Study of an anti-high-temperature and salt-resistance alkyl glycine foaming agent and its foam stabilizing mechanism

Abstract

The development of high-temperature and salt-resistant foaming agents is critical to the successful drilling of complex and low-pressure reservoirs. In this study, a novel alkyl glycine surfactant (AGS-8) was synthesized by the one-step method. The foam quality of AGS-8 at high temperatures (140–180 °C) and the salt solutions (5–36%wt) was evaluated by the Waring-Blender method to explore its applicability in harsh reservoirs. Results show that: (1) The successful synthesis and chemical structure of AGS-8 was determined by FTIR and ¹H-NMR. (2) AGS-8 shows good thermal stability within 330 °C and has high surface activity. (3) AGS-8 generated stable foams after aging at 180 °C for 16 h. The outstanding high-temperature foam stability of AGS-8 is an important feature different from the conventional commercial foaming agents. (4) AGS-8 generated stable foams in saturated salt solution (36%wt NaCl) after 150 °C aged. A synergistic foam stabilization effect was found between high concentrations of NaCl (≥25%wt) and AGS-8. (5) The foam stabilization mechanism of AGS-8 was discussed and can be summarized as the electrostatic attraction effect of head groups and the enhancement of inter-molecular repulsive force. In conclusion, AGS-8 was found to be a promising foaming agent in the drilling of high-temperature salt-gypsum formations.

Graphical Abstract

Keywords:

• Amino acid surfactant
• high-temperature resistant foam
• salt resistance
• foaming agent
• foam stabilization mechanism

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 41872184) of “Properties of Colloid Gas Aphron Drilling Fluid and its Mechanism of Loss and Formation Protection for High Temperature Geothermal Reservoir.”