Historically, operators have used thread compound (commonly referred to as "pipe dope") because it prevents both galling and corrosion of tubing and casing and helps ensure a tight seal on connections. However, with the advent of TenarisBlue Dopeless Technology, the need for pipe dope and its associated problems are becoming a thing of the past.

Extensive studies, coupled with an active commitment to research and development in corrosion, metallurgy and connection design, resulted in the first commercial dope-free connection for the petroleum industry, which completely eliminates the need to use thread compounds for tubing and casing. Research focused on improvements to thread pitch and taper, thread profiles, seal geometry, interferences, and thread and seal contact pressures.

Many benefits

Eliminating the need for dope eliminates the associated environmental problems, which include water contamination from heavy metals and other non-metallic substances used in the thread compounds, as well as the disposal costs associated with preparation and running of the tubing and casing. Other operational benefits include simplified cleaning and preparation of the pipe for running, improved safety on the drill floor, easy stabbing, fast make-up and reduced galling, and easier tubing cleanout operation prior to setting completion tools. The technology is also suitable for both carbon steel and corrosive-resistant alloy (CRA) materials, thereby providing greater versatility in well design programs.

North Sea debut

Soon after its introduction to the oil field in late 2002, ConocoPhillips ordered the dopeless technology for an Ekofisk well scheduled to be drilled in the Norwegian sector of the North Sea. In July 2003, ConocoPhillips completed the first successful offshore running of a 51⁄2-in., 32 lb/ft Q125 liner string using dopeless connections on two sections of the string for the X50 well.

X50 is a horizontal well and required a high-performance connection to withstand additional pressure and compression, including being used as a rotating liner. The dopeless technology was used in the two more critical sections of the string and worked under over-torque conditions of 25,000 ft-lbs, well exceeding the standard value of 18,000 ft-lbs make-up torque.

Øystein Ekeli, Ekofisk drilling director, said, "ConocoPhillips has a strategic objective to improve drilling operations with new technology, while ensuring safety and reducing the environmental impact. TenarisBlue Dopeless dramatically reduced time for rig preparation, but more importantly it eliminated the risk of having personnel on the drill floor to apply dope, which resulted in a safer operation."

The event marked the initial debut of the technology in some of the world's most complex offshore wells. This was the first time that a dry dope-free connection had ever been run. The goal was to carry out a reliable and efficient operation with minimum impact on the environment. The technology was well suited for this objective, and it also provided good operational performance and reliability in its initial trial and subsequent runnings in these offshore wells.

Snøhvit goes totally dope-free

Early in 2004, Statoil joined other operators in endorsing the new technology by announcing that all permanent tubulars installed in the Snøhvit field would use the dopeless technology. Statoil chose dope-free connections because the Barents Sea is a key commercial fishing area, subject to stringent environmental regulations, and this technology was the only dry, dope-free connection that could meet Statoil's and Norway's strict environmental requirements.

This made Snøhvit the first field in the world to adopt the dopeless technology for all casing, production tubing and liners. Statoil signed a contract calling for the company to supply connections in several carbon and chrome steel grades, including L80, TN110, 13Cr L80 and 25 Cr Duplex and in sizes ranging from 7 in. to 14 in. to satisfy the casing and tubing needs for 10 wells and an injector well.

As a result, Statoil's Snøhvit organization ultimately eliminated the use of all pipe dope when connecting permanently installed downhole tubulars. Accordingly, the elimination of the use of dope significantly reduced their chemical discharges to the sea and resulted in a safer, more efficient working environment on the rig.

Total chooses dopeless

In Autumn 2004, the introduction of dopeless premium connections into the Venezuelan market led to Total Venezuela's successful running of a dopeless string of 9-5⁄8-in., 53.5 lb/ft TN 110SS casing in a high-temperature, high-pressure (HT/HP) well in the Jusepin field. Faster make-up and cleaner, safer working conditions were cited as several of the benefits Total Venezuela wanted for its Jusepin drilling operations.

In its initial use of the connections, Total Venezuela considered the Jusepin field well a test. The successful results included no rejections and no cross threading during the running of the connections and a good make-up speed of 17 joints/hr, including the installation of 90 centralizers on the same casing section. Given that fast make-up directly affects rig time, the smooth installation resulted in cost savings for the operation, and the use of the technology also allowed for a safer and cleaner work environment.

After looking at the results of its first run, the company is considering using the connections for the HT/HP completion strings as well.

First dope-free chrome string

In late December 2004, 330 dopeless joints of 51⁄2-in., 17 lb/ft L80Cr13 pipe were successfully installed by ConocoPhillips in a North Sea Ekofisk well. The dope-free connection was used in the well because a clean tubing string was needed to reduce the risk of problems during the installation of completion hardware that can be caused by debris inside the tubing. According to ConocoPhillips, the connections were very strong, easy to stab, and allowed for a much cleaner and safer running operation.

The installation marked the first time that a 13Cr string with dry dope-free connection has been commercially installed in a production well. The application of the proprietary technology to a corrosion-resistant alloy was challenging because chrome steel is harder than carbon steel and is therefore more prone to galling. The dopeless technology solves not only the anti-galling (lubrication) problem, but also the anti-corrosion protection needed for shipment and storage.

Steady growth in North Sea

Since the first running of a chrome string in the North Sea, ConocoPhillips has installed an additional 1,200 joints of dopeless in four new Ekofisk wells. The chrome completion strings totaled 40,000 ft (12,200 m) and were installed in wells on two different Ekofisk platforms. When the initial well is included, the total chrome presently installed in Ekofisk wells totals approximately 50,000 ft (15,250 m). ConocoPhillips has commented positively on the make-up speed, ease of running and ruggedness of the technology and looks for further benefits as this technology matures.

In January 2005, two more "firsts" occurred in the Snøhvit field's 4-F-2H well. The well became the first ever 100% dopeless well and, as part of this installation, a 25Cr dope-free string was run for the first time.

Additionally, during the early months of 2005, some 18 strings totaling 118,000 ft (35,990 m) of dopeless technology were installed in 13 wells with an additional 4 to 6 strings totaling 25,000 ft (7,625 m) being installed each month. Also, the size in which the technology is being deployed has expanded rapidly. Currently, four different tubing sizes and three different casing sizes are being successfully used by operators.

For the remainder of 2005, 550,000 ft (167,750 m) of dopeless technology are expected to be installed worldwide.

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