CPC E21B 33/13 (2013.01) [E21B 31/12 (2013.01)] | 14 Claims |
1. A plug for wellbore tubing, the plug comprising:
an internal portion;
a first external portion which surrounds the internal portion; and
a second external portion disposed axially adjacent to the first external portion, with respect to a central longitudinal axis of the plug;
wherein the second external portion expands to:
engage an interior surface of the wellbore tubing in response to a trigger as the plug displaces downhole through the wellbore tubing; and
create an annular gap between the second external portion and the internal portion to permit a fluid to progress in an uphole direction to the first external portion;
wherein the first external portion expands to engage the wellbore tubing in response to the expansion of the second external portion and upon contact with the fluid.
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