A Multifunctional Coated Proppant: A Review of Over 30 Field Trials in Low Permeability Formations

Abstract This paper presents a tailored coated proppant that provides improved solutions for various hydraulic fracturing challenges. The coating aims to enhance proppant transport with slickwater fluids while improving the hydrocarbon mobility into the proppant pack and reducing respirable crystalline silica during the operations. The paper discusses results from over 30 field trials in multiple low permeability formations. The novel multifaceted coating was designed to modify the wettability of proppants’ surfaces to increase the surface's affinity for gases and reduce the generation of respirable airborne particles. By adding small volumes of gases into the proppant-laden slurry, gas bubbles get attached to the surface of the proppant leading to significant reduction in its apparent specific gravity. In order to prove the operational and economic advantages of the multifunctional proppant, a series of novel laboratory experiments were conducted under various operational conditions, followed by numerous field trials in several low permeability formations. The laboratory tests showed that the coated proppant can stay suspended in the presence of gases for extended period of time. The laboratory evaluation involved testing under pressures and temperatures up to 12,500 psi and 400°F with different fluid systems made from both fresh and high-salinity waters. Oil mobility tests showed that the oil flow rate was increased by 74% compared to uncoated sand. Several multistage fracturing treatments executed with significantly higher proppant concentrations up to 6.1 lbs/gal in typical slickwater treatments when used with 1.5 – 10 % foam quality. Onsite measurements have proven that the coating reduced the generation of respirable airborne particles down to 10 – 30 μg/m3 throughout the proppant lifecycle. Data obtained from numerous field trials showed that the novel proppant technology resulted in improved well productivity, increased oil cuts and reduced water production.