NO341987B1

NO341987B1 - Directional drill

Info

Publication number: NO341987B1
Application number: NO20161162A
Authority: NO
Inventors: Arnstein Løvø; Viktor Tokle
Original assignee: Devico As
Priority date: 2016-07-13
Filing date: 2016-07-13
Publication date: 2018-03-12
Also published as: AU2017295458A1; AU2017295458B2; CA3027346A1; WO2018012985A1; NO20161162A1

Abstract

A directional drill (10) for directional drilling of arced holes having a predetermined coursein jointed and fractured rock formations, comprising a drill string (11) with a foremost diamond full-face drill bit (20) with a reamer (30) and drive shaft connection assembly(40), wherein the directional drill (10) is provided with a underiying of the drill bit (20) arranged notation preventing assembly (100) including at least one pressure pad or packer element (102) for engagement with a borehole wall by activation by pressure from supply of drilling fluid and displaceable axially along the borehole wall during drilling for fixed orientation of the directional drill (10).A directional drill (10) for directional drilling of arced holes having a predetermined course in jointed and fractured rock formations, comprising a drill string (11) with a foremost diamond full-face drill bit (20) with a reamer (30) and drive shaft connection assembly (40), wherein the directional drill (10) is provided with a base of the drill bit (20) arranged notation preventing assembly (100) including at least one pressure pad or packer element (102) for engagement with a borehole wall by activation by pressure from supply of drilling fluid and displaceable axially along the borehole wall during drilling for fixed orientation of the directional drill (10).

Description

Directional drill

The present invention is related to a directional drill for diamond core drilling, especially for rock drilling, more exactly a directional drill as described in claim 1, especially for directional drilling of arced holes having a predetermined course with high accuracy in jointed and fractured rock formations.

Background

A directional core drill is described in NO 168962 which is provided with a locking device or packer which is supplied with drilling fluid under pressure in order to push out locking elements or pressure pads which can be brought in contact with the borehole wall and lock the main body of the directional core drill head and its eccentric bushing relative to the wall. Such pressure pads may be utilized for locking the high side of an eccentric housing in a certain position or be used to bring upon the drill bit a skewed position, for thereby performing directional drilling.

It is known to make directional core drills with a rotary core barrel extending through an eccentric bushing arranged in a non-rotatable outer tube. A packer is also described in NO 308552, where drilling fluid is used to press pressure pads against the borehole wall. Directional core drill heads may also carry navigational instruments, such as geotechnical instruments, as well as magnetometers, accelerometers, etc.

From NO 305713 it is known a rock drill where several pressure pads are arranged in at least two ring sections, so that the pressure pads become oriented in axial rows with projecting guiding bars oriented in a row. This solution is intended to reduce the frictional forces, which are effective in the axial direction when the drill is moved forward and shall at the same time ensure a frictional force against rotation sufficient to avoid a rotational movement. The guidance is in this case ensured by a permanent eccentric bushing positioned between the packer and the drill bit, known from the patent publication mentioned above.

US 4,620,601 disclose a turbodrill which is connected to a string of drill pipe as a rotating shaft for driving a drill bit which may be a rotary bit or a high speed solid head diamond bit.

A publication, which improves the above presented solutions, is patent publication NO 316286. In NO316286 it is known a wireline-operated directional core barrel drill for rock drilling, especially for rock drilling of curved holes with a predetermined path, having an outer drilling tube with a foremost rotatable drill bit and a part connected behind arranged for being locked against rotation. The outer body of the directional core drill is provided with pressure pads that can be pressed against the borehole by means of pressure from supplied drilling fluid. In the front section of the main body it is arranged an eccentric bushing for bending the front part of the rotating internal drive shaft, so that the shaft and the drill bit are provided with a rotational axis deviating from the existing borehole and the non-rotatable central section of the main body. In the drive shaft it is arranged an inner tube for receiving core samples when drilling, as the upper end is provided with space for a survey instrument to be able to measure and log data, such as inclination, direction and angle of rotation of central section of the main body, incl. high side of the eccentric bushing.

The above-mentioned wireline-operated directional drills are however not suitable for drilling in strongly jointed and fractured rock as they are exposed to core block.

Further, they are not suitable for continuous drilling without retrieving a core sample.

The mentioned solutions further suffer from having many movable parts requiring maintenance.

The mentioned solutions also suffer from a locking device that in difficult drilling conditions or upon operator error may unintentionally activate and cause damage on the drill.

Further, thrust bearings of prior art solutions are not arranged to act in relation to the drill bit resulting in uneven load on the bearing.

When increasing or decreasing the offset in the eccentric bushing the direction of deflection also changes, resulting in that orientation tool and bit direction must be reset.

Alternative solutions to the above mentioned wireline-operated directional drills are by using mud motors in the borehole, such as e.g. disclosed in US2004211570 A1, EP1308599 A2, US2005236187 A1, and WO2013028074. Disadvantages with these solutions are that they have limited power and that they require holding the drill string in fixed orientation at surface. While drilling, twist in the drill string can cause the orientation of the motor at the hole bottom to change significantly over short sections. To function properly, mud motors will normally also require additional equipment not always present on the drill site, e.g. larger mud pumps, and smaller diameter drill string.

From US2009126997 A1 is known a counterbalance enabled power generator for horizontal directional drilling systems, which can only be used in horizontal drilling systems due to the generator is based on the use of an eccentric mass.

In US2011056750 A1 is disclosed an automatic control of oscillatory penetration apparatus. The solution in US2011056750 A1 discloses a sonic actuator that is arranged to the end of the drill string being above the borehole.

For use of downhole power generators references are also made to US 20130292110 A1 and US 20130219997 A1.

A further lack of prior art is that they do not provide energy efficient push increasing means, and in solutions where push increasing means are arranged, these means are arranged far from the drill bit, resulting in low efficiency. They further are not arranged for working both at horizontal and vertical boreholes which is a key requirement when drilling directional holes. In addition they require supply of power from the rig.

Object

The main object of the present invention is to provide a directional drill partly or entirely solving the above drawbacks of prior art.

It is further an object to provide a directional drill with diamond full-face drill bit operated with a fixed oriented outer tube which is moved forward during drilling.

An object of the present invention is to provide a directional drill arranged for continuous drilling without requiring retrieving of a core sample.

It is further an object of the present invention to provide a directional drill where the orientation is independent of twist in the drill string providing a more even deviation compared to prior art solutions.

An object of the present invention is to provide a directional drill provided with a locking system being robust and secure and without possibilities for entering locking position during drilling.

Another object of the present invention is to provide a directional drill where drilling fluid amount can be adjusted externally.

It is further an object of the present invention to provide a directional drill being arranged for adaption of drilling fluid flow in a simple manner to different rock types.

A further object of the present invention is to provide a directional drill being provided with energy efficient push increasing means, and especially push increasing means which can be arranged in the drill string accompanied with power sources for the push increasing means in the drill string, accordingly providing the directional drill with downhole push increasing means being self-supplied with power.

It is further an object of the present invention to provide a directional drill being provided with push increasing means working both at horizontal and vertical boreholes.

Further objects of the present invention will appear from the following description, claims and attached drawings.

The invention

A directional drill according to the present invention is described in claim 1. Preferable features of the directional drill are described in the remaining claims.

The present invention provides a directional drill for drilling of arced holes having a predetermined course in jointed and fractured rock formations.

The directional drill according to the present invention includes a drill string with a foremost diamond full-face drill bit with a reamer and a drive shaft connection assembly, wherein the directional drill is provided with a underlying the drill bit at least one rotation preventing assembly including at least one pressure pad or packer element arranged for engaging a borehole wall by activation by pressure from supply of drilling fluid and displaceable axially along the borehole wall during drilling for fixed orientation of the directional drill.

The directional drill according to the present invention further preferably includes a underlying the drill bit deflection assembly, arranged in lower part of the directional drill, the deflection assembly being adjustable in a single plane to bend lower part of an inner drive shaft, so that a front part of the drill string, hereunder drive shaft connection assembly, reamer and drill bit, are provided with a rotational axis deviating from a non-rotatable section of the drill string.

The above mentioned deflection assembly is arranged in lower part of the directional drill, i.e. below the rotation preventing assembly. The components of the deflection assembly are preferably made of hard metals, cemented carbide or Polycrystalline Diamond (PCD).

Accordingly, the present invention provides a solution for accurate directional drilling for a directional drill with diamond full-face drill bit.

The directional drill is according to the present invention further provided with a thrust bearing assembly being adjusted according to the drill bit by that the thrust bearing assembly includes a spherical sleeve. Further, contact surfaces of the thrust bearing assembly are preferably formed by hard metals, cemented carbide or Polycrystalline Diamond (PCD). The thrust bearing assembly according to the present invention further provides a thrust bearing having larger surface which results in extended operating time compared to prior art solutions.

The directional drill according to the present invention is further provided with an instrumentation assembly comprising a survey instrument accommodating metering elements to measure direction and inclination, including angle of rotation, as well as a muleshoe, wherein the muleshoe is arranged for orientating deflection direction in an orientation and connector assembly for the directional drill, the orientation and connector assembly forming upper part of the drill string. The muleshoe is further arranged for orienting the instrumentation assembly in the directional drill by means of the orientation and connector assembly.

The directional drill according to the present invention further preferably includes a magnetic orientation assembly, wherein a magnetic sensor is arranged for reading/measuring orientation of the instrumentation assembly.

The orientation and connector assembly further provides a locking system to lock rotatable and non-rotatable sections of the directional drill. According to the present invention the locking system is activated by the instrumentation assembly with muleshoe or by a magnetic sensor accommodated in the magnetic orientation assembly.

According to a further embodiment of the directional drill according to the present invention the directional drill is provided with ultrasonic push increasing means in the form of an ultrasonic actuator assembly and generator assembly, wherein the ultrasonic actuator assembly is arranged at a front part of the directional drill, i.e. close to the drill bit and in physical contact with the drill bit.

The ultrasonic push increasing means according to the present invention is arranged to work both at horizontal and vertical boreholes, which is not the case with prior art solutions. Accordingly, it will provide downhole push increasing means being self-powered.

According to the present invention there is provided a directional drill which is not exposed to blocking in jointed and fractured rock, accordingly providing a solution which is well adapted for directional drilling in jointed and fractured rock.

By the present invention it is provided a directional drill which can be used for continuous drilling without stopping to retrieve a core sample.

Prior art solutions using mud motors in the borehole will have limited power. With the directional drill according to the present invention one will have all power of the drill bit from the drill string and the drill rig.

The directional drill according to the present invention will maintain the orientation down in the borehole, while by use of mud motors in drilling the drill string is held in a fixed orientation at surface. By means of the present invention the orientation is independent of twist in the drill string, resulting in a more even deviation.

The present invention provides a robust design with useful interior space in the directional drill for instruments and power means.

The present invention provides a directional drill with fewer movable parts compared with prior art solutions.

As the locking system is only active when the instrumentation assembly is down in the borehole, it is provided a robust and secure locking. Further, there is no possibility for the locking system to go in lock position during drilling.

The directional drill according to the present invention is further arranged for exterior adjustment of drilling fluid amount, accordingly providing a solution being arranged for adaption of drilling fluid in a simple manner to different rock types.

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

Example

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

Figure 1 shows a principle drawing of a directional drill according to the present invention,

Figure 2 shows a principle drawing of an instrumentation assembly according to the present invention,

Figure 3 shows an axial cross section through the front end of the directional drill,

Figure 4 shows an axial cross section of a deflection assembly according to the present invention,

Figure 5 shows an axial cross section of a magnetic orientation assembly according to the present invention,

Figure 6 shows an axial cross section of an orientation and connector assembly according to the present invention, and

Figure 7 shows axial cross section revealing details of ultrasonic push increasing means according to the present invention.

Reference is now made to Figures 1 and 2 illustrating a directional drill 10 according to a first embodiment of the present invention, comprised by numerous parts in the longitudinal direction forming a drill string 11. The drill string 11 comprises, in order from below and up, a foremost diamond drill bit 20 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 assembly 100, a magnetic orientation assembly 200 and an orientation and connector assembly 300. The thrust bearing assembly 50, lower outer tube 60, deflection assembly 70, stabilizer assembly 90, rotation preventing assembly 100 and magnetic orientation assembly 200 being arranged for accommodating an inner drive shaft 150 for driving the drill bit 20, wherein the drive shaft 150 is driven by a drill rig.

The directional drill 10 further includes an instrumentation assembly 400, shown in Figure 2, formed by a survey instrument 401, in which survey instrument 401 is arranged metering elements to measure direction and inclination, including angle of rotation, e.g. magnetometer and accelerometer, wherein a muleshoe 402 is arranged on the survey instrument 401, above the metering elements. Above the muleshoe 402 is arranged a pump-in assembly 403 for drilling fluid.

The instrumentation assembly 400 reads the orientation of the directional drill 10 and allows for re-orientation.

Reference is no made to Figure 3, illustrating the lower part of the directional drill 10 in an axial cross-section. The drill bit 20 including external water recesses 21 (shown in Figure 1), is tubular and exhibits an inner stem 22 with a thread for insert into the reamer 30, which in a similar manner is thread-connected to the lower end of the drive shaft connection assembly 40, which in turn is thread-connected to a lower part of an interior rotating drive shaft 150.

The drive shaft connection assembly 40 is further provided with an adjustable nozzle or valve 41 adjustable via exterior adjustment means 42, such as an adjusting screw extending to the surface of the drive shaft connection assembly 40, providing a throttle control for drilling fluid supplied through the drill string 11, thus forming a pressure inside the drill string 11 sufficient to activate the rotation preventing assembly 100 (Fig. 1). The pressure upstream of drive shaft connection assembly 40 may be 20-30 bars.

The rotation preventing assembly 100, shown in Figure 1, is in a preferable embodiment formed by a packer pipe 101 including a packer housing having at least one pressure pad or packer element 102, lower 103 and upper 104 end pieces, respectively, and front 105 and rear 106 stuffing boxes, respectively. Accordingly, the rotation preventing assembly 100 is provided with sealings and connections at both sides thereof enabling arrangement into the drill string 11. The at least one pressure pad or packer element 102 of the rotation preventing assembly 100 is arranged for, at activation, to extend out of the packer pipe 101 and into engagement with a borehole wall for locking rotation of the rotation preventing assembly 100, as well as parts of the directional drill 10 between the orientation and connector assembly 200 and the drill bit 20, in relation to the borehole wall. The at least one pressure pad or packer element 102 is/are arranged to be pressed outward to the borehole wall by means of pressure from drilling fluid being supplied to the drill string 11 via the pump-in assembly of the instrumentation assembly 400 and is/are arranged to be displaced axially along the borehole wall during drilling.

Accordingly, the pressure acting upon the rotation preventing assembly 100/pressures pad/element 102, is adjustable by using the exterior adjustment means 42 to control the adjustable nozzle or valve 41. In this way, it is possible to adapt the directional drill 10 in accordance with the present invention in a simple manner to different rock types requiring varying water quantities and varying pressure of the rotation preventing assembly 100.

The directional drill 10 according to the present invention further includes a radial thrust bearing assembly 50, shown in Figure 3, formed by a thrust bearing housing 51 spherically arranged in relation to the drill bit 20 connected to the drive shaft connection assembly 40 at lower side and an outer tube 52 accommodating the inner thrust bearing housing 51 by exhibiting a recess 53, which outer tube 52 is arranged to the upper side of the lower outer tube 60 of the drill string 11. The thrust bearing assembly 50 further includes a stator assembly 54 including a stator ring 55 which have a contact surface 56 provided with sliders or slider bits, which stator assembly 54 is fixed at upper part of the thrust bearing housing 51. The thrust bearing assembly 50 further includes a rotor assembly 57 including a rotor ring 58 which have a contact surface 59 provided with sliders or slider bits and which rotor ring 58 is arranged to lower part of the inner drive shaft 150. All sliding or contact surfaces of the thrust bearing assembly 50 are preferably formed by hard metals, preferably chosen among tungsten (wolfram carbide) or titanium carbide or ceramic, cemented carbide or Polycrystalline Diamond (PCD). Especially, the sliders or bits are formed by these mentioned materials. The inner diameter of the stator 54 and rotor 57 assemblies is adapted to accommodate the lower part of the inner drive shaft 150.

The lower part of the inner drive shaft 150 can further be hardened, e.g. by means of plasma hardening, or applied spray metal/ceramic on whole or sections of the inner drive shaft 150 being in contact with the thrust bearing assembly 50.

The stator ring 55 or rotor ring 58 can further be provided with holes (not shown) for allowing a flow of cooling fluid for cooling of the thrust bearing assembly 50.

Reference is now made to Figure 4 showing an axial cross-section of an adjustable deflection assembly 70 according to the present invention, arranged between the lower outer tube 60 and upper outer tube 80. The adjustable deflection assembly 70 is formed by an outer tube 71 and an inner sleeve 72 provided with a circumferential flange 73 at one side thereof, the inner sleeve being accommodated in a recess 74 in the outer tube 71, wherein the recess 74 exhibiting a shape for accommodating the inner sleeve 72 with the flange 73 with a clearance thereof, enabling adjustment of the inner sleeve 72 in the outer tube 71 in one plane thereof. The deflection assembly 70 further includes adjustment means, such as at least two screws 75, extending from outer surface of the outer tube 71, from each side thereof and into engagement with corresponding recesses 76 at outer surface of the inner sleeve 72, at each side thereof. By means of the adjustment means at each side of the inner sleeve 72 is arranged movable in relation to the outer tube 71 such that the vertical plane through center of the inner sleeve 72 can be adjusted in relation to the vertical plane through center of the outer tube 71 by adjustment of the inner sleeve 72 in transversal direction of the outer tube 71.

Accordingly, by adjustment of the inner sleeve 72 in relation to the outer tube seamlessly changing of the deflection is achieved without the need of replacing components of the drill string 11 to bend lower part of the drive shaft 150, so that a front part of the drill string 11, i.e. drive shaft connection assembly 40, reamer 30 and drill bit 20 are provided with a rotational axis deviating from a non-rotatable central section of the drill string 11 formed by the rotation preventing assembly 100, stabilizer assembly 90, upper outer tube 80, deflection assembly 70, lower outer tube 60, and orientation and connector assembly 200.

Further, the outer tube 71 is preferably on its outer diameter provided with centralizing pads 78 (Figure 1) made in wear resistant material, for engaging with a borehole wall and centralize the drill string 11 and creating distance between the drill string 11 and the borehole wall for allowing drilling fluid to pass freely.

Bending of the inner drive shaft 150 is accordingly achieved by the adjusting the position of the inner sleeve 72 in a single plane in the outer tube 71. With this approach the direction of the deflection of the drill bit 20 is independent of the intensity of the bend of the inner drive shaft 150. Further, when the vertical plane of the outer tube 71 and inner sleeve 72 coincide, there is no deviation enabling drilling in a straight line.

The deflection assembly 70 according to the present invention can further be provided with means 77 for enabling lubrication of the deflection assembly 70.

The parts of the deflection assembly 70-72 can in some embodiments preferably be made of hard metal, preferably chosen among tungsten (wolfram carbide) or titanium carbide or ceramic, cemented carbide or Polycrystalline Diamond (PCD).

Reference is now made to Figure 5 showing an axial cross section of the magnetic orientation assembly 200. The magnetic orientation assembly 200 is formed by an outer tube 201 wherein a magnetic sensor 202 is arranged for reading/measuring orientation of the instrumentation assembly 400.

Reference is now made to Figure 6 showing an axial cross-section through an orientation and connector assembly 300 providing a locking system arranged to lock the rotatable and nonrotatable sections of the directional drill.

The orientation and connector assembly 300 is formed by landing assembly 310 and a locking tube 320, the orientation and connector assembly 300 being arranged for accommodating the instrumentation assembly 400. The landing assembly 310 is formed by an outer tube 311 arranged for accommodating an inner sliding tube 312 and an adapter and orientation tube 313 connecting the outer tube 311 and locking tube 320. The inner sliding tube 312 is at lower part thereof exhibiting narrower circumference providing an annular compartment 314 between the outer tube 311 and the inner sliding tube 312 for arrangement of a dampening device 315, such as a helical spring. The inner sliding tube 312 is further at upper end thereof provided with a muleshoe pin 316 extending perpendicularly from the exterior surface thereof and into the inner sliding tube 312.

The adapter and orientation tube 313 is further at upper part thereof provided with an orientation pin 317 extending from the surface of the orientation tube 313 and into the interior thereof for orientation of the instrumentation assembly 400 in the orientation and connector assembly 300.

The locking tube 320 may further at intermediate part or lower part thereof be provided with a lock pin 321 for locking rotatable and non-rotatable sections of the drill string 11, which lock pin 321 can be activated by the muleshoe 402 arranged in connection with the instrumentation assembly 400 or magnetic sensor 202 in the magnetic instrumentation assembly 200. When activated, the deflection position can be determined in order to control the orientation of the directional drill 10 and optionally adjust the deflection position.

Accordingly, as the instrumentation assembly 400 is inserted into the orientation and connector assembly 300, the muleshoe 402 via the orientation pin 317 is oriented in the orientation and connector assembly 300, while instrumentation assembly 400 is dampened by the dampening device 315 at landing in the orientation and connector assembly 300. The muleshoe 402 or magnetic sensor 202 then activates the lock pin 321 and the instrumentation assembly 400 is rotated until the lock pin 321 enters engagement with a recess 322 in the locking tube 320.

By removing instrumentation assembly 400, inner sliding tube 312 is guided upward and the inner part of the directional drill 10 can rotate independently from the stationary outer part of the directional drill 10.

By bringing the lock pin 321 into engagement, after drilling has been completed, the deflection position can be determined in order to control the orientation of the directional drill 10 and optionally adjust the deflection position.

The directional drill 10 accordingly is provided with a connecting mechanism which enables a simple adjustment and control of the drilling direction. Moreover, it is convenient to adapt the drilling fluid flow rate as desired without compromising the rotation preventing assembly 100 when drilling in different rock types.

The directional drill 10 according to the present invention is accordingly so arranged that by supplying drilling fluid under pressure to rotation preventing assembly 100, the drill bit 20, reamer 30 and drive shaft connection assembly 40 can rotate independent of the stationary part of the drill string 11.

The present invention accordingly provides a directional drill 11 which has a connection mechanism making it easy to monitor, make adjustments and regulate the drilling direction and borehole curvature. Further, it is easy to adapt the drilling fluid flow without compromising the rotation preventing assembly 100 pressure as needed when drilling in different kinds of rock, which requires different flow rate for optimal penetration rates.

Reference is now made to Figures 1, 3 and 7 showing a second embodiment of a directional drill 11 according to the present invention which is provided with ultrasonic push increasing means 500-512. The ultrasonic push increasing means include an actuator assembly 500 and a generator assembly 510. The actuator assembly 500 is formed by an outer tube 501 for housing at least one actuator 502 in the form of e.g. piezo transducer, which actuator assembly 500 is arranged at front part of the directional drill 10, e.g. arranged between the reamer 30 and the shaft connection assembly 40. The actuator assembly 500 is further arranged to guide drilling fluid via center of the actuator assembly 500 or arranged to guide drilling fluid in the wall of the outer tube 501. It should further be mentioned that it is important that the actuator 502 should be in a strong physical contact with the drill bit 20 to have high efficiency.

The ultrasonic push increasing means further includes a generator assembly 510 formed by an outer tube 511 used for arrangement of at least one generator or generator segment 512 and wherein the generator assembly 510 is arranged for accommodating the inner drive shaft 150 of the directional drill 10, wherein the generator assembly 510 e.g. is arranged between the stabilizer assembly 90 and rotation preventing assembly 100, as shown in the example, or between the rotation preventing assembly 100 and magnetic orientation assembly 200.

The actuator assembly 500 and generator assembly 510 are connected by means of wires or conductive layers in the inner drive shaft 150 via appropriate connection means in the actuator assembly and generator assembly 510.

Accordingly, the push increasing means 500 according to the present invention provides downhole push increasing means which is self-supplied with power.

It should here be mentioned that the above described push increasing means also can be used in traditional drills, i.e. drills which are not arranged for directional drilling, only drilling of straight holes. Accordingly, a drill where deflection assembly, rotation preventing assembly, instrument assembly, magnetic orientation assembly and orientation and connector assembly are missing, i.e. only a drive shaft connection is arranged at upper end of the drill string. It should however be mentioned that for a push increasing means to have high efficiency it would be favorable to have some sort of retaining device retaining the outer tube in the borehole.

Modifications

In an alternative embodiment of the directional drill according to the present invention the deflection assembly can be replaced with an adjustable eccentric bushing assembly as described in WO2013/028075 in the name of applicant, the contents of which are incorporated herein by reference.

Claims

1. A directional drill (10) for directional drilling of arced holes having a predetermined course in jointed and fractured rock, comprising a drill string (11) with a foremost diamond full-face drill bit (20) with a reamer (30) and drive shaft connection assembly (40), wherein the directional drill (10) is provided with a underlying of the drill bit (20) arranged rotation preventing assembly (100) including at least one pressure pad or packer element (102) for engagement with a borehole wall by activation by pressure from supply of drilling fluid and displaceable axially along the borehole wall during drilling for fixed orientation of the directional drill (10), characterized in that it includes an ultrasonic push increasing means in the form of an ultrasonic actuator assembly (500) and a power generator assembly (510),

wherein the power generator assembly (510) is formed by an outer tube (511) used for arrangement of at least one generator or generator segment (512) and wherein the power generator assembly (510) is arranged for accommodating an inner drive shaft (150) of the directional drill (10), and

the ultrasonic actuator assembly (500) is arranged at front part of the directional drill (10), behind the drill bit (20), and in physical contact with the drill bit (20).

2. Direction drill according to claim 1, characterized in that the ultrasonic actuator assembly (500) formed by an outer tube (501) for housing at least one actuator (502).

3. Direction drill according to claim 1, characterized in that the ultrasonic actuator assembly (500) is arranged between the reamer (30) and the shaft connection assembly (40).

4. Direction drill according to claim 2, characterized in that the ultrasonic actuator assembly (500) is arranged to guide drilling fluid via center of the ultrasonic actuator assembly (500) or arranged to guide drilling fluid in the wall of the outer tube (501).

5. Direction drill according to any one of the preceding claims, characterized in that the ultrasonic actuator assembly (500) and power generator assembly (510) are connected by means of wires or conductive layers in the inner drive shaft (150) via appropriate connection means in the ultrasonic actuator assembly (500) and power generator assembly (510).

6. Directional drill according to claim 1, characterized in that it further includes an instrumentation assembly (400) comprising a survey instrument (401) accommodating metering elements to measure direction and inclination, including angle of rotation, as well as a muleshoe (402), wherein the muleshoe (402) is arranged for orientating deflection direction in an orientation and connector assembly (300) for the directional drill (10), the orientation and connector assembly (300) forming upper part of the drill string (11).

7. Directional drill according to claim 6, characterized in that the orientation and connector assembly (300) is arranged for accommodating the instrumentation assembly (400) and providing a locking system to lock stationary section of the directional drill (10) to rotatable section of the directional drill (10).

8. Directional drill according to claims 6-7, characterized in that it further includes a magnetic orientation assembly (200) provided with a magnetic sensor (202) for reading/measuring orientation of the instrumentation assembly (400).

9. Directional drill according to claims 6 and 7 or 8, characterized in that the muleshoe (402) of the instrumentation assembly (400) or magnetic sensor (202) of the magnetic orientation assembly (200) is arranged for activating the locking system.