With the continual development of offshore drilling operations comes new ways to approach old challenges. For any operator in a mature field, it is commonplace to enhance value by sidetracking existing wellbores to unswept areas within the reservoir where using a new drill would not be economically feasible. However, this approach often involves inherent risk. By using an existing wellbore, hole size and casing combinations are limited to the largest outer diameter (OD) casing string the operator can exit from and still safely case and cement the objective with a high probability of success. A bicenter drilled or under-reamed hole in combination with the use of noncoupled tubular connections (flush connections) is often required to construct a wellbore of sufficient size that does not constrict eventual production rates. Tight annular clearances and subsequent enlarged holes create standoff problems for subsequent cementing operations. In addition, sidetracks commonly drilled with only limited casing strings require efficient use of the minimal amount of casing sizes available. This often requires washing, rotating, or reaming casing to bottom when borehole conditions deteriorate. This paper describes a creative solution to the challenge of achieving casing standoff in an enlarged borehole while being robust enough to ream lengthy distances and retain the flexibility to properly centralize a tubular string for a quality cement job.

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