| 摘要 |
A lower formation of a multizone well is perforated by a perforating gun lowered by wireline, and then fractured. A packer (modified Pengo packer) with a central bore and a valve seat is positioned within the casing between the lower and upper formations. A plug is set into the packer valve seat by a perforating gun and released by shearing a shear pin. The well is pressurized to maintain the plug in the valve seat, the perforating gun raised, and the casing opposite the upper formation perforated. The gun is removed, and the upper formation fractured. After a suitable flow-back period, another packer is then positioned in the casing above the upper perforated formation. The pressure differential between formations maintains the plug seated, allowing the upper formation to be produced. When a change in pressure differential raises the plug off the valve seat, the lower formation may be produced. After pressures in the formations have equalized, the plug is removed by a retrieving tool constructed to permit simultaneous bailing of sand and grappling of the tool. After retrieval of the tool, the formations may be produced by conventional mechanical lift methods.
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