Effect of Mixed-Chain-Length Surfactants on Fluid Displacement in Porous Media by In-Situ Foaming Process

Abstract

Summary A laboratory study was designed to improve fluid displacement efficiency in porous media by an in-situ foaming process and to determine the effect of mixed surfactant chain length on surface properties of foaming solutions, bubble size, breakthrough time, and fluid displacement in porous media. We screened various mixed surfactant systems, such as sodium dodecyl sulfate and alkyl alcohols. Maximum breakthrough time and fluid displacement efficiency were observed when both components of the mixed foaming system possessed the same chain length. Results were compared with data obtained using water, brine, and sodium dodecyl sulfate alone. The microscopic studies revealed that the order of bubble size measured outside the porous medium for various mixed surfactants was indeed maintained in a micromodel. The increase in the porous medium length improved breakthrough time and fluid displacement efficiency in sandpacks and in Berea cores. Mixed surfactant systems showed a correlation among surface properties of foaming solutions, bubble size, break-through time, and fluid displacement efficiency in a porous medium. Maximum foaminess, minimum bubble size, minimum surface tension, maximum surface viscosity, maximum breakthrough time, and maximum fluid displacement efficiency were observed when the two components of the surfactant system had the same chain length.