Offshore Europe

Aug. 1, 2002
Marathon's Kinsale Head complex in the Celtic Sea will serve as the hub for Ireland's newest offshore development, Seven Heads.

Seven Heads gas heading to Ireland

Marathon's Kinsale Head complex in the Celtic Sea will serve as the hub for Ireland's newest offshore development, Seven Heads.

Following a successful appraisal well on this neglected gas discovery last October, new operator Ramco Energy had considered piping the gas direct to the Cork coast, on the lines of Enterprise's current subsea-shore development of Corrib off the west coast. It chose the more commercial and conventional pipeline link, to the Kinsale A process platform 35 km to the northeast.

Marathon has agreed to process and transport initially 60 MMcf/d, expandable to 100 MMcf/d, from Seven Heads through the Kinsale 24-in., export pipeline to the Inch terminal near Cork. In return, Ramco and partners Island Petroleum and Sunningdale Oil will share the operating costs of the Kinsale offshore/onshore facilities.

Map shows proximity of the Ramco-operated fields to the Kinsale Head complex and Ireland's southern coast.
Click here to enlarge image

Ramco secured a gas lease undertaking (GLU) for Seven Heads in August 2001, with a view toward early development. Its appraisal well last fall flowed up to 13.7 MMcf/d from Upper Wealden sands. Subsequent reservoir analysis suggested recoverable quantities of over 300 bcf.

The field lies in just over 100 m of water. Assuming approval from the Irish government, six development wells will be drilled next year, up to 8 km apart. Gas will feed through 8-in. flowlines to a collection manifold, and from there through a 35-km, 18-in. pipeline connecting to a new riser on Kinsale A. In time, Ramco may also exploit the nearby Galley Heads gas find, covered by the same GLU, through its capacity arrangement with Marathon.

Oil activity on the rise

Significant UK oilfield projects are moving forward. Appraisal drilling was recently completed on Buzzard, the UK North Sea's largest oil discovery for over a decade. BG, a partner to operator EnCana, announced that recoverable reserves could be well over 400 MMbbl. Some reports have suggested nearer 800 MMbbl. Eight wells and sidetracks have been drilled since the discovery last year. A development plan should be issued by early 2003.

BP has approved a fourth development phase for Schiehallion, West of Shetland, to tap a potential 7 MMbbl in the "Claw" area. A new drill center will be installed 6 km west of the field's FPSO, with two producer and two water injector wells, a 10-in. control umbilical and gas lift. The floater in turn will undergo a topsides upgrade, including an additional gas turbine.

Around 20 km to the north is Suilven, a 1996 discovery by BP that was later proven to extend into acreage operated by Conoco. At one point the field's oil potential was rated at 100 MMbbl. Austria's OMV has since bought Conoco's 32.5% stake in this acreage, and claims that new operator BP is pursuing development.

Finally, ChevronTexaco is closing on first oil from two new subsea projects budgeted at £120 million. The semisub Stena Spey is currently drilling a 60-day producer well on Caledonia before completing three more wells drilled on Alba South. The former will be tied back to the Britannia platform through a 6-km pipeline. A 5.5-km bundle will connect the manifolded subsea Alba South wells to the Alba Northern platform.

Tax critics go unheeded

Industry groups in the UK have been lobbying the government in a vain attempt to annul the 10% petroleum tax rise sprung by the chancellor in his April budget. He sees North Sea revenues as the solution to Britain's public health sector woes, and is banking on oil company compliance to carry the day. He may be right. Although BP reacted with a wave of job cuts across its UK operations, the other majors have so far responded with polite words of concern. They are probably mindful of Britain's approaching gas supply crisis, which has led to talk of several big new North Sea trunklines to pull in supplies from continental Europe.

Coincidentally, there has been a flurry of activity recently relating to new UK gasfield developments:

  • Centrica Resources agreed to swap its share of the Liverpool Bay project for Agip's interests in the new Armada and Goldeneye developments (plus R block interests)
  • Consort Resources, an upcoming independent gas developer/marketer, bought southern gas basin equity held by Agip in Ravenspurn North, Johnston, and other undeveloped satellite accumulations. It also picked up Kerr-McGee's share of the prospective Chiswick development
  • Venture Petroleum secured operatorship of the Annabel gas discovery in the same basin (again, from Agip)
  • Burlington Resources launched a £165 million development of the Rivers gasfields in the East Irish Sea, involving a new minimal platform and 45-km export pipeline to a process center in Barrow.

It has also been reported that Centrica has signed up for 80 bcm of imports from Holland's Gasunie over the next decade. This could lead to construction of a second Netherlands-UK trunkline across the North Sea divide.

Kollsnes to treat Visund gas

Norsk Hydro and its partners have decided to pipe gas from Visund in the Norwegian North Sea to Statoil's new NGLtreatment plant in Kollsnes. Visund has a 55 bcm gas cap, but so far, all production has been reinjected since the field came onstream as an oil producer in 1999. Under the new plan, gas will pass through a new 34-km line into the Kvitebj rn export system (also new) that heads directly to Kollsnes. There, liquids will be stripped out and transported to the Mongstad refining complex, via the Vestprocess pipeline.

TotalFinaElf is also pushing ahead with its plans for the Skirne and Byggve gas condensate fields. Single wells on each field will be tied back to the Heimdal gas center, 20 km to the east. The project looked to be in jeopardy at the last moment due to higher than expected gas tariffs, proposed under Norway's new gas transportation ownership laws.

Electrical solution cuts out emissions

ABB is installing a new 4,000-ton compression module for Statoil's Troll A platform, which will be driven by electrical power. It will also supply and install the submarine DC cables that will bring in the electricity from Kollsnes, 65 km away. The compressors will raise processing capacity on the platform from 85 MMcf/d to over 100 MMcf/d. The high voltage direct current power transmission system, which includes two 40 MW HV ABB Motorformers to drive the compressors, should eliminate emissions from both the offshore and onshore plants, ABB says. The alternative, adding new turbines to drive the compressors, would have generated 255,000 t/yr of carbon dioxide and 230 t of nitrogen oxide.

On Statoil's Heidrun platform in the Norwegian Sea, new equipment is being installed for re-injection of produced water. This follows a one-year trial with a system that injects sulfate-free seawater, and produced water for reservoir pressure support. The partners' dual aim is to limit harmful discharges to the sea and to raise oil recovery from Heidrun by around 100 MMbbl.