WO1993015302A1

WO1993015302A1 - In-line sub for drilling equipment

Info

Publication number: WO1993015302A1
Application number: PCT/AU1993/000041
Authority: WO
Inventors: Darcy Lester Flynn
Original assignee: Advanced Drilling Technologies Pty. Ltd.
Priority date: 1992-01-31
Filing date: 1993-01-29
Publication date: 1993-08-05
Also published as: KR950700477A; AU664420B2; CA2128878A1; JPH07503294A; AU3444593A

Abstract

An in-line sub (10) connects first and second drill pipes (11, 12) and has a sleeve (26) and mounting block (29) movable vertically relative to a body (16) along vertical or helical splines (25). In the drilling position, vibration dampener means (34) (e.g. of resilient material) isolate the first drill pipe (11) from shocks transmitted to the sub (10) by the second drill pipe (12). A spring loaded sealing plug (22) seals the central bore (18) of the body (16) when no air is flowering through the bore (18), while stabilizer fins (35) bear on the hole to locate the sub (10) therein.

Description

TITLE: "IN-LINE SUB FOR DRILLING EQUIPMENT" BACKGROUND OF THE INVENTION

1. Field of the Invention

THIS INVENTION relates to an in-line sub for drilling equipment.

2. Prior Art

The operator of a drilling rig must operate the rig under a number of conflicting conditions. As he is paid by the metre depth drilled, a high drilling rate increases his operating profit on the rig. Therefore, he will tend to operate the rig at the highest drilling rate possible. This, however, will place greater loads on the drilling rig and maintenance costs may increase to an uneconomic level. Shock loads on the bit are transmitted up through the drill string to the drilling machine and platform and the loads are magnified when the equipment is operated at full capacity. Therefore, the likelihood of damage, or equipment failure, is increased. This, in turn, increased down time and maintenance and repair costs.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an in-line sub for drilling equipment which can be used to isolate, or reduce, the shock loads transmitted to the drilling equipment by the drilling bit.

It is a preferred object to provide a sub which can be provided at regular locations along the drill string.

It is a further preferred object to provide an in-line sub which can act to stabilize the drill string in the hole.

It is a still further preferred object to provide an in-line sub which incorporates sealing means to prevent the travel of debris up the pressurized air passage.

Other preferred objects of the present invention will become apparent from the following description. In one aspect the present invention resides in an in-line sub for a drilling string for a percussion hammer or a rotary drill bit including: a body having a head screw-threadably mounted on the lower end of the first drill pipe in the drilling string, and having at least one intake passage extending substantially radially through the body and arranged to communicate with the pressurized air passage in the first drill pipe; a sleeve rotatably mounted on the body and longitudinally movable relative therewith; a mounting block ountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connection to the upper end of a second drill pipe in the drilling string or to a percussion hammer or rotary drilling bit and having at least one air intake connectable with an air intake port in the second drill pipe, hammer or bit; air passage means between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block; and vibration dampener means on the mounting block engageable by the body; so arranged that in a first drilling position, the vibration dampener means is engaged by the body to limit, or isolate, the first drill pipe from shocks transmitted to the sub by the second drill pipe, hammer or bit; and in a second withdrawal position, the body is spaced from the vibration dampener means.

In a second aspect the present invention resides in an in-line sub for a reverse circulation drilling string including: a body having a head screw-threadably mounted on the lower end of a first drill pipe of the drilling string, a substantially central exhaust passage and at least one intake passage extending substantially radially through the body and arranged to communicate with a pressurized air passage in the first drill pipe; a sleeve member rotatably mounted on the body and longitudinally movable relative thereto; a mounting block mountable on the lower end of the sleeve and arranged for connection to a second drill pipe or hammer or drilling bit and having a substantially central exhaust passage to provide a connection between the exhaust port in the second drill pipe, hammer or bit, and at least one air intake passage connectable with an air intake port in the second drill pipe, hammer or bit; vibration dampener means on the mounting block engageable by the body; so arranged that in a drilling position, the vibration dampener means is engaged by the body to limit, or isolate, the first drill from shocks transmitted to the sub by the second drill pipe, hammer or bit; and in a second withdrawal position, the body is spaced from the vibration dampener means.

In the third and fourth aspects, respectively, the subs of the first and second aspects are modified by the mounting of the vibration dampener means on the lower end of the body for engagement by the mounting block.

In the fifth and sixth aspects, respectively, the subs of the first and second aspects are modified by the mounting of the vibration dampener in two respective engageable portions on the lower end of the body and the upper end of the mounting block.

Preferably, seal means are provided in the intake passage in the body and are operable to close the intake passage and/or pressurized air passage in the first drill pipe when the sleeve is in the second withdrawal position to prevent debris entering the first drill pipe.

Preferably a plurality of stabilizing fins or wings are provided around the sub to engage the wall of the drilled hole to stabilize the drill string.

The vibration dampener means may comprise an annular ring, or plurality of buttons or cones of resilient (e.g. plastics or rubber) material which may have a metal backing. In a seventh aspect, the present invention resides in an in-line sub for a drilling string for a percussion hammer or a rotary drill bit including: a body having a head screw-threadably mounted on the lower end of the first drill pipe in the drilling string, and having at least one intake passage extending substantially radially through the body and arranged to communicate with the pressurized air passage in the first drill pipe; a sleeve rotatably mounted oh the body and longitudinally movable relative therewith; a mounting block mountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connection to the upper end of a second drill pipe in the drilling string or to a percussion hammer or rotary drilling bit and having at least one air intake connectable with an air intake port in the second drill pipe, hammer or bit; air passage means between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block; and port means through the body arrange to allow communication between the pressurized air passage and the exterior of the body; so arranged that in a first drilling position, the sleeve allows communication of the one intake passage to the pressurised air passage and closes the port means, to allow pressurised air, grout, drilling mud or the like to pass through the in-line sub from the first drill pipe to the second drill pipe; and in a second withdrawal position, the sleeve allows communication between the pressurized air passage and the exterior of the body to allow the air, grout, drilling mud or the like to be pumped into the cavity about the first drill pipe. In an eighth aspect, the present invention resides in an in-line sub for a reverse circulation drilling string including: a body having a head screw-threadably mounted on the lower end of a first drill pipe of the drilling string, a substantially central exhaust passage and at least one intake passage extending substantially radially through the body and arranged to communicate with a pressurized air passage in the first drill pipe; a sleeve member rotatably mounted on the body and longitudinally movable relative thereto; a mounting block movable on the lower end of the sleeve and arranged for connection to a second drill pipe or hammer or drilling bit and having a substantially central exhaust passage to provide a connection between the exhaust port in the second drill pipe, hammer or bit, and at least one air intake passage connectable with an air intake port in the second drill pipe, hammer or bit; and port means through the body arrange to allow communication between the pressurized air passage and the exterior of the body; so arranged that in a first drilling position, the sleeve allows communication of the one intake passage to the pressurised air passage and closes the port means, to allow pressurised air, grout, drilling mud or the like to pass through the in-line sub from the first drill pipe to the second drill pipe; and in a second withdrawal position, the sleeve allows communication between the pressurized, air passage and the exterior of the body to allow the air, grout, drilling mud or the like to be pumped into the cavity about the first drill pipe.

In the seventh and eighth aspect, the present invention preferably where the body and the sleeve member have complementary helical splines to enable the rotatable, longitudinal movement of the sleeve relative to the body; and the angle of inclination (or the rate of feed) of the splines is different in each in-line sub, or group of in-line subs, to allow selective movement of the sleeve member along the body in any one (or group) of in-line subs when the in-line subs are incorporated in a drilling string.

Preferably, the angle of inclination of the helical splines (relative to the horizontal axis) is increased in successive in-line subs up the string to enable the sleeves of the in-line subs to move to the second position to open the port means and thereby allow the air, grout, drilling mud or the like to be flushed up the hole. (Hereinafter, the term "drilling fluid" shall be used to cover the air, grout, drilling mud or the like.)

The in-line subs may be fitted with the vibration dampeners hereinbefore described.

In a ninth aspect, the present invention resides in a drilling string incorporating at least one sub hereinbefore described. BRIEF DESCRIPTION OF THE DRAWINGS To enable the invention to be fully understood, a number of preferred embodiments will now be described with reference to the accompanying drawings, in which:

FIG 1 is a sectional front view of a sub for a percussion hammer or rotary drilling string, the sub being in the drilling mode;

FIG 2 is a similar view to FIG 1, the mounting block being shown suitable for attachment to a percussion hammer, and the sub being in the withdrawal mode;

FIG 3 is a sectional front view of a sub for a reverse circulation drilling string, the sub being in the drilling mode;

FIG 4 is a similar view to FIG 3 showing the sub in the withdrawal mode; and

FIGS 5 to 8 correspond to FIGS 1 to 4 respectively, where the in-line subs are modified to include the port means to enable the drilling fluid to be flushed up the annular cavity about the first drill pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS 1 and 2, the sub 10 is attached to the lower end of the first drill pipe 11 and to the upper end of a second drill pipe 12 (see FIG 1) or a pneumatic percussion hammer 13 (see FIG 2). The first and second drill pipes 11, 12 may be incorporated in the drilling string for a percussion hammer 13 or a rotary drill bit (not shown). The first drill pipe 11 has a central pressurized air passage 14 and its lower end is received in a coupling 15 having a tapered screw- threaded bore.

The coupling 15 is welded to the upper end of the body 16 and the latter has a central bore 18 with a plurality of radially extending intake passages 19, while exhaust ports 20 extend radially from an exhaust bore 21 at the lower end of the body 16.

A sealing plug 22, of resilient plastics or rubber material, is slidably received in a bore 23, coaxial with central bore 18, and is backed by a compression spring 24.

Three helical (or vertical) splines 25 are provided around and extend down the body 16.

The sleeve 26 has pairs of internal helical (or vertical) splines 27 engaged with the splines 25 on the body 16 to enable the sleeve 26 to move rotatably and longitudinally with respect to the body 16. When the sleeve 26 is mounted on the body 16, intake passages 28 are defined by the sleeve 26 and the body 16, between the pair of helical splines 27.

The mounting block 29 is welded to the lower end of the sleeve 26 and has a tapered screw-threaded extension 30, engageable with the upper end of second drill pipe 12, or helical splines 31 engageable in a socket 32 at the upper end of the hammer 13. A central air intake passage 33, extends through the mounting block 29.

An annular vibration dampener ring 34, of resilient plastics material, is fixed to the top of the mounting block 29, surrounding the air intake passage

34, and engageable by the lower end. of the body 16 when the sub is in the drilling mode (see FIG. 1).

Stabilizer fins 35, extend radially from the sleeve 26 and bear on the wall of the hole (not shown) . The drilling string is assembled, with one sub

19 (see FIG. 2) attached to the percussion hammer 13 or bit, and sub 10 between e.g. every third drill pipe in the string.

When the drill bit reaches the bottom of the hole, the body moves down relative to the sleeve 26 and mounting block 29 until the lower end of the body 16 engages the annular vibration dampener ring 34.

The pressurized air through central air passage 14 and the central bore 18 moves the sealing plug 22 from a seat 36 and the air travels out through the intake passages 19 and the intake passages 28. The air passes down the intake passage 28, enters the exhaust ports 20 and travels through the exhaust bore 19 and the air intake passage 33 to the second drill pipe 12 or hammer 13. Any shocks which are transmitted up the drill string via the second drill pipe 12 or hammer 13 will be dampened (and possibly isolated) by the dampener ring 34 between the mounting block 29 and- the body 16 so the potential for damage to the drilling string is reduced (or eliminated).

When drilling is finished, or a fresh drill pipe is to be added to the string, the drilling string is lifted and the body 16 moves to the position shown in FIG. 2. When the air is shut off, sealing plug 22 engages the seat 35 to prevent debris passing up through the sub into the drill pipe 11 above it. (In practice, only the lower most sub 10 will incorporate the sealing plug 22.)

Referring now to the reverse circulation sub 110, the body 116 has a coupling 115 attached to the first drill pipe 111 and the mounting block 129 is connectable to a second drill pipe 112 or a reverse circulation hammer 113 as hereinbefore described.

The intake passages 119 are connected to a plurality of intake ports 118 which surround a central exhaust port 140 and the intake passages 119 are selectively closed by an annular sealing ring 122, in an annular groove 123, backed by a compression spring 124.

The intake passage 128, defined by splines 125, 127 on the body 116 and sleeve 126 communicates with air intake ports 133 in the mounting block 129 and a tubular extension 141 on the mounting block 129 is slidably reversed in a bore 142 in the body 116. The tubular extension 147 connects the central exhaust port 140 to exhaust passage 143 in the mounting block. The annular vibration dampener ring 134 is provided at the upper end of the mounting block 129 around the tubular extension 141.

The operation of the sub 110 is substantially as hereinbefore described with the pressurized air travelling through intake ports 118 (connected to the intake passages of the drill pipe 111) , intake passages 119, intake passages 128 and intake ports 133 to the drill pipe 112 or hammer 113. The exhaust air is returned via exhaust passage 143, tubular extension 141 and central exhaust port 140.

As hereinbefore described, the vibration dampener ring 134 will reduce, or isolate shocks transmitted up the drill string when the ring 134 is compressed between the body 116 and the mounting block 129.

As an alternative to a ring 34, 134 of vibration dampening material, buttons and/or cones may be mounted on the top of the mounting block 29, 129 and/or bottom of the body 16, 116. The splines 25, 125 and 27, 127 may be helical or vertical and the stabilizer wings or fins 35, 135 may extend radially or inclined to the sleeve 26, 126.

Referring to FIGS 5 and 6, the sub 10A is substantially identical, except that the body 16 is provided with one or more radial flushing ports 50, operably connected to the central bore 18 and to the exterior of the body 16. In the drilling position (FIG 5), the sleeve 26 closes the flushing ports 50 and the air (or other drilling fluid) is directed to the intake passages 19 and thereby to the second drill pipe 12. When the first drill pipe 11 is raised, the sleeve 26 closes the air passages 19 and opens the flushing ports 50.

By variation of the angle of inclination of the helical splines 25 on the body 16, and the complementary helical splines 27 on the sleeve 26, the longitudinal movement of the sleeve 26 relative to the body 16 can be selectively controlled. As the angle of inclination of the splines 25, 27 relative to the horizontal is increased, the sleeve will move along the body earlier for those in-line subs than for those with a lower angle of inclination of the splines. This movement can be initiated by lifting, or lifting and rotating, the first drill pipe relative to the second drill pipe at each in-line sub. By arranging a plurality of in-line subs down the hole where the angles of inclination are decreased, eg. from 85° to 10° relative to the horizontal, the sleeves of the subs can be selectively, progressively moved to the second withdrawal positions down the hole to allow selective flushing of the hole by the drilling fluid.

For example, if lost circulation occurs in a hole, the drills can be raised until the in-line sub just below the lost circulation is opened and grout can be pumped down the drill pipes and out the flushing ports 50, to travel up the hole and seal the lost circulation.

Where the hole has at least partially filled with water after a shut-down, the first sub below the water level can have air flushed through the flushing ports to lift this water thereabove as the hole to enable the hole to be cleaned. The next sub is opened to flush the hole above it, and the water is progressively flushed in zones down the hole. Just as the different angles of inclination of the splines 25, 27 enables the flushing ports to be selectively opened down the hole, they also allow the ports of sub to be selectively closed by lowering the drill pipes as the higher subs will return to the first drilling position quicker than the lower subs and so with skill, the operator can selectively open and close the flushing ports of the subs down the drilling string.

The operation of the reverse circulation drilling sub 110A is substantially as for the sub 110, where the flushing ports 150 co-operate with the sleeve 126 to operate in the manner described as for sub 10A.

The in-line subs 10A, 110A may be sold in sets, with the angle of inclination reducing down the hole in, eg. 5° steps from, eg. 90° to 5° relative to the horizontal, a range of, eg. 60° to 20° being more preferred.

Various other changes and modifications may be made to the embodiments described without departing from the scope of the present invention defined in the appended claims.

Claims

1. An in-line sub for a drilling string for a percussion hammer or a rotary drill bit including: a body having a head screw-threadably mounted on the lower end of the first drill pipe in the drilling string, and having at least one intake passage extending substantially radially through the body and arranged to communicate with the pressurized air passage in the first drill pipe; a sleeve rotatably mounted on the body and longitudinally movable relative therewith; a mounting block mountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connection to the upper end of a second drill pipe in the drilling string or to a percussion hammer or rotary drilling bit and having at least one air intake connectable with an air intake port in the second drill pipe, hammer or bit; air passage means between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block; and vibration dampener means on the mounting block engageable by the body; so arranged that in a first drilling position, the vibration dampener means is engaged, by the body to limit, or isolate, the first drill pipe from shocks transmitted to the sub by the second drill pipe, hammer or bit; and in a second withdrawal position, the body is spaced from the vibration dampener means.

2. An in-line sub according to Claim 1 wherein: the vibration dampener means is mounted on the lower end of the body for engagement by the upper end of the mounting block.

3. An in-line sub according to Claim 1 wherein: the vibration dampener is mounted in two respective engageable positions on the lower end of the body and the upper end of the mounting block.

4. An in-line sub for a reverse circulation drilling string including: a body having a head screw-threadably mounted on the lower end of a first drill pipe of the drilling string, a substantially central exhaust passage and at least one intake passage extending substantially radially through the body and arranged to communicate with a pressurized air passage in the first drill pipe; a sleeve member rotatably mounted on the body and longitudinally movable relative thereto; a mounting block mountable on the lower end of the sleeve and arranged for connection to a second drill pipe or hammer or drilling bit and having a substantially central exhaust passage to provide a connection between the exhaust port in the second drill pipe, hammer or bit, and at least one air intake passage connectable with an air intake port in the second drill pipe, hammer or bit; vibration dampener means on the mounting block engageable by the body; so arranged that in a drilling position, the vibration dampener means is engaged by the body to limit, or isolate, the first drill from shocks transmitted to the sub by the second drill pipe, hammer or bit; and in a second withdrawal position, the body is spaced from the vibration dampener means.

5. An in-line sub according to Claim 4 wherein: the vibration dampener means is mounted on the lower end of the body for engagement by the upper end of the mounting block.

6. An in-line sub according to Claim 4 wherein: the vibration dampener is mounted in two respective engageable positions on the lower end of the body and the upper end of the mounting block.

7. An in-line sub according to any one of Claims 1 to 6 wherein: seal means are provided in the intake passage in the body and are operable to close the intake passage and/or pressurized air passage in the first drill pipe when the sleeve is in the second withdrawal position to prevent debris entering the first drill pipe.

8. An in-line sub according to any one of Claims 1 to 7 wherein: a plurality of stabilising fins or wings are provided around the sub to engage the wall of the drilled hole to stabilize the drill string.

9. An in-line sub according to any one of Claims 1 to 8 wherein: the vibration dampener means comprises an annular ring, or a plurality of buttons or cones of resilient material with an optional metal backing.

10. An in-line sub for a drilling string for a percussion hammer or a rotary drill bit including: a body having a head screw-threadably mounted on the lower end of the first drill pipe in the drilling string, and having at least one intake passage extending substantially radially through the body and arranged to communicate with the pressurized air passage in the first drill pipe; a sleeve rotatably mounted on the body and longitudinally movable relative therewith; a mounting block mountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connection to the upper end of a second drill pipe in the drilling string or to a percussion hammer or rotary drilling bit and having at least one air intake connectable with an air intake port- in the second drill pipe, hammer or bit; air passage means between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block; and port means through the body arrange to allow communication between the pressurized air passage and the exterior of the body; so arranged that in a first drilling position, the sleeve allows communication of the one intake passage to the pressurised air passage and closes the port means, to allow pressurised air, grout, drilling mud or the like to pass through the in-line sub from the first drill pipe to the second drill pipe; and in a second withdrawal position, the sleeve allows communication between the pressurized air passage and the exterior of the body to allow the air, grout, drilling mud or the like to be pumped into the cavity about the first drill pipe.

11. An in-line sub for a drilling string for a percussion hammer or a rotary drill bit including: a body having a head screw-threadably mounted on the lower end of the first drill pipe in the drilling string, and having at least one intake passage extending substantially radially through the body and arranged to communicate with the pressurized air passage in the first drill pipe; a sleeve rotatably mounted on the body and longitudinally movable relative therewith; a mounting block mountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connection to the upper end of a second drill pipe in the drilling string or to a percussion hammer or rotary drilling bit and having at least one air intake connectable with an air intake port in the second drill pipe, hammer or bit; air passage means between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block; and port means through the body arrange to allow communication between the pressurized air passage and the exterior of the body; so arranged that in a first drilling position, the sleeve allows communication of the one intake passage to the pressurised air passage and closes the port means, to allow pressurised air, grout, drilling mud or the like to pass through the in-line sub from the first drill pipe to the second drill pipe; and in a second withdrawal position, the sleeve allows communication between the pressurized air passage and the exterior of the body to allow the air, grout, drilling mud or the like to be pumped into the cavity about the first drill pipe.

12. An in-line sub according to Claim 1 or Claim 11 wherein: the body and the sleeve member have complementary helical splines to enable the rotatable, longitudinal movement of the sleeve relative to the body; and the angle of inclination (or the rate of feed) of the splines is different in each in-line sub, or group of in-line subs, to allow selective movement of the sleeve member along the body in any one (or group) of in-line subs when the in-line subs are incorporated in a drilling string.

13. An in-line sub according to Claim 12 wherein: the angle of inclination of the helical splines (relative to the horizontal axis) is increased in successive in-line subs up the string to enable the sleeves of the in-line subs to move to the second position to open the port means and thereby allow the air, grout, drilling mud or the like to be flushed up the hole. (Hereinafter, the term "drilling fluid" shall be used to cover the air, grout, drilling mud or the like. ) 14. An in-line sub according to any one of Claims 10 to 13 wherein: a vibration dampener is mounted on the lower end of the body, and/or the upper end of the mounting block, and is engageable by the upper end of the mounting block, or the lower end of the body, in the first drilling position to isolate the first drill pipe from shocks transmitted to the sub by the second drill pipe, hammer or bit. 15. A drilling string incorporating at least one in-line sub of the type claimed in any one of Claims 1 to 14.