The Displacement of Viscous Oil by Associative Polymer Solutions

Abstract

About half of world oil production results from waterflooding. The remaining resources, however, are more viscous and less amenable to waterflood as conventional oil reserves are produced. In offshore and Arctic environments improved methods of cold production for viscous oil are needed because the introduction of heat to thin viscous oil appears to be unlikely. Unfavorable mobility ratio and sweep is modified by use of polymer solutions. Of the various 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 two-dimensional 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 ppm to 2500 ppm were tested. The crude oil had a viscosity of 210 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 1500 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 water flooding. The associative and conventional polymer solutions improved oil recovery by about the same amount. The associative polymers, however, showed more stable fronts in comparison to conventional polymer solutions.

Review on Polymer Flooding: Rheology, Adsorption, Stability, and Field Applications of Various Polymer Systems

“…Polymers enhance the viscosity of displacing fluid and decrease the water/oil 2 M. S. Kamal et al mobility ratio. 4 Reduction in the mobility ratio leads to an increase in the macroscopic displacement efficiency. 5,6 Recently, it was discovered that the viscoelastic nature of the polymers also helps in increasing the microscopic efficiency.…”

Study on Variation of Physicochemical Parameters of the Polymer/Surfactant Binary Multisystem in Porous Media

“…Polymers in binary multisystem are hydrophobic associating polymer HNT300 provided by CNOOC Research Institute, the molecular weight is about 1600×104 [12]; surface active agent is sulfonate Gemini surfactant BH-M2 provided by Southwest Petroleum University [13].…”

A double‐tailed acrylamide hydrophobically associating polymer: Synthesis, characterization, and solution properties

“…10 Thus, hydrophobically associating water soluble polymers (HAP) with small amounts of hydrophobic segments (generally less than 2 mol % [11][12][13][14] ) is expected to replace PAM and HPAM as oilfield chemical additives for its excellent thickening, viscoelasticity, and antisalt properties. 15,16 Meanwhile, the intermolecular association of the hydrophobic groups in the backbone of HAP leads to the formation of reversible three-dimensional network structures, 17,18 showing excellent antishearing property.…”