Abstract
We report the results of laboratory experiments designed to evaluate the performance of the sodium salt of tall oil acid, TOA, as a steam-foam surfactant. The objective of the experiments was to determine if this inexpensive material could be used to reduce the chemical costs of the steam foam process. Tall oil acid is a commercially available blend of oleic and linoleic carboxylic acids obtained by distillation of the wastes from pine pulping mills. The sodium salt soap, TOA−Na+, is easily produced by one-step neutralization of TOA with sodium hydroxide.
The performance of TOA−Na+was measured in terms of the rate and magnitude at which the foam pressure gradient, Vp, increased when TOA−Na+and nitrogen were injected into a two-foot sandpack. Performance was also measured as a function of temperature, TOA−Na+ concentration, foam liquid volume fraction, foam velocity, salinity, pH, and oil saturation.
Experimental results show that TOA−Na+ is an effective foaming agent that can produce pressure gradients of hundreds of psi per foot in a sandpack. The dominant parameters found to control TOA−Na+ performance were salinity, temperature, and pH. To generate a large Vp at high temperature and in the presence of oil, the salinity of the TOA−Na* solution had to be increased by adding between 1.0 and 1.5 wt% sodium chloride. The TOA−Na+ was effective up to 400°F, but a large Vp could not be produced at 500°F. The pH of the TOA−Na+ solution had to be greater than about nine to achieve a large Vp. Sodium sesquicarbonate was used to buffer the solution at a pH of ten. Other notable results include that TOA−Na+ foam performance was not adversely affected by oil and that stable foams were produced at high and low foam velocities and at low liquid volume fractions.
