Adsorption of a Switchable Cationic Surfactant on Natural Carbonate Minerals

Abstract

A switchable cationic surfactant, e.g., tertiary amine surfactant Ethomeen C12, has been previously described as a surfactant that can be injected in high pressure CO 2 for foam mobility control. C12 can dissolve in high pressure CO 2 as a nonionic surfactant and equilibrate with brine as a cationic surfactant. Here we describe the adsorption characteristics of this surfactant in carbonate formation materials. The adsorption of this surfactant is sensitive to the equilibrium pH, the electrolyte composition of the brine, and the minerals in carbonate formation materials.Pure C12 is a nonionic surfactant. When it is mixed with brine, the solution has high pH and limited solubility. However, when the surfactant solution in brine is equilibrated with high pressure CO 2 , the pH is about 4, the surfactant switches to a cationic surfactant and becomes soluble. Thus the adsorption is also a function of pH. The adsorption of C12 on calcite at low pH is low, e.g., 0.5 mg/m 2 . However, if the carbonate formation contains silica or clays, the adsorption is high, as is typical for cationic surfactants. The adsorption of C12 on silica decreases with increase in divalent (Ca 2+ and Mg 2+ ) and trivalent (Al 3+ ) cations. This is due to the competition for the negatively charged silica sites between the multivalent cations and the monovalent cationic surfactant. An additional effect of the presence of divalent cations in the brine is that it reduces the dissolution of calcite or dolomite in presence of high-pressure CO 2 . The dissolution of calcite and dolomite is harmful because of formation damage and increased alkalinity. The latter raises the pH and thus increases adsorption of C12 or even cause surfactant precipitation.

High Temperature CO2-in-Water Foams Stabilized with Cationic Quaternary Ammonium Surfactants

“…However, anionic surfactants adsorb strongly on the surface of positively charged minerals, for example calcium carbonate in the presence of CO 2 and water at a pH below 6. 21,22 Thus for high temperature applications with positively charged minerals, cationic surfactants are utilized. Recently, a switchable cationic tertiary amine surfactant bis (2-hydroxyethyl) cocoalkylamine (C 12−14 N(EO) 2 ) soluble up to 393 K even for a very high salinity 22% TDS brine.…”

Understanding aqueous foam with novel CO2-soluble surfactants for controlling CO2 vertical sweep in sandstone reservoirs

“…Those hybrid surfactants combined the high cloud points of ionic surfactants with high solubility in CO 2 of nonionic surfactants. The adsorption characteristics of this surfactant were described by Cui et al (2014), and the interfacial tension (IFT) between CO 2 /water was around 5 mN/m (Elhag et al 2014). Sagir et al (2014a, b) synthesized several CO 2 -philic surfactants using maleic anhydride with either 4-tert-butylbenzyl alcohol or dipropylene tertiary butyl alcohol.…”

Mobility control during CO2 EOR in fractured carbonates using foam: Laboratory evaluation and numerical simulations

“…Hence, the reported unsuccessful foam pilots in fractured reservoirs may be related to operational issues or lack of optimized, field-specific surfactants (Castanier and Hanssen, 1995;Prieditis and Paulett, 1992), rather than lack of foam generation mechanisms in fractured reservoirs. With the development of better surfactants (Buchanan, 1998;Cui et al, 2014;Elhag et al, 2014;Ryoo et al, 2003), the injection of foam in naturally fractured reservoirs is increasingly recognized as a potential EOR technique in fractured reservoirs (Farajzadeh et al, 2012;Haugen et al, 2012;Lopera Castro et al, 2009;Panahi, 2004;Pancharoen et al, 2012;Zuta and Fjelde, 2010). A comprehensive literature review of CO2 mobility control, including foam, may be found in (Enick et al, 2012).…”