Statoil starts production at the smallest field ever to be developed with a stand-alone development on the Norwegian Continental Shelf (NCS) this month when PGS' Petrojarl 1 begins to tap the Glitne reservoir.
Glitne could be the first of many Statoil-operated fields developed in the same way on the NCS as the company is trying to find economic ways to unleash the reserves in several of its smaller finds.
However, the success of projects such as Glitne is dependent on several aspects, including location in relation to existing infrastructure, availability of production units, special reservoir conditions such as low gas-oil ratio, relatively low pressure and simple wells.
Several challenges had to be met in order to achieve the goal of first production in July.
The availability of the Petrojarl 1 made it necessary for Statoil to go for a fast-track development drilling and completion project. It therefore had to turn around quickly and secure a rig in an already tight market.
Delivery of casing, tubing and other downhole equipment was accelerated through Statoil's frame agreements. It also decided to reuse the Christmas trees from its abandoned Tommeliten field. PGS Production bought the trees from the Glitne license and contracted Framo to refurbish them.
The Petrojarl 1 experienced a 6-month upgrade job at the Kværner Rosenberg yard in Stavanger, Norway, before departing for the field following 15 years of production, mostly on the UK shelf.
The duration of the contract with PGS is expected to be between 26 and 30 months, with the first 18 months guaranteed by Statoil.
This is the first time a contracted production ship has tapped a Statoil-operated field.
6-month conversion
Kværner was awarded the conversion job, valued at US $40 million, in December 2000, and 900 people have been involved with modification and upgrading work. The conversion contract, which includes equipment and work, entailed strengthening the hull - adding another 15 years to its lifetime - and upgrading the process module.
A water-injection package also has been installed, and the vessel has been fitted with a new swivel to handle up to eight wells. A new recompressor to minimize or avoid flaring gas has been installed, in addition to the new diesel generators, which will help reduce emissions in connection with energy production.
Furthermore, the instrumentation and power distribution system has been upgraded, as has the fiscal metering package.
A general upgrade to comply with Norwegian Petroleum Directorate rules and regulations also has been done.
10 fields in a row
Petrojarl 1 is a purpose-built, turret-moored production vessel that has serviced nine fields and conducted more than 1,300 offloading operations without any reportable environmental incidents, according to PGS.
It can operate with flexible or rigid production risers and is equipped with a workover derrick for wireline and coiled tubing work that can be upgraded to heavy-duty workover capability.
Dynamically positioned assisted mooring enhances the operability of the vessel during workover operations with either a wireline or coiled tubing unit.
The Petrojarl 1 can be used in full field development, extended well test or early production mode.
The Tentech design vessel was built at the Nippon Kokan yard in Japan and is 683 ft (208 m) long and 105 ft (32 m) wide. Its process capacity is 60,000 b/d of oil, 30 MMcf/d to 42 MMcf/d of gas and 25,000 b/d of produced water. Storage capacity is 180,000 bbl. It has accommodation for 70 people, but normal operating crew is around 44. Maximum water depth capacity is 5,250 ft (1,605 m).
All crew has remained onboard during the conversion job to be able to survey the work and learn how to use the new equipment. In the production phase, they will have operational responsibility onboard with follow-up by a representative from Statoil.
Small cash cow
Glitne will have a positive cash flow for 2 to 3 years, depending on oil prices, and have a plateau rate of 1½ years.
The project had been going faster than expected when Statoil started its dialogue with PGS in late 1999. Going directly to PGS was done to avoid a time-consuming bid round.
The Norwegian Petroleum Directorate approved the development plan Oct. 3, 2000, and the drilling program kicked off the same month.
The Glitne wells have been drilled in parallel rather than sequentially, saving about $3.8 million. Semisubmersible Byford Dolphin drilled the four producers and one water-injector well.
About Glitne
The Glitne oil field is in blocks 15/5 (PL 048B) and 15/6 (PL 029) in the Sleipner area of the northern North Sea, about 25 miles (40 km) northwest of the Sleipner East development.
The discovery, made in 1995, was delineated with a further well in 1997. Work on production drilling and completion started in October 2000.
Daily production is set to reach a plateau of about 40,000 b/d, and an estimated 25 million bbl of oil will be recovered.
It will be produced with the PGS-owned Petrojarl 1 floating production, storage and offloading vessel under a 2- to 3-year charter, depending on how long profitable output can be sustained.
Total investment in the field is roughly US $90 million, including drilling and completion of four production wells and one water injector as well as engineering work.
Operating costs are expected to total $13 million, excluding the costs of chartering the Petrojarl 1.
Everything above the wellhead has been delivered by PGS, while everything below is Statoil's responsibility.
The reservoir is in the Paleocene age, and the oil column is 115 ft (35 m) at max.
Produced water and seawater will be reinjected for pressure support, and surplus gas from the Utsira formation will be injected.
Statoil holds 28.9% of Glitne, the state's direct financial interest 30%, TotalFinaElf 21.8%, Det Norske Oljeselskap 10% and Norsk Hydro 9.3%.

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