National Oilwell Varco, L.p.

William Tait

Graham Styler

Lewis Facca

Andrew Sushko

Mike Bellavance

D J Radmanovich

Dj Radmanovich

Embodiments of a sleeve assembly, used for stimulating multiple stages in a completion string has a lower shifting sleeve and an upper shifting sleeve and stimulation ports formed therebetween. The sleeves are caused to shift by progressively larger objects pumped through a bore of the completion string and engaging seats formed thereon. The seat on the lower sleeve is a releasable seat. When shifted the lower sleeve opens the stimulation ports. The seat on the upper sleeve is sized to accept the same size object as is required to engage and shift the lower sleeve on the stage uphole therefrom to close the ports. Thereby, stimulation ports are opened and closed without increasing a number of objects required to stimulate the wellbore. Further, as the ports at each stage below the stage being stimulated are closed, the objects are not required to isolate the bore therebelow.

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Calgary, Canada

William Tait