Banca de DEFESA: RAPHAEL RIBEIRO DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RAPHAEL RIBEIRO DA SILVA
DATE: 26/12/2025
TIME: 10:00
LOCAL: LABCIM
TITLE:

BRAZILIAN ROCK-BASED ONE-PART GEOPOLYMERS FOR OILWELL CEMENTING: DEVELOPMENT, OPTIMIZATION, AND PERFORMANCE ASSESSMENT

 

KEY WORDS:

Geopolymers; JAW systems; Aluminosilicate precursor; Sustainable cementitious materials

 

PAGES: 136
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

The increasing global demand for safe, sustainable cementing operations in the oil &gas industry has intensified the search for alternative cementitious materials that can outperform or complement Ordinary Portland Cement (OPC) under harsh downhole conditions. As thousands of wells approach the end of their productive life, the industry faces challenges related to long-term zonal isolation, chemical durability, and temperature–pressure resilience. In this context, geopolymers have emerged as promising candidates due to their low-carbon footprint, superior thermal stability, and chemical resistance. This work explores the development of one-part rock-based geopolymers derived from a Brazilian aluminosilicate precursor, aiming to provide a technically robust, environmentally favorable solution for oil and gas cementing applications. In the first phase, the precursor was blended with ground granulated blast-furnace slag (GGBFS) and microsilica, and activated with potassium silicate to evaluate its performance as a cementing system. Fresh-state properties, including rheology, consistency, and thickening time, were systematically evaluated. At the same time, hardened-state behavior was assessed using compressive strength testing at multiple curing ages and temperatures representative of downhole conditions. The geopolymer exhibited pronounced temperature- and pressure-sensitive behavior, underscoring the importance of optimized formulations for P&A scenarios. The second phase focused on optimizing the slurry design to enhance reactivity and mechanical performance. A Central Composite Design (CCD) was implemented to assess how precursor composition and water-to-solid ratio influenced compressive strength at 70 °C. The input variables included Brazilian rock aluminosilicate content, GGBFS, microsilica, activator (KOH and K2SiO3) content, and water-to-solid ratio. The resulting formulations achieved compressive strengths of up to 50 MPa under laboratory curing, demonstrating their suitability for oil well cementing applications. Microstructural observations using SEM and EDS confirmed the formation of amorphous geopolymeric gels and indicated the incorporation of Si and Al into a cohesive three-dimensional matrix. Collectively, these results confirm that the Brazilian rock-based precursor is suitable for wellbore applications after slurry design optimization. Overall, this research advances understanding and practical development of sustainable one-part geopolymers for oil and gas well cementing, offering a viable pathway to improve long-term integrity in P&A operations while reducing environmental impact and enhancing operational reliability.

 

COMMITTEE MEMBERS:
Presidente - 1979301 - RENATA MARTINS BRAGA
Externa ao Programa - 2621720 - ANA CECILIA VIEIRA DA NOBREGA - UFRNExterno ao Programa - 1913849 - EDGAR PERIN MORAES - UFRNExterno ao Programa - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS - UFRNExterna à Instituição - ERIKA PINTO MARINHO - UFPE
Externa à Instituição - FABÍOLA DIAS DA SILVA CURBELO - UFPB