Displacement Mechanisms of Micellar Solutions

Abstract

Abstract This paper describes displacement mechanisms of micellar solution slugs, displaced by a thickened water "mobility buffer", in a glass micromodeland in consolidated Berea sandstone cores. Colored motion pictures, takenthrough a microscope, recorded interactions on a pore-to-pore basis in themicromodel. Production and differential pressure data from consolidated corespreviously waterflooded to residual oil saturation revealed displacementmechanisms macroscopically. Oil is displaced miscibly, while interstitial water is displaced immisciblyby the injected micellar solution slug. Part of this water is dispersed andcarried near the leading edge of the slug, and some may remain as a residualsaturation. Thickened water displaces any residual water. It also emulsifieswith the slug material, thereby displacing it. The displacement sequence formsbanks of oil and water with relatively constant fractional flows, saturations, and mobilities. The mobility of oil and water flowing ahead of the slug definesslug viscosity required for stable displacement. Equations are presented that describe several aspects of the displacementflow behavior: oil breakthrough, oil cut during production of the stabilizedbank, breakthrough of banked water and the resulting decreased fractional flowof oil, fluid mobilities, etc. Breakthroughs, calculated from the equations, are compared with experimental data. Slugs of micellar solution, ranging from 1 to 5 percent PV, producedunusually high oil recoveries (up to 100 percent) in previously waterfloodedconsolidated cores. Investigation of the effect of mobility buffer size on oilrecovery indicated that recovery is reduced in 3-in. X 4-ft cores for mobilitybuffer sizes smaller than 50 percent of the pore volume.