Carbon dioxide (CO2) sequestration into deep underground reservoirs such as saline aquifers, oil reservoirs and coal seams have found out to be one of the best practical solutions to reduce significant amount of greenhouse gases from the environment. The success of any large scale CO2 sequestration project depends on many factors, and two of the important factors are (a) the stability of injection well and (b) well cement. To date, OPC based cement has been used as well cement, and it has been found that it is unstable in CO2 environments as it undergoes degradation, strength reduction, and shrinkage. Therefore, a comprehensive experimental study has been undertaken to investigate the suitability of geopolymer as well cement and the mechanical behavior of geopolymer and class G cement was compared under different down-hole temperatures. When the uniaxial compressive strength (UCS) of geopolymer and G cement was compared, it was found that geopolymer possess higher UCS values at elevated temperatures (above 50 oC) and G cement possesses the highest values at ambient conditions. The peak strength of both geopolymer and class G cement was observed at curing temperatures of 50-60 oC. In addition, acoustic emission (AE) test data revealed that the crack propagation stress thresholds of class G cement are higher at ambient conditions, whereas geopolymer possesses highest values at elevated temperatures. The photogrammetric results of strain measurement show that geopolymer undergoes shear failure at lower curing temperatures, whereas the failure was splitting at elevated temperatures. In addition, the type of failure of class G cement was shear failure for all the curing temperatures and the ultimate failure strain did not vary much with the curing temperature.
Greenhouse gas emissions in the globe are rapidly increasing due to the excessive usage of fossil fuel including coal.
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