(706b) Improving CO2-EOR in Shale Reservoirs Using Dilute Concentrations of Wettability-Altering Nonionic Surfactants during Lab-Scale Huff-and-Puff
AIChE Annual Meeting
Tuesday, November 16, 2021 - 12:45pm to 1:00pm
The solubility of various nonionic surfactants (Indorama SURFONICÂ® N-100, an ethoxylated nonylphenyl alcohol with 10 ethylene oxide (EO) groups; Indorama SURFONICÂ® TDA-9, -6 and -3, ethoxylated branched tridecyl alcohols with 9, 6 or 3 EO groups, respectively; Indorama SURFONICÂ® TDA-8PO, a tridecyl propoxylated alcohol with 8 propylene oxide groups; and Indorama SURFONICÂ® L12-6, an ethoxylated normal C10-C12 natural alcohol with 6 EO groups) in CO2 has been measured between 25 â 100 Â°C. The surfactants exhibit a solubility of roughly 1 wt% at pressures of 2000 - 5000 psia, with lower pressures required for lower temperatures, lower surfactant concentrations, and increased oil solubility of the surfactant.
The rock samples were first aged by via immersion in dead Eagle Ford crude oil at high temperatures and high pressure for a prolonged period of time. Then, the oil-wetness was verified by measuring the contact angle of water droplets on the shale exposed to air. To determine CO2-induced or CO2-surfactant solution-induced changes in wettability, the oil-wet, oil-saturated shale disk was immersed in CO2 or a CO2-surfactant solution for 16h at 4000 psi and 80â. No significant changes in contact angles were observed in samples immersed in CO2, whereas immersion of the shale in CO2-surfactant solutions showed dramatic changes in wettability toward water-wet for some of the surfactants. Small cylindrical shale samples were then used in huff and puff tests to assess oil recovery. Ultimate oil recovery after 8 huff and puff cycles increased substantially when some of the surfactants were added to the CO2, especially during the early cycles. A comparison of the performance of these surfactants will be presented.