Alkyl Glycine Surfactant: An Efficient High-Temperature Resistant and Biodegradable Foaming Agent for Colloidal Gas Aphron (CGA) Drilling Fluid
Abstract Colloidal Gas Aphron (CGA) drilling fluid is one of the most promising techniques in underbalanced drilling with excellent plugging and reservoir protection functions. Due to the limitation of poor thermal stability of commercial foaming agents used in oilfields, the research on high-temperature resistant CGA drilling fluid is still a challenge. In this study, a biodegradable glycine foaming agent AGS-12 was synthesized via a one-step method. The surface activity, foaming performance (25–150°C) of AGS-12 and the high temperature performance of AGS-12 based CGA drilling fluid (120–150°C) were studied. All the results provide a basis for the potential application of AGS-12 as an eco-friendly foaming agent in high-temperature CGA drilling fluids: 1) The product AGS-12 with 87% conversion rate was synthesized successfully by one-step method, which can be verified by FT-IR. TGA analysis suggested that AGS-12 had good thermal stability within 315°C. Moreover, AGS-12 is easily biodegradable and fully meets the first level discharge standard of petrochemical industry pollutants. 2) AGS-12 can reduce the surface tension of solvent water from 72.38 to 28.44 mN/m. Analysis of fundamental surface activity parameters illustrates the higher surface activity of AGS-12, compared with a variety of amino acid surfactants. 3) Waring-Blender test showed that foams generated by 3% AGS-12 always have higher half-life, foam quality and lower drainage speed than the foaming agents available on market within 150°C. 4) At 120/140/150°C, aphrons with diameter of 10–150 µm have been successfully generated in CGA drilling fluid by using AGS-12 as foaming agent. Rheological and filtration tests suggested that AGS-12 based CGA drilling fluid is a high-performance drilling fluid with strong shear thinning behavior, high viscosity, and low filtration invasion.
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