In hydraulic fracturing treatments, proppant is used to keep the fracture open for hydrocarbon production. Sand is gaining popularity to be used as proppant. With vast sand resources available in Saudi Arabia, this study reports the qualification of Saudi Arabian sand for use in fracturing to stimulate the unconventional and tight gas formation.<br/>In the current study, as received 30/50 mesh sand was analyzed, tested and modified to meet the requirements for use in hydraulic fracturing applications. Raw sand has been characterized by (1) single grain crush test, (2) Krumbein chart and optical method for sphericity and roundness, (3) XRD for mineral composition, and (4) petrography for mineral content, microstructure, texture, and crystalline phases. Petrographic evaluation of sand has revealed a significant presence of high quality plutonic monocrystalline grains as well as polycrystalline and metamorphic grains with inner weak planes. Quartz content was found to be greater than 95 wt% with some impurities such as CuO and FeO. Microscopic analysis showed that sand has a mix of both spherical and angular grains with moderate to poorly sorting and roundness and sphericity greater than 0.6. This sand has a crush resistance stress of 5000 psi as measured by Proppant Crush Resistance Test (ISO 13503-2) and is suitable only for applications in shallow wells. For deeper wells with higher stresses, the sand needs to be strengthened to be efficiently used in hydraulic fracturing applications.<br/>Phenolic formaldehyde (novolac) resin systems with novel additives providing nano-reinforcement and altering the surface wettability have been used to coat the sand improving its crush resistance stress and chemical compatibility to meet the field requirements. Coated sand has been tested for loss on ignition (LOI), API proppant crush resistance test, API long-term proppant conductivity, and fracturing fluid compatibility test. The 30/50 mesh sand coated with the novel resin system has shown 78% less fines generated at 12,000 psi compared to the same uncoated sand. The long-term proppant pack conductivity measured on coated sand with nano-reinforcement and wettability-altering agent exhibited enhanced performance compared to control sand without reinforcement and wettability alteration. The performance of the coated sand was not compromised when exposed to fracturing fluid at elevated temperature making it a suitable candidate for field applications.

Nanocomposite coating of Saudi sand for fracturing applications

256th National Meeting (2018)

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