ABSTRACT

A gas network optimization program (GassOpt) has been developed for transport analysis and planning purposes in order to calculate optimal routing of natural gas in pipeline networks. The simulation program is a steady state network solver based on linear programming and optimization engine. The program can optimize with respect to energy (i.e. minimize pipeline pressure) and it is possible to include quality restrictions as well. The optimization tool handles blending of different gas qualities from different producing fields, and includes other features such as compression and process units. The optimization tool is being used in connection with analyses of various transport conditions in the subsea gas transmission network system which transports sales gas from the Norwegian Continental Shelf (NCS) to the European and UK market. The gas transmission network is characterized by long distance/large diameter pipelines and various blending and routing possibilities, as well as some pressure restrictions. This paper gives a description of the network optimization tool GassOpt, the focus being on the various usage of the program. Typical transport scenarios from the dry gas network system at the NCS will be used to demonstrate the usage of Gassopt.

INTRODUCTION

New requirements from the Norwegian authorities' required new methods for better analysing consequences caused by large accidents (and low frequency) in the Norwegian Gas Transport Network. Since the infrastructure was growing fast and thereby increasing the complexity of calculating the consequences, the need for a specific software tool was obvious. A gas network optimization program (GassOpt) is a result of that development and has its main purpose to calculate optimal routing of natural gas in pipeline networks and thereby minimising the consequences for a given scenario. GassOpt is developed to find an optimal flow in a generic network, thereeby the program is not limited to the Norwegian Gas Network. The optimization tool is being used in connection with analyses of various transport conditions in the subsea gas transmission network system transporting sales gas from the Norwegian Continental Shelf to the continental European and UK market. GassOpt is being used both by the Operator and some of the Owners/Shippers of the dry gas transport system at the Norwegian Continental Shelf (NCS). Figure 1 shows an overview of the dry gas network at the NCS. The usage of the program includes:

  • Identify bottlenecks

  • Transportation planning

  • Infrastructure development (pipeline, process units etc)

  • Yearly field maintainance planning

  • Quality nomination process (GCV/WI)

  • Deliverability studies (analyze unexpected incidents leading to reduced capacity)

  • Blending studies

DESCRIPTION OF THE NETWORK OPTIMIZATION PROGRAM

The following sections give a brief description of the network optimization program GassOpt. A detailed description of the underlying theory and assumptions is published elsewhere [1]. Description of another network optimization program has been presented by van der Hoven [2] at PSIG conference in 2002.

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