Viscosity Reduction Mechanism of Wax Inhibitor on Waxy‐Contaminated Oil‐Based Drilling Fluids

ABSTRACT To address the detrimental low‐temperature viscosity increase and flow impairment in oil‐based drilling fluids caused by wax precipitation, this study designs and synthesizes a novel polymeric wax inhibitor featuring long alkyl chains and ester groups via two‐stage copolymerization. Comprehensive characterization by FT‐IR, 1 H NMR, GPC, and TGA confirms the molecular structure and thermal stability. Rheological measurements demonstrate that adding merely 2 wt% wax inhibitor suppresses viscosity escalation in both model waxy systems and wax‐intruded drilling fluids. Crucially, the wax inhibitor preserves emulsion stability with demulsification voltages exceeding 2048 V post‐wax intrusion. Mechanistic studies reveal molecular‐level disruption of wax crystallization: alkyl chains anchor into wax crystals through structural similarity, while polar ester groups interfere with ordered stacking. This is evidenced by XRD showing reduced interplanar spacing and attenuated diffraction peaks, DSC confirming depressed phase transition enthalpy with low‐temperature shoulder peaks, and SEM revealing collapsed non‐network morphologies. The molecularly engineered copolymer thus effectively mitigates flow assurance challenges in deepwater and cryogenic drilling operations.