ABSTRACT

The Dispatching Computer Operations system (DISCO) is a package of simulation tools developed for the Gas Dispatching Department of El Paso Natural Gas Company. Though originally conceived as a means of monitoring Compressor Station operations, the value of the System as an aid in training Gas Dispatchers became immediately apparent. DISCO is an Inter active Graphics System consisting of a series of Input and Display Screens and Menus providing the user with the means of easily selecting a Compressor Station, running a simulated operation; then viewing the results of the operation at the station as well as the effect on the pipeline segments downstream from the station.

INTRODUCTION

The El Paso Natural Gas Pipeline Network encompasses a large geographical region stretching from off-shore platforms in the Gulf of Mexico to the California border. With gathering facilities included. approximately 21,000 miles of pipeline are used to transport gas from the Permian, San Juan and Anadarko basins to customers in Texas, New Mexico, Arizona and California. The Mainline Gas Transmission system was designed to run at maximum efficiency when fully loaded. In recent years, a number of factors have negatively impacted gas sales and as a result the main lines have been operated at a less than fully loaded condition. All indications point to continued below-capacity operations for the foreseeable future. Additionally, large swings in sales at the California border have placed a severe strain on the operational flexibility of the overall system. Working within this scenario and with increased emphasis on reducing operating costs, we have a Dispatching Department undergoing a dramatic decrease in the experience index of Senior Mainline Dispatchers, from 17 years down to 7 years, due to both job abolishment and retirements. To replace the years of judgement, knowledge and experience being lost, it was obvious that certain types of tools were needed: Diagnostic, Analytic, and Informational Tools that could easily be picked up and implemented by the current dispatching staff in their day-to-day decision making tasks required for the efficient operation of the transmission system. From within the Engineering Department, the Systems Engineering Group responded to this need with a proposal to provide an interactive compressor station simulation model for simple throughput calculations. Subsequent to the proposal being accepted and during the development process, the simple model grew. As obvious extentions to the information being generated became apparent, they were added (i.e., pipeline flow simulation, pipeline data base lookup capabilities, etc.) until the current state of the System was reached. As it stands now, DISCO is seen primarily as a training tool; a means of familiarizing the inexperienced Dispatcher with the way Compressor Stations and Gas Pipelines operate and respond to different sets of pressure, temperature and flow conditions. Additionally though, it also allows the older, more experienced personnel to run both individual and/or series of Station and Pipeline simulations providing answers to realistic what-if types of questions and helping them to anticipate and react to operating situations more rapidly and effectively.

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