Application of Natural Surfactants for Enhanced Oil Recovery - Critical Review

The huge worldwide energy demand, and the need for more crude oil production, together with the low-efficiency of the conventional abstraction methods are part of the reasons for increasing interest in Enhanced Oil Recovery (EOR) techniques for recovering more oil from existing reservoirs. Utilization of different types of surfactants (synthetic or natural) in order to decrease the water-oil interfacial tension (IFT) is one of the most common methods for EOR. However, polymers and synthetic chemicals have a number of disadvantages such as linking to fossil fuels, high cost and environmental impacts. In this review, the application of natural surfactants produced from the leaves of Olive, Spistan, Prosopis, Mulberry, Zizyphus spina Christi, Soapnut and Chamomilla plants in EOR processes are investigated. The effects of natural surfactants extracted from the leaves of the mentioned plants on reduction of the oil-water interfacial tension (IFT) are studied and compared extensively. Pendant drop and ring methods have been employed by most of researchers to identify the IFT values as a determining parameter in performance of natural surfactant flooding to increase ultimate oil recovery. This comparative study in the application of natural surfactants in EOR will pave the way for future studies and helps further research in EOR schemes.