregation of 0.005% of asphaltenes in (a) toluene and n-heptane 3:4 and (b) toluene and n-heptane 2:5. References [1] Silva, I.P.G. et al, Society of Petroleum Engineers (SPE International) 2007, SPE 107727 [2] Oliveira, G.E. et al, J. Disp. Sci. Technol. 2007, 28, 1 [3] Mansur, C.R.E., et al, J. Appl. Polym. Sci. In press [4] Spinelli, L.S. et al, J. Petrol. Sci. Eng2007, 58, 111 Acknowledgements: CNPq, CAPES, FAPERJ and PETROBRAS * Presenting author: elucas@ima.ufrj.br