Adaptor for drilling strings with a controllable air passage

Abstract: The invention relates to an adaptor for drilling strings. The adaptor comprises a body (16) having a head screw-threadably mountable on the lower end of a drilling string, having at least one intake passage (19) extending substantially radially through the body and arranged to communicate with a pressure pipe in the drilling string; a sleeve (23) rotatably mounted on the body and longitudinally movable relative thereto; a mount­ ing block (26) mountable on the lower end of the sleeve and movable therewith relative to the body and arranged for connecting to drilling equipment and having at least one air intake passage connectable with an air intake port in the drilling equipment; and air passage means between the intake passage defined between the body and the sleeve arranged to connect the intake passage in the body to the air intake passage in the mounting block. The adaptor is so arranged that in a first position of the sleeve relative to the body, pressurized air from the pressure pipe is directed through the intake passage in the body, the air passage means (33) and the air intake passage (32) in the mounting block to the air intake port of the drilling equipment; and in a second position of the sleeve relative to the body, the pressure air is directed by the intake passage (20) to the drill hole above the adaptor to clear debris from the drill hole.

Description: THIS INVENTION relates to an adaptor for drilling strings. 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. However, a loss of the drilling equipment (e.g. the hammer and/or drilling bit) down the hole can incur a monetary loss of $50,000 (Aust.) plus, easily cancelling the operating profits. Generally the drilling equipment is lost due to a collapse of the hole wall above the drilling equipment, the dislodged material jamming the drilling equipment down the hole. The collapse may be due to a physical failure in the soil stratum around the hole, or the dislodgement of rocks or soil from the wall of the hole by the drilling equipment as it is withdrawn from the hole or while geological samples are being taken. In certain areas of Western Australia, the clay strata at depth around the hole swells to "choke" the hole, when contacted by ground water from another level in the hole. When the hole wall collapses, or the clay chokes the hole, the operator either has to abandon the drilling equipment down the hole or use a second rig to try to recover the equipment by drilling a second hole closely adjacent the first. It will be readily apparent to the skilled addressee that the second rig could suffer the same fate as the first rig. In EP-A-65601 (corresponding with the features of the preamble of claim 1) there is described an adaptor for drilling strings, including valve means for selectively circulating fluids from the drill string to the well bore above the drill bit, and from SU-A-825838 a flushing and wash-over valve for drilling is known, comprising three isolated chambers with specified link ports to allow bottomhole scavenging. It is an object of the present invention to provide an adaptor for drilling strings which can enable the down-hole equipment to be recovered. It is a preferred object to provide an adaptor where air can be used to flush the hole, to provide an adaptor which enables grout or the like to be pumped down the hole to stabilize the hole, which can stabilize the drilling strings and which can be used to connect percussion hammers, cross-over-subs, drilling bits and the like to the drilling strings. The present invention resides in an adaptor for drilling strings according to the characterising features of claim 1. Preferred embodiments are described in the dependent claims. In the description, the term "drilling equipment" shall be used to include a drilling bit, a cross-over-sub, a percussion hammer or the like drilling equipment. To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which: FIG. 1 is a side view of a reverse circulation adaptor connecting a hammer to a drilling string; FIG. 2 is an exploded, part-sectional view of the adaptor components; FIG. 3 is a sectional side view of the adaptor in the drilling mode; FIG. 4 is a similar view with the adaptor in its flushing or withdrawal mode; FIG. 5 is a sectional plan view of the adaptor taken on line 5-5 on FIG. 4; FIG. 6 is a part-sectional isometric view of the sleeve of an adaptor for a percussion hammer or rotary drill; FIG. 6A is an exploded, part-sectional view of the adaptor components for the adaptor for a percussion hammer or rotary drill; FIGS. 7 and 8 are respective sectional side views of the adaptor in its drilling mode and its flushing or withdrawal mode; FIG. 9 is a sectional plan view taken on line 9-9 on FIG. 8; FIG. 10 is an exploded schematic isometric view of the body and sleeve showing alternative vertical guide and ramp means to allow rotational longitudinal movement between the body and sleeve; and FIGS. 11 and 12 are schematic isometric views showing the sleeve in its respective positions in the drilling and flushing or withdrawal modes. Referring to FIGS. 1 to 5, the adaptor 10 is attached at the lower end of a drilling string 11 (shown in dashed lines in FIGS. 3 and 4) which has inner and outer pipes 12, 13 forming co-axial pressure and exhaust passages 14, 15. A reverse circulation pneumatic hammer 100, with a drill bit 101, is attached to the lower end of the adaptor 10. The adaptor body 16 has a head 17 with a tapered, screw-threaded bore 18, to enable it to be screwed onto the lower end of the drilling string 11. A central exhaust passage 19, with an enlarged lower portion 19a, extends through the body and communicates with the exhaust passage 15. A plurality of intake ports 20 in the head 17 communicate with the pressure passage 14 and with radially extending intake passages 21. Three helical splines 22 are provided around, and extend down, the body 16. The sleeve 23 has pairs of internal helical splines 24 engaged with the splines 22 on the body 16 to enable the sleeve 23 to move rotatably and longitudinally with respect to the body. When the sleeve 23 is mounted on the body 16, intake passages 25 are defined by the sleeve and the body, between the pairs of helical splines 24. A mounting block 26 is welded to the lower end of the sleeve 23 and has helical splines 27 engageable in a socket 28 at the upper end of the hammer 100. A tubular extension 29 on the mounting block 26 is slidably and rotatably received within the exhaust passage 19a in the body. An exhaust passage 30, connected to the exhaust port 31 in the hammer 100, extends up through the mounting block 26 and communicates with the exhaust passage 19a in the body 16. A plurality of intake passages 32 extend down through the mounting block 26 and communicate with intake ports (not shown) in the hammer 100. A first variable passage chamber 33 is defined by the body 16 and sleeve 23 and is connected by the intake passages 25 to a second variable volume chamber 34 defined by the body 16, sleeve 23 and mounting block 26. The chambers 33, 34 provide manifolds interconnecting the intake passages 21 and passages 25, and the passages 25 and intake passages 32 respectively. A plurality of upwardly directed teeth 35, with tungsten-carbide cutting inserts 36, are provided around the periphery of the upper end of the sleeve 23, and similar teeth 37, with inserts 36, around the periphery of the lower end of the sleeve 23. The upper and lower teeth 35, 37 are aligned and respective teeth are separated by vertical grooves or reliefs 38. In the drilling mode shown in FIG. 3, the pressurized air from the pressure passage 14 of the drilling string is directed via the intake ports 20 and the intake passages 21 into the first chamber 33, down the air passages 25 to the second chamber 34 and then via air intake passages 32 to the intake ports of the hammer 100. The exhaust air, carrying the drilled earth, travels up the exhaust passages 31, 19a, 19 to the exhaust passage 15 in the drilling string 11. To clear the hole of any debris e.g. to allow the hammer 100 and bit 101 to be withdrawn from the hole, the drilling string is reversed (or rotation simply stopped) and the body 16 moves up within the sleeve 23 until the intake passages 21 are exposed to direct the pressurized air up the hole (see FIG. 4). If the debris cannot be cleared with the air, the debris can be loosened with the teeth 35, and then blown up the hole. Where the wall of the hole has collapsed, the drilling string can be positioned with the hammer 100 and drill bit 101 below the collapsed section. Grout can be pumped down the passage 14 and out the intake passages 21 and up the hole. When the grout has at least partially set, the drilling string can be rotated and raised so that the teeth 35 can cut a smooth bore in the grouted (repaired section) of the hole. Preferably the diameter of the adaptor 10 is just smaller than the diameter of the drill hole so that the adaptor 10 can act to stabilize the lower end of the drill string 11. In a modified embodiment not shown, the sleeve 23 can be of smaller diameter than the drill hole and have an enlarged section or periphery flange with an external diameter substantially equal to the diameter of the hole so that the adaptor can act as a stabilizer for the lower end of the drilling string 11. With the reverse circulation pneumatic percussion hammer 100 attached to the adaptor 10, the adaptor 10 can be in the flushing or withdrawal mode (see FIG. 4) as the hammer 100 is lowered to the bottom of the hole so that the hammer is isolated from the pressurized air. When the bit 101 in the hammer 100 engages the bottom of the hole, the sleeve 23 will move up the body 16 to place the adaptor in the operating mode (see FIG. 3) and air is supplied to the hammer 100 to drive it. If the drilling string 11 is raised, the hammer 100 will be automatically shut off. (The hammer 100 will also be shut off if it drills down a preset depth and the drilling string 11 is not simultaneously advanced down the hole.) Referring now to FIGS. 6 to 9, the adaptor 110 for a pneumatic percussion hammer or a rotary drilling string, the body 116, sleeve 123 and mounting block are generally similar to those components hereinbefore described. The body 116 has a head 117 with a screwthreaded bore 118 attachable to the lower end of the drilling string 111 which has a central pressure line 114. Intake passages 121 extend radially through the body 116 from the bore 118; while exhaust ports 119a extend radially from an exhaust bore 119 at the lower end of the body. The sleeve 123 has upper and lower teeth 135, 137, with tungsten-carbide inserts 136 hereinbefore described with reference to the sleeve 23 but the grooves or reliefs 138 are much wider to allow the air and earth to pass up the outside of the adaptor 10 while the drilling is being effected. The mounting block 126 has helical threads 127 to engage the hammer or drill bit 200 and it has a central air intake passage 132. The operation of the adaptor 110 is generally as for adaptor 10. As shown in FIG. 7, in the drilling mode, pressurized air from the central pressure line 114 of the drill string 111 is directed via the bore 118 and intake passags 121 to the first chamber 133, down the air passages 125 to the second chamber 134, through the exhaust ports 119a and exhaust passage 119 in the body and down the air intake 132 in the mounting block 126 to the hammer or drilling bit 200. The air and earth then passes up past the adaptor 110, through the grooves or reliefs 138 about the sleeve. To clear the hole, the rotation of the drill string 111 is stopped and the sleeve 123 moves down relative to the body 116 via the helical splines 122, 124 on the body and sleeve respectively. The air is then directed via the intake pasages 121 to the drill hole to clear the debris as shown in FIG. 8. If necessary the drill string 111 may be rotated to enable the teeth 135 or 137 to cut through the obstruction in the drill hole. Referring now to FIGS. 10 to 12, the sleeve 223 and body 216 may be modified. The helical splines 22, 122 on the body are replaced by vertical ribs 222 with an inclined (or ramp face) 222a over at least the lower half of one side of the vertical rib 222. The sleeve 223 has respective pairs of vertical ribs 224 where one has an inclined face 224a complementary to the ramp face 222a. As illustrated in FIGS. 11 and 12, the vertical ribs 222, 224 and their inclined faces 222a, 224a allow the required rotational and longitudinal movement between the body 216 and sleeve 223 to selectively direct the pressurized air to the drilling equipment or to flush the drilling hole as hereinbefore described with reference to FIGS. 1 to 5 and FIGS. 6 to 9 respectively. It will be readily apparent to the skilled addressee that the present invention enables the drilling equipment to be recovered and it is virtually impossible that it will become jammmed or stuck in the hole and have to be abandoned; provides means to repair or stabilize the hole; provides stability for the drilling string; full flushing of the hole; accurate sample drilling as the adaptor is substantially the same size as the drilling bit; enables fluids, chemicals, additives, grouts to be pumped back up the hole and enables quick change between drilling equipment. For extended life, the adaptor may be provided with an anti-wear coating. Various other advantages of the present invention will be apparent to the skilled addressee, who will appreciate that modifications and variations can be made to the embodiments described without departing from the scope of the present invention defined in the appended claims.

Claims: An adaptor (10) for drilling strings including: a body (16) having a head (17) screw-threadably mountable on the lower end of a drilling string (11), having at least one intake passage (21) extending substantially radially through the body (16) and arranged to communicate with a pressure passage (14) in the drilling string (11); a sleeve (23) mounted on the body (16) and longitudinally movable relative thereto; a mounting block (26) mounted on the lower end of the sleeve (23) and movable therewith relative to the body (16) and arranged for connecting the drilling equipment and having at least one air intake passage (32) connectable with an air intake port in the drilling equipment; and air passage means defined between the body (16) and the sleeve (23) arranged to connect the intake passage (21) in the body to the air intake passage (32) in the mounting block; so arranged that in a first position of the sleeve relative to the body, pressurized air from the pressure pipe is directed through the intake passage (21) in the body (16), the air passage means and the air intake passage (32) in the mounting block (26) to the air intake port of the drilling equipment; and in a second position of the sleeve relative to the body, the pressure air is directed by the intake passage (21) to the drill hole, characterized in that that body (16) has inclined faces (22) engaging corresponding inclined faces (24) at the sleeve (23) such that, when reversing the direction of rotation of the drilling string, the sleeve (23) moves relative to the body (16) to clear or cover said intake passage in the body. An adaptor according to claim 1, characterized by a first variable volume chamber (33) defined by the body (16) and the sleeve (23); a second variable volume chamber (34) defined by the body (16), sleeve (23) and the mounting block (26); and said air passage means connecting the first (33) and second chambers (34). An adaptor according to claim 2, characterized by being connected to a percussion hammer (100) or a rotary drill bit (101). An adaptor according to any of the preceding claims, characterized in that the mounting block (26) has a tubular upper portion slidably received in an exhaust passage (19) of the body to provide communication with a third passage (19) and an exhaust passage (30) in the mounting block. An adaptor according to any one of claims 1-4, characterized in that a plurality of cutting teeth (35) are provided around the periphery of the upper end of the sleeve (23) to enable the adaptor to cut through any debris in the drill hole when the drilling string is rotated and retracted. An adaptor according to claim 5, characterized in that a plurality of similar cutting teeth (37) are provided around a periphery of the lower end of the adaptor. An adaptor according to claim 5 or claim 6, characterized in that the cutting teeth are separated by longitudinal grooves or reliefs (38) extending substantially vertically on the outside of the sleeve (23); and the cutting teeth each have hardened inserts (36). An adaptor according to any of the claims 1-7, characterized in that the external diameter of the sleeve (23) or of an enlarged portion or peripheral flange of the sleeve (23) is just less than the diameter of the drill hole to enable the adaptor to act as a stabilizer for the lower end of the drill string in the drill hole.

Inventors: FLYNN DARCY LESTER, FLYNN, DARCY LESTER
Applicants: ADVANCED DRILLING TECH, ADVANCED DRILLING TECHNOLOGIES PTY LTD (A.C.N. 011 003 759)
Application year: 1989
Main classification: E21B34
IPC codes: F16K31, E21B44, E21B43, E21B21, E21B34, E21B17, E21B31, E21B10