'Redrilling' archives

Oct. 19, 2001
Almost 25 years ago, reports appeared that a giant discovery had been made in the Atlantic waters to the west of Scotland. Previously, all activity off northern Europe had been in the North Sea to the east.

Almost 25 years ago, reports appeared that a giant discovery had been made in the Atlantic waters to the west of Scotland. Previously, all activity off northern Europe had been in the North Sea to the east.

However, since then, little was heard of the find, but now details are re-emerging and reinforcing the view held by many that rich resources may still underliethe region's waters and thus much more riches may lie in dusty files in company offices.

Clair update

That 1977 discovery was indeed a giant. It is now calledClair field and stretches across five blocks 40 miles west of the Shetland Islands and is thought to hold about 4 billion bbl of OOIP.

Unfortunately, it turned out to be an extremely complex and technically difficult reservoir. So while oil prices yo-yoed in the intervening years, technical teams have regularly picked up, looked at, and reshelved the prospect.

Now, technological advances have resolved many of the problems. BP PLC is pushing a first phase of Clair, involving development of probably 250 million boe from a platform in the central area of the field at a cost of $1.5 billion. If the UK government approves development plans by yearend, first oil from Clair could come in 2004, with production reaching a plateau of 60,000 b/d.

Besides giving a boost to Shetland's Sullom Voe terminal, where Clair crude will be piped, it will offset recent disappointments further west, where the first wells drilled off the Faroes have proved of little interest.

And if Clair Phase 1 is successful, BP would look at tapping the field's outlying satellites to significantly boost production.

In addition to BP 29%, partners Conoco Inc. 24 %, Chevron Corp. 20%, Enterprise Oil PLC 18%, and Amerada Hess Corp. 9% will all be pleased that they stuck with this difficult enterprise.

Other possibilities revisited

But Clair isn't the only development once thought uneconomic but that will keep Offshore Northern Europe hydrocarbons flowing. In the southern UK gas basin, Royal Dutch/Shell Group brought several small gas accumulations into play by using underbalanced drilling techniques and small, unmanned platforms costing around $10 million. More of these accumulations, known about for over 30 years, will now become viable.

In the deeper waters of the Norwegian sector, previous exploration sites are being revisited, although so far with little success. Statoil AS recently completed an exploration well without finding any traces of hydrocarbons in Skuld field on Block16/2-2. Originally, a well had been drilled in 1967 on the block when it was the first Norwegian area licensed. ExxonMobil Corp. forerunner Exxon Corp. was at that time operator and reported that traces of hydrocarbons were found.

However, Statoil has not been discouraged, and several other areas are under reassessment.

Progress on the Clair prospect and Shell's use of new technology are pointing the way ahead for the industry to revisit its archives.