EXPERIMENTAL STUDY OF ENVIRONMENTAL-FRIENDLY MODIFIED CELLULOSE AS RHEOLOGY MODIFIER IN CLAY-FREE WATER-BASED DRILLING FLUIDS

摘要

This research demonstrates the effectiveness of environmental-friendly modified cellulose to replace synthetic polymer as the rheology modifier in enhancing the environmental-friendly performance of clay-free water-based drilling fluids. This paper first introduces the long-chain hydrophobic groups into hydroxyethyl cellulose (HEC) molecules to synthesize the hydrophobically modified hydroxyethyl cellulose (HMHEC). The evaluation results indicate that after the HMHEC concentration exceeds its critical associating concentration (CAC), HMHEC exhibits excellent viscosity, salt and shear resistance due to hydrophobic modification. Compared with the synthetic polymer PAM, HMHEC presents better environmental-friendly performance, with the EC50 value being 60000mg/L and the BOD5/COD& ratio being 18.21%. Furthermore, this paper performs rheological and filtration measurements to investigate the feasibility or compatibility of HMHEC as the rheology modifier for clay-free water-based drilling fluids. The results demonstrate that HMHEC has better rheological behavior, higher temperature stability and greater salt resistance than PAM and XC, and that it can be an environmental-friendly alternative to conventional rheology modifier in clay-free water-based drilling fluids.