Naphthenic acids (NA) are proposed as a surfactant to be used in the remediation of oil-contaminated sand grains. Its viability for such a role was assessed based on its pore-scale interfacial properties. Micropipette techniques were introduced to quantify interfacial tensions (IFTs) and contact angles on the micron scale. It was found that the addition of NA could (a) reduce the IFT between water and diluted-bitumen to less than 1 mN/m, and (b) render the solid surface much more hydrophilic. Both these effects favour the liberation of oil ganglia from the sand grain surface. (C) 2013 Elsevier Ltd. All rights reserved.