Major modifications are planned to the Troll platforms offshore Norway to accommodate new field developments and to combat falling reservoir pressure. The more imminent scheme involves the addition of a $54 million production module to Troll C to handle production from Fram West in Norwegian North Sea block 35/11. Reserves are estimated at 210 million bbl and 18 bcm. Operator Norsk Hydro plans four wells producing 60,000 b/d at peak, with the drilling center located 24 km from Troll C. Startup is scheduled for October 2003.
Hydro may subsequently tie-in other discoveries in the area, but by then it will be chiefly concerned with pressure decline at the Troll Field. The licensees are considering a $326 million project that would mean adding up to four new compressors to the Troll A gas platform. These would have to be powered via additional subsea cables connected to an onshore generating station 67 km distant. Troll is the sole Norwegian field with a shore-based electricity source.
On Valhall, operator BP is looking to extract more oil from the field's northern and southern flanks, where up to 300 million bbl of extra oil is thought recoverable. It is expected to invite tenders shortly for two small wellhead platforms. However, the company would then have to decide whether to go for a more intensive redevelopment of existing facilities on the field if it wants to maintain production through 2030.
BP to decide on Skarv
BP's appraisal on Skarv in the Norwegian Sea, spudded in February, proved up oil and gas, but did not clarify the reserves picture. The well, which was drilled in the southern tip of the elongated structure, found hydrocarbons in both Jurassic and Cretaceous sandstones and was then sidetracked and extensively logged. This sidetrack also encountered oil in the Jurassic.
BP has been itching to launch a development that might also encompass last year's Snadd gas discovery 17 km to the south. Depending on its current evaluation of the recent well, it will opt either for a floating producer or subsea facilities linked to a third party platform (probably Statoil's Heidrun to the south). The Norwegian Petroleum Directorate's new estimate for Skarv puts recoverable liquids and gas beyond BP's own commercial cut-off point of 180-200 million bbl and 57-70 bcm.
Statoil was non-committal about the success of its successful appraisal of Svale, 9 km northeast of its Norne Field FPSO in block 6608/10. The well was drilled by semisubmersible Borgland Dolphin to a total depth of 2,320 meters. Statoil sought enlightenment on this recent oil discovery, which was initially bracketed at 60-120 million bbl. Norne appears to be an obvious host, but an upbeat assessment of Svale could lead to further exploration of nearby prospects such as Falk, leaving options open for a platform-based development.
Siri ceases flaring
Statoil's Siri platform effectively is the first Danish sector installation to stop flaring gas. Two years into the production program, a flare gas recovery system has finally come into operation; the platform was designed with such a system in mind. Around 300 cu m/d are still being burned at the flare tip, but the previously wasted 25,000 cu m/d are now being either reinjected into the reservoir or diverted for power generation. Statoil uses the remaining quantities for simultaneous water and gas injection in the field.
Another Danish platform, the DUC's Gorm C, was recently put out of action following a gas explosion that injured two personnel. The cause is thought to have been a rupture in a high pressure pump associated with a gas compressor. Normally, Gorm C handles more than 120,000 b/d of oil from Gorm and four other fields.
Triple strike in UK sector
In the UK southern gas basin, Amerada Hess successfully appraised York, 10 years after the original discovery. Well 47/3a-11 - drilled in 45 meters water depth by the jackup Glomar Adriatic VI - tested up to 24.7 MMcf/d from Rotliegend Leman sandstone.
The reserves prognosis is around 200 bcf. Although Amerada has not dropped any hints, BG may have a say with three of its fields currently under development in adjacent blocks under the Easington Catchment Area project. York, which lies 8 km north of BG's offshore Rough storage facility, could be drawn into a future ECA phase.
Amerada also applied to the UK government to develop Perth in North Sea block 15/21b through its Scott platform via five subsea wells and an 8-in. flexible flowline. The control scheme also involves an umbilical and gas-lift line. Perth's recoverable potential is put at 19-39 million bbl of oil and 450 bcf of hydrogen sulfide-heavy gas. This toxicity will be partly addressed through installation of a membrane filter unit on the Scott platform.
Talisman Energy reports yet another oil discovery close to producing infrastructure - this time 5 km northwest of the floating producer on the firm's Ross Field. The semisubmersible Ocean Princess penetrated an oil column in the Jurassic and underlying Parry formation, which flowed 2,200 b/d on test. Talisman seems keen to fasttrack the new find through the Bleo Holm floater, recently modified to take production from BG's Blake Field.
Also in the central sector, PanCanadian Petroleum has become the latest foreign independent to notch exploration success. Its Buzzard well in 320 ft water depth in license P986 (100 km northeast of Aberdeen) encountered a 360-ft oil column. On test, the well flowed 6,547 b/d of light oil and 0.97 MMcf/d of gas on a 36/64-in. choke. Test rates were constrained by limits of the testing equipment. The well, drilled on the partners' behalf by BG, has since been sidetracked.
Template, topsides recycled
Norway's abandonment season got underway in late May when Statoil's first-ever multi-well subsea template was removed from the Tommeliten Gamma Field by the Saipem crane vessel S7000. The 13 year-old, 1,100 ton template was not considered redeployable due to advances in subsea designs, and was therefore removed to Mekjarvik for scrapping and recycling at a local steelworks. Tommeliten, situated southwest of Ekofisk, ceased operations in 1998, although plugging of its wells was only completed this April.
Concurrently, Heerema's Thialf barge was preparing to lift the unused 2/4-S riser platform topsides modules and gangway to other Ekofisk platforms. These were then to be shipped to a recycling plant in Lyngdal for a new life as nails or running-track surfaces. Another well abandonment exercise is currently in progress on TotalFinaElf's Froy Field.
