Effective viscosification of supercritical carbon dioxide by oligomers of 1-decene

Viscosification of carbon dioxide by polymers can make large scale CO₂ sequestration safe and efficient. We present solubility of branched hydrocarbon oligomers in CO₂ and viscosification measurements at relevant subsurface conditions. Polymers of 1-decene (P1D) with about 20 repeating units are found to be effective in CO₂ viscosification, increasing it by 6.5-fold at 1.8 wt% concentration at 308 K and 31 MPa. We reason that methyl groups and branching promote solubility and viscosification. Low molecular weight oligomers can have lower solubility in CO₂ than higher molecular weight ones and the trend in solubility is non-monotonic at constant pressure and temperature. Analysis of solubility trend of P1D oligomers in CO₂ advances our understanding of molecular structure and functionality and opens the path to engineering of oligomers effective in viscosification and widespread use of CO₂.