Ultra-Stable Silica Nanoparticles as Nano-Plugging Additive for Shale Exploitation in Harsh Environments
1
School of Science, Xihua University, Jinzhou Road, Chengdu 610039, Sichuan, China
2
State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 8 Xindu Avenue, Chengdu 610500, Sichuan, China
3
College of Chemistry and Chemical Engineering, Southwest Petroleum University, 8 Xindu Avenue, Chengdu 610500, Sichuan, China
4
Chengdu Graphene Application Institute of Industrial Technology, Leshan Road, Chengdu 610500, Sichuan, China
*
Authors to whom correspondence should be addressed.
Nanomaterials 2019, 9(12), 1683; https://doi.org/10.3390/nano9121683
Received: 6 November 2019 / Revised: 20 November 2019 / Accepted: 21 November 2019 / Published: 25 November 2019
Owing to the harsh downhole environments, poor dispersion of silica at high salinity and high temperature can severely restrict its application as the nano-plugging agent in shale gas exploitation. The objective of this study is to improve salt tolerance and thermal stability of silica. Herein, silica was successfully functionalized with an anionic polymer (p SPMA) by SI-ATRP (surface-initiated atom transfer radical polymerization), named SiO2-g-SPMA. The grafted pSPMA brushes on silica provided sufficient electrostatic repulsion and steric repulsion for stabilizing silica in a harsh environment. The modified silica (SiO2-g-SPMA) had excellent colloidal stability at salinities up to 5.43 M NaCl (saturated brine) and standard API brine (8 wt% NaCl + 2 wt% CaCl2) for 30 days at room temperature. Simultaneously, the SiO2-g-SPMA was stable at 170 °C for 24 h as well as stable in weakly alkali environment. Furthermore, the plugging performance of SiO2-g-SPMA in water-based drilling fluids for low permeate reservoir reached to 78.25% when adding a small amount of 0.5 wt% SiO2-g-SPMA, which effectively hindered the water invasion into formation and protected the reservoir.
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Keywords:
silica; SI-ATRP; anionic polymers; brine stability; nano-plugging additive
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MDPI and ACS Style
Ma, L.; Luo, P.; He, Y.; Zhang, L.; Fan, Y.; Jiang, Z. Ultra-Stable Silica Nanoparticles as Nano-Plugging Additive for Shale Exploitation in Harsh Environments. Nanomaterials 2019, 9, 1683.
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