Influência dos constituintes do LC³ em pastas para cimentação de poços de petróleo

Abstract

The use of blends with lower clinker content in their composition (Limestone Calcined Clay Cement – LC³) has gained prominence in recent years, primarily due to the significant CO2 emissions associated with clinker production in the cement industry. Therefore, developing blends with reduced clinker content, like Portland cement and utilizing abundant and naturally available materials, is innovative as it becomes both environmentally and economically viable. This study developed slurries intended for oil well cementing, using LC³ blends with varying cement percentages. The influence of LC³ components, namely Portland Class G cement, metakaolin, dolomitic limestone filler, and alpha gypsum, was evaluated via Response Surface Methodology for slurries with a specific gravity of 14.2 lb/gal (1.66 g/cm³). Additionally, the impact of LC³ slurry materials on essential oil well cementing properties (rheological parameters and compressive strength at 8 hours, 24 hours, and 7 days of curing) were studied. After a detailed analysis of these properties, along with a literature review, an optimized and promising LC³ slurry was developed. However, its high plastic viscosity and final gel strength require corrective additives. The optimized LC³ blend (55% Portland Class G cement, 23% metakaolin, 16% dolomitic limestone filler, and 6% gypsum) produced an LC³ slurry with consistencies of 23 Bc and 20 Bc at 27 °C and 52 °C, respectively, and a setting time of 5 hours. The porosity of this slurry at 24 hours of curing was 55.0525% of its volume, significantly reducing at 7 and 28 days to 9.0511% and 3.3306%, respectively. The permeability of the slurry at 24 hours of curing was 7.4106 mD, decreasing to 0.0051 mD and 0.0026 mD at 7 and 28 days, respectively. Uniaxial compressive strength tests performed on 11 LC³ slurries, derived from the experimental design, demonstrated their satisfactory and promising nature. The lowest compressive strengths for these slurries were 7.79 MPa and 17.04 MPa, while the highest were 10.68 MPa and 23.68 MPa, at 24 hours and 7 days, respectively. These results confirm that LC³ slurry can potentially be applicable for oil well cementing in the future.