Surface-modified biopolymer as an environment-friendly shale inhibitor and swelling control agent

Abstract

The efficiency of the oil well drilling process primarily depends on the shale inhibition features of the water-based mud (WBM). The current study describes the effect of surface-modified biopolymer swelling control and rheological properties of clay. The cellulose is a biopolymer with a huge surface area, eminent toughness, a prominent number of functional groups, and relatively non-toxic nature. The surface structure of cellulose gives the freedom to functionalize the surface with specific functionalities. Styrene-modified cellulose (MC) is used for the first time as an environment-friendly swelling inhibitor. The inhibition profile of the WBM was assessed by applying the % dispersion recovery test, shale inhibition stability test, and linear swelling test. MC added water-based mud (MC-WBM) demonstrated the best performance in the dispersion recovery test and 77.8% of the shales were recovered as related to 70.2% from unmodified WBM, 73.6% commercial shale inhibitor-WBM, 46.5% KCl (aq), and 24.7% from water. The bentonite clay shows 31% swelling in MC, while 37%, 41.6%, 61%, and 87% in commercial shale inhibitor, unmodified mud, KCl, and water respectively during the linear swelling test. Whereas the rheological properties of the MC modified drilling mud remain almost the same. To confirm the adsorption of MC on the surface of the clay, various characterization techniques such as Fourier transforms infrared spectroscopy (FTIR) analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results disclosed that MC blocks the nanopores on the shale surface that causes a prominent decrease in the swelling of bentonite clay. The anticipated swelling inhibition mechanism of the MC demonstrates that the MC carries functional groups that can interrupt the hydrogen bonding between water molecules and clay surfaces. Consequently, the clay surface is being protected against water-reactive action.