Effect of Elevated Temperature on the Microstructure of Metakaolin-Based Geopolymer

Currently, geopolymer is being considered as a future oil-well cement. For wellbore applications, geopolymers are initially tested at specific temperature conditions. However, an oil-wellbore may experience a sudden increase in temperature which may adversely affect geopolymer systems designed for low to moderate temperature conditions. In this work, the effect of elevated temperatures on the microstructure of the geopolymer was simulated. Metakaolin-based geopolymer systems cured at 163 degrees F for 48 h were subjected to a temperature ramp of 194 degrees F and 248 degrees F for 24 h. X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetry analysis techniques were used to study the microstructural changes. The analytical techniques show the formation of new crystalline phases when the geopolymer cured at 163 degrees F was suddenly exposed to higher temperatures. These crystalline phases, for instance, gobbinsite and anorthite, observed in the microstructure have the potential to cause thermal stress, weaken the system, and ultimately affect the geopolymers ability to effectively isolate the formation and support the casing.

Automated summary

This study investigates the effect of elevated temperatures on the microstructure of geopolymer systems. The results show that sudden exposure to higher temperatures can lead to the formation of new crystalline phases, which may cause thermal stress, system weakening, and ultimately affect the geopolymer's ability to isolate the formation and support the casing.