Method and apparatus for multizone oil and gas production
First Claim
1. A method for producing an upper formation and a lower formation in a well comprising;
- penetrating said upper and lower formations with a casing,cementing said casing in said well,perforating said casing adjacent to said lower formation,setting a first packer with a valve seat in said casing between said upper and lower formations,lowering a setting tool assembly comprising a perforating gun having a plug releasably attached thereto into said casing,setting said plug into said packer valve seat,releasing said plug from said perforating gun,pressuring said well sufficient to maintain said plug in said valve seat,perforating said casing adjacent to said upper formation,setting a second packer in said casing above said upper formation,said plug being vertically movable relative to said valve seat by differential pressure between said upper and lower formations to allow said upper formation to be produced when said plug is closed and said lower formation to be produced when said plug is open, andremoving said plug from said well after the pressure in each formation has equalized allowing both formations to be produced by mechanical lift.
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Abstract
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.
65 Citations
17 Claims
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1. A method for producing an upper formation and a lower formation in a well comprising;
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penetrating said upper and lower formations with a casing, cementing said casing in said well, perforating said casing adjacent to said lower formation, setting a first packer with a valve seat in said casing between said upper and lower formations, lowering a setting tool assembly comprising a perforating gun having a plug releasably attached thereto into said casing, setting said plug into said packer valve seat, releasing said plug from said perforating gun, pressuring said well sufficient to maintain said plug in said valve seat, perforating said casing adjacent to said upper formation, setting a second packer in said casing above said upper formation, said plug being vertically movable relative to said valve seat by differential pressure between said upper and lower formations to allow said upper formation to be produced when said plug is closed and said lower formation to be produced when said plug is open, and removing said plug from said well after the pressure in each formation has equalized allowing both formations to be produced by mechanical lift. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for producing a cased well penetrating a plurality of vertically spaced productive formations comprising;
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first packer means adapted to be positioned within said casing of said well between lower and upper formations, said packer having a central bore and a valve seat therein for receiving a movable and retrievable bore closure member, said packer means having circumferential gripping means and sealing means for effectively gripping and sealing on the interior surface of said well casing to resist both upward and downward forces, a setting tool and perforating gun assembly having connecting means at its upper end for connection to a wireline and connecting means at its lower end for releasably attaching a bore closure member, and a movable and retrievable bore closure member releasably attached to and carried by said setting tool and perforating gun assembly and releasable therefrom to be operatively received within said packer valve seat to close the central bore, said bore closure member being vertically movable relative to said valve seat by differential pressure between said upper and lower formations to permit a selected formation to be produced according to whether said valve seat is open or closed. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification