Studies of wax deposition in the Trans Alaska pipeline

The crude oil being pumped into the Trans Alaska pipeline experiences considerable cooling during its 800-mile (1,287 km) journey from Prudhoe Bay to Valdez. The conditions during the initial flow period were favorable especially for the deposition of the waxy constituents of the crude on the pipeline wall. As time passed and the crude oil flow rate increased, segments of the pipeline warmed up to temperatures greater than that at which wax deposition occurs. This study investigated mechanisms of wax deposition and determined the expected nature and thickness of deposits in the pipeline as a function of time and distance. Results indicate that deposition during start-up is a consequence of 3 separate mechanisms which transport both dissolved and precipitated waxy residue laterally. 31 references.