West Sole - General History

The West Sole field was discovered in September 1965 in acreage licensed to BP Amoco in the first UK licensing round. The field lies 70 kilometres off the east Yorkshire coast, in block 48!6, in approximately 28 metres of water covering an expanse 19 kilometres long by 5 kilometres wide.

This discovery marked the beginning of a period of gas developments in the Southern North Sea, which within a decade was supplying almost all of Britain’s gas.

The reservoir, which is estimated to contain recoverable reserves of 1.85 trillion cubic feet of gas, lies some 2,745 metres beneath the seabed as Holland’s gaint Croningen gas field. It is a faulted sandstone of Permian age, some 280 million years old, which is particularly dense because it was subjected to extreme pressures. As a result both porosity (the space between particles in which gas collects) and the permeability (the flow channels between these spaces) are low. Gas has to be extracted through natural hairline fractures and by means of artificially induced fractures.

Development of the field involved new skills in engineering and construction; the large jacket and module fabrication yards of today did not exist and the laying of subsea pipelines in the hostile North Sea was in its infancy. The original development plan called for;

Two fixed steel production platforms – West Sole ‘A” (WA) and West Sole ‘B’ (WB), with facilities to dry the water-saturated gas.
A 70 Kilometre, 16-inch diameter pipeline from the field to a shore terminal at Easington, 40 kilometres east of Hull.

WA began drilling the production wells in July 1966, and in March 1967 the first North Sea natural gas was piped ashore. By spring of 1968, most of the essential work on the field had been completed. Four production wells had been drilled from WA, and six from WB.

Easington Terminal was fully instrumented and the telemetry system had been installed. Development continued over the next few years; in 1967 a single well production platform WE was installed; in 1969 the six-well production platform WC was installed; and in 1974 the satellite platform WAS was connected to WA and two further wells drilled.

In 1978, platform WE was removed after eleven years in production because it was uneconomic to undertake a major overhaul. This was the first North Sea platform to be decommissioned; examination of the jacket for corrosion and stress reaveld that, within the design parameters, the platform was in remarkably good condition – useful information for future North Sea developments.

By 1980, West Sole was in a production decline due to a combination of the drop in reservoir pressure and low gas prices which deterred further capital investment. However, following negotiations over the gas price, the decision was made to recover more of the remaining reserves in the field. The West Sole Gas Compression Project was undertaken to improve gas recovery, and involved the installation of gas compression facilities and additional electrical power generation plant onshore at Easington; the laying of a new 24-inch pipeline from WB to Easington to handle the lower pressure gas; and associated modifications to all three platforms.

Produced gas is discharged into a three phase separation process. The saturated gas is separated into gas, condensate and water. The separated clean water is discharged into the sea. With the removal of dehydration offshore, the 16” and 24” sealines are operated wet, using an innovative Threshold Hydrate Inhibitor (THI).

More recently, in 1988, a major programme of modifications, the GBP60m

West Sole Modification Project, commenced to improve platform facilities and comply with new legislation particularly in respect of accommodation, fire protection and utilities. These modifications should ensure that the West Sole platforms have a productive life well into the next century.

In early 1996 the Newsham subsea satellite began exporting via WA platform.

Also see the The West Sole - Field History or download the West Sole Area Asset Portfolio (PDF Document).