Shear Stability of EOR Polymers
- Alain Zaitoun (Poweltec) | Patrick Makakou (Poweltec) | Nicolas Blin (Poweltec) | Rashid S. Al-Maamari (Sultan Qaboos University) | Abdul-Aziz Rashid Al-Hashmi (Sultan Qaboos University) | Mahmoud Abdel-Goad (Sultan Qaboos University)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- June 2012
- Document Type
- Journal Paper
- 335 - 339
- 2012. Society of Petroleum Engineers
- 1.7.5 Well Control
- Shear stability, Polymer, Shear, Capillary, degradation
- 5 in the last 30 days
- 1,629 since 2007
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An experimental study of shear stability of several high-molecular-weight polymers used as mobility-control agents in EOR projects has been performed in well-controlled conditions. The shearing device was made of a capillary tube with an internal diameter (ID) of 125 µm, through which polymer solution was injected at a controlled rate. The setup enables a precise measurement of the shear rate to which the polymer macromolecule is submitted. The degradation rate was measured by the viscosity loss induced by the passage into the capillary tube. The shear rate was gradually increased up to 106 sec-1 while checking degradation rate at each stage.
Different commercial EOR polymer products were submitted to the test with polyacrylamide backbone and different substitution monomer groups. All macromolecules behave as flexible coils in solution. The parameters investigated were
- Molecular weight (between 6 and 20x106)
- Nature of substitution group (acrylate, ATBS/sulfonate, nVP/vinyl-pyrrolidone)
Polymer shear degradation increases with molecular weight and salinity, but decreases with the presence of acrylate, ATBS, and nVP. All results can be interpreted in terms of chain flexibility. The highly flexible polyacrylamide homopolymer is the most sensitive to shear degradation. Introduction of acrylate groups in the polymer chain induces some stability because of the rigidity provided by charge repulsion, which vanishes in the presence of high salinity because of the screening of acrylate negative charges. ATBS and VP groups, which are larger in size, provide significant chain rigidity, and thus better shear stability. It is also shown that some very-high-molecular-weight polymers, after passing the shearing device, attain a final viscosity lower than lower-molecular-weight products with the same chemical composition. This factor has to be taken into account in the final choice of a polymer for a given field application.
As a comparison, although less popular today than 2 decades ago, xanthan gum (XG), which behaves like a semirigid rod, is shown to be much less sensitive to the shear-degradation test than the coiled polyacrylamides (Sorbie 1991).
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Buchholz, B.A., Zahn, J.M., Kenward, M., Slater, G.W., and Barron,A.E. 2004. Flow-induced chain scission as a physical route to narrowlydistributed, high molar mass polymers. Polymer 45 (4):1223-1234. http://dx.doi.org/10.1016/j.polymer.2003.11.051.
Caulfield, M.J., Qiao, G.G., and Solomon, D.H. 2002. Some Aspects ofthe Properties and Degradation of Polyacrylamides. Chem. Rev. 102 (9): 3067-3084. http://dx.doi.org/10.1021/cr010439p.
Chauveteau, G. 1986. Fundamental Criteria in Polymer Flow Through PorousMedia. In Water-Soluble Polymers, ed. J.E. Glass, No. 213, 227-268.Washington, DC: Advances in Chemistry Series, American Chemical Society.
Chauveteau, G. and Moan, M. 1981. The onset of dilatant behaviour innon-inertial flow of dilute polymer solutions through channels with varyingcross-sections. J. Physique Lett. 42 (10): 201-204. http://dx.doi.org/10.1051/jphyslet:019810042010020100.
Ghoniem, S., Chauveteau, G., Moan, M., and Wolff, C. 1981. Mechanicaldegradation of semi-dilute polymer solutions in laminar flows. The CanadianJournal of Chemical Engineering 59 (4): 450-454. http://dx.doi.org/10.1002/cjce.5450590406.
Maerker, J.M. 1975. Shear Degradation of Partially Hydrolyzed PolyacrylamideSolutions. SPE J. 15 (4): 311-322. SPE-5101-PA. http://dx.doi.org/10.2118/5101-PA.
Maerker, J.M. 1976. Mechanical Degradation of Partially HydrolyzedPolyacrylamide Solutions in Unconsolidated Porous Media. SPE J. 16 (4): 172-174. SPE-5672-PA. http://dx.doi.org/10.2118/5672-PA.
Moan, M., Chauveteau, G., and Ghoniem, S. 1979. Entrance effect incapillary flow of dilute and semi-dilute polymer solutions. J. Non-NewtonianFluid Mech. 5: 463-474. http://dx.doi.org/10.1016/0377-0257(79)85030-2.
Seright, R.S. 1983. The Effects of Mechanical Degradation and ViscoelasticBehavior on Injectivity of Polyacrylamide Solutions. SPE J. 23 (3): 475-485. SPE-9297-PA. http://dx.doi.org/10.2118/9297-PA.
Seright, R.S., Adamski, R.P., Roffall, J.C., and Liauh, W.W. 1983. Rheologyand mechanical degradation of EOR polymers. Presented at the SPEI BritishSociety of Rheology Conference on Rheology in Crude Oil Production, ImperialCollege, London, 13-15 April.
Sorbie, K.S. 1991. Mechanical stability of polymers. In Polymer-ImprovedOil Recovery, ed. Chap. 4.4, 114-124. Glasgow, Scotland: Blackie &Sons/CRC Press.
Vazquez, M., Schmalzing, D., Matsudaira, P., Ehrlich, D., and McKinley, G. 2001. Shear-Induced Degradation of Linear Polyacrylamide Solutionsduring Pre-Electrophoretic Loading. Anal. Chem. 73 (13):3035-3044. http://dx.doi.org/10.1021/ac001294+.