Service Companies See Export Market For Equipment Developed In Norway

As operators tackle increasingly difficult field developments off Norway, the country's service companies are designing new, exportable tools to help them.

The service companies are looking to market products developed to meet Norway's particular offshore challenges in regions where similar problems exist, such as the Gulf of Mexico, West Africa, Brazil, and the Caspian Sea.

Norway's experiences in development of large, complex reservoirs in comparatively deep water and hostile weather conditions have enabled its service companies to specialize in deepwater, floater, and high-tech well technologies.

Downhole devices

Børge Kolstad, president of Maritime Wells Services AS (MWS), Stavanger, a unit of Aker Maritime AS, said his company aims to more than double its turnover to 1 billion kroner ($150 million) by 2000.

"We focus on two types of wells-horizontal and high temperature-in any combination," said Kolstad. "Increasingly we provide intervention and data acquisition equipment for smart wells.

"One of the products being developed is a Well Tractor, a sort of downhole robot to transport equipment along the horizontal sections of wells. Logging is one of the most common jobs for a well tractor, which can also be used for perforating and setting of plugs (Fig. 1 [83,442 bytes])."

MWS claims to be the only service company anywhere operating well tractors. It says its product runs with standard wireline equipment and tools available in the field.

"We have been operating well tractors for more than 1 year," said Kolstad. "Our well tractor is theoretically capable of a 9,000 m reach, but our top operating range is now about 3,500. The limitation in not on the tractor itself, but the cable."

MWS has also developed a high expansion bridge plug, designed to shut off water in horizontal wells rather than produce it to surface. The device is mounted on a well tractor for deployment and is said to be unique in being retrievable.

Kolstad said Norway's operators are producing more water than oil in the North Sea, and downhole separation of oil from water has become one of their big challenges.

This year MWS aims to be first to market with a tool called an Advanced Production Logging (APL) device designed to give accurate production logging in horizontal wells.

"Production logs in horizontal well sections are all incorrect," said Kolstad, "because current production logging tools are designed for low angle conditions, while many recent wells are angled from 75° to horizontal.

"This is particularly a problem with multiphase flow, since no instruments give true flow readings down horizontal holes. So almost 4 years ago we set out to develop a new logging tool from scratch."

Kolstad expects the APL device to see its first application this year, in a Norwegian field. A benefit for MWS of the APL project has been development of downhole electronic devices.

"The APL tool electronics are designed to operate at temperatures up to 230° C.," said Kolstad. "We had to develop electronics for small, reliable, downhole devices, and we plan to use this technology in smart wells.

"We are working on a smart well system, which is due to be ready in 1999, which can be put into a well after completion to make it smart. No other system can do this without a workover of the well, involving use of a drilling rig."

Development of the smart well system is being sponsored by Saga Petroleum AS, Norske Shell AS, Norsk Hydro AS, and Enterprise Norge AS. MWS is working on the project with the Norwegian Research Council and Norwegian research institutes and universities.

CO₂ handling

Norway's carbon taxes are forcing offshore operators, who now have to pay a levy on the amount of CO₂ they emit from platforms, to seek more-efficient methods for platform power generation.

Falk Pedersen, technical manager at Kvaerner AS, Oslo, said reducing the need for offshore power has become a major issue for operators, who pay $53/ton of CO₂ produced, amounting to almost $400 million/year offshore Norway.

Kvaerner has developed a biphase gas turbine, which has been tested in the U.S. for operator Texaco Inc. The company has also developed the air bottoming cycle (ABC) turbine, an alternative to combined cycle turbines. It is being commercialized for geothermal power projects.

For offshore platform power generation Kvaerner is working to commercialize a system comprising a biphase gas turbine, ABC turbine, and heat exchanger, which Kvaerner reckons can reduce fuel consumption and CO₂ by 25% compared with conventional power plants.

Pedersen said the company hopes to make the system available in 2001. Kvaerner is working with Saga to develop a CO₂ reduction system for installation on the Snorre 2 platform, now under construction.

Also for Snorre, Kvaerner has built a full-scale CO₂ removal demonstration unit that recovers CO₂ from turbine exhausts. The waste gas can be injected in reservoirs under enhanced oil recovery schemes.

"CO₂ can be used this way to increase oil output by about 20%," said Pedersen. "Oil companies in Norway are very interested in this approach, which is already in operation in the U.S."

Kvaerner has begun development of a membrane gas-liquid contactor unit for removal of CO₂ from flue gases, using amine as an absorption liquid. Pedersen said a membrane unit can be 65-70% smaller and lighter than a comparable absorption column.

Subsea technology

More than 900 subsea wells are planned to be installed worldwide during 1998-2002, and the percentage of wells in deep water will rise significantly.

This is the prediction of Christian Bakken, senior vice-president of ABB Offshore Technology AS, Billingstad, Norway, who says the typical cost of a subsea well has fallen over 10 years to less than $3 million from $18 million.

"Subsea technology drivers," said Bakken, "are life-cycle costs, difficult reservoirs, deep water, long offsets, and enhanced recovery. ABB's focus is on modular subsea systems, which can easily be configured according to the different requirements of each operating area."

The company is undertaking a deepwater research and development program intended to prove equipment for subsea production in 3,000 m of water. Work started last year, and qualification is due to be completed in 1999.

Among equipment under development is the Subsea Separation and Injection System (Subsis), which Norsk Hydro intends to install in Troll field to begin production next year (Fig. 2 [286,048 bytes]).

Stig Gustafson, Subsis project manager at ABB, said the system was developed in response to the trend towards development of old reservoirs, marginal fields, and satellite finds.

"Many difficulties in these types of development boiled down to problems with water," said Gustafson. "It is of great benefit to remove water from the well stream as soon as possible.

"Benefits include reduced back-pressures, production optimization, reduced environmental impact, reduced transportation costs, and a reduced need for downhole chemicals."

ABB studied two main options: dumping produced water straight into the sea at the well site, where the legal oil content limit is 40 ppm; and reinjection in the reservoir, where the allowable content is 500-1,000 ppm.

"There is no monitoring device available yet to check oil in water contents for seabed dumping," said Gustafson, "though there is one under development. So seabed reinjection is the way forward (OGJ, Aug. 25, 1997, p. 66)."

Subsis is being developed for use in up to 1,500 m of water, said Gustafson. The equipment destined for Troll is now being built and is expected to be completed in October. Delivery is slated for July 1999.

ABB is also developing a Subsea Electric Power Distribution System (Sepdis), which is intended to enable use of a wide range of electric tools, and pumps in particular, up to several megawatts capacity in up to 2,000 m of water.

Nils Arne Sølvik, Sepdis project manager, said current seabed electric power systems are not cost-effective. Sepdis is being designed to reduce the cost of cables and risers and also reduce space requirements and module weights.

The Sepdis system under development will be a subsea production power unit able to deliver 7.5-10 MW of power to 11-36 kv electrical equipment installed up to 60 km from a mother platform in 2,000 m of water.

Sølvik said ABB has completed conceptual design for Sepdis in a study funded by Shell, Norsk Hydro, Saga, Statoil AS, and Mobil Development Norway AS.

"We aim to qualify Sepdis by the end of 1999," said Sølvik. "We already have some field applications in mind and have undertaken preliminary studies. Ultimately, we may need to go to 150 km step-outs for tie-in of subsea fields straight to shore."