Development and Validation of an Integrated Microbial Wax Mitigation Model for Waxy Crude Oil

Abstract

Wax deposition represents a critical flow assurance challenge in the production and transportation of waxy crude oils, frequently resulting in diminished production efficiency, increased operational expenditures, and potential pipeline occlusion. While various mathematical models have been established to predict wax deposition, conventional frameworks predominantly focus on thermophysical properties and often overlook the impact of microbial biodegradation on wax-forming hydrocarbons. This study developed and validated an Integrated Microbial Wax Mitigation Model (IMWMM), which synthesizes crude oil physicochemical properties, hydrocarbon composition, and microbial biodegradation kinetics into a unified predictive framework to evaluate wax deposition tendencies following microbial intervention. Waxy crude oil samples were subjected to treatment with Pseudomonas aeruginosa, Bacillus subtilis, and a microbial consortium. Experimental analyses were conducted to determine density, viscosity, molecular weight, and hydrocarbon composition, while Wax Appearance Time (WAT) served as the response parameter to quantify the retardation of wax crystallization. A Wax Deposition Index (WDI) was formulated by integrating density, viscosity, molecular weight, and hydrocarbon fractions. The microbial contribution was incorporated via first-order biodegradation kinetics, and the model was calibrated using an average microbial mitigation coefficient of 0.231 mL⁻¹ derived from experimental WAT data. Microbial treatment facilitated reductions in viscosity, density, molecular weight, and heavy hydrocarbon fractions compared to untreated crude oil, thereby lowering the wax deposition indices. The developed IMWMM effectively predicted wax deposition tendencies with a Mean Absolute Percentage Error (MAPE) of 3.87% and an overall predictive accuracy of 96.13%. The findings demonstrate that integrating microbial biodegradation kinetics with conventional wax deposition parameters significantly enhances the prediction of microbial wax mitigation performance. The proposed IMWMM offers a robust engineering tool for evaluating biological wax control strategies, optimizing microbial dosage, and supporting sustainable flow assurance management in waxy crude oil pipeline systems.