Phase Behaviour of Surface Active Ionic Liquids for Enhanced Oil Recovery

Chemical flooding with surfactants is well known to have huge potential in Enhanced Oil Recovery (EOR) processes. One of the main challenges for surfactant EOR is finding a surfactant or a surfactant blend able to generate a Winsor Type III microemulsion. The main objective of this thesis is to obtain optimal formulations with surface active ionic liquids (SAILs) able to improve current surfactant EOR methods. To achieve this goal, the phase behaviour of a set of SAILs or blends containing a SAIL has been studied in the presence of water or brine and oil at different temperatures and atmospheric pressure. Based on the results obtained, a formulation containing a blend of IOS15-18 and [C12mim]Br is suggested as the best option, since an ultra-low interfacial tension was achieved and an injectable optimal formulation, tolerant to divalent ions, was found at a particular salinity

Phase Equilibria of 1-hexyl-3-methylimidazolium acetate with water and oil

Ionic liquids have increased the possibilities of Enhanced Oil Recovery (EOR) with surfactants. However, results obtained with only one of these salts as surfactant are not particularly promising. Best results are obtained with blends of these salts or blends with traditional surfactants. This work aims to break new ground regarding the role of ionic liquids in this application. Many traditional surfactants in EOR fail because they are not sufficiently soluble at optimal salinity in water. The possibilities of design of ionic liquids must also be considered to use them as co-surfactants in optimal formulations for oil recovery. In this work, the phase behaviour of the ionic liquid 1-hexyl-3-methylimidazolium acetate with water and different model oils (n-octane, cyclohexane and toluene) was determined at 298.15 K and 323.15 K. The complete miscibility of the ionic liquid with water and its low miscibility with the different oils, point to the use of 1-hexyl-3-methylimidazolium acetate as co-surfactant with surfactants with high oil solubilising capacityThe authors acknowledge the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015-68496-P (including European Regional Development Fund advanced funding)S

Ionic liquids for low-tension oil recovery processes: Phase behavior tests

This is the accepted manuscript of the following article: Rodriguez-Escontrela, I., Puerto, M., Miller, C., & Soto, A. (2017). Ionic liquids for low-tension oil recovery processes: Phase behavior tests. Journal Of Colloid And Interface Science, 504, 404-416. doi: 10.1016/j.jcis.2017.05.102Chemical flooding with surfactants for reducing oil-brine interfacial tensions (IFTs) to mobilize residual oil trapped by capillary forces has a great potential for Enhanced Oil Recovery (EOR). Surface-active ionic liquids (SAILs) constitute a class of surfactants that has recently been proposed for this application. For the first time, SAILs or their blends with an anionic surfactant are studied by determining equilibrium phase behavior for systems of about unit water-oil ratio at various temperatures. The test fluids were model alkane and aromatic oils, NaCl brine, and synthetic hard seawater (SW). Patterns of microemulsions observed are those of classical phase behavior (Winsor I-III-II transition) known to correlate with low IFTs. The two anionic room-temperature SAILs tested were made from common anionic surfactants by substituting imidazolium or phosphonium cations for sodium. These two anionic and two cationic SAILs were found to have little potential for EOR when tested individually. Thus, also tested were blends of an anionic internal olefin sulfonate (IOS) surfactant with one of the anionic SAILs and both cationic SAILs. Most promising for EOR was the anionic/cationic surfactant blend of IOS with [C12mim]Br in SW. A low equilibrium IFT of 2 10 3 mN/m was measured between n-octane and an aqueous solution having the optimal blend ratio for this system at 25 CA. Soto acknowledges the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015-68496-P (including European Regional Development Fund advanced funding)S

Ionic Liquids derived from proline: application as surfactants

This is the peer reviewed version of the following article: V. Fernández-Stefanuto, R. Corchero, I. Rodríguez-Escontrela, A. Soto, E. Tojo, ChemPhysChem 2018, 19, 2885, which has been published in final form at https://doi.org/10.1002/cphc.201800735. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsIonic liquids derived from prolinium esters, previously described as fully green and stable, were found to decompose in the presence of water by ester hydrolysis. To avoid this problem, a new family of these biodegradable salts incorporating an alcohol instead of the ester group is proposed. From this family, two novel ionic liquids that incorporate the prolinolium cation [HOPro] and the [DS] or [DBS] anion were selected (DS=dodecylsulfate; DBS=dodecylbenzenesulfonate). Both salts are liquid at room temperature, a property not usually found in ionic surfactants, and are also chemically and thermally stable. Moreover, they are more effective in reducing the surface tension of water than the corresponding traditional surfactants in the form of sodium salts, being useful for applications related to their aggregation capacity. They were tested for surfactant enhanced oil recovery and an optimal formulation for reservoirs at high salinity and temperature, able to produce ultra‐low interfacial tension, was found with [HOPro][DBS]A.S. acknowledges the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015‐68496‐P (including European Regional Development Fund advanced funding). E.T. thanks the Xunta de Galicia (ED431D 2017/06) for their financial supportS

Correlation of three-liquid-phase equilibria involving ionic liquids

The difficulty in achieving a good thermodynamic description of phase equilibria is finding a model that can be extended to a large variety of chemical families and conditions. This problem worsens in the case of systems containing more than two phases or involving complex compounds such as ionic liquids. However, there are interesting applications that involve multiphasic systems, and the promising features of ionic liquids suggest that they will play an important role in many future processes. In this work, for the first time, the simultaneous correlation of liquid–liquid and liquid–liquid–liquid equilibrium data for ternary systems involving ionic liquids has been carried out. To that end, the phase diagram of the water + [P6 6 6 14][DCA] + hexane system has been determined at 298.15 K and 323.15 K and atmospheric pressure. The importance of this system lies in the possibility of using the surface active ionic liquid to improve surfactant enhanced oil recovery methods. With those and previous measurements, thirteen sets of equilibrium data for water + ionic liquid + oil ternary systems have been correlated. The isoactivity equilibrium condition, using the NRTL model, and some pivotal strategies are proposed to correlate these complex systems. Good agreement has been found between experimental and calculated data in all the regions (one triphasic and two biphasic) of the diagrams. The geometric aspects related to the Gibbs energy of mixing function obtained using the model, together with the minor common tangent plane equilibrium condition, are valuable tools to check the consistency of the obtained correlation results

Thermo-rheology of a proline-based surface active ionic liquid and their binary and ternary mixtures with water and n-octane

This is the peer reviewed version of the following article: Torres, M.D., Corchero, R., Rodríguez-Escontrela, I., Soto, A. and Moreira, R. (2019), Thermo‐Rheology of a Proline‐Based Surface‐Active Ionic Liquid: Mixtures with Water and n‐Octane. Chem. Eng. Technol., 42: 1952-1959. doi:10.1002/ceat.201800269, which has been published in final form at https://doi.org/10.1002/ceat.201800269. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsSurfactant flooding is one of the most promising techniques to recover oil from unprofitable reservoirs. Surface‐active ionic liquids can overcome the limitations of the current surfactants. The rheology of the injecting solutions and the formed slugs is critical in the evaluation of an enhanced oil recovery process. The thermo‐rheological behavior of a biodegradable surface‐active ionic liquid, [ProC4]DS, and the corresponding binary and ternary mixtures with water and n‐octane was studied. All flow curves exhibited shear‐thinning and thixotropic behavior. The viscoelastic behavior of the ternary samples depended strongly on the [ProC4]DS content. Three different regions were identified: typical liquid‐like behavior, weak gel, and true gel. The thermal profiles indicated that the tested systems were fully thermoreversibleMinistry of Economy and Competitiveness (Spain). Grant Number: PGC2018‐097342‐B‐I00S