Experimental Investigation of Wax Deposition in Crude Oil Pipelines

Wax deposition is one of the most critical flow assurance challenges in the petroleum industry, leading to pipeline restrictions, pressure drops, and catastrophic production shutdowns. This study presents a comprehensive experimental investigation of wax deposition under dynamic conditions using a custom-engineered, high-pressure laboratory flow loop. The effects of wall shear stress (۱.۵ to ۷.۵ Pa), oil temperature (۳۵ to ۵۵ °C), radial temperature gradient (۵ to ۲۵ °C), and run time on the wax deposition rate and deposit composition (wax fraction) were systematically evaluated. Gas chromatography (GC-FID) analysis was utilized to characterize the carbon number distribution (C۱۵-C۵۰) of the recovered deposits. The experimental results reveal that wax deposition thickness increases asymptotically over time, reaching a thermal-diffusion equilibrium within ۲۰ to ۲۴ hours. Crucially, higher shear rates reduce the overall deposit thickness but increase the hardness (wax content) of the gel through a shear-induced aging mechanism that expels trapped liquid oil. A critical evaluation of existing molecular diffusion models indicates that while diffusion is the dominant driver of initial deposition, shear stripping must be integrated to prevent overestimation in long-term predictions. These findings provide critical empirical insights for optimizing thermodynamic models and mitigating wax issues in subsea transport lines

کلیدواژه ها:

Flow Assurance ، Wax Deposition ، Crude Oil Pipelines ، Cold Finger ، Flow Loop ، Shear Stripping ، Aging