Experimental Analysis of Paraffin Deposition in Slug Flow

Paraffin (wax) deposition poses a significant challenge in oil and gas production, particularly in ultradeepwater and harsh environments where temperatures drop below the wax appearance temperature (WAT). Over the years, extensive research has been conducted to understand the mechanisms behind wax deposition, predict its behavior, and develop prevention and remediation strategies to mitigate its impact and ensure safe and efficient production. However, although most studies focus on wax deposition in single-phase systems, real-world conditions are more complex. Multiphase flows involving oil, water, and gas introduce additional dynamics that can significantly influence wax deposition. This study investigates wax deposition in slug flow. Three different gas velocities were tested to examine their effect on deposition. As the gas velocity increased, a slight increase in wax deposition was observed due to an increase in heat transfer, leading to a greater radial temperature gradient and, consequently, more wax deposition (∼5 g increase). However, increasing gas velocity further led to higher shear stress, which resulted in a reduction in wax buildup through shear stripping (∼62 g decrease). Additionally, comparing wax deposition across different flow regimes, single-phase, stratified, and slug flows, reveals how flow patterns affect wax distribution along the pipe circumference. While the overall wax content is similar between single-phase and slug flow with the same actual liquid velocity, the localized wax content in slug shows a ∼20% increase from the overall value.