A visitor sees few pumpjacks nodding on the prairie outside Cushing, Okla., nowadays, and the area produces little oil. Still, the town’s name looms large in the world’s oil business.

Thank its extensive storage and pipeline infrastructure dating from the early 20th Century’s northern Oklahoma oil boom for that. Cushing’s midstream legacy provides the trading hub infrastructure today for one of the world’s best-known crude blends: West Texas Intermediate.

In a similar way, the North Sea field that lent its name—Brent—to another, well-known crude type, no longer produces much oil. Three of its four production platforms have gone offline and the last, Brent Charlie, is down to a trickle and is expected to be shut in soon. No firm date has been set, according to the U.K. unit of Shell, which is a partner with ExxonMobil’s Esso Exploration and Production U.K. in the field.

But the gathering, processing and transportation infrastructure needed to support the supergiant field helped make other North Sea fields commercial. That infrastructure still moves production from other North Sea fields, in particular Norway’s Ekofisk and Oseberg fields and Scotland’s Forties Field, which make up Brent blend. The light, sweet crude serves as a benchmark for the world’s crude pricing system.

Brent’s current flow is in contrast to the 504,000 barrels per day the field averaged in its peak year of 1982. Located 112 miles east of Scotland’s Shetland Islands, Brent was a historic find when discovered in 1971. It came along shortly after the 1969 discovery of the Ekofisk Field in Norway’s sector of the North Sea and proved supergiant Ekofisk was no fluke—the North Sea held bountiful crude and natural gas reserves. Brent went on production in 1976 and at the time industry analysts expect it to produce for 25 years.

The partners made a further investment in Brent in the 1990s that extended its commercial life, although in recent years most production has been gas. Operating in the rugged North Sea climate for four decades has proved challenging and, despite the partners’ efforts, there were accidents and fatalities over the years.

“To date, the field has produced about 4 billion bbl. of oil equivalent, which is almost 10% of all the oil and gas produced in the U.K. sector of the North Sea,” according to a Shell U.K. publication. Handling that much crude required a massive investment in gathering and processing infrastructure. The four platforms, 64 miles of pipelines and 64 oil storage cells beneath the platforms’ topsides served 140 wells.

Decommissioning and removal of that infrastructure will take years, according to Shell U.K. The Brent Delta platform ended production in 2011 and the Alpha and Bravo platforms ceased production in fourth-quarter 2014. The decommissioning process may extend until 2040, the company added.

A fifth structure, the Brent Spar oil storage and tanker loading buoy, became an international environmental cause in 1995 following completion of a pipeline to the Sullom Voe terminal in the Shetlands. Shell U.K. had proposed to sink the buoy at sea but following protests moved the buoy to Stavanger, Norway, where it is used in the harbor following refitting.

Offshore