The Effect of Tube Orientation and Pour Point Depressant on Paraffin Wax Deposition

Abstract

A flow loop was used to study wax deposition in the laboratory. Data are presented to demonstrate that the tube orientation and pour point depressants have significant effects on the paraffin wax deposition for oil from the Octh Louie, a Cretaceous formation in the Manderson Field, Wyoming. Changing the tube orientation from horizontal to vertical reduced the amount of wax deposited by 28% for a tube wall (Twall) temperature of 42°F. The circulating oil temperature (Tbulk) was held constant at 76 ± 3°F. The amount of wax deposited was found to be a linear function of the driving force (Tbulk – Twall) and the wax appearance temperature (WAT) was estimated by extrapolating this linear relationship to a point of zero wax deposition. The WAT thus obtained (94.5°F) varied considerably with the cloud point (62°F) obtained using the ASTM D2500 method. Change in viscosity with time has also been investigated. Addition of a specific pour point depressant (PPD) at a concentration of 5 mL/gallon reduced wax deposition by 52%; concentrations of 10 mL/gallon of oil reduced the wax by 61%. Changing the flow regime from laminar to turbulent also had a significant effect, reducing the wax deposition by up to 42%. Gas chromatography–mass spectrometry (GC-MS), gas chromatography–flame ionization detection (GC-FID) analyses and other relevant property data pertaining to the oil are also presented.