Abstract From the first hydraulic fracturing in the 40’s until nowadays, the techniques of each process step have evolved significantly. This study presents a new approach on the development of metakaolin (MK) and geopolymer based proppant with and without nanocarbon materials such as multi-walled carbon nanotubes and graphene oxide. For manufacturing the microspheres, the chosen method was intensive mixing of raw material with dispersed nanocarbons followed by sintering metakaolin and curing the geopolymer using an alkaline medium (NaOH). Compression mechanical tests, bulk density, turbidity, and K&S method analysis were made following API RP 19C standard. The sample containing 4.3 M NaOH to produce alkali-activated metakaolin sintered at 1300 ºC for 2 h presented higher mechanical resistance generating 2.4% of fines at 3 K (3000 psi). The geopolymer samples showed higher crushing strength and lower bulk density when compared to the MK samples without heat treatment. Furthermore, reduced graphene was produced and incorporated into activated MK. Morphology and presence of carbon nanostructures on the proppants were evaluated by scanning electron microscopy. Crushing test reached 3 K enabling it to be used as a ceramic synthetic proppant containing carbon nanomaterials.

Resumo Os reservatórios de hidrocarbonetos podem ser classificados como não convencionais ou convencionais de acordo com a dificuldade de extração de óleo e gás, como a necessidade de tecnologia e técnicas de alto custo. Atualmente a extração de hidrocarbonetos do xisto betuminoso, conhecido popularmente como gás/óleo de xisto (“shale gas/oil”), é realizada por meio da técnica de fraturamento hidráulico em reservatórios não convencionais onde se utilizam 95% de água, 0,5% de aditivos e 4,5% de propantes. Problemas ambientais relacionados à técnica de fraturamento hidráulico e ao desenvolvimento de novos tipos de propantes são os desafios atuais enfrentados pelas empresas, pesquisadores, agências regulatórias, ambientalistas, governo e a sociedade. É previsto um aumento na produção de combustível nos EUA por meio do “shale” que traz consigo o desenvolvimento de novos propantes e tecnologias de exploração. Esse artigo apresenta uma revisão sobre propantes: suas definições, usos, classificações além de informações sobre o mercado mundial, principais produtores e suas características técnicas. A produção de produtos em nanoescala como propantes anticorrosivos, propantes inteligentes e contendo nanotubos de carbono já é realizada em países como Bélgica e Alemanha, além de vários países asiáticos.

Abstract Hydrocarbon reservoirs can be classified as unconventional or conventional depending on the oil and gas extraction difficulty, such as the need for high-cost technology and techniques. The hydrocarbon extraction from bituminous shale, commonly known as shale gas/oil, is performed by using the hydraulic fracturing technique in unconventional reservoirs where 95% water, 0.5% of additives and 4.5% of proppants are used. Environmental problems related to hydraulic fracturing technique and better performance/development of proppants are the current challenge faced by companies, researchers, regulatory agencies, environmentalists, governments and society. Shale gas is expected to increase USA fuel production, which triggers the development of new proppants and technologies of exploration. This paper presents a review of the definition of proppants, their types, characteristics and situation in the world market and information about manufacturers. The production of nanoscale materials such as anticorrosive and intelligent proppants besides proppants with carbon nanotubes is already carried out on a scale of tonnes per year in Belgium, Germany and Asia countries.