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.

The use of proppants in hydraulic fracturing has significantly grown worldwide in recent years. Discoveries of large unconventional reservoirs in the north of Brazil have collaborated to give it the 10th position among countries with the world's largest shale reserves. Nowadays, studies on nanomaterials that are used as additives in proppants are the focus of North America's companies and universities in order to develop either proppants that can suffer mechanical and chemical changes inside the reservoir or that enable their traceability and direction. This paper presents a study on synthesis and characterization of metakaolin’s based ceramic proppants incorporating different types of nanocarbon materials. The method adopted was based on use of high intensive mixing of raw material (metakaolin) granulated with alkaline water solution of dispersed carbon nanomaterials. The SEM analysis testify the carbon nanomaterials dispersion on proppant bulk structure. Mechanical tests (crush resistance or K-value) indicated that metakaolin based proppants reached similar characteristics of white sand natural proppants.

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Blasting remains as an economical and reliable excavation technique, but there are some environmental shortcomings such as the control of blast-induced vibration. The impacts of vibration over surrounding communities in a blast area have been investigated for decades and researchers have been using a myriad of empirical predictive attenuation equations. These models, however, may not have satisfactory accuracy, since parameters associated to geomechanical properties and geology affect the propagation of seismic waves, making vibration modeling a complex process. This study aims for application of an Artificial Neural Network (ANN) method and Geomechanical parameter relationships to simulate the blast-induced vibration for a Brazilian mining site and then compare them to the traditional approach. ANN had the best performance for this mine despite having demanded large datasets (as much as for the traditional approach), while geomechanical parameters like RQD and GSI may be used to deliver a fair approach even without seismic data. Also, ANN methods may be useful in dealing with a large amount of information to facilitate the simulation process when combined with other methods. Therefore, alternative prediction methods may be helpful for small budget mining operations in planning and controlling blast-induced vibration and helping mining in urban areas becoming a more sustainable activity.

A methodology for rock-excavation structuralreliability analysis that uses Distinct Element ResumoEsse artigo apresenta uma metodologia para incorporação de incertezas à modelagem numérica pelo méto-do dos elementos distintos em análises de confiabilidade estrutural de escavações em rocha. A metodologia foi desenvolvida levando em conta que os métodos de modelagem numérica normalmente empregados fornecem resultados pontuais, determinados a partir de parâmetros de entrada fixos, sem que sejam considerados seus respectivos erros. Entretanto a análise da estabilidade de estruturas em rocha envolve incertezas decorrentes da variabilidade inerente aos processos geológicos, da incerteza a respeito da hipótese de comportamento mecâni-co adotada e, também, das incertezas associadas aos parâmetros adotados na formulação do modelo numérico. Essas fontes de incerteza podem ser levadas em conta em modelos determinísticos simples, mas, na modelagem numérica, onde os resultados são de diversas naturezas, cabendo ao pesquisador analisá-los para obter suas conclusões, faz-se necessário o desenvolvimento de uma metodologia nova, baseada em simulações de Monte Carlo, com o emprego dos princípios da Lógica Paraconsistente, e que será apresentada na análise de um talude final de uma cava de mineração de grandes dimensões. Palavras-chave:Modelos numéricos, método dos elementos distintos, Lógica Paraconsistente, mineração, talude.

ResumoEsse trabalho emprega o método para avaliar a abrasividade proposto por Golovanevskiy e Bearman (2008). Esse método, ensaio de abrasão por impacto deslizante (Gouging Abrasion Test), é realizado em condições de alta tensão/alto impacto de desgaste. O método consiste de uma ponteira cilíndrica com uma ponta cônica de 90º, que, em trajetória pendular, atinge uma amostra de rocha com energia de impacto de 300 J e velocidade da ordem de 5,2 m/s. O Gouging Abrasion Index (Gi) é calculado como sendo a média do diâmetro da ponta cônica, após desgaste, em milímetros e o resultado é multiplicado por 10. Esse trabalho verificou a adequabilidade do Gouging Abrasion Test, para um pequeno número de amostras de rocha, que representam, qualitativamente, os principais tipos de rocha encontrados em trabalhos de corte, perfuração e britagem no Brasil, e a sua correlação com outros ensaios consagrados como a resistência à compressão, o desgaste Amsler e a dureza Knoop. Essa análise mostrou alta correlação entre Gi e a dureza Knoop (R² = 0,94), baixa correlação com o desgaste Amsler (R² = 0,41) e nenhuma correlação com resistência à compressão uniaxial. Palavras-chave: Mecânica de rochas, abrasão, esclerometria pendular. Abstract This paper employs the method for evaluating abrasion proposed by Golovanevskiy e Bearman (2008). This method, Gouging Abrasion

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