%0 Journal Article
%T Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery Seuil de d¨¦gradation m¨¦canique de solutions de polym¨¨res utilis¨¦s en r¨¦cup¨¦ration assist¨¦e des hydrocarbures
%A Dupas A.
%A H¨¦naut I.
%A Argillier J.-F.
%A Aubry T.
%J Oil & Gas Science and Technology
%D 2013
%I Institut Fran?ais du P¨¦trole
%R 10.2516/ogst/2012028
%X Water soluble polymers such as polyacrylamide are used in polymer flooding, which is an advanced technique of Enhanced Oil Recovery (EOR). It aims at improving crude oil displacement in reservoir by pushing it with a viscous injected fluid. Polymer flood is challenged by mechanical degradation of long macromolecules during intense flows. Many studies reported that above a critical extensional rate hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ¦Å c ¡¤ , polymer chains can break and lose their rheological properties. The molecular weight (M) dependence of hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ¦Å c ¡¤ for dilute solutions in laminar flows was shown to follow a power law: hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ¦Å c ¡¤ ¡Ö Mw¨Ck. An experimental study has been performed to investigate the onset of mechanical degradation in both laminar and turbulent flows and for both dilute and semi dilute polyethylene oxide aqueous solutions. It reveals that the exponent k strongly depends on the concentration and flow regimes and also on solvent quality. Results show that mechanical degradation mainly affects long chains, that it is favoured at high concentrations, under poor solvent conditions. They also evidence that the extensional viscosity at low strain rates decreases to the same extent as shear viscosities due to mechanical degradation. However, the decrease of the extensional viscous properties at high strain rates is much more pronounced. Les polym¨¨res hydrosolubles comme les polyacrylamides peuvent ¨ºtre utilis¨¦s en r¨¦cup¨¦ration assist¨¦e des hydrocarbures (Enhanced Oil Recovery (EOR)) par injection de polym¨¨re. Cette technique vise ¨¤ augmenter la production de brut en le poussant du r¨¦servoir vers un puits producteur ¨¤ l¡¯aide d¡¯une solution de polym¨¨re suffisamment visqueuse. Les polym¨¨res utilis¨¦s ¨¤ cet effet ont des masses mol¨¦culaires sup¨¦rieures ¨¤ 106 g/mol, ce qui les rend sensibles ¨¤ la d¨¦gradation. En raison des d¨¦bits ¨¦lev¨¦s utilis¨¦s lors de leur injection, mais aussi en raison des taux d¡¯¨¦longation ¨¦lev¨¦s rencontr¨¦s dans le r¨¦servoir, les polym¨¨res peuvent se rompre et perdre leurs propri¨¦t¨¦s viscosifiantes. Dans la litt¨¦rature, il a ¨¦t¨¦ clairement montr¨¦, pour des solutions dilu¨¦es en r¨¦gime laminaire, que la d¨¦gradation des macromol¨¦cules n¡¯¨¦tait initi¨¦e qu¡¯au-del¨¤ d¡¯un taux d¡¯¨¦longation critique not¨¦ hbox{$varepsilon^{mathrm{cdot }}_{mathrm{c}}$} ¦Å c ¡¤ , et que ce taux d¡¯¨¦longation ¨¦tait une fonction puissance de la masse mol¨¦culaire du polym¨¨re : hbox{$varepsilon^{mathrm{cdot }}_{c}$} ¦Å c ¡¤ ¡Ö Mw¨Ck. La pr¨¦sente ¨¦tude exp¨¦rimentale de la d¨¦gra
%U http://dx.doi.org/10.2516/ogst/2012028