The success of surfactant flooding for enhanced oil recovery (EOR) process depends on the efficiency of designed chemical formula. In this chapter, a thorough discussion on Winsor Type III microemulsion was included which is considered the most desirable condition for achieving an ultra-low interfacial tension during surfactant-flooding process. A brief literature review on chemicals, experimental approaches, and methods used for the generation of the desirable phase was presented. Phase behavior studies of microemulsion are a very important tool in describing the interaction of an aqueous phase containing surfactant with hydrocarbon phase to form the Type III microemulsion. Microemulsion highly depends on brine salinity and the interfacial tension (IFT) changes as microemulsion phase transition occurs. At optimal salinity, Type III microemulsion forms, whereas salinity greater or lower than optimal value causes a significant increase in the IFT, resulting in insufficient oil displacement efficiency. Type III microemulsion at optimum salinity is characterized by ultra-low IFT, and extremely high oil recovery can be achieved. In addition, this chapter also stated various other mechanisms relating to oil entrapment, microemulsion phase transition, and surfactant loss in porous media.
Part of the book: Science and Technology Behind Nanoemulsions
Unconventional reservoirs have gained substantial attention due to huge amount of stored reserves which are challenging to produce. Innovative recovery techniques include horizontal drilling coupled with hydraulic fracturing are required to optimize the production of hydrocarbons. There are numerous concerns associated with the utilization of conventional water-based polymeric solutions for fracturing shales. However, the gas utilization has been found as an exceptional stimulation approach providing various benefits. CO2 foam, an energized fracturing fluid, has been used to overcome the limitation of conventional fracturing fluid. CO2 foam is able to enhance hydrocarbon production by addressing the critical issues associated with the conventional technique. The rheological property of CO2 foam fracturing fluid is a key factor controlling the efficiency of overall processes. Different models describing the foam flow behavior have been produced and numerous investigations have been conducted to explain the rheological behavior of foam for fracturing purpose. Various process variables, such as foam quality, temperature, pressure, shear rate, surfactant concentration, and salinity strongly affect foam rheology behavior giving an impact on designing foam fracturing fluid at required fracturing conditions. In-depth analysis and information gathering are substantially required to ascertain the performance of CO2 foam as an improved fracturing fluid system.
Part of the book: Exploitation of Unconventional Oil and Gas Resources