Abstract
Thermal stability, salt tolerance, and solubility in normal and high salinity brine are the major requirements for any surfactant designed for oilfield applications because the surfactant stays in a non-ambient environment inside the reservoir for a long period of time. Herein, a series of new gemini cationic surfactants (GSs) with varying spacer hydrophilicity were synthesized and elucidated using MALDI-ToF-MS, NMR (1H, 13C), as well as FTIR spectroscopy. GSs found to be soluble in normal as well as high salinity brine and aqueous stability tests revealed that GSs possess the ability to retain their structural integrity at high salinity and high temperature conditions because no suspension formation or precipitation was detected in the oven aged sample of GSs at 90 °C for 30 days. Thermal gravimetric analysis displayed a higher decomposition temperature than the real reservoir temperature and the GS with a secondary amine spacer exhibited high heat stability. The significant reduction in surface tension and critical micelle concentration was observed using 1 M NaCl solution in place of deionized water. The difference in surface tension and critical micelle concentration was insignificant when the 1 M NaCl solution was replaced with seawater. The synthesized surfactants can be utilized for oilfield applications in a challenging high temperature high salinity environment.
Highlights
Surfactants are extensively applied in the petroleum industry such as enhanced oil recovery (EOR) [1,2,3,4,5], fracking fluid [6], swelling prevention [7], reservoir stimulation [8], corrosion inhibitor [9], drag reduction [10], and drilling mud [11,12]
Migahed et al reported the synthesis of two gemini cationic surfactants containing different spacer lengths as anti-corrosion for X-65 steel dissolution in oilfields produced water under sweet conditions [29]
The SW and formation water (FW) were formed through the addition of a specific amount of MgCl2, CaCl2, NaHCO3, Na2 SO4, and NaCl (Table 5), and the material was received from Panreac
Summary
Surfactants are extensively applied in the petroleum industry such as enhanced oil recovery (EOR) [1,2,3,4,5], fracking fluid [6], swelling prevention [7], reservoir stimulation [8], corrosion inhibitor [9], drag reduction [10], and drilling mud [11,12]. The important features of GSs are smaller critical micelle concentration (CMC), good solubilizing capability, antibacterial activity, required low quantity, and unique aggregation behavior [16] Due to these distinctive properties, GSs have found application in the oilfield industry. Migahed et al reported the synthesis of two gemini cationic surfactants containing different spacer lengths as anti-corrosion for X-65 steel dissolution in oilfields produced water under sweet conditions [29]. They observed that the surfactant with a shorter spacer length exhibited better inhibitive properties than the surfactant with a comparatively larger spacer length. The solubility of the GSs in normal and high saline water was achieved by adding a sufficient number of ethoxy units [33]
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