A new inhibitor of P(AM‐DMDAAC)/PVA intermacromolecular complex for shale in drilling fluids

ABSTRACT A new poly(acrylamide‐dimethyldiallyammonium chloride)/poly(vinyl alcohol) [P(AM‐DMDAAC)/PVA, ADVA] intermacromolecular complex inhibitor of shale‐hydrated swelling was studied for its ability to counter well instability. ADVA exhibited excellent inhibitory performance, and the probable inhibition mechanism was determined. The hydrophilic groups in ADVA adsorbed to montmorillonite (MMT) through hydrogen bonding and cation exchange, and the hydrophobic groups isolated water from MMT. ADVA adhered to the MMT and entered the interlayer instead of water due to the PVA structure. ADVA could also form a thin film and reduce the hydrophilic property of the shale core to prevent water from contacting the shale formation. With the structure of poly(acrylamide‐dimethyldiallyammonium chloride) (AD), the complex adsorbed and bridged MMT to reduce the filtration loss of the basic mud after hot‐rolling. This prevented contact of free water from drilling fluids with the shale formation during the drilling process. With these properties, ADVA demonstrated potential application as an inhibitor for use in drilling fluids. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45584.