Phase Behavior Study of Branched Alcohols as Additives in Surfactant Flooding

The application of surfactant flooding for enhanced oil recovery is often precluded in reservoir where there is high brine salinity, high temperature and presence of hard water or divalent ions. This is because all these factors will degrade the surfactant to the extent that it will no longer be useful to be used in reducing the interfacial tension of oil-water phase. Therefore additives are usually used as part of the slug mixture to counter the negative effects inflicted by the above factors. As such we investigate the use of branched alcohols as possible additives to enhance surfactant flooding. Branched alcohol is chosen because it has lower miscibility in water and its potential for withstanding high temperature and high salinity. Previous research shows that the use of lower concentration of branched alcohol result in similar amount of interfacial tension reduction by using alkali. In this work branched alcohol samples were tested with anionic surfactants such as Dodecyl Trimethyl Ammonium Bromide (DTAB) and Sodium Dodecyl Sulfate (SDS) to evaluate their compatibility. Furthermore the formulations were optimized in order to withstand high temperature, hard water (> 500 ppm Mg2+) and high brine salinity (>50,000 PPM). Phase behaviour study were also conducted to obtain low interfacial tension (<1.0 mN/m) and Winsor type III microemulsion suitable for surfactant flooding. In this work it was found that the formulation of 0.3 wt% of 2-methyl 1-butanol and 0.2 wt% of 3-(n, n –dimethylocatadecylamminia) propane sulfonate would form a Winsor Type III microemulsion. This will give an optimum salinity of 58,000 PPM with low interfacial tension of 0.12 mN/m, thus fulfill the objectives of this study.
As the demand of oil worldwide increased, the oil price is also increased gradually and with this enhanced oil recovery is becoming more important to oil and gas industry. These projects confer three solid objectives. First objective is to produce chemical formulation that can withstand high temperature, hard water (>500 PPM) and high brine salinity (>50,000 PPM). Second objective is to produce low interfacial tension (<1.0 mN/m) that form Winsor type III for the study of phase behavior-microemulsion characteristic in surfactant flooding. . Third objective is to measure the absorption of surfactant formulation above for fluid-fluid study. The
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problem statement identified is that; surfactant flooding for enhanced oil recovery does not tolerant to (1) high salinity (2) high temperature (3) high hardness. For the methodology, author focus on phase behavior screening, and then the formation was tested to demonstrate their performance in porous media. For the acceptable result, the next step is to run the core floods to test the potential use of chemical flooding for a field application with Dulang crude oil. The methodology will be discussed further in the phase behavior section. The scopes of studies include branched alcohol studies, phase behaviour, Winsor type system, and high salinity of brine, interfacial tension, and fluid properties such as density, refractive index etc and absorption test. Previous research showed that primary alcohols are able to reduce the interfacial tension (IFT) between surfactant and oil when added even in small amounts. The finding for this research is the formulation of 0.3 wt% of 2-methyl 1-butanol and 0.2 wt% of 3-(n, n –dimethylocatadecylamminia) propane sulfonate would form a Winsor Type III microemulsion. This will give an optimum salinity of 58,000 PPM with low interfacial tension of 0.12 mN/m, thus fulfill the objectives of this study.