INTERFACIAL TENSION AND FORMULATION PRINCIPLE OF ULTRALOW INTERFAC1AL TENSION SYSTEMS FORMULATED WITH CARBOXYMETHYL ETHOXYLATES UNDER EXTREMELY HIGH CALCIUM ION CONCENTRATION

ABSTRACT

This paper will present some data of ultralow interfacial tension obtained in carboxymethylated ethoxylate-crude oil systems under extremely high calcium ion concentrations (0.5-1,5 M). A commercial surfactant, Huls B433 is used in the formulation of the surfactant systems. Dynamic interfacial tension (IFT) was measured with a spinning drop apparatus at 25 C. The measurements were performed by varying the surfactant and CaCl²-concentrations in the formulation. An IFT minimum (∼10 dyne/cm) was found at 0.01 wt% surfactant concentration and 1.0 M CaCl² concentration. Laser light scattering technique was applied to study the micellar size in the surfactant solutions. Large surfactant micelles around 100 nm seemed to be present in the surfactant solutions containing the optimum electrolyte concentration. Tentative correlation between IFT and surfactant micellar size will be given. It is suggested that the micellar size, a measurable and controllable factor, can be used as a guidance for surfactant formulation.