Study on aging mechanism of ceramic proppant soaked in formation water

The quality of ceramic proppant directly affects the recovery efficiency of unconventional gas reservoirs. Two types of proppant were isothermally soaked in formation water and the proppant soaked for different time was characterized by XRF, XPS, XRD, SEM, EDS, TEM and FT-IR. The characterization results show that H+, Cl−, CO32− and HCO3− ions in the formation water can migrate to the proppant surface by diffusion and chemically react with the proppant components. The acidic environment of formation water can make alumina of the proppant change into Al3+ ions, and then react with the CO32− or HCO3− ions of formation water to generate Al(OH)3, precipitating in the formation water. Silica of the proppant can react with the Cl− ions of formation water to form SiCl4, which meets water to produce silica gel on the surface of proppant. Therefore, these reactions will undoubtedly destroy the dense structure of proppant and reduce its conductivity and crushing resistance. This study provides some theoretical direction for preventing the aging of proppant.