Assess the possibility of wax deposition from oil-in-water dispersion

Abstract

Paraffin deposition in subsea pipelines posses severe challenge in the transportation of crude oil. In field operations, water commonly co-exists with oil further complicating the wax deposition characteristics. Several oil / water two-phase flow patterns can occur depending on the operating flow rates of oil and water. Among the possible two-phase flow patterns, the paraffin deposition from oil-in water dispersed flow is not well understood. This study investigates the possibility of wax deposition from oil-in-water dispersed flow as well as the effect of operating conditions on the deposit thickness. A model oil-in-water emulsion was prepared and its stability characterized. Paraffin deposition experiments performed with model emulsions using a cold finger apparatus. The oil content of the emulsion was varied from 5 vol% to 50 vol%. The bulk fluid temperature was set at 45 °C. Deposit formed on a clean cold finger surface tends to slough off while deposit can continue to grow on a n-C28 surface. It was observed that the deposit grows rapidly and reaches plateau thickness. Sloughing off deposit was also observed over the course of deposit growth, leading to large uncertainties in the recorded deposit weight. Deposit wax content was also characterized