This paper describes the gas compression facilities on Ekofisk Area platforms in the North Sea. It discusses the operator?s experience with several compressors, the problems encountered and the solutions to correct them.
It also describes the improvements that are being made to reduce unscheduled maintenance and improve the reliability of the equipment.
Phillips Petroleum Company Norway (PPCON) has developed and operates seven oil and gas fields in the Norwegian Sector of the North Sea. This operation consists of 25 platforms, with export thru a gas pipeline to Germany and an oil pipeline to England. Oil and gas are partly processed on the outlying platforms, and then transported via subsea pipelines and/or bridges to the Ekofisk Center. This is shown in figure 1.
PPCON has an important role in the transportation of gas from Norwegian fields. The transportation system is used to deliver gas from Elcofisk Area fields and other fields in the Norwegian Sector.
Compressors have a critical role in this operation. They are used in the transportation of gas from the outlying platforms to the center and from the center to Germany. They compress gas and vapor, which has been collected from various parts of the process, before it enters the final stages of processing. Gas above sales quantities is compressed and reinjected into the reservoir.
Operation and maintenance problems developed on some of these compressors after they were installed. These problems had to be solved to operate satisfactory and to keep the maintenance to a reasonable level.
Standby compressor capacity was installed on all critical functions. Increased gas production and gas transport for other fields will require that all installed compressors operate simultaneously in certain functions. Increased reliability and reduced unscheduled maintenance are required to avoid costly installation of additional machines.
Some "key" compressors at Ekofisk Center are discussed below.
The process is the separation of oil and gas. The liquid goes to England and the gas is processed and piped to Germany.
At Ekofisk Center the oil and gas are routed to different separators depending on the pressure. The separators and the pressures at which they operate are:
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A simplified diagram of this process is shown in figure 2.
Machines recompressing the different gas streams are the Flash Gas Compressors, Booster Compressors, and the Pipeline Compressors.
