Propagation of Polymer Slugs Through Adsorbent Porous Media

The effects of adsorption on the propagation of polymer slugs through oil reservoirs determine the efficiency of polymer flooding for increasing oil recovery. However, up to now the adsorption laws introduced in polymer flood simulation models were oversimplified due to a lack of knowledge. 

High molecular weight and polydisperse water soluble polyelectrolytes, such as xanthans and hydrolyzed polyacrylamides are currently used to enhance oil recovery. They are dissolved in injection water to decrease its mobility and thus to improve its efficiency for sweeping the oil from oil bearing reservoirs. 

This paper proposes a phenomenological analysis, based on laboratory experimental work, of the effects of adsorption properties on pol3nner slug propagation. The adsorption properties studied include kinetic aspects, i.e. instantaneous adsorption, reorganization of macromolecules inside adsorbed layer, exchanges between free and adsorbed polymer, desorption as well as properties at thermodynamic equilibrium which can be described by a partially reversible adsorption isotherm. The conditions for hydro-dynamic retention are also discussed. In addition, an analysis of the effects of polymer polydispersity on each of these adsorption phenomena shows that these effects cannot be neglected in a predictive simulator. 

The properties of the two polymer samples used in this study, a partially hydrolyzed (t = 30%) polyacrylamide (HPAM) and a fully pyruvated single stranded xanthan (XCPS) have been reported in previous papers (1, 

Successive pol3nmer solution slugs ( 1.5 VP) separated by water injections at the same salinity were injected into porous media immersed in a thermostatic bath (30 C) at constant flow rates (v = 0.3 m/d and 0.6 m/d). At these flow rates, the wall shear rates in the pore throats Yp-p is low enough (Ypx = 4.2 s and 8.4 s calculated as suggested in Ref. 26) to ensure that the flow regime is Newtonian for the pol3n[ner solutions used. 

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PROPAGATION OF POLYMER SLUGS THROUGH ADSORBENT POROUS MEDIA... 

Chauveteau, G. and Lecourtier, J. (1988) Propagation of polymer slugs through adsorbent porous media. In Water Soluble Polymers for Petroleum Recovery, eds. Stahl, G. A. and Schulz, D. N., Plenum Publishing Corp., New York. 

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