| 摘要 |
A multiple stage inflation packer with secondary opening rupture disc. The inflatable packer comprises a case with a closing sleeve, an opening sleeve and a releasing sleeve therein. An opening plug is dropped into the casing string and is allowed to free fall, or is pumped down, to actuate the opening sleeve to allow inflation of the packer element. A back check valve prevents the packer from deflating. After the packer is inflated, additional pressure is applied which ruptures a rupture disc to open a port to the well annulus above the set packer element. Cementing may be carried out through this port, and after the cementing operation, a closing plug is pumped down the well casing behind the cement to actuate the releasing sleeve and move the closing sleeve to seal off the ports. Another check valve insures that pressure is equalized on both sides of the rupture disc as the packer is run into the well bore. After cementing is complete, the center of the packer may be drilled out, leaving the closing sleeve to permanently seal the ports.
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