Premier files plans to decommission North Sea pipelines

UK oil and gas company Premier Oil has filed its draft decommissioning programs for the Hunter & Rita subsea pipelines to the UK authorities.

Hunter & Rita field layout; Source: Premier Oil
Hunter & Rita field layout - Premier Oil
Hunter & Rita field layout; Source: Premier Oil

The document contains four decommissioning programmes for the Hunter and Rita fields’ subsea pipelines and installations.

The Hunter field is located in the Southern North Sea (SNS), in UKCS block 44/23a, approximately 170 km northeast of the Lincolnshire coast of the United Kingdom.

The field was discovered in 1992 by an exploration well 44/23a-10, and developed with a single well in 2005. The first gas production started in January 2006.

The gas field comprises a single subsea well, tied back to the Murdock K field via an 8 km 8” diameter carbon steel gas pipeline.

The Rita field is also located in the SNS, in UKCS blocks 44/21b and 44/21c, approximately 150 km north-east of the Lincolnshire coast.

It was discovered in 1996 by an exploration well 44/22c-9, and developed in 2008 with a single dual-lateral well, with first-gas in March 2009.

Rita is tied back to the Hunter gas field via a 14 km 8” diameter gas pipeline.

Hunter & Rita field location - Premier Oil
Hunter & Rita field location; Source: Premier Oil

Premier: Plans for Rita & Hunter

In September 2016, the Hunter field owners received a notice of termination for the Transportation & Processing Agreement (TPA) that governs the provision of processing services provided to the field by TGT.

As a consequence of the cessation of operations at the terminal, the CMS owners and the CMSIII owners were no longer in a position to offer transportation services, and notices of termination for the remaining CMSIII/CMS export pipeline system were received in October 2016, with an effective date of the 1 October 2018.

Premier Oil explained that, as the Hunter field is cash flow negative, an assessment to replumb the field to alternative gas export infrastructure has not been undertaken, where the capital expenditure required would be far in excess of the remaining reserves, and therefore, production revenue.

The cessation of operations at TGT and subsequently the CMS offshore facilities, the CMIII fields and the Hunter field, from October 2018, would also reduce the benefit to be gained from cost reduction initiatives, production optimisation solutions and enhanced recovery methods designed to extend the Rita field’s life.

Hence, the licensees submitted to the Oil & Gas Authority (OGA) for consideration a Cessation of Production (CoP) document.

Cessation of Production from both Hunter and Rita fields was approved on 21st January 2019.

Under the decommissioning programs, subsea installations will be returned to shore for recycling or appropriate treatment and disposal.

Furthermore, trenched and buried pipelines and trenched and buried flexible flowlines (failed) and umbilical will be left in situ.

In addition, exposed ends & areas of exposure will be removed & returned to shore for recycling or appropriate treatment and disposal.

Local rock placement will be used to mitigate snag hazard from cut ends.

Finally, trenched and buried flexible flowlines & umbilicals rigid spool pieces and jumpers will be fully removed and returned to shore for recycling.