Hydration induced morphological change on proppant surfaces employing a calcium-silicate cement system

- Proppant particles have been coated with Ca-Si oxides.
- Si reagents during the synthesis increase the particle size and the adherence of the coatings to the proppant.
- Hydration provides an in-situ increase in the angularity to immobilize the proppant.

Commercial aluminosilicate proppant particles have been coated with Ca-Si oxides, with the aim to provide an in-situ increase in the angularity (decrease in Krumbein roundness value) to facilitate their immobilization. Ca-Si oxide systems have been synthesized via sol-gel, cured, and sintered at 1200 °C using (a) CaCO3, (b) CaCO3 + orthosilicic acid (Si(OH)4, SA), and (c) CaCO3 + fused silica (SiO2, FS). When the proppant is cured in the presence of CaCO3 and silicic acid the coatings undergo a significant compositional change, while sintering results in the conversion of the cured samples to ceramic agglomerates with the desired “popcorn” shapes. The best results are obtained in the presence of Si reagents, and hydration of these sintered proppants allows for a distinct increase in the angularity, which is the desired transformation to allow the proppant to be locked-in-place once located in the reservoir. The samples have been characterized at each stages of preparation by scanning electron microscopy (SEM) with associated energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and infrared (IR) spectroscopy.

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