Preparation of hydrophobic and high‐strengthpolymer microspheres based on constructing a “Functionalmonomer‐St‐DVB” copolymer structure:Ultra‐low‐densityproppants

Abstract

Ultra‐low‐density proppants are of great significant in slick water fracturing system, but the polymer composite microspheres can hardly promise the quality of oil and gas due to their poor hydrophobicity. To address the issue, we prepared several types of modified styrene‐divinyl benzene copolymer microspheres (MSDBs) with long‐term durable hydrophobicity and high strength, including O‐MSDBs (hydrophobic MSDBs), LO‐MSDBs (long‐time hydrophobic MSDBs), and CO‐MSDBs (coated O‐MSDBs) on the basis of a molecular structure of “KH570‐styrene (St)‐divinyl benzene (DVB)” copolymer. In this article, the design concept and the structure of MSDBs was clarified, and performances of MSDBs are systematically discussed and compared with commercially available hydrophobic microspheres. The O‐MSDBs, a kind of nanoparticle patterned St‐DVB copolymer microspheres, were prepared by a one‐step suspension polymerization undergoing a sol–gel process, showing strong hydrophobicity with a water contact angle up to 140.7°, but short durability in strong hydrochloric acid or hydrofluoric acid; On the contrary, LO‐MSDBs perform better in the stability and durability of hydrophobicity with a slightly lower water contact angle about 135.9°. The LO‐MSDBs were designed by coating functionalized St‐DVB copolymer microspheres with fluororesin. Similarly, CO‐MSDBs from fluororesin‐coated O‐MSDBs were designed. As expected, CO‐MSDBs have a stronger hydrophobicity (139.0°) than LO‐MSDBs and longer durability than O‐MSDBs. Moreover, the MSDBs exhibit better properties than the commercially available hydrophobic polymer and ceramic microspheres.

Carbon dots enhanced ultra‐low‐density fluorescence proppants with both high‐compressive strength and anti‐deformation ability

“…Compared with the blank-SDBs, both CDs-SDBs and MG-SDBs show the same polymer crosslinking framework. All of them show the same structure as polystyrene as reflected by their broad diffraction peak at about 18.8 in XRD patterns (Figure 4A) 22 and aromatic carbon skeleton as reflected by their stretching adsorption peaks in IR spectra (Figure 4B). In detail, the peaks at 1452, 1493, and 1602 cm À1 belong to the benzene ring vibrations (ν C C ) of poly (St-DVB), the peaks at 698 and 756 cm À1 belong to flexural vibrations (δ C H ) of benzene ring, the peak at 2924 cm À1 is attributed to vibrations of saturated C H groups, and that at 3024 cm À1 is assigned to ν C H of a benzene ring, the peak at 1630 cm À1 corresponds to stretching vibration of C C bond in residual double bonds from DVB.…”

“…Composite microspheres were synthesized through a suspension polymerization process. 22 Briefly, 10.0 g styrene, 2.0 g divinylbenzene, 0.2 g benzoyl peroxide and 0.1 g CDs or MG were mixed uniformly under mechanical stirring at room temperature to prepare an oil phase. The 1.0 g polyvinyl alcohol and 0.05 g methyl cellulose were dissolved in 100 ml deionized water to prepare an aqueous phase.…”

Constructing low-cost and high-strength ultra-low-density proppants based on the modification of activated carbon framework with in situ hydrolyzed silane

“…Finally, their mass loss and compressive strength were recorded aer the abrasion experiment. 19 2.3.3 Acid resistance. The mass loss of the ACs, PF-ACs, KH-ACs and KP-ACs microspheres was recorded aer treating with the mixed acid solution according to the Chinese Petroleum and Gas Industrial Standard (SY/T5108-2014).…”