Application Performance Evaluation of an Ionic-Liquid-Enhanced Composite Drag Reducer with Pour-Point-Depressing Functionality

To address the critical problems of wax crystallization and deposition, high viscosity and friction, and pipeline gelling risk during the pipeline transportation of high-wax crude oil, a PAO/IL/JN-3 ternary composite drag reducer was constructed via physical blending, using poly(α-olefin) (PAO) as the drag-reducing main agent, JN-3 as the pour point depressant component, and ionic liquid as the functional regulator, and its application performance was systematically evaluated. Proportion optimization showed that the optimal mass ratio of PAO to JN-3 was 1:2, IL-C14 provided the best enhancement, and the optimal mass fraction of IL was 30 wt%. Rheological tests showed that at a concentration of 40 mg/kg, the storage modulus G′ was approximately 82% lower and the loss modulus G″ was approximately 78% lower than those of the PAO-only system. Wax deposition evaluation showed that for the model oil containing 30 wt% paraffin, the reduction rate of the wax deposition amount reached 38% at 40 mg/kg. In the flow loop tests, a drag reduction rate of 50.5% was achieved at 40 mg/kg, and in the field pipeline test, the pressure drop decreased from 2.15 MPa to 1.15 MPa, corresponding to an average drag reduction rate of 46.5%. Overall, the ionic liquid reconciles the functional conflict between the drag-reducing and pour-point-depressing components, and the PAO/IL/JN-3 ternary composite drag reducer integrates drag reduction with pour-point-depressing functionality inferred from rheological, wax deposition, and crystal morphology evidence, providing a theoretical basis for the pipeline transportation of high-wax crude oil.