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.

Hydraulic fracturing is a very important technique to increase the productivity and recovery of oil reservoirs with low pressure or high depth. The hydraulic fracturing technique is a method of well stimulation in which liquid under high pressure is pumped down a well to fracture the reservoir rock adjacent to the wellbore. Propping agents are used to keep the fractures/cracks open. They can be made from the reject of mineral extraction processes when they present specifics characteristic. The aim of this paper is the evaluation of the use of industrial rejects to the development of ceramic synthetic proppants that are resistant to chemical corrosion and high mechanical strength in aqueous acid and salt water environment. In this study, industrial rejects from nickel sulfide ore flotation (grey mud - GM), red mud (RM) from Bayer process and black mud (BM) from Caron processing of nickel was used as raw material for the production of ceramic synthetic proppants. The material processing was performed through drying, milling, pressing, sintering and characterizing raw material. Several characterization techniques such as X-ray powder diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), high temperature dilatometry and compression strength test were performed after sintering to evaluate the technological potential of recycling these metallurgical and mineral rejects. Mechanical properties were improved after sample sintering. The results show that it is possible to manufacture ceramics of high strength and resistance to acidic/salt water environment as a result of processing minerals reject.

Unconventional shale gas reservoirs have driven the growth of the oil and gas market to a new reality: till 2035 a 26% increase in US fuel production is predicted. Thus, the hydraulic fracturing technique has been increasingly used as a resource for shale gas extraction and the consequent use of proppants. Several studies have now evaluated the use of nanostructures to produce special proppants, such as nanosensors, coatings, membranes and special fluids. This work presents the perspective of the market for oil, gas, shale, hydraulic fracturing and proppants in addition to a current development of proppants. Proppants were characterized through API RP 19C, DTA and DRX analysis. The morphology of carbon nanostructures (carbon nanotubes, carbon black and few layers’ graphite from reduced graphene oxide synthesis) produced and introduced on AM (alkali-activated metakaolin) matrix composites were evaluated using scanning transmission electron microscopy (STEM).

pela amizade, orientação, apoio, confiança, comprometimento, ensinamentos e pela oportunidade de realizar este trabalho.Aos Professores(as) Drª. Carina Ulsen, Dr. Douglas Gouvêa, Dr. Marcelo Breda Mourão e Dr. Eduardo Sansone pela amizade, atenção, ajuda e pelas discussões e explicações em momentos de dúvidas. À Drª. Gisele A. Labat e ao M.Sc. César Y. Narita, por toda ajuda e amizade ao longo do trabalho, por todos os dias de trabalho em conjunto e incansável ajuda com os procedimentos laboratoriais e revisões.Ao Eng. Andrey Rocha Scheidt por toda atenção, suporte e ajuda com os procedimentos laboratoriais mecânicos e de produção, principalmente pela amizade.

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.