Coiled tubing drilling (CTD) is an economical method of re-entering existing cased wells in mature fields to exploit bypassed reserves because of its versatility in accommodating a variety of candidates and its technological edge in drilling more efficiently.

In re-entry drilling, kicking off with the right bearing attenuates the single biggest issue when drilling long laterals—weight transfer problems. Correct re-entry wellbore placement from vertically cased wells has traditionally required many single-function trips. The magnetic interference from the steel casing makes the acquired magnetic tool face measurements from traditional instruments inaccurate. Verification of the kickoff direction is usually performed with a wireline multi-axis gyro instrument. This process can be time-consuming and still requires additional correctional runs or directional changes prior to beginning drilling in the desired direction toward the target.

Hence, the entire process of intervention, from setting a whipstock in the right orientation to drilling in the least tortuous direction from these vertically cased wells, requires a more efficient approach if CTD is to be a viable option in marginal projects.

This paper assesses the limitations in the current methods of kicking off and details an innovative approach to improve re-entry wellbore quality through the use of an integrated coiled tubing gyro measurement-while-drilling (MWD) instrument.

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