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A downhole plug for use in oil and gas well completions made of aluminum, dissolves in natural wellbore fluids, has a dissolvable seal made of aluminum split rings or a degradable elastomer, has a backup pump out ring, and may be provided to the well site as an interchangeable parts kit for adaption

A downhole plug for use in oil and gas well completions made of aluminum, dissolves in natural wellbore fluids, has a dissolvable seal made of aluminum split rings or a degradable elastomer, has a backup pump out ring, and may be provided to the well site as an interchangeable parts kit for adaption to the well's requirements, to provide an interventionless plug in a well.

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1. A kit for providing multiple settable downhole tool configurations on a common subassembly, the tool adapted to seal against the inner wall of a casing in a well, the common subassembly comprising a mandrel having a first end and second end, an exterior surface, and an interior surface and includ

1. A kit for providing multiple settable downhole tool configurations on a common subassembly, the tool adapted to seal against the inner wall of a casing in a well, the common subassembly comprising a mandrel having a first end and second end, an exterior surface, and an interior surface and including a ball seat, a slip, a wedge, and a sealing element entrained on the outer surface of the mandrel, the kit including: a top ring dimensioned to engage the upper mandrel;a bottom sub for engaging the lower mandrel;a sealing element for being located about the mandrel and for forming and at least substantially fluid tight seal between the tool and the casing;a pump-out ring assembly including a pump-out ring having a ball seat, a pump-out ring ball and shear elements, the pump-out ring assembly configured for being coupled to the lower end of the mandrel or the bottom sub by inserting a chosen number of shear elements inserted through the mandrel or bottom sub and into the pump-out ring assembly, and to be decoupled from the mandrel or the bottom sub when downward hydrostatic pressure in the well on the assembled downhole tool exceeds a preset release downward hydrostatic pressure and shears the shear elements between the mandrel or bottom sub and the pump-out ring assembly;a keeper pin for keeping the pump-out ring ball from flowing upward and out of the mandrel;when the kit is assembled into a settable downhole tool and immersed in the well's wellbore fluid, the pump-out ring assembly is coupled by shear elements to the mandrel and, upon receipt of the pump-out ring ball into the pump-out ring ball seat, prevents downward fluid flow through the mandrel until the downward hydrostatic pressure on the tool exceeds the preset release downward hydrostatic pressure, the shear elements then shearing and the pump-out ring assembly then decoupling from the mandrel or the bottom assembly, to open the mandrel to downward fluid flow through the mandrel; andchanging the number of shear elements to couple the pump-out ring assembly with the mandrel or the bottom sub when assembling the tool will change the preset release downward hydrostatic pressure. 2. A settable downhole tool for temporarily isolating a zone above the tool from a zone below the tool in a cased well, the tool comprising: a mandrel;one or more elements for holding the tool to the casing and sealing the tool to the casing; anda pump-out ring assembly located within or near the lower end of the mandrel, coupled to the mandrel, either with or without a bottom assembly located between the pump-out ring assembly and the mandrel; and comprising a pump-out ring with a ball seat, and one or more shearable shear elements,fluid may flow through the ball seat and the mandrel when the ball seat is open;fluid may not flow downward through the ball seat and the mandrel when a ball is seated in the ball seat, a seated ball in the ball seat when the pump-out ring assembly is coupled to the mandrel isolating a zone below the tool from downward fluid flow from a zone above the tool;the one or more shear elements couple the pump-out ring assembly to the mandrel;the minimum relative downward hydrostatic pressure on the pump-out assembly needed to shear the shear elements coupling the pump-out ring assembly to the mandrel is the first release downward hydrostatic pressure;the cumulative number and the shear strength of the one or more shear elements coupling the pump-out ring assembly to the mandrel determine, in part, the first release downward hydrostatic pressure;the tool is comprised so the number and strength of the one or more shear elements is selected and inserted into the tool before the tool enters the well;responsive to a first relative downward hydrostatic pressure on the tool, which is less than the first release downward hydrostatic pressure, the ball is in pump-out ring's ball seat and the mandrel is closed; andresponsive to a second relative hydrostatic pressure on the tool, which is equal to or greater than the first release downward hydrostatic pressure, the one or more shear elements shear, decoupling the pump-out ring assembly from the mandrel, and opening the mandrel to downward fluid flow. 3. The tool of claim 2, further comprising: at least one hole in the mandrel or the bottom assembly extends through the mandrel or the bottom assembly;at least one hole in the outer surface of the pump-out ring;the at least one hole in the mandrel or the bottom assembly corresponds to the at least one hole in the pump-out ring assembly;at least one shear element located in the at least one hole in the mandrel or bottom assembly and extending into the corresponding at least one hole in the outer surface of the pump-out ring assembly; andthe at least one shear element couples the pump-out ring assembly to the mandrel; andshearing the shear element will decouple the pump-out ring assembly from the mandrel. 4. The tool of claim 3, further comprising: multiple holes in the mandrel or the bottom assembly which extend through the mandrel or the bottom assembly;multiple holes in the outer surface of the pump-out ring;at least some of the holes in the mandrel or the bottom assembly correspond to at least some of the holes in the pump-out ring assembly;multiple shear elements located in at least some of the multiple holes in the mandrel or bottom assembly and extending into multiple corresponding holes in the outer surface of the pump-out ring assembly;the multiple shear elements extending through the mandrel or the bottom assembly and into the pump-out assembly coupling the pump-out ring assembly to the mandrel; andshearing the shear elements will decouple the pump-out ring assembly from the mandrel. 5. The tool of claim 4 wherein the number of shear elements inserted from the mandrel or the bottom assembly and into the pump-out ring holes may be selected at the well site and the shear elements inserted into the tool at the wellsite to correspond to a selected release downward hydrostatic pressure. 6. The tool of claim 3 wherein inserting shear elements with a relatively higher shear strength produces a higher release downward hydrostatic pressure needed to decouple the pump-out ring assembly from the mandrel. 7. The tool of claim 2 wherein inserting a higher number of the shear elements from the mandrel or the bottom assembly into the pump-out ring holes produces a higher release downward hydrostatic pressure needed to decouple the pump-out ring assembly from the mandrel. 8. The tool of claim 2 wherein not all of the tool's pump-out ring hole and mandrel or bottom assembly hole pairs contain a shear element. 9. The tool of claim 2 wherein the shear elements are shear screws or shear pins and at least two shear screws or shear pins are used in the tool, each is made of metal, and each has shear strength in the range of 800 to 1100 PSI. 10. The tool of claim 2 further comprising the pump-out assembly having a keeper located above the ball seat for keeping a ball below the keeper, and a ball located between the keeper and the ball seat. 11. The tool of claim 2 further comprising the bottom subassembly engaged with the mandrel, and coupled by the shear elements with the pump-out assembly. 12. The tool of claim 11 further comprising the pump-out assembly having a keeper located above the ball seat for keeping a ball below the keeper, and a ball located between the keeper and the ball seat. 13. The downhole tool of claim 2, further comprising an upper ball seat located at the upper end of the mandrel and configured to receive an upper ball after the tool is set and seal the mandrel against downward fluid flow through the mandrel. 14. A settable downhole tool for temporarily isolating a zone above the tool from a zone below the tool in a cased well, the tool comprising: a mandrel;one or more elements for holding the tool to the casing and sealing the tool to the casing;a bottom subassembly engaged with the mandrel;a pump-out ring assembly comprising a pump-out ring with a ball seat, and multiple shearable shear elements, namely shear screws or shear pins;multiple holes in the bottom assembly which extend through the bottom assembly, and multiple holes in the outer surface of the pump-out ring, wherein at least some of the holes in the bottom assembly correspond to at least some of the holes in the pump-out ring assembly;multiple shear elements inserted in at least some of the holes in the bottom assembly and extending into at least some of the corresponding holes in the outer surface of the pump-out ring assembly;the shear elements extending through the bottom assembly and into the pump-out assembly couple the pump-out ring assembly to the mandrel;the cumulative number and shear strength of the shear elements coupling the pump-out ring assembly to the mandrel determine, at least in part, a first release downward hydrostatic pressure needed to shear the shear elements and decouple the pump-out ring assembly from the mandrel;the first release downward hydrostatic pressure is settable before the tool enters the well by varying the number and strength of the shear elements inserted into the tool;fluid may flow through the ball seat and the mandrel when the ball seat is open;fluid may not flow downward through the mandrel and ball seat when a ball is seated in the ball seat, and the pump-out ring assembly is coupled to the mandrel, the tool then isolating a zone below the tool from downward fluid flow from a zone above the tool;responsive to a first downward hydrostatic pressure on the tool which is less than the first release downward hydrostatic pressure, the mandrel remains closed, and the tool continues to isolate a zone below the tool from downward fluid flow from a zone above the tool;responsive to a second hydrostatic pressure on the tool, which is equal to or greater than the first release downward hydrostatic pressure, the shear elements shear, decoupling the pump-out ring assembly from the mandrel, and opening the mandrel so the tool will permit downward fluid flow from the zone above the tool into a zone below the tool. 15. The tool of claim 14 wherein the tool is capable of having number of shear elements inserted into the pump-out ring holes at the well site to correspond to a selected release downward hydrostatic pressure for the well and to have the selected number of the shear elements inserted into the pump-out ring holes at the wellsite so the pump-out ring will decouple from the mandrel at the selected release downward hydrostatic pressure. 16. The tool of claim 14 further comprising the pump-out assembly having a keeper located above the ball seat for keeping a ball below the keeper, and a ball located between the keeper and the ball seat. 17. A kit for providing a settable downhole tool for temporarily isolating a zone above the tool from a zone below the tool in a well, the kit comprising a mandrel, and one or more elements for holding the tool to the casing and sealing the tool to the casing; further comprising: a pump-out ring assembly located near the lower end of the mandrel, coupled to the mandrel, and comprising a pump-out ring with a ball seat, and one or more shearable shear elements;wherein fluid may flow through the ball seat and the mandrel when the ball seat is open;wherein fluid may not flow downward through the ball seat and the mandrel when a ball is seated in the ball seat, a seated ball in the ball seat when the pump-out ring assembly is coupled to the mandrel isolating a zone below the tool from downward fluid flow from a zone above the tool;wherein the one or more shear elements couple the pump-out ring assembly to the mandrel;wherein the minimum downward hydrostatic pressure on the pump-out assembly needed to shear the shear elements coupling the pump-out ring assembly to the mandrel is the first release downward hydrostatic pressure;multiple holes in the mandrel or the bottom assembly which extend through the mandrel or the bottom assembly, and multiple holes in the outer surface of the pump-out ring, and at least some of the holes in the mandrel or the bottom assembly correspond to at least some of the holes in the pump-out ring assembly;multiple shear elements located in at least some of the multiple holes in the mandrel or bottom assembly and extending into multiple corresponding holes in the outer surface of the pump-out ring assembly;the multiple shear elements extending through the mandrel or the bottom assembly and into the pump-out assembly coupling the pump-out ring assembly to the mandrel;wherein the cumulative number and shear strength of the one or more shear elements coupling the pump-out ring assembly to the mandrel determine; at least in part, the first release downward hydrostatic pressure;wherein the number and shear strength of the one or more shear elements can determined before the tool is put into the well and the selected shear elements can be inserted into the tool before it is put into the well;wherein responsive to a first downward hydrostatic pressure on the tool, which is less than a first release downward hydrostatic pressure, the mandrel remains closed;wherein responsive to a second hydrostatic pressure on the tool, which is equal to or greater than a first release downward hydrostatic pressure, the one or more shear elements shear, decoupling the pump-out ring assembly from the mandrel, and opening the mandrel to downward fluid flow;wherein changing the number of shear screws to couple the pump-out ring assembly with the mandrel or a bottom assembly when assembling the tool changes the preset release downward hydrostatic pressure;wherein the pump-out ring may couple with the bottom assembly through multiple possible combinations of shear elements, and the assembled tool's selected combination of the shear elements provides can provide a selected preset release downward hydrostatic pressures. 18. A method of making a downhole tool for temporarily isolating a zone above the tool from a zone below the tool in a hydrocarbon well, the method comprising the steps of: providing the components of the tool of claim 7, including a mandrel and one or more elements for holding the tool to the casing and sealing the tool to the casing;providing a pump-out ring assembly located near the lower end of the mandrel, coupled to the mandrel, and comprising a pump-out ring with a ball seat, and one or more shearable shear elements;wherein fluid may flow through the ball seat and the mandrel when the ball seat is open;wherein fluid may not flow downward through the ball seat and the mandrel when a ball is seated in the ball seat, a seated ball in the ball seat when the pump-out ring assembly is coupled to the mandrel isolating a zone below the tool from downward fluid flow from a zone above the tool;wherein the one or more shear elements couple the pump-out ring assembly to the mandrel;wherein the minimum downward hydrostatic pressure on the pump-out assembly needed to shear the shear elements coupling the pump-out ring assembly to the mandrel is the first release downward hydrostatic pressure;multiple holes in the mandrel or the bottom assembly which extend through the mandrel or the bottom assembly, and multiple holes in the outer surface of the pump-out ring, and at least some of the holes in the mandrel or the bottom assembly correspond to at least some of the holes in the pump-out ring assembly;multiple shear elements located in at least some of the multiple holes in the mandrel or bottom assembly and extending into multiple corresponding holes in the outer surface of the pump-out ring assembly;the multiple shear elements extending through the mandrel or the bottom assembly and into the pump-out assembly coupling the pump-out ring assembly to the mandrel;wherein the cumulative number and shear strength of the one or more shear elements coupling the pump-out ring assembly to the mandrel determine the first release downward hydrostatic pressure;wherein the number and strength of the one or more shear elements is determined before the tool enters the well;wherein responsive to a first downward hydrostatic pressure on the tool, which is less than a first release downward hydrostatic pressure, the mandrel remains closed;wherein responsive to a second hydrostatic pressure on the tool, which is equal to or greater than a first release downward hydrostatic pressure, the one or more shear elements shear, decoupling the pump-out ring assembly from the mandrel, and opening the mandrel to downward fluid flow;wherein the pump-out ring may couple with the bottom subassembly through multiple possible combinations of shear elements for the unassembled tool, and the assembled tool's selected combination of the shear elements providing multiple possible preset release downward hydrostatic pressures; andselecting the number of shear screws to couple the pump-out ring assembly with the mandrel or a bottom sub when assembling the tool to set the preset release downward hydrostatic pressure; andassembling the components to produce the tool of claim 7. 19. A method of fracing, completing and producing a well comprising the steps of: providing the tool of claim 14 to a well site;selecting and installing shear elements into the tool at the wellsite to set the tool's preset release hydrostatic downward pressure;setting the tool of claim 14 in the well;using the tool to isolate a zone above the tool from a zone below the tool;fracing a zone above the tool;applying downward hydraulic pressure on the tool which exceeds the shear strength of the pump-out ring's shear elements, shearing the tool's shear elements in opening the tool's mandrel to downward fluid flow through it; andcompleting and producing the well.