Hydrophobic modified polymer based silica nanocomposite for improving shale stability in water-based drilling fluids

In this paper, a novel hydrophobic modified polymer based silica nanocomposite (NFC) was successfully prepared by emulsion polymerization and it was characterized by FTIR, PSD, TEM and TGA analysis. The results indicated that NFC possessed uni-modal distribution from 38 nm to 164 nm with the D50 value of about 72 nm and had good thermal stability. A variety of methods including the contact angle measurement, pressure transmission test, hot-rolling cuttings dispersion test and compatible test were adopted to evaluate the comprehensive effect of NFC on shale stability. And the shale cores before and after interacting with NFC were also characterized by scanning electron microscope (SEM) analysis. The experimental investigations revealed that NFC could effectively retard the pore pressure transmission and internally bridge and seal the pore-throats of shale. And it also exhibited preferable shale inhibition performance compared with KCl and JHC at the same concentration. After adsorption, the shale surface was more hydrophobic, which was more advantageous to shale stability. Furthermore, the compatibility test results confirmed that NFC had no negative effect on rheological performance and possessed a positive influence on filtration control performance of water-based drilling fluids.