الفهرس 
AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
Hydraulic fracturing process is applied for enhancing the production of petroleum fluids from oil and gas formations. This technique involves injecting a fluid at a pressure sufficiently high to break down the rock. Proppant slurries are pumped into the induced fracture to keep it open so that the petroleum production from the well can be significantly promoted. High strength proppants are always in demand for hydraulic fracturing techniques used in unconventional reservoirs for oil and gas extraction processes. To support this concept, relatively novel low-alumina content glass-ceramic proppants based on the system Fe2O3-TiO2-MgO-CaO-SiO2-Al2O3 have been prepared by using frit, kaolin and bentonite in a glaze formulation. By a deposition of glaze drops on porous ceramic tile, a green and semi-dry proppant beads were obtained. Different frit compositions of aluminum oxide replacing calcium oxide were used to obtain highly sintered proppants with a robust glassy matrix at 1100 ◦C in a fast firing cycle. Microstructures by scanning electron microscopy (SEM), and phase structures by X-ray diffraction (XRD) of samples were investigated.
The obtained results revealed the formation of two main phases; cristobalite and calcium aluminum silicate in addition to other two minor phases of mullite and Diopside ferrian in some samples. By evaluating the employed fabricated ceramic compositions as high conductivity with high strength proppants for hydraulic fracturing process it was found that, all samples exhibited competitive properties according to American Petroleum Institute standards (API RP 19C Standard) for proppants criteria. Crushing loss under 7,500 psi closure pressure was from 6.7 to 1.5%, the weight loss by acids attack was from 0.001 to 0.07%, sphericity and roundness were in the range of 0.9 in addition, the apparent and bulk densities were from 2.51 to 2.58 g/cm³ and from 1.46 to 1.50 g/cm³, respectively. It can be seen that the compressive strength or the crush loss in this type of proppants based on frit with these particular chemical compositions can be correlated and controlled by three important factors; First, is the alumina content or Al2O3/SiO2 ratio as in case of sample P3 in which it has the highest alumina wt.% (27.8%) and the highest Al2O3/SiO2 ratio (0.486). This resulted in the formation of mullite phase that enhance the mechanical strength over the other samples that have not this crystalline phase. The second significant factor is the calcium oxide content or particularly the CaO/SiO2 ratio in which the samples with higher ratio tend to have a relatively lower strength or higher crush loss compared to other samples with lower CaO ratio. This may be attributed to the relatively lower density of proppant samples that contain higher amount of CaO if it has a lower Alumina content as in samples P1 and P4. By comparing the frit-based proppant samples (P1-P5) with relatively low alumina content obtained in the current work with the other types of bauxite-based proppants that have alumina content exceeded 55 wt.% as reported in the published literature, the frit-based proppants have the feasibility for application in the hydraulic fracturing processes. It can obviously be found that these frit-based ceramic proppants possess an acceptable and competitive crushing resistance under 7,500 psi as strong as other bauxite-based ceramic proppants even in the samples that have not any detection for mullite or corundum phases as it was known in the structures of the traditional ceramic proppants. The third factor is related to the formation of many crystalline phases that formed inside this aluminosilicate system and acted as a supporting material within the glassy matrix, thereby provoking the reinforcement of the frit-based ceramic proppant and hence, they show high crushing resistance. Also, these phases provide a robust glass-ceramic construction particularly in the presence of a proper amount of iron oxide (ilmenite-sourced).