Advancements in sidetracking and re-entry operations have progressed greatly over the past decade. However, these advancements have been predominantly in rotary applications. Milling systems for coiled tubing (CT) operations have evolved much slower. Size limitations have played a major role in the technology transfer from rotary applications. Currently multiple trips are required to successfully complete window milling operations.

Over the last 18 months a single trip CT sidetracking system has been developed that optimizes the efficiencies of the bottom hole assembly and the whipstock in CT sidetracking operations. This paper will discuss the bottom hole assembly analysis used to develop a specialized whipstock and mills for coiled tubing operations with the limited available power from smaller downhole motors.

Results of conventional one trip rotary systems will be compared to the new design in yard testing. These results will be followed by an analysis of each of the first six field trials performed utilizing the new system in vertical and horizontal applications.

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