Abstract

The main objective of a pipeline operating company is to continuously find ways of improving profitability while maintaining adequate grid pressure to ensure security of supply. In addition, today's deregulated markets and the public's concern over the environment are increasing the focus on the operational and maintenance activities in order to gain competitive advantages. However, the complexity of pipelines / networks and associated process equipment makes this challenge potentially overwhelming unless decomposed into smaller issues. It has been long recognized that optimized control and management is the way forward. But even with the advent of powerful microprocessors which have permitted extensive plant automation and computer based monitoring, few companies have yet to fully utilize these technologies to close the gap between latent and possible business performance. Whilst dedicated tools are necessary modularize the problems and produce specific solutions, the unification of this diversity is also essential. This is the only way to take a balanced view of business needs, process performance and asset capabilities. It will facilitate better decision making towards true long-term value maximization.

Introduction

Gas Companies are normally responsible for;

  • gathering gas from producers,

  • transmission of natural gas,

  • distribution of natural gas to end-users,

  • construction, operation and maintenance of pipeline network and all associated assets. Figure.1 shows the economic theory of profit maximization concludes that the optimum supply rate (Qoptimum) is at the point where marginal revenue (MR) equals marginal cost (MC). However for Gas Companies the minimum supply rate is often fixed by contracts with customers. They must satisfy demand and ensure security of supply. So Gas Companies must seek to influence the marginal revenue curve and the marginal cost curve in such a manner that they meet at the contractual supply rate (Qcontract). Since no Gas Company has infinite resources at its disposal to try to perfect each area activity, priorities will have to be determined such that the future marginal cost and marginal revenue curves will tend to meet at the nominal contractual supply rate. Once they are decided, projects can be initiated to realize the benefits. Typically, they concentrate on;

  • ensuring security of supply (i.e. satisfying minimum pressure requirements to all customers),

  • reducing operating costs (i.e. fuel consumption),

  • reducing environmental impact (i.e. NOX, CO, CO2 emissions),

  • reducing maintenance costs (i.e. extending overhaul intervals). Some advanced tools are required to meet these objectives:

  • process data historian,

  • performance, emissions and life usage monitoring systems,

  • equipment health management system,

  • demand forecaster,

  • optimizer incorporating first principles models and multivariable predictive control.

Demand Forecasting

Pipeline operators require tools that can accurately forecast consumption for a given time window, so that they can determine which configuration of machinery and associated set points are necessary to meet the demand at the lowest operational cost. Thus, uncertainty and the need for line packing can be minimized. An advanced forecasting tool is required to predict consumption of gas at each off-take. Modeling the consumption patterns at each off-take should allow this.

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