Research on foaming agents for gas flooding in medium-temperature and high-salinity clastic reservoirs

Abstract

Anionic surfactants are commonly used as foaming agents in foam-enhanced oil recovery, but their performance is seriously affected by high temperature and high salinity environment. However, there are not many studies on the adsorption pattern and salinity resistance performance of anionic surfactants on solid surfaces. This study evaluated the foaming performance of several anionic surfactants suitable for hightemperature, high-salinity salinity reservoirs. It was found that α-olefin sulfonate (AOS) showed good foaming performance under high temperature and high salt condition. However, the solubility of the foaming agent was low in brine with a salinity of 11×104 mg·L-1. Therefore, a co-solvent (ABS), which is a strong hydrophilic alkyl benzene sulfonate, was chosen to be compounded with AOS in this study. In this study, a foaming agent with excellent foaming performance and solubility at a temperature of 90°C and a salinity of 11×104 mg·L-1 was constructed. The adsorption of the foaming agent was less than 0.3mg/g on the surface of quartz sand, and its foaming rate and foam decay half-life after three adsorptions maintained more than 85% of the original performance. The results of the study can guide the selection of foaming agents for gas injection and mobility control in medium temperature and high salinity clastic reservoirs.