Synergistic Composite Additives for Rheological Optimization of High-paraffin Crude Oil

Abstract

This study investigates the rheological behavior and wax-deposition tendency of a model high-paraffin crude oil prepared by blending samples from the Palchig–Pilpilasi field. The oil is characterized by a density of 901.0 kg/m³, resin content of 4.3 wt%, asphaltenes of 0.18 wt%, and paraffins of 15.2 wt%, forming a stable paraffin–resin–asphaltene system suitable for laboratory evaluation.
The performance of individual depressor additives, Difron-3971 and HY-154, was first assessed and resulted in a moderate viscosity reduction of 15–25% at low temperatures while preserving non-Newtonian behavior. To enhance treatment efficiency, a composite formulation was developed and tested at a dosage of 600 g/t. Rheological measurements showed that the composite reduced the viscosity by 3.5–4.0 times and decreased the yield stress from 0.1625 Pa to 0.0325 Pa, indicating a pronounced weakening of the internal structure and a transition toward near-Newtonian flow.
Cold-finger experiments confirmed a strong suppression of wax deposition, with inhibition efficiency reaching approximately 95% at low temperatures. The results highlight the synergistic effect of the composite formulation and its potential as an effective flow-assurance solution for high-paraffin crude oils.