SPE Reservoir Evaluation & Engineering
Volume 14, Number 3, June 2011, pp. 269-280

SPE-122400-PA

A Microvisual Study of the Displacement of Viscous Oil by Polymer Solutions

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DOI  More information 10.2118/122400-PA http://dx.doi.org/10.2118/122400-PA

Citation

  • Buchgraber, M., Clemens, T., Castanier, L.M., and Kovscek, A.R. 2011. A Microvisual Study of the Displacement of Viscous Oil by Polymer Solutions. SPE Res Eval & Eng  14 (3): 269-280. SPE-122400-PA. doi: 10.2118/122400-PA.

Discipline Categories

  • 6.4.6 Chemical Flooding Methods Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex)
  • 6.3.2 Multi-phase Flow
  • 6.3.1 Flow in Porous Media

Keywords

  • Associative polymer, Pore level, Microfluidics, Enhanced oil recovery

Summary

Of the various enhanced-oil-recovery (EOR) polymer formulations, newly developed associative polymers show special promise. We investigate pore and pore-network scales because polymer solutions ultimately flow through the pore space of rock to displace oil. We conduct and monitor optically water/oil and polymer-solution/oil displacements in a 2D etched-silicon micromodel. The micromodel has the geometrical and topological characteristics of sandstone. Conventional hydrolyzed-polyacrylamide solutions and newly developed associative-polymer solutions with concentrations ranging from 500 to 2,500 ppm were tested. The crude oil had a viscosity of 450 cp at test conditions. Our results provide new insight regarding the ability of polymer to stabilize multiphase flow. At zero and low polymer concentrations, relatively long and wide fingers of injectant developed, leading to early water breakthrough and low recoveries. At increased polymer concentration, a much greater number of relatively fine fingers formed. The width-to-length ratio of these fingers was quite small, and the absolute length of fingers decreased. At a larger scale of observation, the displacement front appears to be stabilized; hence, recovery efficiency improved remarkably. Above a concentration of 1,500 ppm, plugging of the micromodel by polymer and lower oil recovery was observed for both polymer types. For tertiary polymer injection that begins at breakthrough of water, the severe fingers resulting from water injection are modified significantly. Fingers become wider and grow in the direction normal to flow as polymer solution replaces water. Apparently, improved sweep efficiency of viscous oils is possible (at this scale of investigation) even after waterflooding. The associative- and conventional-polymer solutions improved oil recovery by approximately the same amount. The associative polymers, however, showed more-stable displacement fronts in comparison to conventional-polymer solutions.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 6 March 2010
  • Meeting paper published: 5 October 2009
  • Revised manuscript received: 29 October 2010
  • Manuscript approved: 6 January 2011
  • Published online: 16 May 2011
  • Version of record: 7 June 2011