Poly(Oxyethylene)-amidoamine Based Gemini Cationic Surfactants with Hydrophilic Spacers as Clay Stabilizers

Abstract

Water-based drilling fluids cause severe formation damage upon interaction with clay-based formations. Therefore, clay inhibitors are commonly used in the oil and gas industry to prevent clay swelling. The selection of a swelling inhibitor is critical and requires careful understanding. This study reports the application of poly(oxyethylene)-amidoamine based cationic gemini surfactants (GSs) as clay swelling inhibitors. These surfactants are different due to the hydrophilicity of the spacer. The synthesized surfactants contain a diethyl ether spacer (GS-A), a secondary amine spacer (GS-B), or an isopropyl alcohol spacer (GS-C). The swelling inhibition was determined with a linear swelling test, a capillary suction timer (CST), a wettability test, X-ray diffraction, particle size, rheology, and filtration experiments. The synthesized surfactants decreased the clay swelling compared to the base mud. The surfactant with a secondary amine spacer (GS-B) showed the best performance compared to the other surfactants. Moreover, the surfactant showed comparable performances with a commonly used clay stabilizer (KCl) and the commercially available cationic surfactant dodecyltrimethylammonium bromide (DTAB) used in the industry. It was observed that the synthesized surfactants reduced rheological properties and increased the particle size of bentonite and the filtration volume. The proposed gemini cationic surfactants can be used as an alternative for commercial clay swelling inhibitors.