A MAGNETICALLY COUPLED DRIVE

The present invention relates to downhole hammering or other vibrational assembly.

In particular, although not solely, the invention relates to methods of ensuring a seal of a reliable kind to prevent the ingress of fluid(s) under downhole pressure differentials to interfere with the zones of interaction of a magnetic shuttling arrangement adapted to provide a hammering or the like output.

In order to maintain performance of a downhole hammer . of a kind reliant on magnetic arrays (e.g. as in our PCT/NZ2008/000217 [published as WO2009028964 on 5 March 2009]), it is preferable that the magnetic arrays can oscillate (ie. shuttle) relative to each other on their relative rotation in a gas space, minimising fluid drag forces acting on any part of the structure, relative to any other part of the structure, can be considered the or a "shuttle" (each whether the rotor, stator or some hybrid).

When operating a tool at depths where hydrostatic pressures are high, the requirement of maintaining a gas space necessitates transferring torque from a high pressure fluid environment (bore pressure) to a low pressure gas space (magnet shuttle chamber).

Proposed solutions for this problem included mechanical lip or clearance seals on a rotating shaft. These may provide high factional torque and heat generation, unknown reliability and life and potentially large pressure induced thrust forces acting on the shaft being sealed.

An alternative to this we have determined is to utilise the ability of magnets to transfer forces at a distance without mechanical contact. This will allow the placement of a structural shell that can resist the high bore pressures. Such a shell is capable of isolating the hammer magnet chamber and its complementary arrays from the bore pressure as well as the slave magnetic drive.

In an or another aspect the invention is a magnetically linked transmission to cause rotation of part of a downhole hammer or downhole magnetic hammer.

Such a transmission involves a drive (from a potentially high pressure side) and a driven (lower pressure side) set of magnets on either side of a pressure transfer resistant divide.

Preferably the magnetic arrays of the preferred downhole magnetic hammer is on the lower- pressure side of the divide.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

The invention also is a downhole apparatus comprising or including

a rotatable assembly ("rotary drive assembly") with at least one magnet as a rotary drive input, and

a complementary assembly with at least one magnet in a distinct environment from that of the rotary drive assembly as the rotary drive output to vibrational apparatus. Optionally the vibrational apparatus is one reliant on magnetic interactions between magnetic arrays arising from the rotary drive output.

Preferably the magnetic arrays of the vibrational apparatus and the complementary assembly are in at least substantially the same environment.

In another aspect the invention is a downhole vibrational apparatus reliant on a torque derived from one or more magnets of an input shaft outside of a sealed, or at least substantially sealed, environment to a magnetic coupled drive to cause vibrational output as a consequence of relative rotation of magnetic arrays causing a relativity of axial movement.

In yet another aspect the invention is a vibrational apparatus of a kind having a vibrational output as a consequence of the relative rotation and shuttling of interacting magnetic arrays wherein one of the interacting magnetic arrays is caused, or can be caused, to rotate relative to the other under an input that rotates at least one magnet ("input magnet") to in turn drag rotate at least one magnet ("driven magnets") of a structure that involves, or in turn rotates, said one of the interacting magnetic arrays.

Preferably said input magnet(s) are in a separate environment to that of the driven magnet(s) and of the interacting magnetic arrays.

The invention also is, in another aspect, a vibrating assembly reliant on a relative rotation of magnetic arrays to provide vibration causing axial relative movements between the magnetic arrays;

wherein the assembly together with a slaved torque transmitting magnet or magnetic array assembly to cause the relative rotation is high pressure sealed to protect the zones of vibration causing relative axial movement;

and wherein a shafted magnet or magnetic array assembly is able, upon its rotation, to provide the torque input to the slaved torque transmitting magnet or magnetic array assembly.

The invention in another aspect is, as a downhole assembly, enclosed hammering apparatus having, within its enclosement, at least one magnet, and

a shaft or shafted assembly, not within the enclosement, having at least one magnet;

wherein rotation of the magnet(s) of the shaft or shafted assembly causes rotation of said at least one magnet of the enclosed hammering apparatus, thereby to cause a hammering affect.

Optionally the hammering apparatus is a magnetic hammering apparatus reliant on magnetic arrays to interact upon their relative rotation to cause relative reciprocation thereof.

In another aspect the invention is a downhole hammering or other vibrational assembly of a kind requiring a relative rotation about an axis between complementary magnetic arrays (array or arrays A and array or arrays B) to provide a vibrational output or hammering outcome as a result of relative axial movement of parts of the structure of, or carrying each array, caused by the relative rotation between arrays A and B,

wherein one of the array(s) A or B is dependent for its rotation upon rotation of an array or arrays C of magnets, such array (s) C being slaved, whether by magnetically dragging or magnetically tying for their rotation on rotation of array or arrays D of magnets to be driven to rotate under the action of a rotary drive.

Preferably there is an outer casing about a common axis for both rotation between arrays A and B and array(s) C and D.

Preferably the assembly is such that array(s) A, array(s) B and array(s) C are encompassed such that the environment of zones of interaction between array(s) A and array(s) B is gaseous or free of any substantial impediment arising from, in use, ingress of fluids and/ or solids.

Preferably the environment of array(s) D is in an environment that does not exclude such ingress.

In another aspect the invention is downhole hammering apparatus comprising or including in, with respect to a hole axis,

a rotatable input shaft aligned with or aligned parallel to the hole axis,

a rotatable shuttle assembly having two structures able to rotate relative to each other (e.g. at least one to the other) to cause interacting magnetic arrays to cause a relative shuttling of such structures, the shuttling axis being aligned to or substantially parallel to the hole axis,

an at least substantially fluid tight enclosure about the rotatable shuttle assembly;

wherein the shaft directly or indirectly rotates one or more magnets and one of the structures (e.g. nominally "the shuttle") the shuttle assembly within the substantially fluid type enclosure carries a magnet or magnets to interact with that, or those, of the input shaft whereby, without direct contact, rotation of the shaft by magnetic interaction can rotate the shuttle.

In another aspect the invention is a method of driving the relative rotation motion of part of a magnetic hammer assembly, which method relies upon a driving rotational magnetic arrangement outside of a closed lower pressure environment to relay, via a slaved or driven magnetic arrangement, a rotational drive to part of such a magnetic hammer assembly:

In still another aspect the invention is, as part of, or to be part of, a downhole

hammering assembly, apparatus defining a pressure resistant chamber having at least an exterior cylindrical shape, and two interior cylindrical shaped zones, one stepping to the other by any suitable transition;

wherein (1) both an assembly (e.g. nominally a stator) with magnets and an assembly (e.g. nominally a rotor) with magnets, the stator and rotor being able to move axially relative to each other of magnetic hammer assembly is in the region of greater radial separation and (2) a set of magnets to rotate with the rotor

are in the region of lesser radial separation.

Preferably there is a shaft carrying a set of magnets outside of the chamber, but within the greater of the two interior cylindrically shaped zones, adapted to magnetically drag or tie to the set of magnets to rotate with rotor.

Preferably at least over the zone of interaction between the inside and outside sets of magnets the means defining the chamber is of a material not substantially obstructive of the required magnetic drive and its reception.

Preferably the chamber is pressurised by a gaseous environment to reduce pressure differentials when downhole.

The invention also includes a downhole vibrational apparatus reliant on a torque derived from one or more magnets of an input shaft outside of a sealed, or at least substantially sealed, environment to cause vibrational output as a consequence of relative rotation of magnetic arrays causing a relativity of axial movement.

Preferably the torque is derived by magnetic coupling.

The invention also or instead is a magnetically vibrating assembly reliant on a relative rotation of magnetic arrays to provide vibration causing axial relative movements;

wherein the assembly together with a slaved torque transmitting magnet or magnetic array assembly to cause the relative rotation is high pressure sealed to protect the zones of vibration causing relative axial movement;

and wherein a shafted magnet or magnetic array assembly is able, upon its rotation, to provide the torque input to the slaved torque transmitting magnet or magnetic array assembly.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

In another aspect the invention is a downhole vibrational apparatus (eg. a hammer), having a magnetic drag or tie drive from a rotatable input shaft into a sealed (or at least substantially sealed) subassembly or assembly to rotate one of two structures, each of one or more magnetic arrays, such structures able upon their relative rotation, to cause axial relative movement thereby to provide a vibrational or hammering output.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

In still a further or alternative aspect the invention is, as a downhole assembly, enclosed hammering apparatus having, within its enclosement, at least one magnet, and a shaft or shafted assembly, not within the enclosement, having at least one magnet; wherein rotation of the magnet(s) of the shaft or shafted assembly causes rotation of said at least one magnet of the enclosed hammering apparatus, thereby to cause a hammering affect.

Preferably the enclosed hammering apparatus is a magnetic hammering apparatus (eg. reliant on magnetic arrays to interact upon their relative rotation to cause relative reciprocation thereof).

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

The present invention also or instead relates to a downhole hammering or other vibrational assembly of a kind requiring a relative rotation about an axis between complementary magnetic arrays (array or arrays A and array or arrays B) to provide relative axial movement of parts of the structure of or carrying each array caused by the relative rotation between arrays A and B, wherein one of the array(s) A or B is dependent for its rotation upon an array or arrays C of magnets, such array(s) C being slaved (whether by magnetically dragging or magnetically tying) for their rotation on rotation of array or arrays D to be driven to rotate under the action of a rotary drive.

The vibrational apparatus, if not a hammer or also a hammer, can be of any kind and irrespectively of whether or not a downhole tool is required to be vibrated.

Optionally, and in one preferment, the assembly is a hammer.

Optionally, such relative axial movement can be utilised by any tool or apparatus. Preferably such tool or apparatus is used downhole. Preferably such tool or apparatus requires a dynamic (e.g. rotational) input and/ or output, generated from the axial movement, and requires a gaseous environment to operate that is under high hydrostatic pressure.

Optionally, for still other downhole tool or downhole apparatus, that must operate in a gaseous environment under high ambient hydrostatic pressure, (eg. where dynamic forces are being applied and sealing might be an issue) there can be, if desired, be no vibrational or hammering outcome and instead the tool or apparatus or part of the apparatus (eg. a shaft that might benefit from oscillation axially) relies on the axial movement to operate.

Preferably there is an outer casing about a common axis for both rotation between arrays A and B and array (s) C and D.

Preferably the assembly is such that array(s) A, array(s) B and array(s) C are encompassed (in some way) such that the environment of zones of interaction between array(s) A and array(s) B is gaseous or free of any substantial impediment arising from, in use, ingress of fluids and/ or solids.

Preferably the environment of array(s) D is in an environment that does not exclude such ingress.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components. Preferably the arrangement is substantially as hereinafter described.

In a downhole vibrational apparatus (eg. a hammer), the use of a magnetic drag or tie from a rotatable input shaft to rotate, and when in use dependent on the drag or tie, one of two structure(s), each of one or more magnetic arraysj-such structure(s) able, upon their relative rotation, to cause axial relative movement thereby to provide a vibrational or hammering output.

Preferably the vibrational apparatus has a common rotational axis for magnetic arrays to cause by axial relative movement the vibrational or hammering axis and for the input magnetic drive for the to be dragged or the to be tied slave magnets which are to be caused to rotate together with or synchronically with one of the magnetic arrays to provide the vibrational or hammering output.

Preferably the arrangement is substantially as herein described.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

In a further aspect the invention consists in downhole hammering apparatus comprising or including in, with respect to a hole axis,

a rotatable input shaft aligned with or aligned parallel to the whole axis,

a rotatable shutde assembly having shuttle carried magnetic array or magnetic arrays a non- shutde carried magnetic array or magnetic arrays, the shuttling axis being aligned to or substantially parallel to the whole axis,

an at least substantially fluid tight enclosure about the rotatable shuttle assembly;

wherein the shaft direcdy or indirecdy rotates one or more magnets and the shuttle of the shuttie assembly within the substantially fluid type enclosure carries a magnet or magnets to interact with that or those of the input shaft whereby, without direct shaft to shuttle contact, rotation of the shaft by magnetic interaction can rotate the shuttle.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

In another aspect the invention is a method of driving the relative rotation motion of part of a magnetic hammer assembly, which method relies upon a driving rotational magnetic arrangement outside of a closed lower pressure environment to relay, via a slaved or driven magnetic arrangement, part of such a magnetic hammer assembly.

The hammer zone may also be pre-charged to a suitable pressure with an appropriate gas to minimise the physical thickness of structural components.

The present invention is also, as part of, or to be part of, a downhole hammering assembly, means defining a pressure resistant chamber having at least an exterior cylindrical shape, and two interior cylindrical shaped zones (one stepping to the other by any suitable transition): wherein both a stator (with magnets) and rotor (with magnets) [the stator and rotor being able to move axially relative to each other] of magnetic hammer apparatus is in the region of greater radial separation and a set of magnets to rotate with the rotor are in the region of lesser radial separation.

Preferably the apparatus includes a shaft carrying a set of magnets outside of the chamber, but within the greater of the two interior cylindrically shaped zones, adapted to magnetically drag or tie to the set of magnets to rotate with rotor.

Preferably at least over the zone of interaction between the inside and outside sets of magnets the means defining the chamber is of a material not substantially obstructive of the required magnetic drive and its reception.

Preferably the chamber is pressurised by a gaseous environment to reduce pressure differentials when downhole.

In another aspect the invention is an at least substantially magnetically non permeable partition between sets of magnets, one set to be rotated downhole as a drive and one set to be rotatably driven to in turn rotate part of a hammer assembly or system.

The partition is preferably part of a chamber wall or surround (eg. a tube, jacket, shell or the like).

The full content of our WO2009028964 is here included by way of reference.

As used herein the term "(s)" following a noun means one or both of the singular or plural forms.

As used herein the term "and/ or" means "and" or "or". In some circumstances it can mean both.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. -

A preferred form of the present invention will now be described with reference to the accompany drawings in which

Figure 1 a section of the magnetic drive tool of the present invention showing an input shaft from the right hand end that via magnetic torque transmitting coupling is able to rotate part of the hammering assembly that is to act, whilst sealed from the downhole environment, in a hammering influence on the drill bit shown to the left end,

Figure 2 shows the nature of the torque coupling from the right hand end in isometric section, Figure 3 shows the pressure exclusion shell in section thereby to emphasise the stepped pressure separation enclosure including its tubing, annular ends and annular step,

Figure 4 is an isometric view of a sector of the pressure exclusion shell shown in Figure 3,

Figure 5 is a sectional view showing staggered arrays of magnets of the input shaft to co-act with surrounding magnets protected (optionally but preferably) in the same pressure resistant encasement as the magnetic hammer assembly, there being shown (as a block) part of the annulus which is the cavity for the hammer magnets of the hammer assembly,

Figure 6 is a transverse isometric section of the torque drive reliant upon the magnets,

Figure 7 is a cross-section of the torque drive region, and

Figure 8 is an outside isometric showing magnet array staggering of the poles.

In the preferred form of the present invention as depicted there is a shell or tubular member 1 (this can be considered as a continuation of a drill string if desired) able to rotate a drill bit 2.

As can be seen from Figures 3, 4 and 6, the casing or shell 1 has internally thereof, as part of the encasement shell for the interacting magnets of the magnetic hammer, a tube 3 closed at its lower end 4 by an annulus in association with the drill bit. It is also closed by annular regions 5 and 6 staggered to support an annular shell or tube 7. These can be seen in Figure 3. Thus an encasing structure, enclosure, etc of 1, 3, 4, 5, 6 and 7 houses the low pressure zone wanted.

This arrangement allows a fluid accessible passageway 8 provided by the region 3.

Suitable materials, not obstructive nor shielding of the magnetic drive into the hammer assembly proper, include such substantially magnetically non-permeable materials as nonferrous metals and alloys, plastics, etc.

The input shaft 9 (eg. from a PDM, or other) carries with it arrays of magnets 10 or 11 disposed circumferentially there about, for example, staggered (in a staggered pole-wise manner if desired as shown in Figure 8). The staggering can provide whatever matching as is required or preferred from the torque transmitting shaft 9 magnets 10, 11 to torque receiving magnets 12 in the low pressure zone annulus between the parts 1 and 7 (i.e. that of lesser radial separation). These torque receiving magnets 12 rotate with other torque receiving magnets 13 to be rotatable within the annulus as part of a rotor assembly (12 also) that includes rotor(s) including magnets 13 of the hammering apparatus in the annulus of greater radial separation. Such rotor have magnetic arrays 13 able, in a known interactive manner (as in WO2009028964), to interact with magnets 14 of the other component.

In the preferred option depicted, but not necessarily so, the magnets 14 are of a stator to reciprocate axially without rotation whilst magnets 13 are rotatable as a rotor. Thus the assembly of magnets 14, as the stator, reciprocate along the aligned axis so as to provide, in conjunction with the rotor the hammering output. Of course some other arrangement can be used to like affect. The shell isolating the pressure resistant zone hammer zone may also be pre-char: suitable pressure with an appropriate gas to minimise the physical thickness of structural components by reducing the pressure differential to be expected downhole.