Transient Flow Assurance for Determination of Operational Control of Heavy Oil Pipelines

摘要

Most liquid pipelines design and operational control is based on steady state flow analysis. This neglects dynamic effects that occur as a result of occurrence of surges in a pipeline caused by rapid changes in pressure as a consequence of changes in the flow rate.A transient analysis of liquid pipelines on the other hand assures pipeline performance under all conditions (steady state and dynamic situations) including evaluating the following:• Impact from pump station start up, delivery restriction or shutdown (zero delivery)• Pump unit trip/failure• Rapid mainline valve closures including Slam shut of a non-return (check) valve• Effect of running the pipeline with minimum flow and maximum pump discharge pressure operating condition• Variation in demand including rapid reduction/curtailment of delivery volumes• Bubble collapse (the transition from slack-line to tight-line flow)• Unintentional changes in operational position of control valves• Fluid property delivery conditions• Liquid injection assessment• Surge protection including pressure relief/control system evaluation• Restart requirement to avoid slack-line conditions prevalent in hilly/mountainous parts right of way (ROW)Such a dynamic analysis would indicate whether liquid surges are of concern from design, as well as system operational conditions. It also would provide an evaluation of an automated control or potential automated strategies for overpressure protection.In this paper the dynamic analysis of liquid pipelines resulting in design and operational benefits will bedescribed. Finally their benefits in application to a heavy oil pipeline facilities "Keystone" will be highlighted.