A Double Action P-D (Polymer-Deep Eutectic Solvent) Based Shale Inhibitor in Drilling Mud

Abstract

Shale stabilization is very significant during drilling to avoid wellbore stability issues. Water based drilling fluid results into shale swelling on contact with shale formation. Different additives are added in the drilling mud which inhibits the shale swelling by stabilizing the charge on the clay surface. Various polymers and different Deep Eutectic Solvents (DES) have been proven to be successful shale inhibitors, but their performance can be further improved by using a combination of polymer and DES. This research features a double action P-D (Polymer – Deep Eutectic Solvent|) inhibitor formulated by the combination of Potassium Carbonate based DES and modified oxazoline based polymer and compares its inhibition performance with KCl (Potassium Chloride). Linear Swell meter has been used after compressing the Na-Bt (Sodium bentonite) wafers at 1600 psia and swelling results have been analysed after 24 hours. Moreover, surface tension, d-spacing, and Zeta potential of inhibitors-based samples have been measured to justify and understand the swelling results. The results showed P-D inhibitor showed the best inhibition of 76% with maximum decline of 36% and 73% in Surface tension and Zeta Potential respectively. The double action of P-D inhibitor is associated with its capability to form hydrogen bond and exhibit Vander wall forces with the clay surface altogether.