A Comparative Study on the Implementation of Scheduling Applications on Petroleum Product Pipelines

The scheduling goal of any pipeline company is to fulfil the terminal nominations. This objective is constrained with minimum batch size (for interface minimization), optimal flow rates (for power optimization) and avoidance of operational constraints (i.e., overflow or dry outs of tank pools) during schedule generation by the planners. A plan thus created is reconciled daily to match the actual operations. Typically, most pipeline scheduling and daily reconciliation is performed in legacy applications e.g., spreadsheets. However, as a company’s pipeline infrastructure grows and operations become more complex with time, pipeline planners consider using standard products or tailor-made applications for fulfilling their scheduling needs. Enhanced user experience, automation of recurring tasks, minimization of manual intervention in scheduling and better audit trial are the primary reasons for choosing standard industry applications over legacy applications by a pipeline company. In general, pipeline scheduling considers the tank stocks and their service (product type and in or out), initial pipeline fill and daily upliftment from tanks (sales) as the initial conditions for schedule generation. By means of cycle plan optimization, the scheduling system determines the number of cycles and product sequencing. Thereafter, a simulation identifies the operational constraint violations including tank overflows or dry outs as in daily operations. An expert scheduler will fix violations in a plan by partially shutting down a pipeline, rearranging/adjusting batch sizes. However, every pipeline planner may not have the skill level to manually adjust the plans and create a feasible schedule. Furthermore, a pipeline company may aim at standardizing scheduling operations and avoid room for individual planner interpretations by means of automation. Although automation of all possible planner actions in scheduling is not feasible, this paper highlights the challenges in automation besides recommending the degree of possible automation in scheduling. Various automation strategies adopted and their effectiveness in enhancing the scheduling operations of a pipeline are explained by means of a comparison across pipelines of varying complexities. (Ex: flow reversal in pipelines or data exchange between different pipeline networks whose scheduling requirements are interconnected). The paper highlights how a hybrid scheduling tool with built-in strategies together with manual intervention can help addressing pipeline scheduling requirements. The aim of this paper is to facilitate pipeline planners with a perspective of practices that can be automated and identity those that need modification for possible automation. Finally, the paper addresses the implementation methodology and the strategies adopted by the planners to generate schedules. The acceptance of these methodologies and the suggested improvements for the pipelines under consideration are also included as candidates in scheduling tools for further improvements.