Downhole specialist targets Pacific Rim for unique downhole services

With a strong commitment to research, Maritime Well Service (MWS) has developed a range of downhole well service products which will be of interest to offshore operators in South-East Asia.

Since it was set up in 1980, the company has built itself a strong position in the Norwegian sector, where it claims to be the market leader for wireline, logging and coiled tubing services. In logging services, MWS's alliance with Western Atlas enjoys a 65% market share, according to marketing manager Morten Talgoe. It provides almost all of Statoil's, Phillips' and BP's downhole requirements, for both exploration and fixed platform wells, and also has contracts with Saga, Norsk Hydro, Elf, Conoco and Amoco.

"We think there's a demand in the Far East for this type of technology and for our unique products," says Talgoe. A new entrant to the Far East market, MWS is setting up a joint venture with Hitec (India) for the Indian market, and may follow the same course in other countries in the region, with others or alone.

The company is part of the Maritime Group, which recently merged with Aker Oil and Gas Technology to form Aker Maritime. MWS spends 10-15% of its turnover on R&D, in cooperation with oil companies, research institutes like Sintef and IKU, and the Norwegian Research Council (NRC). Well services generally have not developed as fast as drilling services, Talgoe says. A company which gives priority to tackling downhole problems should therefore have an edge over less pro-active competitors. Its latest product is the downhole tractor, the result of a collaborative effort with Statoil and Danish company Welltec. The tractor provides a solution to the problem of sending downhole tools to the farther reaches of horizontal and highly deviated wells.

Such wells often provide the key to the economic development of reservoirs. Gravity, however, cannot be used as an aid to pushing survey or maintenance equipment into the horizontal section. Until now, coiled-tubing technology has been used. The well tractor, however, provides a simple solution. It is a remotely controlled, six-metre long cylinder with wheels which engage the sides of the well as it flattens out. Tools are pushed along in front of it. There are two main versions: fluid driven for coiled tubing operations, and electrically driven for wireline operations.

A number of problems had to be ironed out in the course of the development, notably the intense downhole heat generated by the tractor. After six months of field trials, the tractor was declared commercial in June 1996.

The tractor operated satisfactorily in bottom-hole temperatures up to 93?C and pressures up to 430 bar. Compared with conventional methods of logging, two days were saved on each operation; over a year, Statoil says, this would enable it to save $7 million on rig costs. MWS has also recently launched the Ultrasonic Downhole Velocimeter (UDV). Aimed at horizontal production logging, the UDV is a solid-state tool which provides a substantially improved quality of data compared with the currently used mechanical spinner. Using technology developed in the medical sector, the UDV emits an ultrasonic signal. Working on the principle that the doppler frequency shift of the back-scattered signal is linearly

proportional to the fluid velocity, the velocity profile is described by analysing the signal to obtain velocity measurements from different points across the wellbore cross-section.

Reliable electronics is needed for the downhole monitoring of high temperature wells, and an advance in this field has come with the development of the High Temperature Application Specific Integrated Circuit (HTASIC) technique. Developed by MWS in conjunction with Sintef, the NRC and a number of oil companies, HTASIC circuits have shown high reliability in testing: after 5,000 hours functioning at 230?C, no circuit failures occurred. This is equivalent to a mean time before failure of 15 years at 175?C, according to Talgoe.

HTASIC circuits have been installed in more than 100 gauges to date, and the technology could prove particularly interesting in Thailand, where there is a prevalence of high-temperature wells.

Another product which could prove attractive to the well service industry in the Far East is the High Expansion Bridge Plug (HEB) for isolating specific zones in the well. The HEB is put in place by a standard setting tool, and can be retrieved with slick-line, braided-line, coiled tubing or the work string. It has an unusually large expansion capability of two inches, and being made of aramid, always returns to its original diameter, unlike traditional steel inserts.