Wax Deposition of Waxy Live Crudes Under Turbulent Flow Conditions

Abstract

Abstract Laboratory test methods have been developed to measure wax deposition of waxy live crudes under turbulent flow conditions. This high pressure wax deposition turbulent flow loop is rated up to 1500 psia and from 32 to 240 °F. The apparatus has been used to study impact of flow regimes, oil composition, water, and paraffin inhibitors. Under turbulent flow conditions the pseudoplastic non-Newtonian behavior of a cold waxy crude significantly affects wax deposition rate. Wax deposition from a waxy crude can be reduced significantly under turbulent flow conditions. The flow turbulence depresses the temperature at which maximum wax deposition rate occurs. The sloughing effect generated under turbulent flow conditions has significant impact on wax deposition rate and can not be neglected in wax deposition modeling. Oil composition is a factor affecting wax deposition. Usually, wax deposition rate decreases with increasing oil bubble point pressure under turbulent flow conditions. The wax hardness and carbon number of the wax deposited on the pipe wall increase with retention time. The high pressure wax deposition turbulent loop has been used to evaluate wax inhibitors, and study optimum flow conditions and oil compositions to prevent wax problems for designing subseapipelines in the North Sea. The results are critical for potential cost savings derived from optimum design for waxy crude transport conditions.