Abstract
Shallow depth cementing is often faced with the challenges of low temperatures and weak formation strength. To handle this challenge, green alternative cementitious material, so-called geopolymer, is proposed as an alternative to Portland-based cement for this specific application. In this article, the potential of using low-density geopolymer, utilizing the water-extended approach, for low temperature shallow depth application is described. Despite its flexibility in operation and slurry design, water-extended slurry is often faced with challenges such as weaker strength, prolonged thickening time, excessive free fluid and increased risk of particle sedimentation. The objective is to reduce the particle size distribution of its precursors to increase its reactivity and performance in the water extended low-density geopolymer. Two granite-based geopolymer mix designs, a normal-density geopolymer design and a low-density design, are compared. Several tests assessing thickening time, rheology, and compressive strength are performed on both geopolymer materials. For the low-density slurry, higher liquid-to-solid ratio is used to extend the slurry. Different source of precursors with smaller particle size distribution are used as the approach to obtain stable low-density slurry for low temperature application. This approach modifies the rheology profile of the slurry and leads to a more rapid hardening, making it suitable for surface casing cementing applications. Prolonged thickening time issue is solved with the low-density geopolymer, allowing the slurry to have a shorter thickening time. Smaller particle size results in water adsorption capacity and increased reactivity of precursor. Moreover, the low-density geopolymer shows rapid strength development for a short period of observation of 7 days at low temperature. The result shows the potential of low-density geopolymer, utilizing a liquid extended approach, for low temperature surface casing cementing applications.
