Southern North Sea gas fields

York gas field consists of reservoirs in blocks 47/2a, 47/3a, 47/3d and 47/3e in the Southern North Sea, at a water depth of about 142ft. The gas field is located about 34km off the coast of East Yorkshire.

The development of the Centrica-owned field comprises of drilling two production wells supported by a wellhead fixed platform. Production from the first well of the gas field started in March 2013.

The engineering, procurement, construction and installation (EPCI) contract of the York platform was awarded to Heerema Fabrication Group (HFG) in February 2011. The platform was constructed at HFG's Hartlepool fabrication yard and delivered in May 2012.

Gas produced from the York field is transported to the Easington gas terminal in Yorkshire via an export pipeline. The gas produced from the field will be capable of serving about 500, 000 households.

The platform and pipelines have been designed for a lifespan of 25 years. The platform has been designed to accommodate future tie-ins from neighbouring fields.

York field gas reserves and development details

"The field is estimated to hold reserves of about 106 billion cubic feet."

The York field was discovered in 1993 through the exploratory well 47/02-1. The well was drilled using the jack-up rig Noble Julie Robertson. The decision to develop the field was made in January 2011.

The field is estimated to hold reserves of about 106 billion cubic feet. It has a capacity to produce around 120 million cubic feet of gas per day, at peak.

Drilling works are currently underway for the second well which is reckoned to be the longest well that the company has embarked.

Details of the York platform

The York platform featuring six well slots weighs 2, 750t. The topsides of the platform measure 20m in length, 15m in width and 16m in height, and weighs 1, 300t. The jacket of the platform measures 30m in length, 20m in width and 69m in height, and weighs 1, 450t.

The jacket of the platform is a four legged and cross-braced structure comprising of rigging risers and J-tubes. The three-tier topsides provide for emergency accommodation and a helipad.

The platform is placed at a water depth of 43m and operates unmanned. Up to 350 people were involved in the construction of the platform.

The installation of the topsides and jacket of the platform were carried out using Heerema's heavy-lift vessel DCV Balder.

Export pipeline

The export pipeline measures 34km in length and 16in in diameter. A 3in pipeline carrying methanol is also piggybacked to the export pipeline.

The pipeline is connected to the landfall at Easington and laid on the beach through cofferdams using a pipelay barge. The final section of the pipeline is connected to the terminal through a tunnel drilled through cliffs.

The project also included the construction of a new onshore gas processing facility at the Easington terminal and upgradation of the terminal. Up to 200 people were involved in the construction of various facilities at the terminal.

Contractors involved with the development of York gas field

The contract for the installation of the export pipeline of the York gas field was awarded to Saipem. The dredging of the trench and the installation of the cofferdams was carried out by Rohde Nielsen. The contract for the transport and installation of the platform was awarded to Heerema Marine Contractors.

"The contract for the installation of the export pipeline of the York gas field was awarded to Saipem."

The construction of the gas processing facility was carried out by Centrica Storage. The company is also involved in selling the condensate and providing logistics and other back up services for the platform. Oil & Gas systems supplied an Ariel Gas Compressor to Centrica Storage for the York platform.