Changes to producing life

Chapter 5: Cessation

Most fields remain on stream for considerably longer than originally planned, and fields and infrastructure capacity must be utilised efficiently. The median extension to producing life beyond the period anticipated in the plan for development and operation (PDO) for all fields on stream is nine years, with an average of almost 12.

A number of factors can contribute to extend producing life for a field:

• producing the resources takes longer than expected
• changes to the resource base
• measures for improving recovery
• Tie-in oil and gas from other Fields.

When the licensees submit a PDO for a field, they also estimate how long it is likely to stay on stream. However, the cessation date can be brought forward or pushed back as assumptions change over a field’s producing life. Some shut down earlier than planned, primarily because production has failed to develop as well as expected.

The average producing life for fields now shut down was just over two years longer than expected when the PDO was submitted.

Mapping and exploring for resources is a matter of urgency in the vicinity of infrastructure set to shut down in the near future. It may be possible to utilise these facilities for phasing-in new discoveries in the area, and thereby contribute to increased value creation.

Most discoveries are developed with subsea installations tied back to existing infrastructure. This reduces overall development costs in an area and makes a number of small discoveries commercial. In addition, it may improve recovery from the host Field.

Extended producing life

A decommissioning plan for the Varg field was government processed in 2001. The plan was then to cease production in the summer of 2002, but measures adopted on the field allowed it to remain on stream. A new decommissioning plan was submitted to the government in 2015. Varg went off stream in June 2016, and the production ship has left the field. Wells are currently being plugged, and the disposal process is due to be completed in late 2021.

Extended producing life

A decommissioning plan for the Varg field was government processed in 2001. The plan was then to cease production in the summer of 2002, but measures adopted on the field allowed it to remain on stream. A new decommissioning plan was submitted to the government in 2015. Varg went off stream in June 2016, and the production ship has left the field. Wells are currently being plugged, and the disposal process is due to be completed in late 2021.