Tool Having an Integral Premature Deployment Guard

Abstract

A downhole tool for preventing flow within a portion of an oil/gas well includes a mechanism for preventing premature deployment of portions of the tool. The bottom portion of the tool is configured to insure flow through the tool from a zone below the tool after certain processes have been completed within the well.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

This invention is directed to a downhole tool for an oil/gas well that is used to isolate a portion of the well from fluid flow. These devices are commonly referred to as frac plugs, packers, and the like.

Background of the Invention

Tools that are currently in use may use bands, adhesive, or pins to hold in place certain components that are designed to radially expand when deployed. These have proven to be unreliable during storage, transportation, and when running the tool into the well and may require additional components.

Furthermore these types of tools have an internal flow path for allowing fluid to flow freely through the tool from the section of the well below the tool to the section of the well above the tool and vice-versa. These flow paths may be block by balls or other items that are used to selectively block flow through other tools in the well.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

The above deficiencies are solved by providing a positive interface between the radially expanding segments of the tool and a second portion of the tool. The downhole portion of the tool is formed with a plurality of intersecting planar faces that will prevent an object such as a ball from blocking flow and will provide passageways for fluid that combined have a flow area equivalent to or greater than the flow area of the central fluid flow passage of the tool at the entrance of the central fluid passage

The arrangement of the radially expanding portions of the tool will result in positive physical interface between a minimum of two components, and positive holding force during deployment where vibration, high speeds and impacts are prevalent.

The interface allows for a one hundred percent disengagement rate upon activation and results in less stress on components during activation, deployment, and transportation compared to the prior art. It also eases the assembly of the tool by providing less components.

Under high rates of deployment speed where fluid is being pumped over the components, the interface is stronger than other restraining methods. Where other pieces may come loose due to the fluid flow above and below the components, differential pressure, impacts, vibration, the invention will have a higher resistance to these forces by providing a positive overlap interface rather than relying on a restraining method such as bands, adhesive, pining, wire, etc.

The planar beveled surfaces on the downhole portion of the tool provide an unrestricted flow area from below the tool to above the tool and always diverts balls or other obstructions below the tool to one side of the well casing thereby maintaining a flow path are below the tool that is equivalent to or greater than the tool's internal flow path area.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:

FIG. 1 is a perspective view of a tool according to an embodiment of the invention.

FIG. 2 is a cross sectional view of the embodiment of FIG. 1.

FIG. 3 is a side view of the anti-premature deployment arrangement for the slips in the non-deployed position.

FIG. 4 is a side view of the anti-premature deployment mechanism at the beginning of deployment.

FIG. 5 is a side view of the slip in a deployed position.

FIG. 6 is a perspective view of the rear portion of the tool having the beveled planar portions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2 a tool 10 according to an embodiment of the invention includes a central mandrel 11 having an internal flow passage 33. A setting ring 12 is axially movable on mandrel 11 and engages a first plurality of slips 13. Slips 13 have pins 20 that are adapted to engage the inner wall of the wall casing on deployment of the tool. Slips 13 surround mandrel 11 and partially rest on annular ramp 14. Slips 13 and ramp 14 have engaging ramp surfaces as is known in the art. The slip may be a single member or a plurality of segments. An expandable elastomeric seal 15 surrounds mandrel 11. A second annular ramp 18 having either an annular ramp or a plurality of beveled ramp surfaces 19 surrounds mandrel 11 such that expandable seal 15 is positioned between ramps 14 and 18. A plurality of slips 17 surround mandrel 11. Slips 17 have a plurality of pins 19 that are adapted to engage the inner wall of the well casing.

The rear portions of slips 17 about an annular stop bottom sub 21 that is pinned to the rear portion of mandrel 11 by pins 31, 32. A pump down seal 22 is positioned around bottom sub 21.

As shown in FIGS. 3-5, a rear portion of each slip 17 includes a transversely extending slot 42. A front face of bottom sub 21 includes an annular rib 41 that is adapted to be positioned within the accurate slots 42 that are formed in a rear face of slips 17. Thus, in the non-deployed condition of FIG. 3, the slips 17 are confined by ramp 18 mandrel 11 and bottom sub 21. The front surfaces of slips 13 may also be provided with a notch that cooperates with a rib on the back surface of setting ring 12. Additionally, other moveable components of the tool may be similarly equipped.

To deploy the tool, setting ring 12 is engaged by a setting tool and is moved axially. This in turn moves slips 13, ramp 14, seal 15, and ramps 18 along mandrel 11. This movement causes radial expansion of seal 15 and causes slips 13 and 17 is to move radially. As deployment begins, ramp ring 18 moves rearwardly on mandrel 11. In so doing, it pushes slips 17 outwardly and annular rib 41 begins to disengage from the slots 42 in slips 17 as shown in FIG. 4. As deployment is completed ramp 18 moves to the position shown in FIG. 5 and slips 17 completely disengage from rib 41 as shown in FIG. 5.

As shown in FIG. 6, the downhole face of bottom sub 21 is formed by three beveled planar surface 23, 24, and 25. Slots 26, 27 and 28 are formed in the planar surface so as to form channels that communicate with internal passageway 33 that extends through bottom sub 22. Thus any balls or constrictions in the well below the tool that flow back will be deflected to the side of the casing. The flow areas of the channels 27 can be selected so that the total flow area of the channels is equivalent to or greater the flow area of the flow passage 33 at the entrance to the central fluid passage at the base of the mandrel. The beveled surfaces may be cut at different angles with respect to the longitudinal axis of the tool. The beveled surfaces are constructed of two or more cuts to the bottoms sub that are not symmetrical along a longitudinal axis of the bottom sub nor are they mirrored about a dividing plane.

Other arrangements and embodiments are possible without departing from the invention which is defined by the following claims.

Claims

1. A downhole tool comprising; a) a mandrel,b) an annular seal surrounding the mandrel,c) an annular ramp mounted on the mandrel,d) a plurality of slips surrounding the mandrel,e) a stationary bottom sub fixed to the mandrel,f) means positioned between the slips and a mating component of the tool for preventing premature deployment of the slips.

2. The downhole tool of claim 1 wherein the ramp includes an inclined surface adapted to engage an inclined surface on the slips.

3. The downhole tool of claim 1 further including a setting ring mounted on the mandrel.

4. The downhole tool of claim 1 wherein a rear face of the bottom sub includes a plurality of planar beveled surfaces having different surface areas.

5. The downhole tool of claim 4 wherein the mandrel and the bottom sub have an axial flow passage.

6. The downhole tool of claim 5 wherein the beveled planar surfaces have notches formed therein that communicate with the axial flow passage of the mandrel.

7. The downhole tool of claim 6 wherein the total flow area of the notches is equivalent to or greater than the flow area of the axial flow of the mandrel.

8. The downhole tool of claim 7 wherein the flow area passages begin at the bottom of the central fluid passage located at the bottom of the mandrel at the point of entrance at a lower end of the mandrel.

9. An assembly for preventing premature deployment of an element of a downhole tool comprising; a) a first member adapted to be fixedly attached to the downhole tool, said first member including rib,b) a second member adapted to move relative to the first member, said second member having a slot which receives the rib of the first member when the tool is in a non-deployed condition.

10. The assembly of claim 8 wherein the rib is an annular rib on a front surface of the first member.

11. The assembly of claim 9 including a plurality of second members forming an annular array.

12. An assembly as claimed in claim 10 further including a mandrel and a slip ring which together with the first member restrict radial movement of the plurality of second members.

13. A bottom sub for a downhole tool comprising a body having an axial flow path and a downhole surface, the downhole surface including a plurality of beveled planar surfaces having different surface areas.

14. The bottom sub of claim 13 wherein the planar surfaces have grooves formed wherein that communicate with the axial flow path.

15. The bottom sub of claim 13 wherein the total flow area of the grooves are equivalent to or greater than the flow area of the axial flow path.

16. The bottom sub of claim 13 wherein the beveled planar surface are constructed of two or more cuts a body that are not symmetrical along a longitudinal axis of the bottom surface.

17. The bottom sub of claim 13 wherein the beveled planar surfaces are not mirrored about a dividing plane.