What is Coiled Tubing?

Coiled Tubing (CT) has been defined as any continuously-milled tubular product manufactured in lengths that require spooling onto a take-up reel during the primary milling or manufacturing process. The tube is nominally straightened prior to being inserted into the wellbore and is recoiled for spooling back onto the reel. Coil Tubing was developed due to the desire to work on live wellbores, but speed and economy have also emerged to be key advantages for application of CT. These advantages, along with a relatively small footprint and short rig-up time have made CT even more attractive for drilling and workover applications.

The original idea for coiled line pipe came from the project "Pipe Line Under the Ocean" (PLUTO) in which pipe was butt welded, rolled onto spools and laid from boats under the English Channel in 1944 to support the Normandy landings. The weak link in the design of this continuous pipe was the tube-to-tube butt welds which caused structural weakness and restricted fluid flow inside the pipe. Coiled Tubing was produced by this process until the late 1980s when NOV Quality Tubing (QT) introduced a new idea. In 1989, QT patented a process for joining strips end-to-end in which the strips are sheared at fixed angles and then welded to each other by computer aided welding machines. This process is known as creating a Bias Weld™ of flat strips.

Downhole Work-String Products:

Product lines defined as downhole work-strings include  QT-1000 ®,  QT-900 ™,  QT-800 ®, & amp;  QT-700 ®. These may be produced as conventionally tapered, or as TRUE-TAPER® (with the exception of QT-700). Some may also be produced as FLASH-FREE® .

 HO-70  Downhole Products for Hang-Off Applications:

The HO-70 product line is intended for use in non-cycling situations, and is subject to certain limitations in terms of outer diameter and wall thickness. HO-70 may also contain tube-to-tube welds.

QT defines all other products as non-standard (i.e. Special).

Ordering Information

When placing orders for downhole coiled tubing applications please include the following information:

• Type of Service
• Size (i.e. OD and wall thickness. Also please specify TRUE-TAPER® , or conventional tapering.)
• Grade
• Length (Allowances should be made for length as measuring instruments used in manufacturing are only accurate to ± 1%).
• Delivery and Shipping Information
• Shipping Spool (i.e. wood, metal or customer supplied reel. See  Spool Capacity Chart  for dimensions.)
• Fitting Type
• Special Packaging (i.e. N2 purge & amp; backfill, corrosion mitigation, & amp; marking requirements)
• Other Special Requirements (i.e. FLASH-FREE®, wireline & amp; capillary installation, additional destructive & amp; non-destructive testing, or a certification test data book.)
• Specal Purchasing Requirements (Customers with special internal purchasing requirements should submit them to QT in advance for review.)
• Inspection and Test Plans (Customers requiring QT to submit an Inspection and Test Plan should allow sufficient time for detailed joint discussions to be held. In addition, the specific role of any customer representative at QT facilities should also be defined.)

  Technical Resource Manual