Clay-water interaction inhibition using amine and glycol-based deep eutectic solvents for efficient drilling of shale formations

Abstract

Water-based muds (WBMs) are preferred over oil-based muds owing to their lower cost and environmentally friendly nature. However, shale instability arising from clay-water interaction is a challenging concern. The current work explores the potential of deep eutectic solvents (DESs) as shale stabilizers for WBMs. Four amine and glycol-based DESs with different chemical composition were synthesized in the laboratory. The rheological and filtration properties of WBMs showed that DES-A, which is composed of tetrabutyl ammonium bromide and diethanol amine, and DES-B, which is composed of tetrabutyl ammonium bromide and diethylene glycol, with less sterically hindered cationic functionality improved the mud functionality. Shale inhibition performance of DESs was collected from capillary suction timer, linear swell meter and shale disintegration tests. These tests revealed that DES-A and DES-B are highly efficient and outperform the conventional shale inhibitor KCl and the commercially available ionic liquid 1-butyl-3-methylimidazolium chloride (BMIM[Cl]). Shale swelling in presence of 0.2 w/v% DES-A and DES-B decreased by ~54.6% and ~70.9%, respectively. Moreover, shale recovery improved by ~17.2% and ~18.2% and capillary suction time decreased by 45% and 48% in presence of 0.5 w/v% of DES-A and DES-B, respectively. The quaternary ammonium functionality helped in shale stabilization which was further improved due to the presence of –OH group in the hydrogen bond donor in DESs. Quick cost analysis showed the feasibility of industry scale application of DES-A and DES-B as shale inhibitors into WBMs.