The completion of most cased-hole horizontal shale wells requires multi-stage stimulations, which calls for some form of plug isolation between the stages. The plugs are normally composite flow-thru plugs that are pumped downhole on electric wire to the required measured depth.

This case history describes a project where the industry’s standard-sized composite plugs with a 3.85-3.92 in. outer diameter (OD) would not pass through the curved section of the horizontal wellbore with an internal diameter (ID) of 4.276 in. Small doglegs in the curved section of the wellbore presented geometrical and completion challenges. Three attempts to push the plugs through this section of the wellbore failed, resulting in the plugs getting stuck. The project faced a challenge:

Could a plug be built in a timely manner that would pass through the curve restrictions, set in the production casing, withstand stimulation pressure, and still be drillable?

The project challenge was successfully answered. A new composite plug was designed that met all of the wellbore requirements and allowed a successful completion of the wellbore. The 3.25 in. OD flow-thru composite plug was set in a 4.276 in. inner diameter (ID) production casing. Altogether, six plugs were pumped down and set in the wellbore of the West Texas, University Land 39 #29-1H well. The plug met all of the required performance expectations during all stages of the completion.

This plug’s application goes beyond the standard horizontal wellbore with multi-stage stimulation requirements. The uniqueness of this plug is its ability to be modified for a variety of applications where reduced internal diameters in production casing create completion challenges below the restriction.

The details of the wellbore deviations and the final plug design solution are included in this paper.

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Copyright 2011, Society of Petroleum Engineers
This paper was prepared for presentation at the SPE North American Unconventional Gas Conference and Exhibition held in The Woodlands, Texas, USA, 14–16 June 2011. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.