Weight transfer and helical buckling eventually leading to lock up is an issue that the industry has had to deal with since the outset of the use of coiled tubing. Limitations imposed by this restriction have reduced the number of available applications that can be carried out. The use of larger sizes, improved materials combined with friction reducers and better modelling techniques have gone a long way to understand and extend these limits. This paper reviews a new dynamic excitation tool, which reduces frictional drag and therefore adds to available options for further extending limits and capabilities of coiled tubing. The paper follows the tools history from developmental testing in Norway and subsequent successful Coiled Tubing Drilling (CTD) field trials in Alaska. Results of reverse friction factor modelling are included and parameters that affect the tools ability to create dynamic excitation are also discussed.
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