Enhanced foam-stabilizing performance by the addition of clays: A comparison of magnesium aluminum silicate with sodium bentonite

Abstract High-temperature-resistant foam stabilizers are desperately required for high-temperature conditions, such as in geothermal wells. In this study, nano‑magnesium aluminum silicate (NMAS) and micro‑magnesium aluminum silicate (MMAS) particles have been studied and compared with sodium bentonite (Na-Bent) as high-temperature-resistant foam stabilizers. It is found that increasing the temperature could facilitate aggregation of clay dispersion, and the increase of particle size results in significant positive effect on apparent viscosity, interface dilational modulus, foam film thickness, and eventually drainage half-life (T0.5) of the foam. Simultaneously, it leads to a negative impact on the initial foam volume (V0) and foam diameter. Moreover, NMAS even possesses excellent foam stabilization effect after being aged at 320 °C for 16 h that it could still dramatically extend T0.5 to 9.78 h, compared to 45.52 and 13.78 min for MMAS and Na-Bent, respectively. Furthermore, V0 of Na-Bent-stabilized foam cannot resist the influence of NaCl and CaCl2 even when only 1.0 wt% NaCl or 0.1 wt% CaCl2 is added. By comparison, V0 of NMAS- and MMAS-stabilized foam drilling fluids are comparatively insensitive to NaCl and CaCl2 until the concentration of 3.0 wt% and 0.2 wt%, respectively. Not only has this study provided a guideline for using clay minerals as foam stabilizers under various high-temperature conditions, but we have also discovered an outstanding high-temperature-resistant foam stabilizer, NMAS, which produces an excellent foam-stabilizing performance even at temperatures as high as 320 °C.