Rough is the largest offshore gas storage facility in the UK, owned and operated by Centrica-subsidiary Centrica Storage (CSL).
Originally a gas field, it was converted into a gas storage facility in 1985 following the depletion of reserves.
The facility stopped storing gas in 2017, but it was reopened for storage in October 2022 to balance supplies into the UK’s gas market.
At the time of reopening, Rough gas storage facility had a gas storage capacity of approximately 30 billion cubic feet (bcf).
In June 2023, Centrica announced increasing the storage capacity at rough up to 54bcf. This is enough to heat 2.4 million UK homes in winter.
The company plans to invest £2bn to repurpose the field into the world’s biggest hydrogen and methane storage facility. The conversion would support the UK’s energy security as well as help in decarbonising industrial clusters in the country by 2040.
Rough field location details
The Rough reservoir is located off the east coast of the UK around 29km from Yorkshire in the Southern North Sea.
The reservoir is situated in Rotliegendes sandstone, 2.7km (9,000ft) under the Southern North Sea bed.
The reservoir is approximately 10km long and 3km wide, with depth ranging between 24m and 36m.
Ownership and Operational History
In the 1960s, Gulf Oil, the Gas Council, Amoco Group, Amerada Hess, and North Sea secured licences for Rough field.
The field commenced gas production and processing in 1975, following the development of offshore facilities and Easington terminal.
Rough, with one-third of its reserves depleted, was bought by BG Corporation (which became British Gas in 1986 after privatisation) in 1980s.
The field was then converted, and it became operational as a natural gas storage facility in 1985.
BG Storage became a separate entity in 1997 after its split from the rest of British Gas business. It sold Rough Storage to electric company Dynegy in 2001.
In November 2002, Centrica acquired Dynegy subsidiaries Dynegy Storage Limited (DSL) and Dynegy Onshore Processing UK Limited (DOPUL), for a net cash consideration of £304m and £11.8m in net working capital.
DSL and DOPUL held the Rough offshore gas storage facility, the associated pipeline and Easington onshore processing facility in Yorkshire.
Centrica Storage Limited (CSL) was established as a wholly owned subsidiary of Centrica in 2003, after the latter provided the UK’s Department of Trade and Industry of Ofgem with a set of Undertakings.
In 2018, Rough resumed operations as a production facility and the undertakings were removed.
Rough Gas Field Geology
Geologically, the 30km2 Rough reservoir is relatively rare and features rock with broad uniform porosity, which enables the flow of gas.
The porous rock of the reservoir is surrounded by non-porous rock preventing the pumped gas from escaping.
The gas in the reservoir consists of working gas and cushion gas.
The working gas includes the gas injected by CSL customers as well as the operational stock held by CSL to meet contractual obligations.
The cushion gas refers to the residual gas that is present in the field following its conversion to a storage facility. This gas, some of which is recoverable, is retained to provide pressure support.
Rough Gas Storage Facility details
The Rough Gas Storage Facility infrastructure includes the Rough reservoir, two manned offshore installations (47/8 Alpha and the 47/3 Bravo) and the Easington Terminal, which is used for injection and withdrawal of gas to and from the reservoir.
The two manned offshore platforms are connected to the field by 30 wells and to each other by a 2km long 18 inches inter-field pipeline.
In normal situations, gas from the project is injected and extracted by CSL through up to 30 wells.
The smaller installation, 47/8 Alpha, consists of six wells, and was used to withdraw gas from the field during peak demand. It was withdrawn from service in September 2016 and currently cold stacked.
The 47/3 Bravo forms the main offshore complex comprising 24 wells across three separate bridge-linked platforms. The installation extracts gas from the wells as a vapour and then it is transported to Easington Terminal via a 900mm (36inch) subsea pipeline.
At Easington Terminal, the gas is processed before it is sent into the National Transmission System (NTS), through an adjacent entry point, for transporting the gas throughout the UK.
The terminal can manage more than 900 million standard cubic feet of gas per day.
Key Contractors of the facility
In November 2022, British multinational engineering and consulting business John Wood Group secured a five-year integrated services contract from Centrica Storage.
The contract included engineering, procurement, construction (EPC) solutions, operations and maintenance services, and project management services for the Rough gas field and Easington Gas Terminal.
Fabricom Offshore Services delivered engineering and construction services for a major plant shutdown on Rough 47/3 Bravo platform. The works will help in boosting gas production during the late life phase of the asset.
