DOWNHOLE VIBRATION TOOL

Abstract

A downhole vibration tool has an outer housing having an inner surface that defines an inner bore and a flow diverter positioned within the inner bore, the flow diverter having an inner passage and an outer surface that defines a flow path between the inner surface of the outer housing and the flow diverter. A removable plug blocks the inner passage, the plug being removable to open the inner passage. A rotating member is rotatably carried within the outer housing and downstream of the flow diverter, the rotating member comprising a rotor in fluid communication with the flow path and an eccentric mass.

Description

TECHNICAL FIELD

This relates to a downhole vibration tool, such as a vibration tool that may be included in a drill string.

BACKGROUND

Downhole vibrating tools are commonly used in drill strings to reduce friction during drilling. U.S. Pat. No. 7,708,088 (Allahar et al.) entitled “Vibrating downhole tool” describes a tool that uses an eccentric mass on an inner mandrel that is driven by turbine blades. As the mandrel rotates, the eccentric mass causes the tool and the drill string to vibrate.

SUMMARY

According to an aspect, there is provided a downhole vibration tool, comprising an outer housing having an inner surface that defines an inner bore and a flow diverter positioned within the inner bore. The flow diverter has an inner passage and an outer surface that defines a flow path between the inner surface of the outer housing and the flow diverter. A removable plug blocks the inner passage, the plug being removable to open the inner passage. A rotating member is rotatably carried within the outer housing and downstream of the flow diverter. The rotating member comprises a rotor in fluid communication with the flow path and an eccentric mass.

According to another aspect, the rotor comprises a plurality of turbine blades.

According to another aspect, the rotor comprises a single stage turbine.

According to another aspect, the eccentric mass is positioned within a sealed chamber below the rotor.

According to another aspect, the flow path is radially concentric and outside the inner passage.

According to another aspect, the rotating member comprises ports below the rotor that provide fluid communication between the flow path and the inner bore.

According to another aspect, the rotating member is supported by axial and radial bearings within the outer housing.

According to an aspect, there is provided a method of drilling, comprising the steps of providing a drill string having an inner bore, the drill string comprising a drill bit at a downhole end, a measurement while drilling tool adjacent to the drill bit, and a vibrating tool as described above; pumping fluid through the inner bore of the drill string, the fluid being diverted by the removable plug through the flow path, the fluid operating the vibrating tool and the drill bit; removing the plug to access the inner passage; and retrieving the measurement while drilling tool through the vibrating tool.

It will be understood that the above aspects may be combined in any reasonable combination.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

FIG. 1 is a side elevation view in section of the vibrating tool.

FIG. 2 is a schematic diagram of a drill string.

FIGS. 3a-3d are detailed side elevation views in section of the vibrating tool.

FIG. 4 is a detailed side elevation view of the plug seat after the plug has been removed.

DETAILED DESCRIPTION

A downhole vibrating tool, generally identified by reference numeral 10, will now be described with reference to FIGS. 1-3d.

Referring to FIG. 2, downhole vibration tool 10 is part of a drill string 100 that has a MWD (measurement while drilling) tool 102 adjacent to a drill bit 104. Downhole vibration tool 10 is used to enhance the operation of drill string 100 as it drills a borehole.

Referring to FIG. 1, downhole vibration tool has an outer housing 12 with an inner surface 14 that defines an inner bore 16 and a flow diverter 18 positioned within inner bore 16.

Flow diverter 18 has an inner passage 20 and an outer surface 22 that defines a flow path 24 between inner surface 14 of outer housing 12 and flow diverter 18. Flow path 24 has upper ports 26 and lower ports 28, each in communication with inner bore 16. Preferably, flow path 24 is concentric with and outside inner passage 20 within outer housing 12. A removable plug 21 is positioned to block the inner passage 20. Plug 21 is removable to open inner passage 20, such as to provide access through flow diverter 18. Preferably, plug 21 allows access to the full bore inner diameter when removed. This may be done to provide access to drill string 100 below vibration tool 10. For example, this may be done to access MWD tool 102 or drill bit 104.

A rotating member 30 is rotatably carried within outer housing 12 and downstream of flow diverter 18. Rotating member 30 has a rotor 32 in fluid communication with flow path 24 and an eccentric mass 33 and flow ports 28 below rotor 32. It has been found that diverting fluid through the flow path 24, which is outside the bore, the effects of washing, or erosion caused by abrasives in the drilling fluid, is reduced.

As shown, flow diverter 18 has a first portion 34 that is threaded into outer housing 12 and locked into place such that it cannot be rotated and a second, and an inner portion 36 that is removed with plug 21. As can be seen, inner portion 36 has a locking piece 37 that engages an inner surface of flow diverter 18. As locking piece 37 is released, plug 21 and second portion 36 are free to be removed. Preferably, referring to FIGS. 3a and 3b, second portion 36 is sealed against first portion 34 by seals 38 and second portion 36 seals against plug 21 by seals 40 when received. Seals 38 and 40 are used to ensure the fluid flows through flow path 24. Second portion 36 also extends downward from flow diverter 18 and engages rotating member 30. As shown, seals 42 are provided that seal between rotating member 30 and second portion 36.

Referring to FIG. 3b, plug 21 has a fishing neck 39 that allows a fishing tool (not shown) to grip and remove plug 21. As plug 21 is removed, inner portion 21 is also removed. Referring now to FIG. 4, by removing inner portion 36 and plug 21, vibration tool 10 is able to provide “full bore” access to the rest of drill string 100, as indicated by the broken lines.

In one example, flow diverter 18 has stators 44 in flow path 24 that direct the fluid onto rotor 32, which may be a turbine 46 with a single stage of turbine blades. While there may be more than one stage, it has been found that a single stage provides for higher speed, particularly at low pressure, due to the lower weight compared to the conventional practice of using multiple stages. While multiple stages increases torque, it also results in a lower speed. In addition, a single stage blade design allows for higher solid contents or LCM content in the drilling fluids pumped through inner bore 16. Preferably, the turbine blades are removable and can be replaced with a different pitch or with more stages.

Referring to FIGS. 3b and 3c, eccentric mass 26 is carried below rotor 32 in a sealed chamber 48. Eccentric mass 26 rotates with rotor 32 and provides radial vibrations that, in a drilling operation, make the operation more efficient by reducing the necessary torque without interfering with typical drilling operations and without transmitting vibrations to the surface or bit. While not required, housing eccentric mass 26 in sealed chamber 48 instead of open to inner bore 16 may be preferred in some circumstances to allow for more efficient operation by reducing the friction during rotation and help reduce pressure loss. As is known, chamber 48 is balanced to reduce any hydrostatic build up. As shown in FIG. 3c, bearing surfaces 50 are provided above and below eccentric mass 26 to properly support the rotation of eccentric mass 26. Bearing surfaces 50 as shown are radial and axial bushings, which have some size advantages given the limited space available. Other bearing surfaces, such as roller bearings could also be used if desired. The lower bearing surfaces 50 are supported from the bottom by a threaded collar 52 and are held stationary relative to outer housing 12.

According to an aspect, there is provided a method of drilling, comprising the steps of providing a drill string having an inner bore, the drill string comprising a drill bit at a downhole end, a measurement while drilling tool adjacent to the drill bit, and a vibrating tool as described above; pumping fluid through the inner bore of the drill string, the fluid being diverted by the removable plug through the flow path, the fluid operating the vibrating tool and the drill bit; removing the plug to access the inner passage; and retrieving the measurement while drilling tool through the vibrating tool.

In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

The scope of the following claims should not be limited by the preferred embodiments set forth in the examples above and in the drawings, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1. A downhole vibration tool, comprising:

an outer housing having an inner surface that defines an inner bore;

a flow diverter positioned within the inner bore, the flow diverter having an inner passage and an outer surface that defines a flow path between the inner surface of the outer housing and the flow diverter;

a removable plug that blocks the inner passage, the plug being removable to open the inner passage; and

a rotating member rotatably carried within the outer housing and downstream of the flow diverter, the rotating member comprising a rotor in fluid communication with the flow path and an eccentric mass.

2. The downhole vibration tool of claim 1, wherein the rotor comprises a plurality of turbine blades.

3. The downhole vibration tool of claim 1, wherein the rotor comprises a single stage turbine.

4. The downhole vibration tool of claim 1, wherein the eccentric mass is positioned within a sealed chamber below the rotor.

5. The downhole vibration tool of claim 1, wherein the flow path is radially concentric and outside the inner passage.

6. The downhole vibration tool of claim 1, wherein the rotating member comprises ports below the rotor that provide fluid communication between the flow path and the inner bore.

7. The downhole vibration tool of claim 1, wherein the rotating member is supported by axial and radial bearings within the outer housing.

8. A method of drilling, comprising the steps of:

providing a drill string having an inner bore, the drill string comprising a drill bit at a downhole end, a measurement while drilling tool adjacent to the drill bit, and a vibrating tool connected in the drill string, the vibrating tool comprising: an outer housing having an inner surface that defines an inner bore; a flow diverter positioned within the inner bore, the flow diverter having an inner passage and an outer surface that defines a flow path between the inner surface of the outer housing and the flow diverter; a removable plug that blocks the inner passage, the plug being removable to open the inner passage; and a rotating member rotatably carried within the outer housing and downstream of the flow diverter, the rotating member comprising a rotor in fluid communication with the flow path and an eccentric mass;

pumping fluid through the inner bore of the drill string, the fluid being diverted by the removable plug through the flow path, the fluid operating the vibrating tool and the drill bit;

removing the plug to access the inner passage; and

retrieving the measurement while drilling tool through the vibrating tool.

9. The method of claim 8, wherein the rotor comprises a plurality of turbine blades.

10. The method of claim 8, wherein the rotor comprises a single stage turbine.

11. The method of claim 8, wherein the eccentric mass is positioned within a sealed chamber below the rotor.

12. The method of claim 8, wherein the flow path is radially concentric and outside the inner passage.

13. The method of claim 8, wherein the rotating member comprises ports below the rotor that provide fluid communication between the flow path and the inner bore.

14. The method of claim 8, wherein the rotating member is supported by axial and radial bearings within the outer housing.