Fabrication and mechanism of microspheres with tunable and control-released hydrophobicity: Ultra-low-density proppants

Abstract

Ultra-low-density proppants with tunable and control-released hydrophobicity can meet different requirements of different fracture environments, thus playing an important role in unconventional reservoir exploration. In this study, for the first time, we designed and synthesized proppants with a molecular structure of γ-methacryloxypropyltrimethoxysilane (KH570)-styrene (St)-divinyl benzene (DVB) (FR-SDB) through suspension polymerization. FR-SDB was examined by Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and X-ray diffraction to understand the mechanism of tunable and control-released hydrophobicity. The results revealed that the hydrophobicity is related to the hydration reaction of chemically bonded KH570 and the difference in the reaction activities under different aqueous environments at different temperatures. The wettability of FR-SDB was evaluated according to the static water contact angle (θw) on its surface. The contact angle θw on the surface of FR-SDB can be tailored from the initial angle of approximately 50° to 80°–125° in a wide time range of 10 min to 144 h. FR-SDB exhibited ultra-low apparent density of approximately 1.028 g/cm3, high compressive strength, and a crushing ratio of ∼ 1.81% at closure pressure of 69 MPa.