When Queen Elizabeth II pushed a gold-plated button on Nov. 3, 1975, in Aberdeen, Scotland, to start production from Forties Field, few foresaw how long-lasting both she and the U.K.’s largest-ever oilfield would prove. Forty years later, she is Britain’s longest-serving monarch, while the field, under a different owner, is firmly established as the U.K. North Sea’s longest-producing field.

The field is recognized as one of the world’s greatest offshore projects. Over the past four decades, its development, an astonishing evolutionary journey from first oil up to the present day, has been unrivaled by any other project in the world. And, it will continue for many years to come, thanks to Apache Corp.

When the original operator, BP, chose to develop this giant field, first confirmed as a discovery in October 1970, no one would have dreamed that it could still be producing in 2015, with plans potentially to take it well into the 2030s. But that is the current plan envisaged by Apache, which gave this declining giant a new lease on life after taking the reins from BP in 2003.

‘Can do’ culture

The industry-leading success of Apache’s ownership and operatorship of the field since acquiring it from BP for $680 million stems from a variety of factors: the company’s bold leaders; its North American industry experience, operational know-how, technological innovation and teamwork approach; and its relationships with key contractors. But the key ingredient has been a “can do” culture.

According to Mark Richardson, Apache’s North Sea Projects group manager, “Culture eats strategy for breakfast”—a quote from American management consultant and author Peter Drucker. In this case, Apache’s culture has eaten strategy for breakfast, lunch and possibly dinner, too.

The story of Forties Field is well-known to oil professionals. It essentially mirrors the birth and rapid growth of production in the U.K. North Sea and is as synonymous with the region as Shell’s Brent Field (found the year after Forties Field).

Forties’ discovery well, 21/10-1, in Block 21/10, hit a 390-foot column of good-quality oil in October 1970. This came only five years after the country’s first-ever offshore discovery, also by BP, at the West Sole gas field, and just 10 months after the U.K.’s first-ever oil find, made by Amoco at Montrose.

World class

When the queen pushed the button that November day and formally began the flow of liquids (the field actually began producing two months earlier) through the 130-mile pipeline stretching from Cruden Bay to Grangemouth, the inauguration signaled the successful start-up of the U.K.’s first world-class offshore development.

Initially, it featured four large fixed steel platforms (a fifth was added in 1985) sited 110 miles east of Aberdeen. The development had a total capacity of more than 100 wells and a production system that could handle up to 600,000 barrels per day (bbl/d). Following start-up, the field’s operational life has set an exemplary industry standard.

Forties’ original oil-in-place was put at 4.6 billion barrels (Bbbl) of good-quality 37° API gravity oil, with that figure now put at more than 5 Bbbl. When Apache—entering the North Sea for the first time with its Forties acquisition—took over operatorship, it was under no illusion that it was taking on anything less than a real-life industry icon.

The field’s revered status was proven by the initial reaction when BP announced the sale to Apache on Jan. 12, 2003: Industry observers likened the deal to selling off the crown jewels. But for both companies, the deal made perfect sense.

BP wanted to strategically divest certain mature assets that it considered economically marginal at a time when the price of oil was floating at about $12/bbl. The U.K. major wanted to concentrate on expanding its global upstream portfolio into new frontiers, a strategy that it implemented and achieved under the bold leadership of Lord Browne—the former BP CEO who earlier in his career had been an asset manager of Forties Field.

In something of a premonition, the company stated at the time of the announcement that the Forties asset “may be worth more to others than to us,” adding, “We believe this is an excellent deal for BP and Apache. Among other things, it brings to the UKCS a powerful U.S. independent for which Forties will be a highly material asset and therefore more likely to attract necessary future investment.”

Ironically, however, it wasn’t Forties Field that Apache initially came to the U.K. to discuss. First, the Houston company cast its eye over BP’s Montrose Field. After deciding that asset was not what it was looking for, Apache turned its attention to Forties Field. Both sides quickly realized a deal could be done, and the initial agreement was in place in less than two weeks.

BP agreed in principle to sell its 97.14% stake in the field (not including the Forties pipeline, which it still owns today), along with a package of other assets in the Gulf of Mexico, to Apache for $1.3 billion.

At the time, Forties was producing about 48,000 bbl/d, having reached a peak plateau between 1978 and 1981 of about 500,000 bbl/d, with that larger figure having been well above early expectations for the reservoir. That peak figure at one point represented 25% of U.K. oil demand.

As of the sale date, an estimated 2.5 Bbbl of oil had been produced from the field, and BP estimated there were only 144 MMbbl of recoverable oil reserves remaining.

Rejuvenated

Under Apache’s stewardship since 2003, however, Forties’ productivity has been transformed by a pioneering approach to the use of seismic and drilling technology.

The company’s intense focus on identifying and acting quickly upon fresh opportunities to access new reserves and enhance recovery rates has resulted in Apache so far achieving total production of more than 235 MMbbl from the field, with 120 MMbbl coming from wells drilled into the Forties reservoir by Apache.

There have been reserve additions of more than 20 MMbbl of oil from new satellite fields, and Apache believes there is the potential for another 100 MMbbl of oil to come. Every 1% increase in the field’s recovery rate equates to about an extra 50 MMbbl of reserves.

Forties Field has become one of the best-known examples in the global offshore industry of how to extract true value from a mature brownfield oil project. Apache managed to pay off the cost of the whole acquisition in less than three years.

Inside the blowout preventer deck on Forties Charlie platform. Source: Apache Corp.

A $4.6 billion investment

Today, Forties Field is expected to be producing well beyond the end of the next decade—all from a mature asset originally expected to be running dry by the early 1990s, and which was penciled in prior to its sale for decommissioning by 2012. Apache has invested close to $4.6 billion so far in Forties, in virtually every facet of its infrastructure and what lies beneath.

Key to the company’s success has been intensive drilling activity, extensive facility upgrades and modifications, the installation in 2013 (38 years after it first came onstream) of a new platform linked to Forties Alpha, and a complete reevaluation of the reservoir using modern seismic techniques. All these operations were delivered with an excellent safety record and a level of operational efficiency that is “best in class” for the U.K. North Sea.

Today, one of the most pioneering projects from the golden era of North Sea discoveries has been transformed from a declining giant into a rejuvenated offshore powerhouse—a flagship in the vanguard of the U.K.’s latest generation of projects.

Offshore