Banca de QUALIFICAÇÃO: RAFAEL AUGUSTO VENTURA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : RAFAEL AUGUSTO VENTURA
DATE: 26/03/2026
TIME: 09:30
LOCAL: Auditório do LABCIM
TITLE:

Development and Optimization of Sustainable Kaolin Waste–Based Geopolymers for Oil Well Applications.

KEY WORDS:

geopolymers; kaolin waste; calcination; experimental design; oil wells

PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Não-Metais e Seus Compostos
SUMMARY:

Oil and gas well operations impose stringent requirements on cementitious materials, particularly regarding mechanical strength, physicochemical stability, and long-term durability under harsh conditions. Conventional Portland cement systems, although widely used, have shown significant limitations when exposed to aggressive environments typical of oil wells, especially in long-term scenarios such as well abandonment. In parallel, the high carbon footprint associated with Portland cement production has intensified the search for alternative and more sustainable binders. In this context, geopolymers have emerged as a promising class of alternative cementitious materials due to their aluminosilicate-based structure, which can provide enhanced chemical stability in saline and CO₂-rich environments, while enabling the use of mineral wastes as precursors. Among these materials, kaolin waste stands out as an abundant aluminosilicate-rich by-product whose valorization can contribute to circular economy strategies and environmental impact mitigation. The main objective of this thesis is the development and optimization of kaolin waste–based geopolymers for oil well applications. Initially, complementary experimental studies addressing the degradation of Portland cement abandonment plugs, the use of clay minerals as modifiers of cement pastes, and the microstructural characterization of cementitious systems are presented. These studies establish the technological limitations of conventional systems and provide the conceptual and methodological foundation that motivates the adoption of geopolymeric binders. The core of the thesis comprises two central studies. The first systematically investigates the influence of calcination conditions on the thermal activation of kaolin waste, focusing on the relationship between temperature, residence time, mineralogical transformations, and geopolymer reactivity. Physicochemical and microstructural characterization techniques are employed to correlate precursor activation with binder performance. The second study applies an experimental design approach to optimize geopolymer formulation parameters, evaluating the effects of key variables on properties relevant to oil well applications, such as compressive strength and material stability. The results demonstrate that properly calcined kaolin waste is a viable and effective geopolymer precursor, enabling the production of binders with properties compatible with oil well requirements. Overall, this thesis contributes to the advancement of geopolymer science and supports the development of more durable and sustainable cementitious solutions for the oil and gas industry based on mineral waste valorization.

COMMITTEE MEMBERS:
Externo ao Programa - 1913849 - EDGAR PERIN MORAES - nullExterna à Instituição - ERIKA PINTO MARINHO - UFPE
Presidente - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS