EFFECT OF THE WATER/BLENDA FACTOR AND THE POLYCARBOXYLATE-BASED DISPERSANT IN LC³ PASTES FOR OIL WELL CEMENTING
calcined clay; rheology; water-to-cement ratio; water-to-binder ratio; oil well cementing; sustainable cementitious systems; petroleum engineering.
Limestone Calcined Clay Cement (LC³) is a low-carbon cementitious blend that has emerged as a sustainable alternative to conventional Portland cement due to its ability to reduce clinker consumption and, consequently, the energy demand and CO₂ emissions associated with cement production. In the context of oil well cementing, traditionally performed using Class G Portland cement, LC³ has the potential to contribute to the decarbonization of the oil and gas industry. However, its application in this sector still requires further investigation regarding its high water demand and compatibility with chemical admixtures. In this context, this study evaluated the influence of the water-to-blend ratio (W/B) and the addition of a polycarboxylate-based dispersant (PCO) on the performance of LC³ slurries. The formulations were subjected to the tests established by ABNT NBR 9831 (2020) for cement slurries intended for oil well cementing. Additionally, isothermal calorimetry, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were performed. The results showed that increasing the PCO content contributed to a reduction in yield stress and gel strengths, indicating improved rheological behavior of the slurries. Conversely, increasing the W/B ratio resulted in lower compressive strength values. The formulations exhibited no free water, indicating adequate stability. Compressive strength at 8 h ranged from 0.97 to 3.28 MPa at 38 °C and from 9.38 to 23.69 MPa at 60 °C. The effect of curing temperature was more pronounced at early ages, promoting significant strength gains at 60 °C, whereas at 7 days the differences in compressive strength became less significant. Formulations with W/B ratios of 0.43 and 0.47 combined with intermediate dispersant contents exhibited the best balance between rheological and mechanical performance, demonstrating the technical feasibility of using LC³ slurries for oil well cementing and contributing to the development of more sustainable cementitious systems for the oil and gas industry.