Field of the Invention The present invention relates to a casing for bore holes. Background of the Invention

Casing is often used to assist in the drilling of bore holes and wells and to also improve production from the hole. Casing comprises lengths of large diameter pipe (in comparison to the diameter of a drill rod) which is lowered section by section into a hole. Each length of casing is attached to a previous length by a screw connection. The casing prevents unstable formations from caving in and sticking to the drill string which would otherwise hamper the drilling of the bore hole. In addition casing can provide isolation of the bore hole from fluids and fluid pressure.

One method of installing a casing comprises supporting a lower end of a casing pipe near a drill bit at the end of the drill string used for drilling the bore hole. As the drill bit advances into the ground, the casing is also lowered into the ground. The weight of the casing bearing on a support adjacent the drill bit creates a frictional coupling transferring torque to the casing so that it rotates with the drill string. The rotation or spinning of the casing assists in advancing the casing into the bore hole. However frictional forces applied by the side wall of the bore hole against the outer circumferential surface of the casing progressively increase with depth. Eventually these forces approach or exceed the frictional coupling between the casing and the drill string. When this occurs the rotation of the casing is either interrupted or stopped completely thereby limiting the penetration of the casing into the bore hole.

When installing casing it is common to flush the bore hole with a fluid such as water. The water carries drill cuttings, dirt and other debris to the surface where it flows in an uncontrolled manner from an annulus between a top of the casing and drill string. This may be problematic in terms of user comfort and safety. Summary of the Invention

In one aspect the invention provides a casing spinner comprising;

a body;

a casing drive assembly supported by the body, the casing drive assembly arranged to couple to an up hole end of a casing and impart torque to rotate a coupled casing;

the body and casing drive assembly being configured to enable a drill pipe to extend through the body and a casing coupled to the casing drive assembly.

In a second aspect the invention also provides a casing spinner comprising: a body;

a casing drive assembly supported by the body and capable of rotating a coupled casing

the body capable of forming a seal about an outer circumferential surface of a rotating drill pipe which extends through a casing coupled to the casing drive assembly. In one embodiment the body comprises an outlet through which fluid flowing in an up hole direction between the drill pipe and casing is directed.

In one embodiment the outlet is positioned to direct the fluid to flow in a direction transverse to a direction of extent of a casing coupled to the casing drive assembly.

In one embodiment the body comprises an opening at one axial end and a sealing system inside the tubular portion wherein the sealing system forms a or the seal between a drill pipe passing through the opening and an inside surface of the body.

In one embodiment the casing assembly comprises a seal locking plate capable of releasably coupling to the one axial end of the body, and wherein the opening is formed in the sealed locking plate.

In the second aspect the the casing drive assembly is capable of imparting torque to an up-hole end of a coupled casing. The casing drive assembly may comprise a motor supported by the body and capable of rotating the casing coupling. The casing drive assembly may comprise a slew ring coupled between the drive motor and the casing coupling.

The casing drive assembly may comprise a drive gear coupled between the drive motor and the slew ring.

The casing coupling may be provided with a radial outwards extending flange coupled to the slew ring.

The invention also provides a drilling system comprising:

a rotation head capable of coupling with, and rotating, a drill string; a casing spinner disposed in axial alignment with the rotation head and capable of imparting torque to a casing;

the casing spinner provided with an axial opening through which a drill string coupled to the rotation head passes, the casing spinner capable of forming a seal about an outer circumferential surface of a drill string coupled to the rotation head.

The rotation head and the casing spinner may be capable of linear motion independent of each other.

Torque may be provided by the rotation head and the casing spinner to the drill string and casing respectively by respective hydraulic motors supplied with hydraulic fluid from a common hydraulic fluid pressure source. The invention also provides a method of drilling and casing a well comprising: locating a drill string within a casing;

coupling an up-hole end of the drill string and an up-hole end of the casing to a rotation head and a casing spinner respectively; and,

simultaneously operating the rotation head and the casing spinner to simultaneously drill and case the well.

The method may comprise: forming a seal about an outer circumferential surface of the drill string coupled with the rotation head and an inside surface of a portion of the casing spinner through which the drill string extends. The method may comprise:

coupling rotary hydraulic motors of the rotation head and the casing spinner which are capable of rotating the drill string and the casing respectively to a common hydraulic fluid pressure source. Brief Description of the Drawings

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of a casing spinner in accordance with an embodiment of the present invention;

Figure 2 is an exploded view from a first angle of the casing spinner shown in Figure 1 ;

Figure 3 is an exploded view from a second angle of the casing spinner shown in Figure 1 ;

Figure 4 is a plan view of the casing spinner shown in Figures 1 - 3;

Figure 5 is a view of section A-A of the casing spinner shown in Figure 4;

Figure 6 is a view of section B-B of the casing spinner shown in Figure 4; and, Figure 7 is a schematic representation of a drill system incorporating the casing spinner shown in Figures 1 - 6.

Detailed Description of Preferred Embodiment

A casing spinner 10 in accordance with an embodiment of the present invention enables torque to be imparted at an up-hole end of the casing when being installed simultaneously with the drilling of a bore hole or well. The casing spinner is also configured to enable a drill string to pass through the casing spinner and attached lengths of casing. The casing spinner provides torque for rotating the casing via a motor separate from the motor(s) providing torque to the drill string.

In one embodiment the casing can be rotated at the same rotational speed as the drill string. This can be achieved by coupling the casing spinner motor and the drill string rotation motor(s) to a common hydraulic fluid pressure source. A sealing system of the casing spinner provides a rotary seal about an outer circumferential surface of the drill string passing through the casing spinner. An outlet is provided in the casing spinner to allow a well flushing fluid such a water to return to the surface. The outlet is positioned so the fluid flows from the casing spinner at an angle substantially perpendicular to a direction of extent of the attached casing. For example the casing spinner may have an upper tubular section which supports the sealing system and is provided with the outlet. A hose or other conduit is plumbed to the outlet to carry the flushing fluid and entrained debris to a location remote from a drilling tower supporting the casing spinner and drill sting.

As torque is provided directly to the casing via the casing spinner rather than being transferred by frictional engagement between the casing and the drill string, it is envisaged that embodiments of the casing spinner will enable casing to be installed in a more efficient manner.

Referring to the accompanying drawings an embodiment of the casing spinner 10 comprises a body 12 and a casing drive assembly 14 supported by the body 12. The casing drive assembly 14 is capable of rotating a coupled casing 16 (shown in Figure 6). A sealing system 18 forms a rotary seal about an outer circumferential surface 20 of a drill pipe 22 which extends through the casing 16 coupled to the casing drive assembly 14.

Often when drilling a bore hole, a fluid such as, but not limited to, water is used to flush drill cuttings, sand and other debris from the well. The water is passed through a drill string composed of a number of drill pipes 22 connected end to end. This water exits from a drill bit connected at a down-hole end of the drill string and flows upwardly between the outer circumferential surface 20 of the drill pipe/drill string and the inner circumferential wall of the casing 16. The body 12 is provided with an outlet 24 through which the flushing water is directed and discharged. A conduit such as a hose or pipe 134 (see Figure 9) is connected to the outlet 24 to enable the flushing water to be discharged at a desired location remote from a drill tower 122 supporting the casing spinner 10.

The body 12 is rotationally fixed and comprises an upper assembly 25 and a base assembly 32 between which the casing drive assembly 14 is located. Upper assembly 25 comprises: a tubular or cylindrical portion 26 extending coaxially with casing 16 and drill pipe 22; and, a first plate 28 formed with a circular opening 30. Base assembly 32 comprises four rectangular mounting blocks 34a, 34b, 34c and 34d (hereinafter referred to in general as "mounting blocks 34"), a second plate 36. The second plate 36 is provided with a circular hole 38 and four parallel slats 40a, 40b, 40c, and 40d (hereinafter referred to in general as "slats 40"). The slats 40 are parallel to each other and arranged in two pairs 40a and 40b; and, 40c and 40d. The slats in each pair are close together but the slat pairs 40a and 40b; and, 40c and 40d are diametrically opposed about hole 36. Tubular portion 26 is coaxial with holes 30 and 38. Outlet 24 is formed in the circumferential wall of tubular portion 26. A flange 42 projects in a radial inward direction from an inner circumferential wall 44 of portion 26 at a location intermediate an upper axial end 46 of portion 26 and outlet 24. A small lip 45 (see Figure 5) projects upwardly from an inner circumferential edge of the flange 42.

Tubular portion 26 may be attached to the plate 28 by welding. The rectangular blocks 34 are attached to plate 36 by welding or alternately by use of mechanical fasteners. Bolts 48 pass through holes 50 formed in plate 28 and screw into threaded holes 52 formed in the rectangular blocks 34. This attaches plate 28 to plate 34 and thus upper assembly 25 to base assembly 32.

Sealing system 18 comprises two annular or washer like seals 54a and 54b (hereinafter referred to in general as "seals 54") each of which has an outer circumferential surface 56 and an inner circumferential surface 58. The surface 56 seals against the inner circumferential surface 44. The surface 58: defines a central hole 60 through which the drill pipe 20 extends; and, forms a seal against outer circumferential surface 22 of the drill pipe 20. Each seal 54 has a thickened outer circumferential band 62 which extends axially an equal distance on opposite sides of a reduced thickness central region 64. Sealing system 18 is supported on flange 42 with the lip 45 seating in a shoulder formed between the junction between band 62 and central region 64 of a first (lower) seal 54a. A second one of the seals 54b sits on the first seal 54a. Both seals 54 are retained in portion 26 by a seal locking plate 66. Plate 66 is of an annular configuration with four evenly spaced outwardly projecting tabs 68 and a central hole 70 coaxial with holes 58, 30 and 38. Tabs 68 enable attachment of plate 66 to portion 26 by use of cam lock clips 71 (see Figure 7)

With reference to Figure 3, an under surface 72 of plate 28 is formed with a plurality of threaded blind holes 74 equally spaced about central hole 30. In addition two further threaded through holes 76 are formed in plate 28 with a further larger diameter hole 78 formed between the two holes 76. The holes 76 and 78 lie along a line that runs parallel with one side of plate 28 with the hole 78 lying along a diameter of hole 30. The casing drive assembly 14 in broad terms comprises a motor 80 (Figures 1 , 2, 4 and 5), drive gear 82, slew ring 84, and casing coupling 86.

Motor 80 is a hydraulic motor which is mounted to plate 28 by screws or bolts that pass through a mounting plate of the motor 80 and engage the thread of holes 76. A drive shaft 88 of motor 80 passes through hole 78 and is attached to the drive gear 82.

Slew ring 84 comprises an inner ring 90 that is fixed to plate 28, and an outer ring 92 that rotates about the inner ring 90. A number of bolts 94 pass through holes 96 formed in inner ring 90 and threadingly engage with the holes 74 to fix inner ring 90 to plate 28. The inner and outer rings 90,92 are provided with respective intermeshing gear teeth (not shown). Similarly drive gear 82 and outer ring 92 are provided with respective intermeshing gear teeth, (not shown).

Casing coupling 86 has a tubular portion 100 of the same inner and outer diameter as casing 16.Conviently, but not necessarily, coupling 86 is formed by cutting an end portion off a length of casing 16. A mounting flange 102 is attached on the tubular portion 100 a short distance inboard of an upper axial end 104 of the portion 100. Flange 102 is also formed with a plurality of holes 106 that extend in the axial direction and positioned to register with holes 98 in the outer ring 92. When the casing drive 14 is assembled, a portion of tube 100 fits inside inner ring 90, while mechanical fasteners in the form of bolts 108 pass through the registering holes 98 and 106. Corresponding nuts 1 10 are screwed onto the bolts 108 to effectively couple the slew ring 84 to the casing coupling 86. By virtue of this arrangement, inner ring 90 is stationary and fixed to the plate 28 while outer ring 92 and casing coupling 86 are free to rotate a central longitudinal axis 112 of a casing spinner 10. A lower end 1 14 of tube 100 projects through hole 38 in the base assembly 32.

Casing coupling 86 is rotated about the axis 1 12 by supplying pressurized hydraulic fluid to motor 80. The supply of pressurized hydraulic fluid causes rotation of drive shaft 88, attached gear 82 and outer ring 92, by virtue of intermeshing with drive gear 82. As a consequence of the mechanical coupling between outer ring 92 and flange 102, the casing coupling 86 rotates about the axis 1 12.

Casing 16 engages a thread formed on an inner circumferential surface at lower end 1 14 of the tubular portion 100. Subsequent lengths of casing 16 are attached in an end to end manner by mating screw threads. Accordingly the casing spinner 10 is able to couple to an upper end of a length of casing and impart torque to the casing causing it to rotate about an axis 1 12 which is also an axis of rotation of drill pipe 22. The rotation of the casing 16 is or can then be arranged to be, independent of rotation of the drill pipe 22. Figure 7 illustrates a drill system 120 comprising the casing spinner 10 and a rotation head 122. In a drill rig, the drilling system 120 would be supported on a drill tower and movable linearly along the tower by use of hydraulic rams which provide pull down and pull back force for the system 120 and a drill string coupled thereto. Drill system 120 also comprises a carriage 124 that couples casing spinner 10 to, and beneath, the rotation head 122. Carriage 124 comprises a first frame 126 and a second frame 128 which are coupled together by rams 130. Casing spinner 10 is attached to frame 126 while rotation head 122 is attached to frame 128. Two rams 130 are provided on each side of the frames. Frame 126 includes square sectioned posts 134 which are attached to the casing spinner 10 and received in complimentarily sectioned sleeves 136 of frame 126. Extension of rams 130 linearly slides casing spinner 10 away from rotation head 122, while retraction of rams 130 slides casing spinner 10 toward rotation head 122. This allows for casing spinner 10 to be moved linearly a limited distance independently of linear motion of rotation head 122. This enables the process of attaching additional lengths of casing 16 to the casing spinner 10. However when drilling is in progress, linear motion of casing spinner 10 is locked or fixed to linear motion of head 124 so that the entirety of the system 120 moves together linearly. To this end, the carriage 124 is attached to the rams which provide pull back and pull down for the system 120. An upper end of frame 128 is also provided with a pair of laterally extending mounts 138. These mounts enable coupling to a pivot bar (not shown) allowing the system 120 to be pivoted or tilted in a plane containing the drill tower to which the system 120 is mounted.

Rotation head 122 imparts torque to a coupled drill string by virtue of one or more hydraulic motors 140. It may be desirable for the drill string and casing 16 to be rotated at the same speed. This can be achieved by coupling motors 140 and 80 to a common hydraulic pressure source 142. That is, motors 140 which rotate the drill string are provided with the same hydraulic fluid pressure as motor 80 which imparts torque to casing 16. Provided gearing between motors 140 and drill string is the same as gearing between motor 80 and casing 16, the drill string will rotate at the same speed as casing 16. When the drill system 120 is used to drill and case a bore hole, water may be directed to flow through the drill string via a water swivel 144 to flush drill cuttings, sand and other debris from the bore hole being drilled. This water passes through drill string, exits a drill bit at the down hole end of the drill string and then flows upwardly through an annular space created between drill string and casing 16, and is discharged via opening 24 and a coupled hose 146. Hose 146 can discharge the flushing water into an onsite dam or catchment area, or into water tankers.

Now that an embodiment of the casing spinner 10 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, the sealing system is described and shown as comprising two sealing discs 54. However alternate sealing structures may be used to produce the same effect. For example, each disc 54 may be replaced by a split disc which in essence is the same as the disc 54 shown but cut in half along a diameter. Also, instead of two sealing discs 54, a single thicker sealing disc may be used or different numbers of sealing discs may be incorporated. Further, more than one motor 80 for imparting torque to the casing 16 may be incorporated. For example two identical motors 80 can be mounted locations on the plate 28 with their respective drive gears 82 engaging the outer gear 92 of slew ring 84 to provide increases torque to the casing 16. All such modifications and variations together with others that would be obvious to persons 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 and the appended claims.