Laboratory Study on Mass Transfer of ASP Flooding
Authors: Wang Jialu , Jia Xu , Shi Fashun 
Published: May 2016

Abstract
The synergic effect of alkali, surfactant and polymer is applied in ASP flooding. ASP flooding is a very complex physical-chemical process, the fluid flow and mass transfer of chemicals in porous media are two major theoretical problems. A physical modeling system of long slim tube was established in present research to study mass transfer of ASP flooding in reservoir condition. Several measuring pressure and sampling points were laid out at different positions along the tube. Through real-time measurement of pressure and chemical concentration of different points, the mass transfer and chemical concentration of ASP flooding in porous media are studied. Due to the impacts of adsorption and retention, the concentrations of the three chemicals decline gradually, the curves are asymmetrical and offset. The motion velocities of the three chemicals from high to low are polymer, alkali and surfactant. In the beginning of displacement, chemicals move fast, the difference among the motion velocities of the three chemicals is bigger, the phenomena of chromatographic separation is obvious. In the end of displacement, the diffusive range becomes larger, the gap among the motion velocities becomes small, and the chromatographic separation phenomena are weakened with the decreasing of chemical concentrations. The motion lag coefficient ? and comprehensive diffusion coefficient D of the three chemicals were obtained by fitting the chemicals concentration curves. The motion lag and comprehensive diffusion are strong, the chromatographic separation of the chemicals is obvious in the vicinity of the inlet. The motion lag and comprehensive diffusion become weakened, and the chromatographic separation of the chemicals is not obvious near the outlet. The adsorption and retention rates of the chemicals are gradually increasing with distance, and the adsorption and retention of polymer is the most serious.

Introduction
The synergic effect of alkali, surfactant and polymer is applied in ASP flooding. Oil recovery is significantly enhanced by improving displacing efficiency and sweep efficiency. The research on the mechanism of enhanced oil recovery has been widely emphasized by researchers in the world (Shen and Yu 2002). ASP flooding is a very complex physical-chemical process, the fluid flow and mass transfer of chemicals in porous media are two major theoretical problems. In the past, the fluid flow mechanism of ASP flooding in porous media, including microscopic fluid flow mechanism and macroscopic fluid flow mechanism, has been studied a lot, and remarkable results have been achieved, the theoretical foundation has been setup for oilfield application (Baviere et al 1995, Guo et al 1990, Yang et al 1999, Arthara et al 1999, Wang et al 2005, Shen and Wang et al 2009). In recent years, researches on the mass transfer of ASP flooding have been begun to study, such as, chromatographic separation (Gao et al 1999), diffusion and dispersion (Wang et al 2006), mass transfer of chemicals (wang et al 2001), and so on. Since the mass transfer of ASP flooding is very complex and involves many physical and chemical phenomena. There exist many problems which need to be studied in detail, and only in this way can the large-scale on-site application of the ASP flooding technology be promoted in the oil fields.