An orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill

Abstract

An orientation adjustment assembly (300) for a directional drill (10) and the method for the same, wherein the activation and deactivation of the orientation adjustment assembly affects the relative rotation between the stationary and rotary parts of the direction drill (10) is dependent on drilling fluid pressure in the directional drill (10).

Description

[0001] An orientation adjustment assembly for a directional drill and a method for orientation or reorientation of a directional drill

[0002] The disclosed embodiments relate to an orientation adjustment assembly for a directional drill.

[0003] The disclosed embodiments further relate to a method for orientation or re-orientation of a directional drill.

[0004] Background

[0005] Directional drilling systems, particularly as used in the mineral exploration industry, often consist of a rotating inner element and a non-rotating outer element. The rotating inner element connects to the drill string in one end and the drill bit in the other end. During the drilling operation, the inner element transfers the rotation from the drill string to the drill bit. The non-rotating outer element sits outside the rotating inner element and contains at minimum a deflection device and an antirotation device. The deflection device exerts a force on the rotating inner element that causes it to bend or deflect, resulting in the drill bit being angled in relation to the remainder of the directional drill. The anti-rotation device may consist of a gripping system that engages the borehole wall to prevent the outer element from rotating during the drilling operation. Preventing the rotation secures that the deflection device, and thereby the angle of the drill bit, is in a fixed orientation during the drilling operation, which causes the directional drill to deflect the borehole.

[0006] Controlling the direction of the directional drill further requires an orientation measurement system and an orientation adjustment system. The orientation measurement system may consist of an instrument that logs the rotational orientation of the outer element and makes the reading available to the operator on surface. An example of such a system is found in NO346195B1 / WO2022154669 Al. The operator can then decide if the orientation is as planned, or if it must be adjusted. To adjust the orientation, an orientation adjustment system is needed.

[0007] An orientation adjustment system rotationally connects the outer element with the inner element, allowing the outer element to be rotated by the drill string and thereby changing its orientation angle. Examples of such orientation adjustment systems can be found in NO346836 Bl and NO344679 Bl. The solution in NO346836 Bl uses a lock and release coupling that disengages the connection with the presence of a retrievable inner assembly. The solution in NO344679 Bl uses a one-way clutch, disengaging the connection when the drill string is rotated in one direction and engaging the connection when the drill string is rotated in the opposite direction. In WO16043752 Al is also described a one-way clutch solution. Another solution is described in US6516900 BA, where drill fluid pressure is utilized to activate a pin that moves back or forth along a slot to engage or disengage the connection between the inner and outer element.

[0008] Each of these solutions have their drawbacks.

[0009] The inner assembly required in NO346836 Bl may not be available in all directional drills. This system can be time consuming in use, as the inner assembly first must be retrieved before an adjustment to the orientation angle can be made. It further relies on a solid mechanical connection between the inner assembly and the lock and release coupling to disengage the connection.

[0010] The one-way clutch system in NO344679 Bl relies on rotating the drill string in the opposite direction of the drilling rotation, which is the same direction used to unthread drill pipes from the drill string. In some cases, particularly deeper holes where there is significant friction between the drill string and borehole wall, this may lead to the drill pipes unthreading. In such situations it will therefore be impossible to adjust the orientation of the outer element of the directional drill.

[0011] In the situation, where pressure drops during the drilling operation, where the directional drill uses an orientation adjustment assembly as set out in US6516900 BA, then the pin as used in such an assembly can start to engage and thereby induce rotational forces to the outer element when this is not required, and therefore subject the assembly to significant damage. This form of assembly further requires an alignment process for the pin to engage, which is both time consuming and challenging in high-torque conditions where the driller may need to make several attempts to ensure engagement.

[0012] There is thus a need for an orientation adjustment system for a directional drill and a method for orientation or re-orientation of a directional drill solving the issues of the prior art solutions.

[0013] Summary

[0014] The disclosed embodiments provide an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill.

[0015] Provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill enabling use of separate controllable states to either enable relative rotation between the inner and outer elements of said directional drill during a drilling operation or not. Also provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill removing the need for mechanical interaction (inner assembly) to activate the engagement / disengagement between the inner and outer element.

[0016] Also provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill preventing damage on or to the orientation adjustment assembly or other parts if accidentally activated during drilling.

[0017] Also provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill engaging and disengaging directly when activated, with no need to manually rotate the same in certain directions or certain orientations with no substantial risk of automatic rotation occurring between the inner and outer element of the direction drill.

[0018] Also provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill reducing the risk of jamming / sticking during deactivation (disengagement).

[0019] Also provided herein is an orientation adjustment assembly for a directional drill and a method for orientation or re-orientation of a directional drill enabling adjustment of the orientation by rotating in the direction of the drilling rotation.

[0020] The invention

[0021] An orientation adjustment assembly for a directional drill according to the present invention is defined by the technical features of claims 1, 2 and 16. Preferable features of the orientation adjustment assembly are described in the dependent claims.

[0022] A method for orientation or re-orientation of a directional drill according to the present invention is defined by the technical features of claim 8. Preferable features of the method are described in the dependent claims.

[0023] The inventive embodiments of the present invention are related to an orientation adjustment assembly for a directional drill and a method for orientation and re-orientation of a directional drill that is robust and efficient allowing the directional drill to operate in a drilling state and an orientation state.

[0024] The present invention is suitable for directional drills having an outer element and an inner element. According to the inventive embodiments of the present invention, the orientation adjustment assembly, in a deactivated state, is configured to allow relative movement between the outer and inner elements of the directional drill, i.e., the outer element of the directional drill remains rotationally stationary while the drill string, inner element and drill bit rotate together, i.e., this is the drilling state. In an activated state, the orientation adjustment assembly prevents relative movement between the outer and inner element, i.e., the outer and inner elements are rotationally fixed, allowing adjustment of the orientation of the directional drilling by rotating the drill string, i.e., this is the orientation state where the outer element, inner element, drill string and drill bit all rotate together.

[0025] The orientation adjustment assembly according to the present invention comprises an engaging assembly comprising one or more first and second engaging members configured for mutual engagement, the first and second engaging members being rotationally fixed and movable within the orientation adjustment assembly enabling said mutual engagement.

[0026] In an alternative embodiment of the present invention, the orientation adjustment assembly comprises an engaging assembly comprising one first and one second engaging member configured for mutual engagement, wherein the first and second engaging members are rotationally fixed in the orientation adjustment assembly and wherein either the first or second engaging member is movable within the orientation assembly enabling said mutual engagement.

[0027] According to one embodiment of the present invention, the first or second engaging member or both are movable in an axial direction of the orientation assembly.

[0028] In accordance with the present invention, the orientation adjustment assembly is configured to prevent relative rotation between the outer and inner element of the directional drill allowing adjustment of the orientation of the directional drill, and by adjustment of drilling fluid pressure in the orientation adjustment assembly is configured to allow relative rotation between the outer and inner element of the directional drill.

[0029] In accordance with one embodiment of the present invention, the first and second engaging members having engaging sides with friction or resistance surfaces that face one another, thus providing a friction-based locking system / friction engaging assembly upon pressure being applied.

[0030] In accordance with one embodiment of the present invention, the first and second engaging members are formed as discs each having engaging sides with friction or resistance surfaces that face one another, causing friction between the adjacent discs when brought into engagement with each other.

[0031] According to one embodiment of the present invention, the first and second engaging members are formed as discs each having engaging sides with friction or resistance surfaces that face one another in an interleaved configuration.

[0032] Even though the orientation adjustment assembly is especially suitable for an engaging assembly comprising multiple first and second engaging members with engaging sides with friction or resistance surfaces, other engaging members may also be used as mentioned above, especially for embodiments with one first and one second engaging members. In accordance with an alternative embodiment, the first and / or second engaging members is provided with complementary male or female parts. In a further alternative embodiment, the first or second may further be provided with complementary shapes, such as cone-shape, truncated frustoconical or similar. In an alternative embodiment, the first and / or second engaging members have complementary conical splines or teeth. In accordance with one embodiment of the present invention, the aforementioned complementary conical splines or teeth are further provided with friction or resistance surfaces.

[0033] According to one embodiment of the present invention the orientation adjustment assembly comprises a manipulation assembly configured to engage, directly or indirectly, with either said first or second engaging member, and a resilient member to retain the orientation adjustment assembly in an activated position.

[0034] According to one embodiment of the present invention the orientation adjustment assembly comprises a manipulation assembly comprising an actuator configured to engage, directly or indirectly, with either said first or second engaging member, and a resilient member to retain the orientation adjustment assembly in an activated position.

[0035] According to one embodiment of the present invention the orientation adjustment assembly comprises a manipulation assembly in form of a hydraulic actuator configured to engage, directly or indirectly, with either said first or second engaging member. The hydraulic actuator may comprise a piston for direct or indirect engagement with the first or second engaging member, and a resilient member to retain the orientation adjustment assembly in an activated position.

[0036] In accordance with another embodiment of the orientation adjustment assembly of the present invention, the resilient member may comprise at least one compression spring or suitable compressible material, or an assembly of compression springs or compressible materials providing a biasing force on the actuator.

[0037] According to another embodiment the first and second engaging members, when affected by the manipulation assembly, directly engage with each other and disengage from each other, without requiring any form of relative rotation.

[0038] The orientation adjustment assembly according to the present invention further comprises an outer and inner body, wherein the one or more first engaging members are rotationally fixed and axially movable to the outer body and the one or more second engaging members are rotationally fixed and axially movable to the inner body, wherein the first and second engaging members are arranged in an alternating pattern in an axial direction of the orientation adjustment assembly, accordingly forming a stack of first and second engaging members. The mentioned manipulation assembly is arranged to one of the outermost first or second engaging members.

[0039] In an alternative embodiment of the present invention with one first and second engaging member, the first engaging member is rotationally fixed to the outer body and the second engaging member is rotationally fixed to the inner body. Further, either the first or second engaging member is arranged to be axially movable to the respective outer or inner body and the other is axially fixed to the respective outer or inner body, wherein the axially movable engaging member is arranged to said manipulation assembly.

[0040] In accordance with the present invention, the first engaging member(s) is / are integrated with, removably connected to or indirectly connected to the outer body. Similarly, the second engaging member(s) is / are integrated with, removably connected to or indirectly connected to the inner body.

[0041] The mentioned first and second engaging members may be rotationally fixed to its respective inner or outer body in a multitude of ways. In accordance with one embodiment of the present invention the first and second engaging members and the respective inner and outer bodies are provided with complementary engaging profiles on mutually engaging surfaces for rotationally fixing the first engaging member(s) to the outer body and second engaging member(s) to the inner body.

[0042] According to another embodiment of the present invention, the first and second engaging members are rotationally fixed to the respective inner or outer body by a tab and slot system. In accordance with one embodiment, the inner and outer bodies are designed with one or more tabs and the first and / or second engaging members are designed with the complementary and / or opposing number of slots. By matching the tab(s) with the slot(s), the respective engaging members and respective bodies are rotationally fixed.

[0043] In accordance with alternative embodiments, a cogwheel or gear shape or a matching wave form may be also used as engaging profiles between the respective body and respective engaging member.

[0044] The first engaging member(s) to be fixed to the outer body will have engaging profiles on the exterior surface thereof and the outer body will have complementary engaging profiles on the interior surface thereof.

[0045] The second engaging member(s) will have engaging profiles on the interior circumference and the inner body will have complementary engaging profiles on the exterior circumference thereof.

[0046] Alternative configurations for rotationally fixing the first and second engaging members to the respective outer and inner body are within the knowledge of a skilled person, and may include direct, indirect or integrated connections.

[0047] Regardless of the method used to rotationally fix the one or more first and second engaging members to the outer or inner body, respectively, it is important that the one or more first and second engaging members are moveable, preferably in an axial direction, within the orientation adjustment assembly, to enable activation and deactivation of the orientation adjustment assembly.

[0048] Similarly, in the embodiment with one first and second engaging member, it is important either the first or second engaging member are moveable, preferably in an axial direction, in the orientation adjustment assembly, to enable activation and deactivation of the orientation adjustment assembly.

[0049] In accordance with the present invention, the axial movement is necessary to create engagement (friction) when the one or more first and second engaging members are engaged by the pretension force of the manipulation assembly acting on the same, whether directly or indirectly, when in an activated state. In a deactivated state then, the one or more first and second engaging members must disengage to allow separation when the biasing force from the resilient member releases before the drilling operation initiates. The activation and deactivation states are a consequence of the drilling fluid acting on the manipulation assembly, more particularly the actuator of said manipulation assembly.

[0050] By using multiple first and second engaging members, where each of the respective engaging members are independently attached to the respective outer and inner body allows for built-in redundancy or a fail-safe mechanism, allowing the orientation adjustment assembly to continue working even if one engaging member or friction surface thereof should fail.

[0051] In accordance with the present invention, the one or more first and second engaging members are separated when the directional drill is operating / dril ling and pushed together when the directional drill is not operating / not drilling. When separated, there is no engagement (friction) between the outer and inner bodies of the orientation adjustment assembly and thus the inner and outer elements of the direction drill, thus the outer element of the direction drill can grip the borehole wall to maintain orientation while the inner element is rotated with the drill string. When pushed together, i.e., into engagement, the one or more first and second engaging members prevent relative rotation between the outer and inner bodies and thus the inner and outer elements of the directional drill, hence if the inner element is rotated, the outer element will rotate accordingly. This allows the orientation of the outer element of the directional drill, thereby the orientation of the directional drill, to be set or adjusted (re-oriented) at any time the directional drill is not drilling.

[0052] In accordance with the present invention, the operation of the manipulation assembly, i.e., adding and removing the axial force on the engaging member(s), is achieved by utilizing drilling fluid pressure. Drilling fluid and pressure is an integral part of most drilling operations, where fluid is utilized to clean and cool the drilling assembly. The fluid pressure from the drilling operation according to the present invention can act directly or indirectly on the actuator of the manipulation assembly causing the actuator to move in an axial direction to act, directly or indirectly, on the engaging members to compress the same whilst enabling the release of the biasing force of the resilient member, said force can transfer via the actuator to then act on the engaging member(s). Without the biasing force from the resilient member pushing on the engaging member(s), the engaging members will separate and enable rotation relative to each other.

[0053] The biasing (axial) force of the resilient member on the engaging member(s) may be configured according to the fluid pressure in use for directional drilling. For instance, directional drills utilizing a packer system as a rotation preventing device typically operate with a high internal differential pressure, which allows for the utilization of a resilient member with a high biasing force. The orientation adjustment assembly according to the present invention is equally suitable for directional drills utilizing low pressure or mechanical rotation prevention devices, by configuring the biasing (axial) force of the resilient member accordingly.

[0054] In further embodiments of the invention, the achievable static friction force from compression of the engagement members when the biasing force is applied from the resilient member can be configured in multiple ways, for instance by the shape or form of the friction or resistance surfaces of the engaging members. A smooth surface will typically achieve less friction / torque than a textured surface, while multiple equal friction or resistance surfaces achieve higher friction / torque than a single friction or resistance surface.

[0055] The present invention is also related to a method for the orientation or re-orientation of a directional drill by using the orientation adjustment assembly system according to the present invention.

[0056] A method for orientation or re-orientation of a directional drill having an outer element, an inner element and an orientation adjustment assembly as described above comprises selectively: utilising the drilling fluid pressure of the directional drill to deactivate the orientation adjustment assembly to allow relative rotation between the outer and inner element of the directional drill; and / or adjusting the drilling fluid pressure from the directional drill to activate the orientation adjustment assembly to prevent relative rotation between the outer and inner elements of the directional drill thereby allowing adjustment of the orientation of the directional drill.

[0057] In accordance with one embodiment of the method according to the present invention, the method comprises directly activating and deactivating the orientation adjustment assembly without requiring any form of rotation.

[0058] In a further embodiment of the method according to the present invention, the method comprises retaining the orientation adjustment assembly in an activated position by a biasing force.

[0059] According to a further embodiment of the present invention, the method comprises, in an activated position, using a drill rig to rotate the directional drill to correct drill bit deflection orientation.

[0060] The method according to the present invention comprises using the biasing force of a manipulation assembly that on activation of the orientation adjustment assembly causes an axial movement of the first and / or second engaging member(s) of the engaging assembly of the orientation adjustment assembly such that the first and second engaging members are forced together.

[0061] The method according to one embodiment of the present invention comprises introducing drilling fluid pressure to act on the manipulation assembly that on deactivation of the orientation adjustment assembly causes an axial movement of the first or second engaging member(s) of the engaging assembly of the orientation adjustment assembly such that the first and second engaging members are separated and / or move out of engagement of one another.

[0062] The orientation adjustment assembly according to the present invention seeks to address the known issues in the prior art.

[0063] As mentioned above, the present invention is especially suitable for directional drills utilizing drilling fluid differential pressure.

[0064] By using a high strength manipulation assembly according to the present invention to engage and disengage the first and second engaging members, a highly robust solution is provided.

[0065] An advantage of the orientation adjustment assembly according to the present invention is in situations where pressure loss occurs in the directional drilling system during drilling, affecting the manipulation assembly and causing deactivation of the orientation adjustment assembly, resulting in the orientation adjustment assembly and directional drill inadvertently entering an orientation mode during drilling which can damage the drill. The use of multiple engaging members provided with smooth or minimal resistant surfaces can assist with minimising any potential damage to the orientation adjustment assembly and drilling system in general. Even if the static friction force over the engaging members is exceeded by the drilling force, the smooth or minimal resistant surfaces of the engaging members can assist with and / or prevent substantial mechanical wear or damage. In any case, this is much less than that experienced if for instance a spline, cog-wheel or locking pin coupling is used.

[0066] Another benefit of the orientation adjustment assembly according to the present invention, is that by using engaging members having sides with friction or resistant surfaces that face one another enables the orientation adjustment assembly to engage at any rotational position completely independently of an inner assembly of the directional drill. This is not possible with the prior art solutions.

[0067] Indeed, prior art orientation adjustment systems that utilise for example locking pins, or spline couplings, rely on specific relative orientation between the inner and outer elements to ensure correct engagement for orientation purposes. This is not a requirement of the present invention.

[0068] Moreover, prior art orientation adjustment solutions suffer from the fact that, to ensure proper reorientation, then the operator at surface must identify engagement. At large depths or in difficult terrain or geology that is fractured this is not a trivial task even for highly experienced operators. The outcome may be that the operator thinks the orientation adjustment system is engaged, whereas in actual fact it is not, leading to compromises to the orientation and / or to the drill itself. The present invention removes the need for the operator to make such an identification.

[0069] A further advantage is that mechanical interaction with an inner assembly of the directional drill to perform the engagement and disengagement between the inner and outer element is not required.

[0070] A further advantage of the present invention is that if engagement is accidentally activated during drilling, damage is minimised.

[0071] An advantage with the orientation adjustment assembly according to the present invention is that engagement and disengagement only occurs directly when activated, with no need to manually rotate in certain directions or to certain orientations. Additionally, there is no risk of automatic rotation occurring between the inner and outer element, there is a reduction in the overall risk of jamming / sticking during disengagement and the orientation adjustment assembly does not require rotation in the opposite direction to the drilling rotation.

[0072] The orientation system according to the present invention can be used for both initial orientation and re-orientation at any time during a stop in the drilling operation.

[0073] The orientation adjustment assembly according to the present invention is very versatile and may be easily optimized to the specific requirements of various directional drilling systems.

[0074] Further preferable features and advantageous details of the present invention will appear from the following example description, claims and attached drawings.

[0075] Example

[0076] The present invention will below be described in further detail with references to the attached drawings, where:

[0077] Fig. 1 is a principle drawing of a directional drill according to prior art,

[0078] Fig. 2a-d are principle drawings of various embodiments of a directional drill with an orientation adjustment assembly of the present invention arranged within the directional drill in different configurations,

[0079] Fig. 2e is a principle drawing of one embodiment of an orientation adjustment assembly according to the present invention showing active components thereof, Fig. 2f is a principle drawing of one embodiment of an orientation adjustment assembly of the present invention further comprising inner and outer bodies,

[0080] Fig. 2g is similar to Fig. 2f illustrating an alternative embodiment of the engaging assembly,

[0081] Fig. 2h is similar to the embodiment of Fig. 2f illustrating a further embodiment of the orientation adjustment assembly,

[0082] Fig. 2i is an exploded perspective view of one embodiment of the orientation adjustment assembly of the present invention,

[0083] Fig. 3a is a cross sectional view of the orientation adjustment assembly of the present invention in an orientation mode where there is no fluid pressure applied,

[0084] Fig. 3b is similar to Fig. 3a where fluid pressure is applied and the orientation adjustment assembly is in a non-orientation mode,

[0085] Fig. 3c-3d are similar to Fig. 3a-3b illustrating another embodiment of the present invention,

[0086] Fig. 4a illustrates one embodiment of a first engaging member according to the present invention,

[0087] Fig. 4b is a cross sectional end view of a first engaging member through A-A of the orientation adjustment assembly as shown in Fig. 3a illustrating the arrangement to an outer body,

[0088] Fig. 4c is an alternative embodiment of the first member as shown in Fig. 4a,

[0089] Fig. 5a illustrates one embodiment of a second engaging member,

[0090] Fig. 5b is a cross sectional end view of the second engaging member through B-B of the orientation adjustment assembly as shown in Fig. 3a illustrating the arrangement to an inner body, and

[0091] Fig. 5c is an alternative embodiment of the first member as shown in Fig. 5a.

[0092] Reference is now made to Figure 1 illustrating an example of a prior art directional drill 10 that comprises numerous parts. The parts of the directional drill 10 will be described in order from the drill bit 20 end upwards; with a reamer 30, drive shaft connection assembly 40, a thrust bearing assembly 50, a lower outer tube 60, a deflection assembly 70, an upper outer tube 80, stabilizer assembly 90, rotation preventing device 100, an orientation measurement assembly 150 and a rear unit 200. In the shown embodiment the thrust bearing assembly 50, lower outer tube 60, deflection assembly 70, stabilizer assembly 90, rotation preventing device 100 and orientation measurement assembly 150 all form parts of a non-limiting example of the outer element 11 of the directional drill 10. In general, the outer element 11 contains all the parts that does not rotate during drilling, i.e. are directly / rotationally coupled to the rotation preventing device 100. The outer element 11 of a directional drill 10 may therefore comprise more or less parts than what is the case for the shown non-limiting embodiment. The outer element 11 being arranged to accommodate an inner drive shaft 110 (Fig. 3a-b) that is directly or indirectly coupled to the rear unit 200 at one end and the drive shaft connection assembly 40 at the opposite end. The drive shaft 110 transfers rotational forces from a drill rig onto the drill bit 20, thereby driving the drill bit 20 during the drilling operation. The drive shaft 110 (Fig. 3a-b) and any of its connection means positioned internally of the outer element 11, forms a part of the inner element 12 (Fig. 3a-b) of the directional drill 10.

[0093] The deflection assembly 70 engages with the drive shaft 110 (Fig. 3a-b) to incur an angle in or on the drill bit 20, which results in the drill bit 20 pointing in a different angle relative to the remaining section of the directional drill 10. The rotation preventing device 100 secures that the angle stays in this set orientation during the drilling operation, and thereby controls the steering direction of the directional drill 10.

[0094] The non-limiting shown embodiment of the rotation preventing device 100 is formed by a housing 101 having at least one pressure-activated member 102, such as a pressure pad or packer element, and sealing and connection means 103, 104 at axially distant ends or on either side of said housing 101, respectively. The at least one pressure-activated member 102 of the rotation preventing device 100 is arranged, such that on activation, it extends out of the housing 101 and into engagement with a borehole wall (not shown) to lock rotation of the rotation preventing device 100, in conjunction with the remaining parts of the outer element 11 of the directional drill 10. This allows the outer element 11 to remain rotationally fixed during the drilling operation, and to glide axially downhole as drilling progresses. The at least one pressure-activated member 102 is arranged to be pressed outwards into engagement with the borehole wall by means of pressure from the drilling fluid in the directional drill. The drilling fluid is pumped down internally inside the drill string in direction F as shown in Fig. 3a-b from the drill rig (not shown) at surface, where the fluid supply is controlled by a drill operator. The main purpose of the drilling fluid is to cool the drilling equipment and flush away drill cuttings. In the case of directional drilling systems with a rotation preventing device 100 that includes a pressure-activated member 102, the fluid can be further pressurized by a constriction, nozzle, valve or other similar device, in order to activate the same. Pressurizing the drilling fluid this way establishes a differential pressure situation where the pressure above the point of pressurization (internal of the directional drill 10) is higher than the pressure below the point of pressurization (external of the directional drill 10). This pressure difference occurs only when the drilling fluid is supplied by the drill operator and it may vary with the drilling fluid flow rate.

[0095] In alternative embodiments of the directional drill 10, the rotation preventing device 100 is activated by low pressure or comprises mechanical gripping devices, e.g., activated by mechanical forces or motors. These alternatives are well known for a skilled person and requires no further description herein.

[0096] The orientation measurement assembly 150 enables measurement or determination of the steering direction of the directional drill 10, thereby giving the operator knowledge of where the borehole will be directed. An example of one such orientation measurement assembly 150 can be found in NO 346195 Bl where at least one magnet in the outer element 11 is aligned with the deflection assembly 70 of the directional drill 10. The magnetic field from the magnet orientates an instrument in an inner assembly (not shown) and aligns the same in a known relation to the at least one magnet and thereby the deflection assembly. The instrument orientation readings can such be related to the orientation of the deflection assembly 70, the rotation preventing device 100 and the remainder of the outer element 11 of the directional drill 10.

[0097] Further detailed functionality of such a directional drill 10 which is well known to a skilled person and requires no further description herein, but the skilled person will find information in, e.g., NO316286 Bl.

[0098] Reference is now made to Fig. 2a-d showing principle drawings of embodiments of a directional drill 10 with an orientation adjustment assembly 300 according to the present invention. The purpose of the orientation adjustment assembly 300 is to enable adjustment of the steering direction of the directional drill 10, where such adjustment is achieved by rotating the outer element 11. As an example, if the operator plans to steer the borehole upwards (0° orientation angle), but the orientation measurement assembly 150 indicates the directional drill 10 is set to steer downwards (180° orientation angle), the outer element 11 must be rotated half a revolution (180 degrees). According to the present invention, the orientation adjustment assembly 300 is configured to be arranged in the directional drill 10, preferably above the rotation preventing device 100, but may be positioned anywhere within the outer element 11 of the directional drill 10. Examples of suitable locations are shown in any one of Fig. 2a-d. In accordance with one embodiment of the present invention, the orientation adjustment assembly 300 is arranged as a separate unit to the rotation prevention device 100, as shown in Fig. 2a-b, where the orientation adjustment assembly 300 is either above or below the orientation measurement assembly 150. The orientation adjustment assembly 300 in an alternative embodiment is an integrated part of the rotation preventing assembly 100, either as a separate unit as shown in Fig. 2c, or wherein an outer body 310 of the orientation adjustment assembly 300 is formed by the housing 101 of the rotation preventing unit 100 as shown in Fig. 2d.

[0099] The orientation adjustment assembly 300 according to the present invention is configured to be activated or deactivated by drilling fluid pressure, as further described below.

[0100] Reference is now made to Fig. 2e showing a principle drawing of one embodiment of the orientation adjustment assembly 300 according to the present invention showing active components thereof. The orientation adjustment assembly 300 according to the present invention comprises, as active components, an engaging assembly 330 and a manipulation assembly 340, wherein the manipulation assembly 340 can act, directly or indirectly, on said engaging assembly 330. The engaging assembly 330 comprises one or more first 314 and one or more second 324 engaging members configured for mutual engagement. The manipulation assembly 340 comprises an actuator 342 arranged to the at least one first 314 or second 324 engaging member, and a resilient member 341. On activation the resilient member 341 provides a biasing force onto the actuator 342 which is then transferred, either directly or indirectly, to the first 314 and second 324 engaging member(s). The manipulation assembly 340 is further configured to be deactivated by drilling fluid pressure exceeding the biasing force of the resilient member 341.

[0101] In Fig. 2f is shown a further embodiment of the orientation adjustment assembly 300 according to the present invention, where the orientation adjustment assembly 300 comprises an outer body 310 that encloses and / or substantially surrounds an inner body 320 that accommodates the engaging assembly 330 and manipulation assembly 340. The engaging assembly 330 and manipulation assembly 340 are arranged on or to said inner body 320. The first 314 engaging members are rotationally fixed to the outer body and second 324 engaging members are rotationally fixed to the inner body wherein either the first 314 or second 324 engaging member is movable, preferably in an axial direction within the orientation assembly 300, enabling said mutual engagement.

[0102] In Fig. 2g is shown a further embodiment of the orientation adjustment assembly 300 according to the present invention, comprising an engaging assembly 330 comprising one first 314 and one second 324 engaging member configured for mutual engagement. Similarly, the first 314 and second 324 engaging members are rotationally fixed to its respective inner or outer body in the orientation adjustment assembly 300 wherein either the first 314 or second 324 engaging member is movable, preferably in an axial direction within the orientation assembly 300, enabling said mutual engagement.

[0103] In Fig. 2h is shown a further alternative embodiment of the orientation adjustment assembly 300 according to the present invention, similar to the embodiment of Fig. 2f, further comprising an abutment member 344 that is located on the inner body 320 that restricts the stroke of the actuator 342 when activated, and a spring holder 343 that restricts and / or constrains the resilient member 341. The spring holder 343 is located on the opposite side of the actuator 342, such that the actuator 342 and resilient member 341 are located between both the abutment member 344 and spring holder 343.

[0104] In each embodiment shown in Fig. 2f-h, the inner body 320 provides at a first (uphole) end a mounting for the manipulation assembly 340 and at a second (downhole) end a mounting for the engaging assembly 330, wherein the assemblies 330 and 340 are separated by the mentioned abutment member 344.

[0105] The outer body 310 is configured as a locking tube encompassing the engaging assembly 330, manipulation assembly 340 and inner body 320.

[0106] Reference is now made to Fig. 2i showing an exploded perspective view of one embodiment of the orientation adjustment assembly 300 of the present invention, as well as Fig. 3a-b showing one embodiment of the orientation adjustment assembly 300 according to the present invention, configured to be connected and / or to form part of the rotation prevention device 100, or the orientation measurement assembly 150, as shown in any one of Fig. 2a-d.

[0107] The outer body 310, such as a locking tube or similar, is at an axially distant first (uphole) end provided with a complementary connection 311, preferably threaded, for connecting to connection means of the orientation measurement assembly 150 or rear unit 200, and at the opposite (downhole) end thereof is provided with a complementary connection 312, preferably threaded, for connecting to the connection means 104 of the rotation preventing device 100 or orientation measurement assembly 150. The outer body 310 forms a part of the outer element 11 of the directional drill 10.

[0108] The inner body 320, such as a sleeve, tube, cylindrical member or similar, is configured to be accommodated inside the outer body 310 with an (annular) spacing 301 therebetween. The inner body 320 at an axially distant first (downhole) end is provided with a complementary connection 321, preferably threaded, for direct or indirect connection to the driveshaft 110 and at the opposite (uphole) end is provided with a complementary connection 322, preferably threaded, for direct or indirect connection to a drill string 210 or rear unit 200 (Fig. 1, 2a-d). Alternatively, the inner body 320 may be positioned between driveshafts, if split or multiple driveshafts are utilized. The inner body 320 may therefore be considered a part of the inner element 12 of the directional drill 10.

[0109] The inner body 320 is configured to provide an interior space for an inner assembly (not shown), which may be an instrument assembly or a core tube assembly for collecting core samples during drilling. Such assemblies are well known to a skilled person and requires no further description herein, but the skilled person will, among others, find information in the mentioned NO316286 Bl.

[0110] The engaging assembly 330 comprises one or more first engaging members 314 rotationally fixed to the outer body 310 whilst being axially movable within the interior of the outer body 310. It further comprises one or more second engaging members 324 rotationally fixed to the inner body 320 whilst being axially movable within or to the exterior of the inner body 320. In an alternative arrangement, the one or more first 314 and second 324 engaging members are removably connected to or indirectly connected to the respective outer 310 or inner 320 body.

[0111] As described above, embodiments of the orientation adjustment assembly 300 is not limited to multiple first 314 and second 324 engaging members, but the principles of the present invention also apply for embodiments with only one first 314 and one second 324 engaging member, wherein one or either is arranged to be axially movable to the outer 310 or inner 320 body, respectively, as shown in Fig. 2g, 3c-d. In embodiments comprising one first 314 and one second 324 engaging members, the first 314 or second 324 engaging member could be provided with complementary male or female parts. The first 314 or second 324 may further be provided with complementary shapes, such as cone-shape, truncated frustoconical or similar. In a further embodiment of the present invention, the first 314 and / or second 324 engaging members have a complementary conical splines or teeth, as e.g. described for the coupling members in NO346836 Bl. In accordance with one embodiment of the present invention, the mention complementary conical splines or teeth are further provided with friction or resistance surfaces.

[0112] The further example description will be based on embodiments comprising multiple first 314 and second 324 engaging members as shown in Fig. 2e-f, 2h-i, and 3a-b.

[0113] In accordance with the shown embodiments of Fig. 2e-f, 2h-i and 3a-b, the first 314 and second 324 engaging members have engaging sides 318 and 328, respectively, with friction or resistance surfaces that face one another to form an engaging assembly 330. In the shown embodiments the first 314 and second 324 engaging members are formed by discs with engaging sides 318 and 328 with friction or resistance surfaces that face one another in an interleaved configuration. In accordance with the present invention, the first 314 and second 324 engaging members may be provided with different surfaces or surface textures, for example the surface can be provided with textures that may be smooth or textured.

[0114] In accordance with one embodiment of the present invention, as shown in Figures 2e-f, 2 h-i and Safa, the engaging assembly 330 comprises multiple (two or more of) first 314 and second 324 engaging members, arranged in an alternating pattern in the axial direction of the orientation adjustment assembly 300, thus forming a stack 331 of first 314 and second 324 engaging members. Alternating pattern does herein not exclusively mean the presence of one-by-one of the first 314 and second 324 engaging members, as shown in the example embodiments, but also includes that a number of first 314 and / or second 324 engaging members are arranged in an alternating pattern, as well as the number of first 314 and second 324 engaging members may differentiate in axial direction of the engaging assembly 330, also within the alternating pattern.

[0115] The orientation adjustment assembly 300 according to the present invention further comprises a manipulation assembly 340 arranged directly or indirectly to at least one of the first 314 or second 324 engaging members as shown in the Figures 2e-i and 3a-d. The manipulation assembly 340 consists of a resilient member 341 and an actuator 342. In accordance with a non-limiting example, the actuator 342 is a piston. The resilient member 341 is formed by a spring or a plurality of springs. The resilient member 341 has two ends, at an axially distant first end the resilient member 341 is restricted and / or constrained by a spring holder 343 and at the opposite end the resilient member 341 is restricted or constrained to be in engagement with the actuator 342. The spring holder 341 is arranged to the rear axial part of the inner body 320 and the spring holder 343 is further configured to rotationally fix or hold the spring(s) to the inner body 320 at the first end. E.g. the inner body 320 and spring holder 343 are provided with complementary engaging profiles at facing surfaces. The spring holder 343 is arranged to be moveable in an axial direction of the inner body 320 enabling adjustment of the biasing force of the resilient member 341.

[0116] The actuator 342 partly encloses and / or surrounds the inner body 320. The actuator 342 has an interior circumference that extends axially in the orientation adjustment assembly 300 / outer body 310 with a first actuator part 342a having an exterior circumference adapted to the interior circumference of the outer body 310. The actuator 342 is at a first (rear / uphole) end arranged to be in engagement with the resilient member 341. The actuator 342 extends at one end to form a first actuator part 342a and extends at the opposite end to form a second actuator part 342b. The second actuator part 342b has an interior and exterior circumference, wherein the interior circumference of the second actuator part 342b is larger than the interior circumference of the first actuator part 342a to create and / or provide a space for the abutment member 344 inside the interior of the second actuator part 342b (further described below). The exterior circumference of the actuator 342 is contiguous, and therefore the exterior circumference of the first 342a and second 342b parts of the actuator 342, are the same or correspondingly the same. The distal end of the second actuator part 342b forms a leading edge 349 that will engage with the first 314 or second 324 engaging member, directly or indirectly, (further described below) upon activation of the manipulation assembly 340 of the orientation adjustment assembly 300.

[0117] The stroke of the actuator 342 is limited by the abutment member 344 arranged at, integrated with or projecting from the exterior surface of the inner body 320. The abutment member 344 radially extends from the inner body 320 and has a height corresponding to the difference between the interior circumferences of the first 342a and second 342b actuator parts. The abutment member 344 separates the engaging assembly 330 and the manipulation assembly 340 as mentioned above.

[0118] The first 310 and second 324 engaging members of the engaging assembly 330 are axially movable in the orientation adjustment assembly 300, where on activation of the manipulation assembly 340 allows the engaging members 314, 324 to move into and out of engagement with each other. In an embodiment with only one first 310 and one second 324 engaging members, the axially movable first 310 or second 324 engaging member will move into and out of engagement with the axially fixed engaging member.

[0119] In accordance with the present invention, the manipulation assembly 340 is deactivated by the pressurised drilling fluid flowing inside the inner element 12 of the directional drill 10, and is activated when no pressurised drilling fluid is flowing. In accordance with the present invention there are arranged a set of seals 345, such as O-rings or similar sealing means, between the actuator 342, inner body 320 and abutment member 344, respectively, to provide a sealed actuator (piston) chamber 346 into which pressurised drilling fluid from drilling fluid channel 347 can flow and act on the manipulation assembly 340. The actuator chamber 346 is uphole of the abutment member 344. The drilling fluid channel 347 extends from the interior of the inner body 320 and into the sealed actuator chamber 346, leading drilling fluid from inside the inner element 12 to the sealed actuator chamber 346, wherein the drilling fluid acts directly on an interior actuator edge 349 (Fig. 2i) of the first actuator part 342b, wherein the mentioned seals 345 restricts the drilling fluid from flowing out of the actuator chamber 346. The effect of the drilling fluid is further described below. In accordance with a further embodiment of the present invention, one or more distance members 348a-b, such as distance rings, is arranged at one or both sides of the stack 331 of engaging members 314, 324 to adapt to the axially movable space of the stack 331 of engaging members 314, 324. The distance rings 348a-b further assist to reduce the wear on contact points with the actuator 342, as the actuator 342 will then be in engagement with the distance member 348a. Accordingly, in such an embodiment the actuator 342 acts indirectly on the engaging members 314, 328 via the distance member 348a. Alternative configurations for the actuator 342 including but not limited to pneumatic actuators, magnetic actuators, and linear motion solenoids are within the knowledge of a skilled person.

[0120] Reference is now made to Figures 4a-c and 5a-c for further details of non-limiting example embodiments of the first 314 and second 324 engaging members, respectively, and their connection to the outer 310 and inner 320 body, respectively. Figure 4a is a principle drawing of a first engaging member 314 configured for arrangement to the outer body 310, while Fig. 4b is a cross-sectional view through A-A of Fig. 3a of the first engaging member 314 arranged in the orientation adjustment assembly 300. Figure 5a is a principle drawing of a second engaging member 324 configured for arrangement to the inner body 320, while Fig. 5b is a cross-sectional view through B-B of Fig. 3a of the second engaging member 324 arranged in the orientation adjustment assembly 300. In the shown embodiments, the engaging members 314, 324 are in the form of discs having engaging sides 318, 328 with friction or resistance surfaces that face one another. The interior circumference of the first engaging member 314 is adapted to the exterior circumference of the inner body 320, and the exterior circumference of the second engaging member 324 is adapted to the interior circumference of the outer body 310. The exterior circumference of the first engaging member 314 and the interior circumference of the outer body 310 are provided with complementary engaging profiles and the interior circumference of the second engaging member 324 and the exterior circumference of the inner body 320 are provided with complementary engaging profiles for rotationally fixing the respective engaging member 314, 320 to the respective body 310, 320, further described below.

[0121] The respective engaging members 314, 324 may be rotationally fixed to its respective outer 320 and inner 310 body in a multitude of ways. In accordance with one embodiment of the present invention, as shown in Figures 4a-b and 5a-c, the respective engaging members 314, 324 are rotationally fixed by using a tab and slot system, where the outer 310 and inner 320 bodies are designed with one or more tabs 315, 325, respectively, and the engaging members 314, 324 are designed with the opposing number of slots, or opposite. By matching the tab(s) 315, 325 with the slot(s) 316, 326 the respective engaging member 314, 324 and body 310, 320 will be rotationally fixed.

[0122] Reference is further made to Figures 4c and 5c showing an alternative embodiment, where the engaging members 314, 324 are provided with a respective cogwheel or gear shape or a matching wave form 317, 327. The outer body 310 is then provided with a complementary form or shape (not shown) on the interior circumference and the inner body 320 is similarly provided with a complementary form or shape (not shown) on the exterior circumference, substantially as described above.

[0123] In another embodiment of the present invention, a combination of slots and tabs and waveform is used.

[0124] Other designs and configurations for rotationally fixing the respective first 314 and second 324 engaging members to the respective outer 310 and inner 320 bodies are within the knowledge of a skilled person.

[0125] Accordingly, the first engaging member 314 is rotationally fixed to the outer body 310 to ensure rotation together, whilst being axially movable in the orientation adjustment assembly 300. Similarly, the second engaging member 324 is rotationally fixed to the inner body 320 to ensure rotation together, whilst being axially movable in the orientation assembly 300. Accordingly, under the direct or indirect action of the manipulation assembly 340, the first 314 and second 324 engaging members can axially move within the orientation adjustment assembly 300 into and out of engagement with each other by the direct or indirect action of the manipulation assembly 340 through drilling fluid pressure. When there is a drop or reduction in drilling fluid pressure the resilient member 341 compresses the stack 331 of the first 314 and second 324 engaging members. This will be further described below. As mentioned above, the orientation adjustment assembly 300 according to one embodiment of the present invention comprises multiple first 314 and second 324 engaging members arranged in a stack 331 wherein the first 314 and second 324 engaging members are arranged in an alternating pattern in the axial direction of the orientation adjustment assembly 300.

[0126] By using a stack 331 of engaging members 314, 324 each having engaging sides 318, 328, respectively, with friction or resistance surfaces facing one another, each engaging member 314, 324 can be independently arranged to the respective outer 310 and inner 320 body, thereby allowing for a redundancy or a fail-safe mode in the orientation adjustment assembly 300 if one or more of the engaging members should fail. This allows the orientation adjustment assembly 300 to continue working even if one engaging member 314, 324 or surface thereof should fail.

[0127] The engaging members 314, 324 ensure that direct engagement / disengagement occurs when acted on by the manipulation assembly 340, without requiring or inducing any form of rotation. This can provide an easy to operate orientation adjustment assembly to a driller with the added security that the orientation of the directional drill 10 is always accurate and unaffected by the engagement / disengagement process.

[0128] How the orientation adjustment assembly 300 according to the present invention works will now be described with references to Fig. 3a-b. The orientation adjustment assembly 300 according to the present invention is controllable between an activated position (state), as shown in Fig. 3a, wherein the engaging members 314, 324 are in engagement with each other, and a deactivated position (state), as shown in Fig. 3b, wherein the engaging members 314, 324 are displaced and not in engagement / disengaged.

[0129] In the activated state, as shown in Fig. 3a, a biasing force is exerted by the resilient member 341 of the manipulation assembly 340 on the actuator 342, resulting in the actuator 342 applying a biasing force directly or indirectly (via the distance ring 348a) on either the first 314 or second 324 engaging member and thus compressing the stack 331 by axially moving the first 314 and second 324 engaging members in the orientation adjustment assembly 300 into engagement with each other. The engagement of the first 314 and second 324 engaging members radially locks the engaging members 314, 324 together by static friction, restricting or substantially preventing any relative rotation between the inner 310 and outer body 320 and thus the inner 12 and outer 11 element of the directional drill 10. Thereby, a rotation of the inner element 12 of the direction drill 10 leads to a corresponding rotation of the outer element 11 of the directional drill 10 to allow adjustment of the direction of the directional drill 10 in a desired direction

[0130] When drilling fluid pressure internally of the inner element 12 of the directional drill 10 is adjusted and thus inner body 320 of the orientation adjustment assembly 300 increases, the drilling fluid pressure increases into the drilling fluid channel 347. Consequently, the drilling fluid pressure acting on the actuator 342 in the actuator chamber 346 gradually increases and when the drilling fluid pressure is greater than the biasing force of the resilient member 341, this gradually forces the resilient member 341 to contract, gradually relieving the downward axial pressure acting on the actuator 342 such that the actuator 342 can now retract uphole. When a certain drilling fluid pressure is reached, the resulting fluid force acting on the actuator 342 becomes greater than the biasing force exerted by the resilient member 341 of the manipulation assembly 340. This results in the actuator 342 moving towards the resilient member 341 to compress the same. This releases the biasing force on the first 314 and second 324 engaging members and allows the engaging members 314, 324 to be moved out of or released from engagement, thereby reducing the static friction force gradually to zero or near zero. The radial lock between the first 314 and second 324 engaging members is thus disengaged, which allows relative rotation between the inner 310 and outer 320 bodies, and thus the inner 12 and outer 11 elements of the directional drill 10. Thereby, a rotation of the inner 12 element of the directional drill 10 causes no rotational effect on the outer element 11 of the directional drill 10.

[0131] The properties of the orientation adjustment assembly 300 can be adjusted to the specific requirements of various directional drilling systems. For instance, in a drilling system with low drilling fluid pressure a higher static friction may be achieved by increasing the number of engaging members 314, 324, adding more surface texture, increasing the contact area by slanting or otherwise adjusting the form of the surface on the engaging members, using an optimized resilient member 341 or adjusting the compression of the resilient member 341.

[0132] In accordance with a further embodiment of the present invention, a controllable or exchangeable valve is associated with the drilling fluid channel 347 enabling control of the properties of the drilling fluid channel 347 and drilling fluid flow into the actuator chamber 346.

[0133] The technical features of the described embodiments may be combined or modified to provide other embodiments within the scope of the attached claims.

Claims

Claims1. An orientation adjustment assembly (300) for a directional drill (10) having an outer element (11) and an inner element (12), wherein the orientation adjustment assembly (300) comprises an engaging assembly (330) comprising one or more first (314) and second (324) engaging members configured for mutual engagement, wherein the one or more first engaging members (314) are rotationally fixed to the outer element(11) and the one or more second engaging members (324) are rotationally fixed to the inner element(12), wherein the first (314) and second (324) engaging members are movable in the orientation adjustment assembly (300) to come into and out of engagement, wherein the orientation adjustment assembly (300) is configured to substantially prevent relative rotation between the outer (11) and inner (12) element of the directional drill (10) thereby enabling adjustment of the orientation of the directional drill (10), and by adjustment of drilling fluid pressure in the orientation adjustment assembly (300) is configured to allow relative rotation between the outer (11) and inner (12) element of the directional drill (10).

2. An orientation adjustment assembly (300) for a directional drill (10) having an outer element (11) and an inner element (12), wherein the orientation adjustment assembly (300) comprises an engaging assembly (330) comprising a first (314) and second (324) engaging member configured for mutual engagement, wherein the first engaging member (314) is rotationally fixed to the outer element (11) and the second engaging member (324) is rotationally fixed to the inner element (12), wherein the first (314) or second (324) engaging member is movable in the orientation adjustment assembly (300) to come into and out of engagement, wherein the orientation adjustment assembly (300) is configured to substantially prevent relative rotation between the outer (11) and inner (12) element of the directional drill (10) thereby enabling adjustment of the orientation of the directional drill (10), and by adjustment of drilling fluid pressure in the orientation adjustment assembly (300) is configured to allow relative rotation between the outer (11) and inner (12) element of the directional drill (10).

3. An orientation adjustment assembly (300) according to claim 1 or 2, the first (314) or second (324) engaging member or both are movable in an axial direction of the orientation assembly (300).

4. An orientation adjustment assembly (300) according to claim 1 or 2, comprising a manipulation assembly (340) configured to engage, directly or indirectly, with either said first or second (324) engaging member(s).

5. An orientation adjustment assembly (300) according to claim 1, wherein the first (314) and second (324) engaging members, when affected by the manipulation assembly (340), directly engage with each other and disengage from each other, without requiring any form of relative rotation.

6. An orientation adjustment assembly (300) according to claim 4, wherein the manipulation assembly (340) comprises an actuator (342) configured to engage directly or indirectly, with either said first (314) or second (324) engaging member(s) and a resilient member (341) to retain the orientation adjustment assembly (300) in an activated position.

7. An orientation adjustment assembly (300) according to any preceding claim 1, 3-6, comprising an outer body (310) and an inner body (320), and wherein the first (314) engaging members are rotationally fixed and axially movable to the outer body (310) and the second engaging members (324) are rotationally fixed and axially movable to the inner body (320), wherein the first (314) and second (324) engaging members are arranged in an alternating pattern in an axial direction of the orientation adjustment assembly (300).

8. An orientation adjustment assembly (300) according to any preceding claim 3-6, comprising an outer body (310) and an inner body (320), wherein the first (314) engaging member is rotationally fixed to the outer body (310) and the second engaging member (324) is rotationally fixed and axially movable to the inner body (320), or wherein the first engaging member (314) is rotationally fixed and axially movable to the outer body (310) and the second engaging member (324) is rotationally fixed to the inner body (320).

9. An orientation adjustment assembly (300) according to any preceding claim, wherein the first (314) and second (324) engaging members have engaging sides with friction or resistance surfaces that face one another.

10. A method for the orientation or re-orientation of a directional drill (10) having an outer element (11), an inner element (12) and an orientation adjustment assembly (300), the method comprising selectively:utilizing drilling fluid pressure in the directional drill (10) to deactivate the orientation adjustment assembly (300) to allow relative rotation between the outer (11) and inner (12) element of the directional drill (10); and / or adjusting the drilling fluid pressure from the directional drill (10) to activate the orientation adjustment assembly (300) to prevent relative rotation between the outer (11) and inner (12) element of the directional drill (10).

11. A method according to claim 10, comprising directly activating and deactivating the orientation adjustment assembly (300) without requiring any form of rotation.

12. A method according to claims 10-11, comprising retaining the orientation adjustment assembly (300) in an activated position by a biasing force.

13. A method according to claims 10-11, comprising, in an activated position, using a drill rig to rotate the directional drill (10) to correct drill bit deflection orientation.

14. A method according to claim 12, comprising using the biasing force of a manipulation assembly (340) that on activation of the orientation adjustment assembly (300) causes an axial movement of first (314) and / or second (324) engaging member(s) of an engaging assembly (330) of the orientation adjustment assembly (300) such that the first (314) and second (324) engaging member(s) are forced together.

15. A method according to claims 10-11, comprising introducing drilling fluid pressure acting on a manipulation assembly (340) that on deactivation of the orientation adjustment assembly (300) causes an axial movement of first (314) or second (324) engaging member(s) of an engaging assembly (330) of the orientation adjustment assembly (300) such that the first (314) and second (324) engaging members are separated.

16. An orientation adjustment assembly for a fluid driven directional drill (10) comprising an inner (11) and outer element (12): an outer body (310), an inner body (320), an engaging assembly (330) comprising one or more first (314) and second (324) engaging members, anda manipulation assembly (340), wherein said engaging assembly (330) and said manipulation assembly (340) are arranged on said inner body (320), wherein said manipulation assembly (340) acts on said engaging assembly (330) to move said engaging members (314, 324) into engagement to substantially prevent relative rotation between the outer (11) and inner (12) element of the directional drill (10) thereby enabling adjustment of the orientation of the directional drill (10), and by adjustment of pressurised drilling fluid flowing in the directional drill (10) said engaging assembly (300) allows relative rotation between the outer (11) and inner (12) element of the directional drill (10).

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