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August 2020
Group Licence list

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Wissey decommissioning programme
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Orwell decommissioning programme
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Horne and Wren decommissioning programme
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Tullow first entered the UK offshore exploration, development and production arena in 2000, when it acquired a significant number of Southern North Sea gas assets from BP.

The acquisition comprised assets in the CMS and Thames-Hewett Areas. The portfolio was then expanded through a number of new licence awards and bolt-on acquisitions including transactions with Shell, Chevron-Texaco and Conoco-Phillips.

Tullow succeeded in extending the life of these mature gas assets through focused cost reduction, successful exploration and innovative developments. However, the fields have now reached their end of life and decommissioning activities for the area are under way.

Completed activities

Plugging & abandoning of wells

In 2015 Tullow commenced the process of flushing, cleaning and disconnecting the pipelines in order to ensure the facilities are hydrocarbon free.

In 2016 Tullow started the planning, engineering and procurement processes to plug & abandon (P&A) 12 operated wells in the UK continental shelf. Two scheduled for 2017, seven in 2018 and three in 2019. Site surveys and other preparatory works were undertaken prior to the commencement of the well P&A operations. The decommissioning programme for all Tullow operated wells in the UK North Sea was completed by the third quarter of 2019. All wells are successfully plugged and abandoned and approved by the UK regulator.

Removal and disposal of infrastructure

In October 2015, the UK Offshore Regulator on behalf of the Secretary of State approved the final decommissioning programmes for the Horne & Wren platform, Wissey and Orwell subsea installations and the connecting pipelines and umbilicals within the Thames Area Complex, in accordance with the provisions of the Petroleum Act 1998. In 2015 the first phase of the Thames Area decommissioning was successfully completed on schedule and on budget. In March 2017 the second phase of the Horne & Wren decommissioning project was completed with the successful removal of the unmanned platform. In 2019, the wellhead protection structures at Orwell, Thurne and Wissey were successfully removed with zero safety incident.

Current activities

Seabed clearance

All Tullow operated wells are abandoned and therefore the decommissioning workplan for 2020 is to clear and restore the seabed around the well, platform and pipeline sites. This will involve the removal of selected stabilisation materials, grout mounds and conductors that could not be removed by the rigs at the end of the P&A operations.  The scope of work includes the cutting of protruding pipe ends and will be concluded with an over-trawlable survey to ensure there are no snagging hazards for the fishing industry. Following a successful survey, it is expected to be able to close out of the decommissioning programme with the regulator by the end of 2020.

Decommissioning the UK non-operated assets

Tullow ceased production from its non-operated UK North Sea assets during the third quarter of 2018. The decommissioning programme commenced in 2019 with the well abandonment and infrastructure removal of these assets. Final close out of all decommissioning programmes is expected to be achieved by 2025.