This paper describes the ongoing development of a new lateral reentry system that provides access to all levels of multilateral wells. The inability to selectively enter Level 1 and 2 lateral extensions (classifications of the Technical Advancement of Multilateral wells, TAML) has traditionally limited rig-based and rig less coiled tubing operations in these wells. Although coiled tubing as a means to work in live wells offers distinct advantages in the late stages of well construction, until recently no reliable coiled tubing reentry technique was available. The new system design includes a reentry bottomhole assembly (BHA), which consists of a surface-controlled orienting tool and a controllable bent sub. The system identifies the window of the selected lateral before attempting reentry, and confirmation of successful identification and entry is visible at surface through a software-displayed pressure log. The technique does not require a wired coiled tubing string; the corrosion-resistant reentry tool is operated solely on flow and is conveyed with standard coiled tubing equipment. Field examples are presented that demonstrate the success of this system in reentering a designated lateral on the first attempt for operations such as matrix stimulation and openhole formation wash treatments. Current developments that enlarge the scope of applications to wellbore logging are also described. With the introduction of a new reentry technique, operations such as openhole formation washes, selective matrix stimulation, production logs and nitrogen kickoff operations can be performed on coiled tubing in live, flowing multilateral wells. The ability to access all levels of multilateral wells with coiled tubing adds a new planning and contingency option to the operator's and driller's decision matrix for the drilling and completion phase. Introduction The potential or anticipated requirement for wellbore cleanouts, formation damage removal, acid stimulations, nitrogen lifts or wellbore logs has traditionally forced the operator to incorporate means to selectively reenter branches of multilateral wells. The decision of whether to install sophisticated completion hardware had to be made prior to confirming that production data warranted the investment. Reentry-enabling completion designs are described as Level 3 to 6 completions in the TAML classification. While adding complexity to the wellbore construction and completion, investments for these installations have to be added to the overall wellbore costs. Traditionally, completing multilateral wells without reentry-assisting equipment meant that formations could not be stimulated selectively or could be stimulated only after going through trial-and-error access methods on jointed pipe or coiled tubing. Both inefficient fluid treatment and extended non-productive times pay out late or do not justify the investment for the production enhancement at all. Clearly this situation could not satisfy the industry, because it reduced the inherent advantage of multilateral wells: minimized costs per length of pay zone. Hence a means was required, that allowed selective reentry to the lateral branches of a multilateral well, regardless of its completion. Assuming that most lateral branches are horizontal, this means should function on coiled tubing. Further assuming that the preferred well configuration is the openhole wellbore, the reentry device had to function reliably even in wellbores that had ledges, washouts, etc. Finally, the reentry technique had to be reliable and fast, reducing overall treatment costs and enabling quick payback.
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