The aim of the project was to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untapped oil.

Program
This project was selected in response to DOE's Oil Exploration and Production solicitation DE-PS26-01NT41048, focus area Reservoir Efficiency Processes.

Columbia University
New York, NY

There is a considerable amount of oil trapped, together with water and gas, in reservoirs made up of porous and permeable rocks after primary oil production. Various chemical methods have been under development in order to recover this additional oil. These methods have been in general inadequate due to the high costs of the processes as well as significant loss of chemicals by adsorption on reservoir minerals and precipitation. There is a need to develop innovative and cost-effective reagent schemes to increase recovery from domestic oil reservoirs. The key criterion for the successful application of the techniques using candidate surfactants is minimal loss of surfactants by adsorption and precipitation.

Project Results
The adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants has been studied to delineate the relationships between aggregate structures and chemical compositions of the surfactants and gain a full knowledge of the aggregate shape, size, and structure, due to the important role these aggregates play in governing crude oil removal efficiency.

Benefits
The findings from this project will provide valuable information for the study of mechanisms of Improved Oil Recovery (IOR) by chemical flooding and for the utilization of surfactant mixture systems in IOR by means of synergistic/antagonistic micellization and adsorption properties.

Project Summary
Among the project milestones:

• A novel analytical ultracentrifugation technique has been successfully employed for the first time to characterize the aggregate species present in mixed micellar solutions.
• A predictive model was developed for the adsorption and aggregation behavior of surfactants, especially mixed surfactant systems in solutions and at solid/liquid interfaces. It was used to explore the crucial role of surfactant aggregates, especially mixed aggregates, in controlling important interfacial properties such as wettability in IOR processes.

This project has been completed, and a new DOE project, Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery is under way to investigate the effects of solid mineralogy on minimum chemical loss and maximum oil release in IOR processes.

Publications
Five semi-annual technique reports and a final report submitted to DOE. 
Zhang, L., Somasundaran, P., Mielczarski, J., and Mielczarski, E., Adsorption mechanism of n-dodecyl-?-D-maltoside on alumina, Journal of Colloid and Interface Science, 256, 16-22, 2002.

Zhang, R., Zhang, L., and Somasundaran, P., Study of mixtures of n-dodecyl-?-D-maltoside with anionic, cationic and nonionic surfactant in aqueous solutions using surface tension and fluorescence techniques, Journal of Colloid and Interface Science, 278, 453-460, 2004.

Zhang, R., Somasundaran, P., Abnormal micellar growth in sugar-based and ethoxylated nonionic surfactant and their mixtures in dilute regimes using analytical ultracentrifugation, Langmuir, 20, 8552-8558, 2004.

Zhang, Rui, and Somasundaran, P., Aggregate Formation of Binary Nonionic Surfactant Mixtures on Hydrophilic Surfaces, Langmuir, 21(11), 4868 - 4873, 2005.

$580,490

$154,307 (21% of total)

NETL - Virginia Weyland (virginia.weyland@netl.doe.gov or 918-699-2041)
Columbia U. - P. Somasundaran (ps24@columbia.edu or 212-854-2926)