COILED TUBING PERCUSSION DRILLING

Abstract

A method of drilling a subterranean wellbore can include extending coiled tubing into the wellbore, and actuating an impact tool interconnected to the coiled tubing, thereby delivering impacts to a drill bit. A coiled tubing drilling system for drilling a subterranean wellbore can include coiled tubing, a drill bit, and an impact tool which delivers impacts to the drill bit.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC §119 of the filing date of International Application Serial No. PCT/US10/28570, filed Mar. 25, 2010. The entire disclosure of this prior application is incorporated herein by this reference.

BACKGROUND

The present disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides for coiled tubing percussion drilling.

Percussion drilling has been used in the past in conjunction with segmented drill pipe, which has sufficient strength to absorb shocks produced by percussion drilling. Coiled tubing has been used in the past for drilling with a drill bit rotated by a positive displacement motor.

However, certain benefits could be achieved if percussion drilling could be used in conjunction with coiled tubing. Therefore, it will be appreciated that improvements are needed in the arts of coiled tubing drilling and percussion drilling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a coiled tubing drilling system and method which embody principles of the present disclosure.

FIG. 2 is a schematic elevational view of a bottom hole assembly which may be used in the system and method of FIG. 1.

FIG. 3 is a schematic elevational view of another configuration of the bottom hole assembly.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a coiled tubing drilling system 10 and associated method which embody principles of the present disclosure. In the system 10 and method, coiled tubing 12 is used to drill a wellbore 14.

The coiled tubing 12 is stored on a spool or reel 16 (e.g., by being wrapped about the reel). A tube guide 18 guides the coiled tubing 12 into an injector 20, which is used to convey the coiled tubing into and out of the wellbore 14.

The coiled tubing 12 extends through a blowout preventer stack 22 connected to a wellhead 24 for pressure control. Although a land-based coiled tubing rig is depicted in FIG. 1, coiled tubing can be deployed from floating rigs, jackups, platforms, subsea wellheads, or any other well location.

Fluid communication with the interior of the coiled tubing 12 is provided via a conduit 26 secured to the reel 16. In various examples described herein, fluids such as air 28, water 30, oil 32, lubricant 34, friction reducer 36, natural gas 37, mist 38, foam 40, surfactant 42, nitrogen 44, various gases 46, drilling mud 47, etc., or any combination thereof, may be flowed through the coiled tubing 12 during a drilling operation.

Natural gas 37 is not currently preferred for use as the fluid, since relatively large amounts of this flammable gas would be needed to fill the coiled tubing 12. Thus, the possible safety hazards may outweigh any economic benefits of using natural gas 37.

The nitrogen 44 may have any purity. For example, 95% purity nitrogen or 99.5 to 99.9% purity nitrogen may be used. The nitrogen 44 may be produced and/or delivered to a wellsite by any method.

The nitrogen 44 may be produced on site (e.g., by a membrane separation process), or the nitrogen could be produced off site and delivered to the well location via piping or pressurized containers. The nitrogen 44 may be produced cryogenically. Preferably, any gas 46 (such as nitrogen 44) used in the drilling operation is substantially free of oxygen, to thereby minimize corrosion of the coiled tubing 12.

At a lower end of the coiled tubing 12, a bottom hole assembly 48 is provided for performing various functions in the drilling operation. Of course, the main function performed by the bottom hole assembly 48 is cutting or drilling into the earth, in order to elongate the wellbore 14.

For this purpose, the bottom hole assembly 48 includes a drill bit 50 at its lower end. The drill bit 50 may be any type of drill bit, but is preferably designed specifically for percussion drilling (i.e., wherein impacts are repeatedly delivered to the drill bit for cutting into the earth).

Connected above the drill bit 50 is an impact tool 52 which delivers the impacts to the drill bit. Various types of impact tools may be used (e.g., pneumatic, hydraulic, electrical, magnetic, etc.).

The impacts may be delivered axially and/or torsionally to the drill bit 50. An impact tool which may be used in the system 10 is the TORKBUSTER™ marketed by Ulterra of Fort Worth, Tex. USA. Impact tools are also described in U.S. Pat. Nos. 6,742,609, 6,659,202, 5,396,965 and 7,424,922, the entire disclosures of which are incorporated herein by this reference.

The bottom hole assembly 48 can also include a variety of other components, such as measurement while drilling sensors, logging while drilling sensors, directional drilling equipment, weights, reamers, motors, shock absorbers, etc. A few of these are described more fully below, but it should be clearly understood that the bottom hole assembly 48 can comprise any number and combination of components, in keeping with the principles of this disclosure.

Referring additionally now to FIG. 2, an example of a configuration of the bottom hole assembly 48, apart from the remainder of the system 10, is schematically illustrated. In this example, the bottom hole assembly 48 includes a shock absorber 54 and one or more weights 56 (e.g., drill collars) connected to the coiled tubing 12.

The impact tool depicted in FIG. 2 is a pneumatic hammer 52a of the type which generates impacts in response to flow of gas 46 or other compressible fluids (such as air 28, natural gas 37, foam 40, nitrogen 44, etc., and/or combinations thereof). The pneumatic hammer 52a may deliver the impacts to the drill bit 50 at regular periodic intervals, the impacts may be delivered at irregular intervals, or the impacts may be delivered only when desired, etc.

Note that, in other examples, the pneumatic hammer 52a (or any other type of impact tool 52) could be combined with any of the other components of the bottom hole assembly 48. For example, the impact tool 52 could be combined with the drill bit 50 (e.g., as in the JACKBIT™ marketed by NovaDrill of Provo, Utah USA), the shock absorber 54 and/or the weight 56.

The shock absorber 54 mitigates the transfer of shock and vibration from the impact tool 52 to the coiled tubing 12. This aids in preventing fatigue damage to the coiled tubing 12 due to the operation of the impact tool 52.

The weight 56 aids the drilling operation by providing a downwardly biasing force to the drill bit 50, and by providing an inertial mass against which the impact delivered by the impact tool 52 can react. The presence of this inertial mass also aids in mitigating fatigue damage to the coiled tubing 12.

In the configuration of FIG. 2, the drill bit 50 may not rotate while the impacts are delivered from the impact tool 52 to the drill bit, and while the drill bit is cutting into the earth in the drilling operation. Thus, this example does not include any downhole means for rotating the drill bit 50 (although the impact tool 52 may cause rotation of the drill bit). However, other examples can incorporate rotation of the drill bit 50 into the drilling operation.

Referring additionally now to FIG. 3, another configuration of the bottom hole assembly 48 is representatively illustrated. In this configuration, the drill bit 50 is rotated while the impacts are delivered by the impact tool 52, and while the drill bit cuts into the earth.

As depicted in FIG. 3, a positive displacement motor or drilling turbine 58 is interconnected in the bottom hole assembly 48 above the impact tool 52. Positive displacement motors are also known to those skilled in the art as Moineau-type motors, progressive cavity motors and mud motors.

Positive displacement motors and drilling turbines produce rotation in response to flow of fluid through the motors and turbines. Examples of positive displacement motors and drilling turbines are described in U.S. Pat. Nos. 6,742,609, 7,416,034, 6,883,622, 6,527,513, 7,500,787, 7,303,007 and 6,827,160, the entire disclosures of which are incorporated herein by this reference.

Preferably, a substantially incompressible fluid (or combination of fluids) is flowed through the motor or turbine 58 to rotate the drill bit 50. The incompressible fluid(s) could be, for example, water 30, oil 32, lubricant 34, friction reducer 36 and/or drilling mud 47.

The impact tool depicted in FIG. 3 is a fluid hammer 52b of the type which generates impacts in response to flow of the incompressible fluid(s) through the fluid hammer. The fluid hammer 52b may deliver the impacts to the drill bit 50 at regular periodic intervals, or the impacts may be delivered at irregular intervals, only when desired, etc.

Thus, the flow of the incompressible fluid(s) can be used for operation of the fluid hammer 52b, as well as for operation of the motor or turbine 58. However, it should be clearly understood that it is not necessary for an impact tool used in combination with the motor or turbine 58 to generate impacts in response to flow of incompressible fluid, since other types of impact tools (such as those which generate impacts electrically, magnetically, etc.) could be used, in keeping with the principles of this disclosure.

It may now be fully appreciated that several advancements are provided to the arts of percussion drilling and coiled tubing drilling by the above disclosure. The system 10 and method described above provide for an overall increased rate of penetration in the drilling operation (in part because connections typically do not need to be made in a coiled tubing string as a wellbore is being drilled, and percussion drilling is highly effective in harder rock formations), fluid-sensitive formations can be drilled using air 28, natural gas 37, nitrogen 44, other gases 46, etc., with the configuration of FIG. 2, whereas substantially incompressible fluids can be used with the configuration of FIG. 3.

In particular, the above disclosure provides to the art a method of drilling a subterranean wellbore 14. The method includes extending coiled tubing 12 into the wellbore 14, and actuating an impact tool 52 interconnected to the coiled tubing 12, thereby delivering impacts to a drill bit 50.

The impact tool 52 may comprise a fluid hammer 52b or a pneumatic hammer 52a.

The method can include interconnecting a shock absorber 54 between the coiled tubing 12 and the impact tool 52.

Actuating the impact tool 52 may include pumping a liquid (such as water 30, oil 32, lubricant 34, friction reducer 36, surfactant 42, drilling mud 47, etc.) through the coiled tubing 12 to the impact tool 52.

Actuating the impact tool 52 may include pumping a gas 46 (such as air 28, natural gas 37, nitrogen 44, etc.) through the coiled tubing 12 to the impact tool 52.

The gas 46 may comprise nitrogen 44. Preferably, the gas 46 is substantially free of oxygen.

Actuating the impact tool 52 can include pumping, along with the gas 46, additional one or more components selected from a lubricant 34, a friction reducer 36, a foam 40, oil 32, mist 38, drilling mud 47, and water 30.

The method may include rotating the drill bit 50 while actuating the impact tool 52. Rotating the drill bit 50 can include operating a positive displacement motor or turbine 58 which rotates the drill bit 50 in response to fluid flow through the coiled tubing 12.

Actuating the impact tool 52 may be performed while the drill bit 50 is not rotated.

Actuating the impact tool 52 can include pumping a compressible fluid (such as air 28, natural gas 37, foam 40, nitrogen 44, other gases 46, etc.) through the coiled tubing 12 to the impact tool 52.

Actuating the impact tool 52 can include pumping an incompressible fluid (such as water 30, oil 32, lubricant 34, friction reducer 36, drilling mud 47, etc.) through the coiled tubing 12 to the impact tool 52.

Also described by the above disclosure is a coiled tubing drilling system 10 for drilling a subterranean wellbore 14. The system 10 can include coiled tubing 12, a drill bit 50, and an impact tool 52 which delivers impacts to the drill bit 50.

It is to be understood that the various embodiments of the present disclosure described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.

In the above description of the representative embodiments of the disclosure, directional terms, such as “above,” “below,” “upper,” “lower,” etc., are used for convenience in referring to the accompanying drawings. In general, “above,” “upper,” “upward” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below,” “lower,” “downward” and similar terms refer to a direction away from the earth's surface along the wellbore.

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present disclosure. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.

Claims

1. A method of drilling a subterranean wellbore, the method comprising:

extending coiled tubing into the wellbore; and

actuating an impact tool interconnected to the coiled tubing, thereby delivering impacts to a drill bit.

2. The method of claim 1, wherein the impact tool comprises a fluid hammer.

3. The method of claim 1, wherein the impact tool comprises a pneumatic hammer.

4. The method of claim 1, further comprising interconnecting a shock absorber between the coiled tubing and the impact tool.

5. The method of claim 1, wherein actuating the impact tool further comprises pumping a liquid through the coiled tubing to the impact tool.

6. The method of claim 1, wherein actuating the impact tool further comprises pumping a gas through the coiled tubing to the impact tool.

7. The method of claim 6, wherein the gas comprises nitrogen.

8. The method of claim 6, wherein the gas is substantially free of oxygen.

9. The method of claim 6, wherein actuating the impact tool further comprises pumping, along with the gas, additional one or more components selected from a lubricant, a friction reducer, a foam, oil, a mist, drilling mud, and water.

10. The method of claim 1, further comprising rotating the drill bit while actuating the impact tool.

11. The method of claim 10, wherein rotating the drill bit further comprises operating a positive displacement motor which rotates the drill bit in response to fluid flow through the coiled tubing.

12. The method of claim 10, wherein rotating the drill bit further comprises operating a turbine which rotates the drill bit in response to fluid flow through the coiled tubing.

13. The method of claim 1, wherein actuating the impact tool is performed while the drill bit is not rotated by a motor.

14. The method of claim 1, wherein actuating the impact tool further comprises pumping a compressible fluid through the coiled tubing to the impact tool.

15. The method of claim 1, wherein actuating the impact tool further comprises pumping an incompressible fluid through the coiled tubing to the impact tool.

16. A coiled tubing drilling system for drilling a subterranean wellbore, the system comprising:

coiled tubing;

a drill bit; and

an impact tool which delivers impacts to the drill bit.

17. The system of claim 16, wherein the drill bit rotates while the impact tool delivers the impacts to the drill bit.

18. The system of claim 16, further comprising a positive displacement motor which rotates the drill bit in response to fluid flow through the coiled tubing.

19. The system of claim 16, further comprising a turbine which rotates the drill bit in response to fluid flow through the coiled tubing.

20. The system of claim 16, wherein the impact tool delivers the impacts to the drill bit while the drill bit is not rotated by a motor.

21. The system of claim 16, wherein the impact tool actuates in response to a compressible fluid flowed through the coiled tubing to the impact tool.

22. The system of claim 16, wherein the impact tool actuates in response to an incompressible fluid flowed through the coiled tubing to the impact tool.

23. The system of claim 16, wherein the impact tool comprises a fluid hammer.

24. The system of claim 16, wherein the impact tool comprises a pneumatic hammer.

25. The system of claim 16, further comprising a shock absorber interconnected between the coiled tubing and the impact tool.

26. The system of claim 16, wherein the impact tool actuates in response to a liquid flowed through the coiled tubing to the impact tool.

27. The system of claim 16, wherein the impact tool actuates in response to a gas flowed through the coiled tubing to the impact tool.

28. The system of claim 27, wherein the gas comprises nitrogen.

29. The system of claim 27, wherein the gas is substantially free of oxygen.

30. The system of claim 27, wherein the impact tool actuates in response to, along with the gas, additional one or more components selected from a lubricant, a friction reducer, a foam, oil, a mist, drilling mud, and water, flowed through the coiled tubing to the impact tool.