Wolverine Pipeline Company operates several product pipeline systems in Michigan, USA. Being able to efficiently schedule a line, import data, work with injections and analyze results become more important as the lines become more complex. There are many tools available to schedule crude and product pipelines. These tools range from manual processes, such as drafted railroad charts, through configurable standard software packages to highly customized solutions. The tools needed by a pipeline scheduler depend on the scheduling scenario and the pipeline network. For example, scheduling a point to point line can often be accomplished using an Excel spreadsheet. However, as soon as the complexity increases by, for example, the addition of a mid-line destination, the simple Excel spreadsheet soon becomes impractical, and programmed logic needs to be included to manage the line. Soon the scheduler is relying on a programmer to maintain the once simple system. Increasing complexity of scheduling scenario and pipeline network can lead to alternative solutions. These include iterative steady states, transient simulation models or specialized flow rate estimation schemes which can handle logical rate changes as well as product and possibly pump sequencing. The injection of Drag Reducing Agents (DRA) to improve schedules and increase line capacity further complicates scheduling. The focus of this paper is to compare and contrast, under different scenarios, a spreadsheet, a transient simulator and a scheduling package, for the accuracy of results, ease of use, speed and performance. An overview of the different methodologies is provided.
The Wolverine Pipeline Systems consist of four pipeline systems comprising of over 1000 miles of various size pipe ranging from six inches to eighteen inches in diameter. There are twelve pumping stations with thirty four units varying from 400 to 3000 horsepower. These pump stations deliver various high-quality products to several customers at twenty-nine delivery terminals covering three states. The largest and most complex of the four systems is the Mainline System. This system consists of ten pipeline segments that come together at a manifold station called Kennedy Avenue. Kennedy Avenue is the origin of the three outgoing segments and the termination point of the seven incoming segments. Because of the relationship of all of these segments of pipe around Kennedy Avenue it is scheduled as one system with the outgoing segments originating at Kennedy Avenue and the incoming (or feeder segments) are then scheduled backwards so that product arrives at Kennedy Avenue in time to meet the schedules of the outgoing segments.
This segment consists of 49.5 miles of 18" diameter pipe, originating at Joliet pump and meter station and terminating at the Kennedy Avenue pump and meter station. This system operates as a closed system, in that no deliveries are made into or out of the system between the origin and destination points. Product enters the system from the refinery and leaves the system by taking one (or more) of three routes through Kennedy Avenue station.