Difference between Pore Wetting and Wettability Measured on Flat Surfaces

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Pore wetting is a principal factor in enhanced oil recovery, CO2 storage and fuel cells. However, few measurements were directly carried in a pore. We recently develop a technique to measure the contact angles of crude oil, water, gas/liquid/supercritical CO2-fluids systems in single capillaries, to understand how pore wetting varies with pore size, how the functional groups and carbon chain length of chemicals affect pore contact angle, and how CO2 phases affect pore wetting. The results indicate that pore wetting is very different from the wettability measured from flat surfaces. The contact angles measured in a pore vary significantly with pore size, CO2 phases, and functional group of chemicals even though their surface tension is very similar. Some amphiphiles have small and similar surface tensions, but their contact angles are large and vary greatly with their chemical molecular structures. The amphiphiles with functional groups have larger pore contact angles than the non-polar organics, and in the order of θ-OH > θ-NH2 ≈ θ-COOH. The contact angle of amphiphiles in a glass pore increases with the straight alkyl chain length. The straight alkyl chain contributes to the pore contact angle most and the side chain on the carbon of backbone tends to reduce the pore contact angle. The symmetrical molecular structure gives the smallest contribution on the pore wetting. The contact angles of CO2-water and CO2-brine systems increase from 120° up to 155°, and CO2-decane contact angles increase from 28° to 38°, when CO2 phase changes from gas to liquid or supercritical under a pressure range from 0 to 100 bar. The contact angle does not change significantly when temperature increases from 20 to 40 °C if there is no CO2 phase change. CO2-fluid contact angles in a FEP pore are in the order of θgasCO2<θsupercritical CO2<θliquid CO2.. The contact angles of CO2-water, CO2-brine and CO2-decane systems stay approximately around 30°, 40° and 26°, respectively, under a pressure range from 0 to 100 bar and at a temperature of 20°C and 40°C. The CO2-fluid contact angles in a glass pore do not change with CO2 phases: θgasCO2 θsupercritical CO2 θliquidCO2.
Original languageEnglish
Title of host publication3rd International Symposium on Energy Challenges and Mechanics (ECM3)
Publication statusPublished - 2015
Event3rd International Symposium on Energy Challenges and Mechanics (ECM3) - Aberdeen, United Kingdom
Duration: 7 Jul 20159 Jul 2015

Conference

Conference3rd International Symposium on Energy Challenges and Mechanics (ECM3)
CountryUnited Kingdom
CityAberdeen
Period7/07/159/07/15

Keywords

  • pore weting
  • dynamic contact angle
  • enhanced oil recovery
  • co2 storage

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