The Problem in Transportation of High Waxy Crude Oils Through Submarine Pipeines at JV Vietsovpetro Oil Fields, Offshore Vietnam

摘要

The transportation of crude oil of high wax contentrnin a submarine pipeline without thermal insulation canrncause serious problems. The heat loss due to the sharprntemperature gradient between the crude and thernenvironment results in the crystallization of wax in therncrude, with the subsequent deposition of the wax on thernwalls of the pipelines. This can result in (1) - reductionrnof the effective pipeline diameters, resulting in higherrnpressure drops; (2) – formation of gelled interlockingrnstructures of wax crystals in pipelines leading tornshutdowns. The safe and continuous operation of thernpipelines has been dependent on the improvement inrnthe flowability characteristics of the Vietsovpetro crudernoils. The use of pour point depressant chemicals canrndrastically reduce the potential risk for wax depositionrnand gelling. Study of the rheological properties of therncrude oil enables evaluation of different chemical typesrnnecessary for the treatment of the crude. The pressurerndrop required for starting to pump crude oil throughrnnewly constructed submarine pipelines or to restartrnflow after an emergency production shutdown has to berndetermined. Pipeline models used to predict restartrnpressures and flow characteristics have played a veryrnimportant role in the technological concept and designrnof the Vietsovpetro fields.