The ability to thicken or gel dense liquid or supercritical CO2 would dramatically enhance its performance in the recovery of petroleum.  It would improve the mobility ratio during CO2 enhanced oil recovery, which would eliminate viscous fingering and diminish the ratio of CO2 injected:oil recovered.  Further, it would eliminate the need for alternate injection of water with CO2, the current technique used that lessens the mobility of CO2 by decreasing its relative permeability.  Thickened CO2 could also serve as a replacement for water during hydraulic fracturing or tight sandstones and shales.  Although pure CO2 has been used on rare occasion to fracture water-sensitive formations, its low viscosity prevents it from effectively carrying high concentrations of large proppant particles into the fractures; thickened or gelled CO2 could dramatically improve the performance.  A review of a series of small molecule associative thickeners designed to dissolve in CO2 and then self-assemble into viscosity enhancing supramolecular networks is presented.  The small molecule consists of a CO2-philic segment (e.g. an oligomer of dimethyl siloxane or propylene glycol, or a very short alkyl chain); in order to render an affordable and environmentally acceptable thickener, highly CO2 philic fluoroacrlylate or fluoroethers are not used.  The thickener also contains one or more mildly CO2-phobic associating groups (e.g. carboxylic acids, naththalene); in some cases the associating group is designed to react with CO2.  A wide variety or thickener architectures will also be presented, such as placement of the associative groups in the center of the molecule, at the ends of the molecule, or randomly positioned along the length of the molecule.

Small associative thickeners for supercritical CO<sub>2</sub>

248th National Meeting (2014)

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Small associative thickeners for supercritical CO2

Small associative thickeners for supercritical CO₂