WO2010139009A1

WO2010139009A1 - A power sub

Info

Publication number: WO2010139009A1
Application number: PCT/AU2010/000679
Authority: WO
Inventors: Ian Mckay
Original assignee: Mortlach Holdings Pty Ltd
Priority date: 2009-06-02
Filing date: 2010-06-02
Publication date: 2010-12-09
Also published as: AU2010256346A1; AU2010256346B2

Abstract

Power sub (10) comprises a sub (12) having a tubular body (18) provided with screw threads (20) and (22) at opposite axial ends. Transmission system (14) is coupled with the sub (12) and is capable of transferring torque from a motor (24) to the sub (12) to cause rotation of the sub (12) about its longitudinal axis. Sub (12) and transmission system (14) are retained within the housing 16 with the first and second screw threads (20) and (22) being accessible from outside of the housing. Motor 24 may be either permanently held within housing (16), or detachably coupled to the housing and engagable with the transmission system (14).

Description

A POWER SUB

Field of the Invention

The present invention relates to a power sub particularly, but not exclusively for use in handling drill rods for a drill rig.

Background of the Invention

During ground drilling, in order to advance a drill string into the ground or pull the drill string from the ground, it is necessary to add or remove drill rods from the drill string. This in turn requires individual drill rods to be picked up and carried between a drill rod storage facility and a drill tower. The storage facility is usually located near a drill tower and stores the rods either horizontally or in a slightly inclined orientation so that a driller can easily access ends of the drill rods. A winch provided with a winch line, standard sub and swivel is attached to the drill tower to enable lifting of a drill rod between the drill tower and the storage facility. A sub in general terms is a short length of tube or pipe with different threads at each end. The threads may differ for example in terms of one or more of: pitch, handedness, diameter and being internal or external. An adapter or cross over sub may also be used which screws onto one end of the sub to facilitate connection to a drill rod when the thread on the drill rod does not mate with that on the standard sub. The swivel couples the standard sub to the winch line. A drill rod operator manually rotates the standard sub in order to engage and disengage the sub from a drill rod.

Summary of the Invention

According to an aspect of the invention there is provided a power sub comprising: a sub having a tubular body and first and second screw threw threads formed on, and at axially opposite ends of, the tubular body; and, a transmission system coupled with the sub and capable of transferring torque from a motor to the sub to cause rotation of the sub about an axis of the body; wherein the first and second screw threads are accessible from opposite ends outside of the power sub. The transmission system may comprise an endless loop coupling device capable of coupling the motor to the sub.

The transmission system may comprise an engagement structure about the sub which engages the endless loop coupling device and a second engagement device arranged to be driven by a motor, wherein the endless loop coupling device engages both the first and second engagement devices.

The first engagement structure may comprise an annular device coupled with the sub.

The endless loop coupling device may comprise a chain and the annular device comprises a sprocket

The power sub may comprise a support structure which maintains a fixed spatial relationship between a motor which provides drive to the sub, and the sub.

The support structure may maintain respective axes of rotation of the first and second engagement structures in a fixed spatial relationship.

The support structure may comprise two spaced apart plates through which the sub and an axis of rotation of a motor capable of driving the sub extends.

The sub may be held in a substantially constant translational position relative to an axis of the tubular body.

The power sub may comprise a stop system capable of holding the sub in the substantially constant translational position.

The stop system may comprises first and second rings fixed at spaced apart locations on the sub, and a sleeve through which the sub extends, the rings being located adjacent opposite ends of the sleeve.

The sleeve may be held in the support structure. The power sub may comprise a housing in which the transmission system and sub are retained, the sub being arranged so that the first and second screw threads are accessible from outside the housing.

The power sub may comprise a motor fixed inside the housing and coupled to the transmission system.

The motor may be an electric motor and the power sub may comprise a power pack mounted in the housing to provide electrical power to the motor.

The power sub may comprise a radio receiver located in the housing and capable of controlling the electric motor and a separate hand held radio transmitter capable of transmitting signals to the radio receiver wherein the radio receiver controls the electric motor in response to control signals transmitted by the hand held transmitter.

The power sub may comprise one or more switches mounted on the housing and coupled to the motor to enable activation and control of the motor.

In an alternate embodiment the power sub may comprise a motor capable of detachably coupling to the housing and wherein the motor engages the transmission system when coupled to the housing.

The motor is selected from one of a pneumatic motor, hydraulic motor, and electric motor.

Brief Description of the Drawings

An embodiment of the present invention will be described by way of example only with reference to the accompanying Figures in which:

Figure 1 is a schematic representation of a first embodiment of a power sub in accordance with the present invention and illustrating components internal of a housing of the power sub; Figure 2 is a perspective view of the power sub shown in Figure 1 ;

Figure 3 is a disassembled view of a second embodiment of the power sub; Figure 4 is a perspective view from a first angle of a transmission system and support system of the second embodiment of the power sub; Figure 5 is a side view of the components shown in Figure 4 but without a drive chain of the transmission system; Figure 6 is a representation of the second embodiment of the power sub from a first angle;

Figure 7 is a representation of the second embodiment of the power sub from a second angle;

Figure 8 is a schematic representation of a second embodiment of the power sub attached to a wire line; and,

Figure 9 illustrates an application of a power sub in accordance with an embodiment of the present invention.

Detailed Description of Preferred Embodiments

With reference to the accompanying drawings and in particular Figures 1 and 2 a power sub 10 in accordance with one embodiment of the present invention comprises a sub 12, a transmission system 14, retained within a housing 16. The sub 12 is in the form of a tubular body 18 having first and second screw threads 20 and 22 respectively formed on, and at axially opposite ends. In this specific example, thread 20 is formed on an outer surface of tubular body 18, while screw thread 22 is formed on an inner surface of tubular body 18. Transmission system 14, which will be described in greater detail below, is coupled with the sub 12 and is capable of transferring torque from a motor 24 to the sub 12 to effect rotation of sub 12 about longitudinal axis 26 of body 18. Both threads 20 and 22 are accessible from opposite ends of power sub 10. Moreover, in this embodiment, both axial ends of sub 12 extend from housing 16.

In the embodiment shown in Figures 1 and 2, the motor 24 is retained within housing 16. However, in an alternate embodiment described in greater detail below, rather than being retained within housing 16, a motor may be releasably clamped or held within housing 16 to engage transmission system 14.

Sub 12 is held in two spaced apart bearings 27 which in turn are fitted inside sleeve 28. Each bearing 27 has an annular outer race fixed to the inside of sleeve 28 and an annular inner race which receives an outer circumferential surface of an intermediate portion 30 of sub 12. Ball bearings between the inner and outer races facilitate the rotation of sub 12 about axis 26.

A support structure 31 in the form of two spaced apart plates 32a and 32b (hereinafter referred to in general as "plates 32") hold sleeve 28 and sub 12 in a fixed spatial relationship to motor 24. Each plate 32 is provided with a first hole marginally greater than an outer diameter of sleeve 28. Sleeve 28 is passed through the holes in the plates 32 and held by grub screws 34. Lubricant such as grease, oil or graphite is provided between sleeve 28, bearings 27 and intermediate portion 30.

Translational or linear motion of sub 12 along its axis 26 is stopped by a stopper system which comprises the sleeve 28 and rings 36 and 38 which are fixed to sub 12. Each ring 36 and 38 has an outer diameter which is greater than an inner diameter of sleeve 28. This outer diameter is also greater than a diameter of respective holes 40 (only one shown in Figure 2) in housing 16 through which respective ends of sub 12 extend. Rings 36 and 38 are fixed by any appropriate means such as screws, welding or a press fit on sub 12. Ring 36 is located between one end of sleeve 28 and an adjacent or closest wall 42a of housing 16. Ring 38 is located between an opposite end of sleeve 28 and an adjacent wall 42b of housing 16. O-ring seal assemblies 43 form seals about holes 40 through which opposite ends of sub 12 extend thereby minimizing the likelihood of the ingress of water or foreign matter into housing 16.

Motor 24 in the present embodiment is an electric motor which is retained in housing 16 by support structure 31/plates 32. In particular, plates 32 are formed with respective second holes of a diameter marginally greater than an outer diameter of motor 24 so that motor 24 can be located within these holes and retained by plates 32 by any appropriate means such as for grub screws 44.

Transmission system 14 transmits torque from motor 24 to drive sub 12. Transmission system 14 comprises: an endless loop coupling device in the form of a chain 46; a first engagement structure in the form of a cog or sprocket 48 that extends about and is fixed or coupled to sub 12; and, a second engagement structure in the form of cog or sprocket 50 attached to a drive shaft 52 of motor 24. Sprocket 48 may be fastened to sub 12 either directly or by attachment to ring 36. For example, sprocket 48 may be attached to ring 36 via a plurality of axially extending screws (as shown in Figure 4 with reference to a second described embodiment) alternately sprocket 48 may be welded or press fit onto sub 12. Chain 46 extends about and engages both sprockets 48 and 50. An adjustable idler sprocket 53 engages chain 46 between sprockets 48 and 50 to enable adjustment in the tension in chain 46.

As previously described, support structure 31 (i.e. plates 32) hold sleeve 28 and sub 12 in a fixed spatial relationship to motor 24. In the transmission system 14 an axis for rotation of sprocket 50 is coincident with the drive shaft 52, and axis of rotation of sprocket 48 is coincident with axis 26 of sub 12. Thus the support structure 31/plates 32 maintain a fixed spatial relationship between the axes of rotation of the sprockets 48 and 50.

Power is provided to motor 24 via battery pack 54 housed within housing 16. An access door 56 in wall 42b of housing 16 enables replacement of battery pack 54. A wall 57 inside housing 16 creates a compartment 59 for the battery pack 54. Electrical power from battery pack 54 is provided to motor 24 via intermediate circuit 58. The circuit 58 comprises a power board 60 and optionally, a radio receiver 62. An externally operable switch 64 (see Figure 2) is provided on the housing 16 to enable an operator holding the power sub 10 to operate the motor 24 to rotate the sub 12 in opposite directions. Power circuit 60 may also include surge protection circuitry to protect motor 24 in the event of a power spike from power pack 54. A surge reset button 63 is provided to enable reset of the surge circuit. Button 63 is accessible from inside compartment 59 by opening door 56.

When the optional radio receiver 62 is provided in circuit 58 it is electrically connected to the power board 60 and is receptive to signals from a hand held transmitter (not shown) which provides control signals to operate power sub 10. The hand held transmitter may for example transmit a first signal which when received by a radio receiver 62 causes motor 24 to rotate in one direction, and a second signal which when received by radio receiver 62 causes the motor 24 to rotate in an opposite direction.

In a further variation, circuit 58 may include a speed control circuit to enable control of the speed of rotation of sub 12. In that event, a further switch or dial may be provided to enable an operator to vary speed of rotation of sub 12. In the event that the radio receiver 62 is incorporated, then the corresponding hand held radio transmitter is provided with an appropriate switch or control to provide speed control signals to the radio receiver 62.

As shown most clearly in Figure 2, housing 16 is of a general rectangular prism shape and provided with a handle 66 to enable gripping and manipulation by a user. It is envisaged that housing 16 will be made from metal or a high impact plastics material.

Figures 3 - 7 depict a second embodiment of a power sub 10'. In this embodiment, features which are the same or functionally equivalent to features of power sub 10 shown in Figures 1 and 2 are denoted with the same reference numbers but with the addition of the prime symbol ('). The main differences between power subs 10 and 10' are that in power sub 10", motor 24', which in this embodiment is in the form of an air gun, is not permanently held within corresponding housing 16', but rather is detachably engagable with transmission system 14'. To this end, housing of power sub 10' comprises a clamp 75 fixed to an outside of housing 16' to detachably hold or retain the motor 24'.

Thus, in its broadest form, power sub 10' comprises a sub 12', transmission 14' and a housing 16' (see Figures 6 and 7), but instead of having an electric motor 24, battery pack 54, and electric circuit 60; torque is provided to sub 12' via a detachably engagable pneumatic motor which in this embodiment is a hand held pneumatic gun 24'. Also the housing 16" is of a cylindrical shape rather rectangular prism shape of housing 16.

Power sub 10' comprises sub 12' having tubular body 18' and first and second threads 20' and 22' at axially opposite ends. Sub 12' is located within sleeve 28' and respective bearings (not shown but functionally the same as bearings 27 described in relation to power sub 10). Opposite axial ends of sleeve 28' lie flush with the outwardly facing surfaces of plates 32'. Sleeve 28' is held to plates 32' by grub screws 34'.

Sub 12' passes through and is rotatably held within sleeve 28' by rings 36' and 38'. Ring 38' is retained on sleeve 12' by a grub screws 70 which, when screwed down, engages in a blind hole formed on an outer surface of sub 12'. Ring 38' is located adjacent an outwardly facing surface of plate 32'b.

Ring 36' is similarly fixed to sub 12' by a grub screws 74 (only one shown) which engages a second blind hole formed in sub 12'. Also, as most clearly seen in Figure 4 sprocket 48' is fixed to ring 36" by a plurality of axially extending screws 76. Rings 36' and 38' prevent axial motion of sub 12' while the support system 31' comprising sleeve 28' and plates 36' and 38' maintain a fixed spatial relationship between the axes of rotation of sprockets 48' and 50'.

Sprocket 50' is formed at one end of a cylindrical body 80. The body 80 is received within bearings 82 which in turn are press fit into a sleeve 84. Body 80 is held against linear motion by circlips 85 (only one shown in Figure 3) which are seated in respective grooves inside sleeve 84 at spaced locations adjacent opposite sides of the two bearings 82. An end of body 80 opposite sprocket 50' is formed with a socket for receiving a drive shaft in the form of a pin or rod 86 attached to the air gun 24'. Thus, when the air gun 24' is fitted into housing 16', torque is transferred from the air gun 24' to the sprocket 50' which in turn drives chain 46' to turn sprocket 48' and thus the sub 12'.

Housing 16' is smaller and lighter than housing 16 as there is no need for a power pack 54 nor the circuit 58 of power sub 10. Housing 16'comprises a cylindrical body 87 closed at opposite ends by disc like plates 89a and 89b. Handle 66' screws into one of three threaded spigots 91 attached to an outer circumferential surface of body 87.

Figure 8 is a schematic representation of how the power sub 10' would be coupled to a winch rope when coupled to a drill rod or drill string. This figure illustrates a winch rope 90 coupled with a swivel 92 which in turn is threadingly coupled with thread 20' of the sub 12'. In this figure a cross over sub or adapter 94 if required is threadingly engaged with the thread 22' of sub 12'. The cross over sub 94 enables coupling to a different sized drill rod 96. Air gun 24' is received and clamped into housing 16' of power sub 10' to provide torque to the transmission system 14'. Air is provided to the air gun 24' via a coiled airline 98 which coils about the cable 90 and appropriate pipes and fittings 100 which provide fluid communication between the coiled airline 98 and an air inlet fitting of the air gun 24'. Power sub 10 can be coupled to winch rope 90 and swivel 92 in an identical manner.

An example of the use of the power sub 10 will now be provided with reference to Figure 9.

Figure 9 depicts a mobile drill rig 110 with a drill tower 112 attached. The drill tower 112 comprises a rotation head 114 for rotating a drill string 116, and a slips table 118 at a lower end of the tower 112 through which the drill string 116 passes. Drill string 116 is made up of a plurality of end to end coupled drill rods 96. Actuators, such as but not limited to, rams (not shown) are used to move the rotation head 114 and thus drill string 116 up and down the tower 112. In order to advance the drill string 116 into the ground, the actuators are operated to control the weight of the rotation head 114 and drill string 116 bearing onto a toe of the hole while the rotation head 114 rotates the drill string 116.

Eventually, the rotation head 114 reaches the end of its downward travel along tower 112 where it lies adjacent the slips table 68.

To add a further drill rod 96 to the drill sting 116, the rotation head 114 is retracted and moved to the top of the tower and at the same time pulls out the drill string 116 until an upper most drill rod 96u of the string 116 is above the slips table 118. The slips table 118 now operates to clamp the drill string 116, and the upper most drill rod 96u is broken out from the drill string 116 by operation of the rotation head 114 to unscrew the drill rod 96u from the drill string 116. The drill rod 96u, which is now hanging from the drill head 114, is racked to one side to give way to provide access for an additional drill rod 96.

In order to advance the drilling of the hole, the additional drill rod 96 now needs to be connected to the drill string 116. To this end, the power sub 10 is operated to couple to a new drill rod 96 held in a supply 122 of drill rods. An operator operates a winch 123 supported on tower 112 to pay out sufficient length of winch line 90 so that an operator can hold swivel 92 and the power sub 10. The power sub is now located or positioned adjacent new drill rod 96. Assuming the internal thread 22 matches the thread on drill rod 96, the motor 24 is now operated to rotate the sub 12 to screw the sub 12 onto drill rod 96. If the internal thread does not match the drill rod thread then a cross over or adaptor 94 is used with appropriate matching threads to couple the sub to the drill rod. The winch 123 may now be operated to lift the new drill rod 96 from the supply 122 and place it into the tower 124 above the drill string 116 and slips table 118. The lower end of the lifted drill rod 96 is then screwed by hand in to the drill string 116 being held by clamps in the slips table 118. The slips table 118 clamps are subsequently released and the drill string 116 is lowered into the hole with the aid of the winch 123. When the power sub has reached the top of the slips table 118 the drill string 116 is clamped. The power sub is then disengaged from the drill rod 96 by reversing the direction of rotation of the motor 24. The upper drill rod 96u which was racked is now reconnected to the drill sting 116 and the rig 110 again operated to continue drilling. This procedure is carried out every time a new drill rod is required.

To remove a drill rod 96 from the drill string 116 the drill head 114 is lowered to be adjacent to the slips table 118, the slip table operated to clamp the drill string 116 and the drill head 114 unscrewed from dill string 116 and raised to the top of the tower 112 out of the way. An operator operates the winch 123 to provide sufficient length of the winch line 90 so that the power sub 10 can be placed over the slips table 118 and drill string 116. Assuming thread 22 matches the thread on the drill string 116, the power sub motor is now operated to rotate the sub 12 so that the internal thread 22 screws onto the drill string 116 (and in particular an uppermost drill rod of the drill string 116). When this is done, the slips table 118 clamp is released and the winch 123, winch line 90, power sub and the swivel 92 takes up the tension of the drill string 114 stopping it from slipping down the hole. An operator operates the winch 123 and pulls the drill string 116 from the hole. When the upper most drill rod 96 of drill string 116 is above the slips table 118 the clamps are applied and that drill rod is broken-out and unscrewed from the drill string 116. An operator then guides that drill rod 96 to the supply 122 for reuse at a later time using the winch 123. When the drill rod 96 is safely stored on the supply 122 the power sub is removed by operating motor 24 in a reverse direction.

Operation of power sub 10' is in substance the same as described above for power sub 10.

It is believed that embodiments of the present power sub may assist in maximising the probability of the sub 12/12' being fully locked onto the thread of the drill rod during handling thereby increasing safety. Safety is further enhanced by use of embodiments of the power sub as this minimises the use of an operator's hands and wrists in engaging and disengaging the sub from the drill rod.

Now that an embodiment of the invention has been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, embodiments of the power sub may use fixed or detachable hydraulic, pneumatic or electric motors. Thus in power sub 10, electric motor 24 could be replaced with a hydraulic or pneumatic motor. Similarly in power sub 10', the air (pneumatic) motor 24' can be substituted with an electric motor (e.g. a hand held, battery powered drill) or a hydraulic motor.

All such modifications and variations together with others that would be obvious to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the above description.

Claims

Claims:

1. A power sub comprising: a sub having a tubular body and first and second screw threw threads formed on, and at axially opposite ends of, the tubular body; and, a transmission system coupled with the sub and capable of transferring torque from a motor to the sub to cause rotation of the sub about an axis of the body; wherein the first and second screw threads are accessible from opposite ends outside of the power sub.

2. The power sub according to claim 1 wherein the transmission system comprises an endless loop coupling device capable of coupling the motor to the sub.

3. The power sub according to claim 2 wherein the transmission system comprises an engagement structure about the sub which engages the endless loop coupling device and a second engagement device arranged to be driven by a motor, wherein the endless loop coupling device engages both the first and second engagement devices.

4. The power sub according to claim 3 wherein the first engagement structure comprises an annular device coupled with the sub.

5. The power sub according to claim 4. wherein the endless loop coupling device comprises a chain and the annular device comprises a sprocket

6. The power sub according to any one of claims 1 to 5 comprising a support structure which maintains a fixed spatial relationship between a motor which provides drive to the sub, and the sub.

7. The power sub according to claim 6 wherein the support structure maintains respective axes of rotation of the first and second engagement structures in a fixed spatial relationship.

8. The power sub according to claim 7 wherein the support structure comprises two spaced apart plates through which the sub and an axis of rotation of a motor capable of driving the sub extends.

9. The power sub according to any one of claims 1 to 8 wherein the sub is held in a substantially constant translational position relative to an axis of the tubular body.

10. The power sub according to claim 9 comprising a stop system capable of holding the sub in the substantially constant translational position.

11. The power sub according to claim 10 wherein the stop system comprises first and second rings fixed at spaced apart locations on the sub, and a sleeve through which the sub extends, the rings being located adjacent opposite ends of the sleeve.

12. The power sub according to claim 11 wherein the sleeve is held in the support structure.

13. The power sub according to any one of claims 1 to 12 comprising a housing in which the transmission system and sub are retained, the sub being arranged so that the first and second screw threads are accessible from outside the housing.

14. The power sub according to claim 13 comprising a motor fixed inside the housing and coupled to the transmission system.

15. The power sub according to claim 14 wherein the motor is an electric motor and the power sub comprises a power pack mounted in the housing to provide electrical power to the motor.

16. The power sub according to claim 14 or 15 comprising a radio receiver located in the housing and capable of controlling the electric motor, and a separate hand held radio transmitter capable of transmitting signals to the radio receiver wherein the radio receiver controls the electric motor in response to control signals transmitted by the hand held transmitter.

17. The power sub according to any one of claims 14 to 16 comprising one or more switches mounted on the housing and coupled to the motor to enable activation and control of the motor.

18. The power sub according to claim 13 comprising a motor capable of detachably coupling to the housing and wherein the motor engages the transmission system when coupled to the housing.

19. The power sub according to claim 18 wherein the motor is selected from one of a pneumatic motor, hydraulic motor, and electric motor.

20. The power sub according to claim 19 wherein the motor is either a pneumatic motor or a hydraulic motor.