The South Morecambe field DP3 and DP4 installations, located in the East Irish Sea, UK were approved for decommissioning by the UK authorities in September 2019.

Spirit Energy Production UK is the owner and operator of the DP3 and DP4 installations, as well as of the associated infrastructure in the South Morecambe field.

Spirit Energy took a decision to decommission the DP3 and DP4 platforms due to a fall in production rates. The decommissioning programme includes the plugging and abandonment of wells and pipelines, and the decommissioning, removal, and disposal of the platforms

The topsides of the DP4 and DP3 platforms were removed by Allseas’ construction vessel Pioneering Spirit in April 2021 and June 2021 respectively.

Location and field details

The South Morecambe field complex is located in blocks 110/2a, 110/3a, 110/3b, and 110/8a in the Morecambe Bay, East Irish Sea, UK. The DP3 and DP4 installations, part of License P153, are situated in blocks 110/8a and 110/3a respectively, approximately 34km west of Blackpool, UK. The water depth in the area ranges from 22m to 25m.

Discovered in 1974, the South Morecambe field commenced operations in 1985. The field consisted of seven fixed jacket platforms, including three bridge-linked platforms that comprise the central processing complex (CPC), and four normally unmanned installations (NUIs), namely DP3, DP4, DP6, and DP8.

The DP3 and DP4 platforms were installed and connected to the central processing complex in 1983 and 1984 respectively.

Decommissioning project details

The DP3 and DP4 decommissioning project involves well plugging and abandonment, as well as full removal of the installations and transportation onshore for reuse or recycling. The production from the DP3 and DP4 platforms ceased in 2019 and 2018 respectively.

The topsides of both the platforms sit on four-leg steel jackets, and each platform was connected to six wells. A 24in-diameter gas pipeline was laid from each platform to transport the well stream to the central processing complex. The platforms also received electricity from the central processing complex.

The topside structures of the DP3 and DP4 platforms are identical in design and weigh approximately 6,763t and 6,760t respectively. Each topside structure consisted of three levels, including a cellar deck, a drill deck, and a partial mezzanine deck, and housed wellhead and Xmas tree access platforms. The jackets of DP3 and DP4 weigh approximately 2,739t and 2,648t respectively, excluding foundation piles and drilling conductors.

The well plugging and abandonment were achieved in July 2020, while the DP3 and DP4 jackets are expected to be removed by Pioneering Spirit in 2023.

Contracts awarded

Allseas was contracted to deploy Pioneering Spirit for lifting the DP3 and DP4 gas platforms by Spirit Energy in November 2019. The contract marked the first decommissioning project for Allseas in the East Irish Sea.

The scope of the contract included the engineering, preparation, removal, and disposal of the DP3 and DP4 installations each weighing approximately 11,000t, and associated subsea infrastructure weighing approximately 1,000t.

Allseas’ construction support vessel Oceanic removed the subsea infrastructure which includes wellheads, pipelines, and umbilicals.

Worley bagged a contract to provide the decommissioning engineering, procurement, and construction services to Allseas for the DP3 and DP4 decommissioning project.

The scope of services includes lean engineering, site construction, management, and assurance services for the removal of platforms.

CessCon Decom received a contract for the onshore decommissioning, dismantlement, and recycling of the DP3 and DP4 facilities from Allseas Engineering in January 2021.

The scope of the contract includes onshore decommissioning, decontamination, dismantlement, and recycling of the topsides, jackets, and subsea structures at CessCon Decom’s Energy Park Fife decommissioning facility in Fife, Scotland. Allseas is responsible for the delivery of DP3 and DP4 installations to the decommissioning facility.