The Path to Sustainable Cementing: Embracing a Non-Portland Cement Solution for Oil and Gas Wells

Geopolymer cement shows great promise as an alternative to Ordinary Portland cement (OPC) in the oil and gas industry due to OPC's environmental concerns and high energy consumption during manufacturing. While geopolymer cement is already widely used in the construction sector, its full-scale application in the petroleum industry is yet to be realized. One critical area where geopolymer cement can play a significant role is in high-pressure well cementing applications. To replace heavy-weight Portland cement slurries in these applications, the development of high-density geopolymer cement becomes essential. However, there is a challenge associated with high-density cement slurries that use dense materials as weighting agents. This challenge is known as sedimentation, which leads to issues like heterogeneity and density variation along the cemented sections. Overcoming this problem is crucial for ensuring the effective and reliable use of high-density geopolymer cement in the oil and gas industry. The target of this work is to introduce a new formulation for heavy weight geopolymer systems and evaluate the use of perlite powder as an anti-sedimentation additive in these systems. The study involved the preparation of Hematite-based Class F fly ash (FFA) geopolymer cement slurries with different concentrations of perlite (0%, 1.5%, and 3% by weight of binder (BWOB)). To assess the sedimentation problem, the API method was used. Various geopolymer properties, such as unconfined compressive strength (UCS), elastic properties, and rheological properties, were examined in relation to the effects of perlite. The results indicated that the inclusion of perlite in high-density hematite-based FFA geopolymer led to a significant reduction in the sedimentation issue. This improvement was achieved by increasing the yield point and gel strength of the slurry. Moreover, the UCS showed an increase with increasing the percentage of perlite. The evaluation of young's moduli (YM) and Poisson's ratios (PR) demonstrated that the developed perlite-based geopolymer systems exhibited greater flexibility compared to Class G cement systems. Based on the findings, it was concluded that the optimal perlite concentration for addressing sedimentation while maintaining desirable mixability and rheological properties was 3% BWOB.