(73a) Thickening of Supercritical Carbon Dioxide By Poly-1-Alkene Oligomers

Supercritical CO₂ (scCO₂) thickening is the most promising approach may be very effective in mobility control to increase sweep efficiency of storage in saline aquifers and in enhanced oil recovery (EOR) processes. Poly-1-decene (P1D) is an oligomer which is very effective as a scCO₂ thickener. The molecule is environmentally friendly and has very low adsorption to mineral surfaces. P1D can be dissolved in CO₂ from low to moderate concentrations. The oligomer of 20 repeat units can increase the relative viscosity of scCO₂ up to 6 times at 1.5 wt% concentration (Kar & Firoozabadi 2022). In this work, a series of poly-1-alkene molecules specifically engineered, based in monomers of 1-octene, 1-decene and 1-dodecene with different molecular weights, are examined for thickening of scCO₂. The goal is engineering of molecules that are even more effective than the poly1-decene oligomer with 20 repeat units (P1D-20) in our recent work. We observe a clear trend in maximum solubility at 35°C and 3500 psi where longer monomer chain lead to less solubility at the same molecular weight. Viscosity of the thickened scCO₂ is higher for molecules with longer monomer alkyl chain at the same molecular weight. Effect of pressure and temperature are also investigated. This is the first set of experiments evaluating the effect of poly1-alkene monomer chain length, concentration, pressure, and temperature in scCO₂ thickening.

Kar, T., Firoozabadi, A. (2022). Effective viscosification of supercritical carbon dioxide by oligomers of 1-decene. IScience, 25(5), 104266.