Experimental studies and computational exploration on an exceptionally salt/condensate resistant gas well foaming mixture compromising amino-betaine-ammonium surfactants and dodecanol

Abstract

Liquid accumulation in natural gas wells is typically addressed by foam-based deliquification. This study systematically investigated the development of a green and cost-effective foaming mixture comprising lauramidopropyl trimethylammonium chloride (LATC), lauramidopropyl betaine (LAPB), sodium lauroyl glutamate (SLG) and dodecanol (LA). Properly combined LATC/SLG/LAPB/LA mixture demonstrated synergistic effects in enhancing foam generation, foam stabilization and liquid unloading. Remarkably, the LATC/SLG/LAPB/LA foam exhibited exceptional performance in unloading liquid, even at a condensate fraction of up to 50 %. Adding a chelator (NTA) to LATC/SLG/LAPB/LA further improved the foaming efficiency and liquid unloading performance at salinity levels of up to 33 × 104 mg/L, which was likely the highest salt tolerance according to the available literature. The negative effect of temperature on the performance of LATC/SLG/LAPB/LA foam was resolved by adding 15 % methanol. At 90 °C, almost all the liquid can be removed from the column by the LATC/SLG/LAPB/LA foam, which produced a liquid unloading efficiency of 90 % and a foaming efficiency of 100 %. Surface tension, viscosity and morphological analysis supported the observed synergistic effects, while molecular dynamic simulations revealed the mechanisms of the excellent salt/condensate resistance of the LATC/SLG/LAPB/LA foam. These findings demonstrated the promising potential of the LATC/SLG/LAPB/LA foam in gas well deliquification.