IMPROVED TOOL

Abstract

A downhole tool (1) for manipulating a target, includes a housing (2). The housing includes an inner surface (5) configured for mounting to a tubular carrier; and an outer surface (10). At least one chamber (20) is provided between the inner surface (5) and the outer surface (10) and contains at least one propellant source (22) and an ignition system. One or more outlets (12) lead from the chamber (20) to the outer surface (10), for combustion products from the at least one propellant source. The downhole tool may be employed for perforating and may be included in a hydraulic fracturing assembly. A method of hydraulic fracturing in a wellbore using the tool is provided.

Claims

1. A downhole tool for manipulating a target, wherein the tool comprises a housing, the housing comprising: an inner surface configured for mounting to a tubular carrier in use; an outer surface; at least one chamber provided between the inner surface and the outer surface and containing at least one propellant source; an ignition system for igniting propellant at the at least one propellant source; and one or more outlets leading from the chamber to the outer surface, for combustion products from the at least one propellant source.

2. The downhole tool of claim 1 wherein the inner surface takes the form of the surface of a bore passing through the tool from a first end to a second end.

3. The downhole tool of claim 1 wherein the inner surface is formed from a portion of the wall of a tubular carrier.

4. The downhole tool of claim 2 wherein the inner surface comprises the surface of a generally cylindrical bore passing through from a first end to a second end of the housing.

5. The downhole tool of claim 1 wherein the outer surface of the tool is generally cylindrical.

6. The downhole tool of claim 1 wherein the at least one propellant source comprises a charge of a propellant composition, or components for a propellant composition, placed at a selected location within the at least one chamber.

7. The downhole tool of claim 6 wherein the at least one propellant source comprises one or more blocks of a solid propellant placed within the at least one chamber.

8. The downhole tool of claim 1 wherein the at least one propellant source is an opening into the at least one chamber from a supply system that feeds a propellant composition or the components for a propellant composition into the chamber for ignition by the ignition system.

9. The downhole tool of claim 1 wherein two or more propellant sources are placed in the at least one chamber so as to direct their combustion products towards each other to provide flows of combustion products that interact as they collide before exiting the chamber via the outlet.

10. The downhole tool of claim 1 wherein at least one outlet comprises two or more apertures each of which acts as a nozzle for jets of combustion products following ignition of propellant.

11. The downhole tool of claim 1 wherein the outlet or outlets are closed before ignition of propellant from the propellent source or sources.

12. The downhole tool of claim 11 wherein the outlet or outlets are sealed before ignition of propellant.

13. The downhole tool of claim 11 wherein pressure generated following ignition of propellant from the propellant source or sources moves a part or parts of the tool to uncover the outlet or outlets.

14. The downhole tool of claim 1 wherein the one or more outlets are provided on at least one circumferential ring, each circumferential ring forming part of the outer surface of the tool.

15. The downhole tool of claim 14 wherein the at least one chamber is provided within a cylindrical sleeve, and the housing comprises the cylindrical sleeve and the at least one circumferential ring, to provide a generally cylindrical housing with a bore therethrough.

16. The downhole tool of claim 1 wherein the tool is a downhole perforator tool.

17. The downhole tool of claim 16 comprising a plurality of outlets spaced apart circumferentially and/or axially about the outer surface.

18. The downhole tool of claim 16, wherein the tool is elongate and generally cylindrical and comprises: a first array of axially spaced apart outlets along the outer surface following a line parallel with the longitudinal axis of the tool and a second array of axially spaced outlets diametrically opposite the first.

19. The downhole tool of claim 16, wherein the tool is elongate and generally cylindrical and comprises: two or more arrays of outlets, each array comprising circumferentially spaced apart outlets with each array axially spaced from the next along the length of the housing.

20. The downhole tool of claim 19, wherein each array of outlets is provided on a circumferential ring that forms part of the outer surface of the tool.

21. The downhole tool of claim 20, wherein the outlets of one array are circumferentially staggered with respect to the outlets of the next array along the length of the housing.

22. The downhole tool of claim 1 further comprising a control module.

23. The downhole tool of claim 1 further comprising at least one protector having a larger diameter than the housing.

24. The downhole tool of claim 23 comprising two protectors having a larger diameter than the housing, placed one at either end of the tool.

25. The downhole tool of claim 24, wherein the tool is elongate and generally cylindrical and comprises generally cylindrical protectors, one fitted to each end of the housing.

26. The downhole tool of claim 23 wherein at least one protector is provided with at least one passage for fluid therethrough.

27. The downhole tool of claim 23 wherein the protectors have a conical end, narrowing in the direction away from the housing.

28. A hydraulic fracturing assembly comprising: a) a tubular carrier comprising one or more frac sleeves and two or more packers; and b) a downhole perforator tool in accordance with claim 16.

29. A method of hydraulic fracturing in a wellbore, the method comprising the steps of: a) deploying a tubular carrier downhole in a rock formation, wherein the tubular carrier mounts at least one downhole perforator tool as defined in claim 16, and includes at least one frac sleeve and two or more packers for isolating sections of the annulus; b) operating the downhole perforator to produce access holes into the rock formation; c) setting the packers to isolate a section of the annulus including the access holes and the at least one frac sleeve; and d) pumping fracking fluid through the tubular carrier and out of the at least one frac sleeve into the annulus, to fracture the rock formation via the access holes.

30. The method of claim 29 further comprising unsetting the packers, to release sealing contact, and removing the tubular carrier from the wellbore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1a shows a downhole tool in schematic perspective;

[0055] FIG. 1b shows in magnification, outlets of the tool shown in FIG. 1a;

[0056] FIGS. 1c and 1d show schematic cross section views of the tool of FIG. 1a;

[0057] FIGS. 1e and 1f show details of outlets of the tool of FIG. 1a;

[0058] FIG. 2 shows a tool carrier in schematic perspective;

[0059] FIG. 3a shows a tool on a carrier in schematic perspective;

[0060] FIG. 3b shows a circumferential ring of the tool of FIG. 3a;

[0061] FIG. 3c shows in perspective view with cut away part of the tool of FIG. 3a; and

[0062] FIGS. 3d and 3e show cross section views of the tool 1 of FIG. 3a.

DETAILED DESCRIPTION OF THE DRAWINGS

[0063] FIG. 1a shows a downhole tool 1 in schematic perspective with some parts cut away to allow viewing of the interior. The tool 1 is a perforator tool and is cylindrical in form. Cylindrical housing 2 has a cylindrical bore 4, the surface 5 of the bore (see FIGS. 1c and 1d) provides an inner surface of the housing, running from a first end 6 through to a second end 8.

[0064] The outer surface 10 of the housing 2 includes outlets 12. The outer surface 10 includes cover plates 13 in this example, through which the outlets 12 emerge. Three outlets 12 are visible and constitute an array of outlets that are spaced axially on the outer surface 10 along a line parallel to the longitudinal axis of the tool. Not visible in this view is a corresponding array of outlets 12 diametrically opposite those that are in view.

[0065] Protectors 14 are fitted to the first 6 and second 8 ends of the housing 2. The protectors 14 are cylindrical and have a larger diameter than that of the housing 2. Ends 16 of the protectors 14 are conical, narrowing in the direction away from the housing 2. The protectors have passages 18 therethrough to allow fluid communication (see FIGS. 1c and 1d). Each outlet 12 has an associated chamber 20 between the inner surface 5 and the outer surface 10, one chamber 20 is visible by the cut away on the figure.

[0066] As shown at the cut away, the chamber 20 has the corresponding outlet 12 placed centrally. Charges 22 of solid propellant are placed in chamber 20 to either side of the outlet 12. Magnified view FIG. 1b shows that the outlets 12 comprise two apertures 24 constituting nozzles for the emanation of combustion products from the propellant charges 22, following their ignition. The apertures 24 are shown sealed with a fusible metal (e.g. zinc) that will be melted or even combusted when the propellant is ignited.

[0067] The tool 1 also includes a control module 25 that can receive wired or wireless communications from the surface and includes the electronics for an ignition system for propellant.

[0068] FIGS. 1c and 1d show cross sections of the tool 1 of FIG. 1a. FIG. 1c shows a section at diametrically opposed outlets 12, FIG. 1d shows the arrangement of propellant charges 22 within chambers 20. Details of outlets 12 are shown in FIGS. 1e and 1f. FIG. 1e shows the interior of an outlet 12 with shaped projections 26 (also visible in cross section FIG. 1c) for directing flows of combustion products (as suggested by arrows C) towards apertures 24. FIG. 1f shows the outer surface of outlet 12. The outlet 12 projects slightly above the surface 27 as a cover plate 13 surrounds it (see FIGS. 1a and 1c).

[0069] FIG. 2 shows a section of a tubular carrier 28 to which tools similar to those depicted in FIG. 1 can be fitted. In this example tubular 28 has a protector 14 fitted. A tool such as that shown in FIG. 1 but without protectors 14 fitted to the housing can be slid onto tubular carrier 28 until an end is adjacent protector 14. A further protector 14 can then be fitted onto tubular 28 adjacent the other end of the tool.

[0070] Part of an alternative tool 1 is shown fitted to a tubular carrier 28 in FIG. 3a. The housing includes circumferential rings 30, each having three outlets 12 about the circumference of the corresponding ring 30. The outlets 12 of one array 30 are staggered circumferentially with respect to the outlets 12 on the next array along the length of the tool.

[0071] FIG. 3b shows a circumferential ring 30 for the tool of FIG. 3a. Outlets 12 are spaced at 120 degrees around the ring 30. Each outlet 12 has an inlet passage 32 for communication with a chamber containing a propellant source. Each outlet 12 has two apertures 24 on the outer surface of ring 30 for emanation of combustion products.

[0072] FIG. 3c shows in perspective view with cut away part of the tool of FIG. 3a. In this example outer surface 10 of housing 2 comprises the outer surface of circumferential ring 30 and cylindrical sleeves 34, of metal. Inner surface 5 formed about bore 4 is formed of a resin, such as a phenolic resin. This arrangement allows access to chambers 20 during manufacture of the tool, to allow placement of propellant charges 22 in chambers 20. In this example blocks of a phenolic resin 36 are placed within the cavity defined by the inner surface 5 of the tool 1 and the inner surface of sleeves 34 to divide it into chambers 20. Thus each chamber 20 provides combustion products from propellant charges 22 to its respective outlet 12.

[0073] FIGS. 3d and 3e show cross section views of the tool 1 of FIG. 3a. In FIG. 3d the cross section is shown at a circumferential ring 30 allowing a view of outlets 12 and the inlet passages 32, through which propellant charges 22 in chambers 20 can be seen.

[0074] In FIG. 3e the cross section is shown through a cylindrical sleeve 34, and shows the arrangement of propellant charges 22 in chambers 20 around the circumference of the tool. Also visible in this view is an outer liner 38 of a phenolic resin provided about the whole inner surface of the cylindrical sleeve 34.