JET CLEANING APPARATUS

Abstract: The present invention provides a rotary jet cleaning apparatus suitable for use in cleaning pipes and/or boreholes. The apparatus comprises a positive displacement motor (22) and a rotary jetting tool (23) drivingly connected (24) to an output drive part (25) of said motor. The motor has a drive fluid supply conduit (30), and the rotary jetting tool (23) has at least one generally radially outwardly directed nozzle means (43) provided with a jetting fluid supply conduit (29). The jetting fluid supply conduit (29) and drive fluid supply conduit (30) are connected in parallel to a common fluid supply inlet means (40) to said apparatus so that jetting fluid may be supplied to said jetting tool nozzle means substantially without reduction in pressure due to running of the motor for rotation of said jetting tool.

Description: JET CLEANING APPARATUS The present invention relates to rotary jet cleaning apparatus suitable for use in cleaning pipes and/or boreholes and the like. Various kinds of rotary jet cleaning apparatus are known for cleaning the insides of pipes and the like. Relatively inaccessible locations such as very long and/or deep pipes, especially those with relatively small diameter, present particular problems in providing the necessary rotary driving of the jetting tool together with the required high energy flow of jetting fluid. Fig.l shows schematically a prior art rotary jet cleaning apparatus 1 having a jetting tool 2 having at an upper end 3 a turbine means 4 provided with a motive fluid inlet 5 and exhaust outlet 6 connected 7 to jetting fluid nozzles 8 at a lower end 9 of the tool 2. In use of the apparatus motive fluid drives the turbine 4 to rotate the jetting tool 2 and the fluid exhausted from the turbine is then expelled through the nozzles to act as jetting fluid for cleaning the inside walls 10 of a pipe or hole 11. As in most turbines it is necessary to limit the rotational speed thereof and this is achieved by means of an eddy current brake 12. In a typical downhole application fluid would be supplied to the turbine at around 200 bar and would be exhausted from it at around 150 bar. As a result the jetting fluid is supplied to the nozzles at a substantially reduced pressure as compared with that supplied at the upper end of the jetting tool. It will moreover be understood that such a loss of say 20% in pressure would correspond to a loss of some 35% in the energy of the jetting fluid expelled from the jetting tool nozzles. As a result the effectiveness of such cleaning apparatus is substantially restricted. Another problem that arises when using conventional Moineau type positive displacement motors with rubber components for well or pipe cleaning is that of damage to the motors and/or very short working life when running at elevated temperatures and/or rubber attacking fluids. Pipe cleaning often requires to be carried out on live wells which can be at relatively high temperatures - typically up to 300°F, and this therefore presents further problems in the design of effective pipe cleaning systems. It is an object of the present invention to avoid or minimise one or more of the above disadvantages. The present invention provides a rotary jet cleaning apparatus suitable for use in cleaning pipes and/or boreholes, which apparatus comprises a positive displacement motor and a rotary jetting tool drivingly connected, directly or indirectly, to an output drive part of said motor, said motor having a drive fluid supply conduit, and said rotary jetting tool having at least one generally radially outwardly directed nozzle means provided with a jetting fluid supply conduit, said jetting fluid supply conduit and a drive fluid supply conduit being connected in parallel to a fluid supply inlet means to said apparatus so that jetting fluid may be supplied to said jetting tool nozzle means substantially without reduction in pressure due to running of the motor for rotation of said jetting tool. Thus with a cleaning apparatus of the present invention it is possible to maximise the effectiveness and efficiency of rotary jet cleaning by avoiding the usual losses in pressure and hence energy of the fluid used for jetting due to use of the fluid for first driving a motor means to rotate the jetting tool. A particularly preferred form of positive displacement motor suitable for use in accordance with the present invention is a motor of a type generally similar to that described in US Patent 5,518,379. Typically such a motor - sized with an outer diameter of 3.125 inches (7.94 cms) is designed to operate at around 700 to 800 rpm with a drive fluid supply at a pressure of the order of 3000 psi (207 bar) . (It will be appreciated that larger diameter motors are generally operated at lower speeds whilst smaller diameter motors are operated at higher speeds, the relation between rotational speed and outside diameter being generally an inverse linear relation. Accordingly references hereinbelow to rotational speeds for motors and jetting tools of the invention with larger or smaller outside diameters should be adjusted correspondingly.) For the purposes of rotary jet cleaning it is generally desirable to limit the rotational speed of the jetting tool to from 30 to 150 rpm as too high a speed will result in ineffective cleaning. On the other hand too low a speed will simply result in wasted cleaning effort as the pipe or borehole would normally have received sufficient cleaning, preferably there is used a jetting tool rotational speed of from 60 to 120 rpm, for example, around 70 rpm. The rotary speed of the motor may conveniently be limited to around 200 rpm or so by limiting the fluid flow therethrough. This may conveniently be achieved by providing a restricted size outlet means at the downstream end of a motor drive fluid pathway passing through the motor. Most conveniently where there is used a motor with a drive fluid pathway which passes radially inwardly of the motor, the drive fluid pathway is extended into part of the jetting tool and terminates at exhaust outlet means provided therein. This has the practical advantage of avoiding the need for a corresponding modification in the motor by incorporating the required speed limiting means in the jetting tool itself so that the principal functions required by the jet cleaning function are substantially incorporated in the jetting tool itself. Generally speaking though it is not possible to reduce the motor rotary speed sufficiently by this means alone as this would lead to excessive loss of motor torque. The rotary drive speed provided by the motor may, however, additionally (or, if desired, alternatively) be reduced to a suitable jetting tool rotation speed, by providing a gearbox, conveniently an epicyclic gearbox, drivingly connected between the motor and the fluid flow jetting tool. The gearbox ratio will depend on the relation between the motor speed and the desired jetting tool speed but would typically be in the range from 5:1 to 2:1, for example around 3:1. It will be appreciated that various arrangements and configurations of the jetting fluid and drive fluid supply conduits are possible. Particularly conveniently though the jetting fluid supply conduit extends axially centrally through the motor into the jetting tool and radially inward parts of the motor drive fluid pathway to and from, and through the motor extend annularly around the jetting fluid supply conduit. Various kinds of positive displacement motor are known in the art. Particularly preferred though is a rolling vane motor of the kind disclosed in US Patent No 5,518,379. The use of such a motor is particularly preferred as it has a particularly high tolerance for operating in high temperature environments and is impervious to rubber attacking fluids, both of which are often encountered in live well cleaning operations. Furthermore this type of motor can be easily modified to have a non-leaking by-pass passage leading through the interior of the rotors to the jetting tool. Thus in a preferred aspect the present invention provides a rotary jet cleaning apparatus of the present invention wherein the motor comprises a housing in which is secured a stator, and a rotor mounted rotatably within said stator, each of said stator and said rotor having at least two angularly distributed recesses in opposed faces thereof for mounting rolling rod seals freely movable therein for sealing engagement, in use of the motor, with the opposed face of the other one of said stator and rotor, said opposed faces of said stator and said rotor being formed and arranged so as to define action chambers extending angularly between the rolling rod seals, said rotor and said stator having motive fluid passages extending generally radially therethrough for conducting motive fluid, in use of the motor, between an outer side of the stator and an inner side of the rotor through said action chambers, so as to rotate said rotor. In one arrangement motive fluid may be supplied from a fluid supply passage inside the rotor, through motive fluid passages in the rotor into the action chambers from which it is then exhausted via motive fluid discharge passages in the stator. In a more preferred arrangement though the motive fluid is supplied from outside the stator, through the motive fluid passages in the stator into the action chambers and then vented through a motive fluid discharge passages in the rotor into an motive fluid exhaust extending along the interior of the rotor. The jetting tool nozzle means are generally formed and arranged so as to provide high energy fluid jets to provide effective cleaning. With a typical fluid supply pressure to the tool and motor of around 3000 psi (207 bar) there can be obtained a localised pressure at a 1 inch (2.54 cms) spacing from the nozzle means of the order of 10,500 psi (724 bar) thereby providing a highly effective cleaning action. The angle at which the generally radially outwardly extending jetting tool nozzle jets are directed may be varied somewhat. Advantageously though, the nozzle jets are directed somewhat rearwardly i.e. away from the distal end of the jetting tool, generally between 0° and 60° rearwardly of a directly radially outwards direction, preferably from 5° to 45°, most preferably from 10° to 30°. In order to prevent the jetting tool from becoming unbalanced in use - given that the reactive force generated at a nozzle jet may be of the order of 120 lbs (54 kg) , there is desirably used a plurality of symmetrically angularly distributed nozzle jets, e.g. two diametrically opposed nozzle jets, so that the reactive forces generated by them cancel each other out. In order to facilitate removal of more substantial deposits which may even bridge across the pipe or borehole, the distal end face of the jetting tool is advantageously provided with a simple bit means, conveniently in the form of an abrasive coating, for boring a passage through such deposits so that the jetting tool can then advance therethrough and then bring the jetting fluid jets to bear against the residual deposits remaining on the pipe or borehole walls. In another aspect the present invention provides a rotary jetting tool comprising an axially extending body having a proximal end for coupling drivenly, in use, directly or indirectly, to a positive displacement motor; jetting fluid supply conduit means leading from said proximal end to jetting nozzle means, and positive displacement motor drive fluid conduit means substantially isolated from said jetting fluid supply conduit means and formed and arranged for coupling, in use, to the motor drive fluid exhaust means of said motor and terminating in discharge outlet means formed and arranged for limiting fluid flow through the motor, thereby to limit the rotational speed of the motor. Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawings in which: Fig.l is a schematic longitudinal section of a prior art jet cleaning apparatus; Fig. 2 is a corresponding view of a cleaning apparatus of the present invention; Fig.3 is detailed longitudinal section of the jetting tool of the apparatus of Fig. 2; Fig.4 is a detailed longitudinal section of a preferred form of motor for the apparatus of Fig.2; and Fig. 5a - 5b is a series of transverse sectional views of the motor of Fig.4 illustrating operation of the motor shown therein. Fig. 2 shows a rotary jet cleaning apparatus 20 of the invention suitable for use in cleaning a pipe or borehole 21, which apparatus comprises a positive displacement motor 22 and a rotary jetting tool 23 drivingly connected via a 3:1 reduction epicyclic gearbox 24, to the driven rotor 25 of said motor. As explained in more detail hereinbelow, the motor 22 comprises two drive units 26,27 interconnected via a hexagonal drive coupling 28 and 90° out of phase with each other. A central longitudinally extending jetting fluid supply conduit 29 extends though the motor 22. The motor 22 is formed and arranged so that in each unit 26,27, drive fluid passes generally radially inwardly 30 through the stator (see below) and the rotor 25 and along a passage means extending in parallel and defined between the jetting fluid supply 29 and the rotor 25. In more detail the jetting fluid supply conduit 29 comprises an elongate tube 38, preferably a pressure resistant thin walled titanium tube, which extends from a receiving chamber 39 in the jetting tool 23 rearwardly through the rotor 25 of the motor 22 to a common fluid supply inlet means 40 so as to provide a flow path 41 for the jetting fluid in parallel to a generally annular flow path 42 for the motor drive fluid. The rotary jetting tool 23 has a plurality, usually 2, 3 or 4, or possibly more, generally radially outwardly directed nozzles 43 supplied from jetting fluid supply conduit 29. In more detail, as shown in Fig. 3, the jetting tool comprises an upper body portion 50 having a pin thread bit box 51 at its upper end 52, and a downwardly extending sleeve portion 53 with a screwthreaded lower end portion 54 connecting it to a lower body portion 55 and defining a cylindrical chamber 56 therebetween in which is mounted a piston 57. A lower end portion 58 of the jetting fluid supply conduit 29 is securely gripped by set screws 57a in the lower end portion of the piston 57 and its free end 59 exhausts into the receiving chamber 39 in the lower body portion 55 of the jetting tool. Two generally radially outwardly directed nozzles 43 are provided at diametrically opposed sides of the lower body portion 55 at the radially outer ends 60 of short communicating passages 61 leading off from the receiving chamber 39. The nozzles 43 are directly slightly upwardly and rearwardly (away from the distal end face 62 of the lower body portion 55) in order to provide some assistance to advancement of the jetting tool along the pipe or borehole whilst also tending to flush away debris removed from the walls of the pipe or borehole (see Fig. 1) . The upper end portion 63 of the piston 57 has a central chamber 64 whose upper end 65 communicates with an annular passage 66 within the upper end 52 of the upper body portion 50 and extending around the outside 67 of the jetting fluid conduit 29 extending therethrough, for receiving motor drive fluid exhausted through the motor 22. Two diametrically opposed passages extend radially outwardly through the piston wall 68 around the central chamber 64 connecting to small bores 69 in the upper body sleeve portion 53 thereby functioning to limit the flow of motor drive fluid through the motor 22 and thereby limiting the rotational speed of the motor . Figs 4 and 5 show a motor substantially similar to that in US Patent 5,518,379 and only the principal parts thereof are specifically identified herein. The motor 22 comprises upper and lower motor units 26,27 each having a stator 81 and a rotor 82 mounted inside an outer casing 83. The rotors 82 of the upper and lower motor units 26,27 are drivingly interconnected in angular alignment with each other (as shown in the transverse cross-sectional views of Figs 5a and 5b) by a hexagonal coupling 84 whilst the stators 81 are angularly offset from each other by 90o so that when one motor unit is in a through-flow condition (as shown in Fig. 5a) the other is still in a driving condition thereby ensuring continued rotation of the motor. The jetting fluid conduit 29 has its upper end 85 projecting up through an otherwise closed end 86 of the upper motor unit rotor 82 and a cap thereof 87. In more detail each of said stator 81 and said rotor 82 have two angularly distributed recesses 88,89 in opposed faces 90,91 thereof mounting rolling rod seals 92,93 freely movable therein for sealing engagement, in use of the motor, with the opposed face 91,90 of the other one of said stator 81 and rotor 82, the opposed faces of said stator and said rotor being formed and arranged so as to define action chambers 94 extending angularly between the rolling rod seals 92,93. The rotor 81 and stator 82 have motive fluid passages 95,96 extending generally radially therethrough for conducting motive fluid, in use of the motor, from between an outer side 97 of the stator 81 and the casing 83 to the inner side 98 of the rotor 82 through said action chambers 94, so as to rotate said rotor 82. The motive fluid passes along between the inner side 98 of the rotor 82 and the outside 99 of the jetting fluid conduit 29 until it reaches the upper end 100 of the lower motor unit rotor 82 where it is forced out through apertures 101 in the hexagonal coupling 84 and then passes along between the casing 83 and the outer side 97 of the stator 81 of the lower motor unit where the above described process is repeated. The motive fluid exhausted from the lower motor unit then passes along the outside of the jetting fluid supply conduit 29 through the interior of a bearing pack 102 and then a gearbox (not shown in this drawing) and down on into the jetting tool as previously described with reference to Fig. 3. In use of the apparatus of the invention the jetting fluid supply conduit 37 and a motor drive fluid pathway are connected in parallel to the common fluid supply conduit 40 to said apparatus so that jetting fluid may be supplied to said jetting tool nozzles 36 substantially without reduction in pressure due to running of the motor 22 so as to rotate the jetting tool 23.

Claims: CLAIMS 1. A rotary jet cleaning apparatus suitable for use in cleaning pipes and/or boreholes, which apparatus comprises a positive displacement motor and a rotary jetting tool 5 drivingly connected, directly or indirectly, to an output drive part of said motor, said motor having a drive fluid supply conduit, and said rotary jetting tool having at least one generally radially outwardly directed nozzle means provided with a jetting fluid supply conduit, said 10 jetting fluid supply conduit and a drive fluid supply conduit being connected in parallel to a fluid supply inlet means to said apparatus so that jetting fluid may be supplied to said jetting tool nozzle means substantially without reduction in pressure due to running of the motor 15 for rotation of said jetting tool. 2. An apparatus according to claim 1 wherein said apparatus includes drive fluid flow limiting means formed and arranged for limiting the rotary speed of the motor to 200 20 rpm. 3. Apparatus as claimed in claim 2 wherein said fluid flow limiting means comprises restricted size drive fluid pathway outlet means. 25 4. Apparatus as claimed in claim 2 or claim 3 wherein said drive fluid flow limiting means is provided in said jetting tool. 305. Apparatus as claimed in any one of claims 1 to 4 wherein is provided a gear box drivingly coupled between said motor and said jetting tool for reducing the rotary drive speed supplied to said jetting tool. 356. Apparatus as claimed in any one of claims 1 to 5 wherein said jetting tool nozzle means is directed at an angle of from 0 to 60° rearwardly of a directly radially outwards direction. 7. Apparatus as claimed in claim 6 wherein said angle is from 5 5 to 45°. 8. Apparatus as claimed in any one of claims 1 to 7 wherein said jetting tool nozzle means comprises a plurality of symmetrically angularly distributed nozzle jets. 10 9. Apparatus as claimed in any one of claims 1 to 8 wherein said jetting tool has a distal end face provided with a bit means. 1510. Apparatus as claimed in any one of claims 1 to 9 wherein the motor comprises a housing in which is secured a stator, and a rotor mounted rotatably within said stator, each of said stator and said rotor having at least two angularly distributed recesses in opposed faces thereof 20 for mounting rolling rod seals freely movable therein for sealing engagement, in use of the motor, with the opposed face of the other one of said stator and rotor, said opposed faces of said stator and said rotor being formed and arranged so as to define action chambers extending 25 angularly between the rolling rod seals, said rotor and said stator having motive fluid passages extending generally radially therethrough for conducting motive fluid, in use of the motor, between an outer side of the stator and an inner side of the rotor through said action 30 chambers, so as to rotate said rotor. 11. A positive displacement motor apparatus wherein the motor comprises a housing in which is secured a stator, and a rotor mounted rotatably within said stator, each of said 35 stator and said rotor having at least two angularly distributed recesses in opposed faces thereof for mounting rolling rod seals freely movable therein for sealing engagement, in use of the motor, with the opposed face of the other one of said stator and rotor, said opposed faces of said stator and said rotor being formed and arranged so 5 as to define action chambers extending angularly between the rolling rod seals, said rotor and said stator having motive fluid passages extending generally radially therethrough for conducting motive fluid, in use of the motor, between an outer side of the stator and an inner 10 side of the rotor through said action chambers, so as to rotate said rotor. 12. Apparatus as claimed in claim 10 or claim 11 wherein motive fluid is supplied from a fluid supply passage 15 inside the rotor, through motive fluid passages in the rotor into the action chambers from which it is then exhausted via motive fluid discharge passages in the stator. 2013. Apparatus as claimed in claims 10 or claim 11 wherein motive fluid is supplied from outside the stator, through the motive fluid passages in the stator into the action chambers and then vented through a motive fluid discharge passages in the rotor into an motive fluid exhaust 25 extending along the interior of the rotor. 14. Apparatus as claimed in any one of claims 1 to 10 or either of claims 12 and 13 when dependent on claim 10 wherein said jetting fluid supply conduit extends axially 30 centrally through the motor into the jetting tool. 15. Apparatus as claimed in claim 11 wherein is provided a bypass fluid supply conduit extending axially centrally through the motor in isolation from a motor drive fluid 35 pathway of said motor, for providing a high energy fluid flow at a distal end of said motor. 16. A rotary jetting tool comprising an axially extending body having a proximal end for coupling drivenly, in use, directly or indirectly, to a positive displacement motor; 5 jetting fluid supply conduit means leading from said proximal end to jetting nozzle means; and positive displacement motor drive fluid conduit means substantially isolated from said jetting fluid supply conduit means and formed and arranged for coupling, in use, to the motor 10 drive fluid exhaust means of said motor and terminating in discharge outlet means formed and arranged for limiting drive fluid flow through the motor, thereby to limit the rotational speed of the motor. 1517. A tool according to claim 16 wherein said discharge outlet means is directed radially outwards at an angle of from 0 to 60° rearwardly of a directly radially outwards direction. 2018. A tool as claimed in claim 17 wherein said angle is from 5 to 45°. 19. A tool as claimed in any one of claims 16 to 18 wherein said discharge outlet means comprises a plurality of 25 symmetrically angularly distributed nozzle jets. 20. A tool according to any one of claims 16 to 19 wherein said jetting fluid supply conduit extends axially centrally through the jetting tool. 30 21. A tool as claimed in any one of claims 16 to 20 which has a distal end face provided with a bit means.

Inventors: STEWART KENNETH RODERICK, VAN DRENTHAM-SUSMAN HECTOR FIL, STEWART, KENNETH, RODERICK, VAN DRENTHAM-SUSMAN, HECTOR, FILLIPPUS, ALEXANDER
Applicants: DRENTHAM SUSMAN HECTOR FILLIPP, ROTECH HOLDINGS LIMITED, STEWART KENNETH RODERICK, STEWART, KENNETH, RODERICK, VAN DRENTHAM-SUSMAN, HECTOR, FILLIPPUS, ALEXANDER
Application year: 1999
Main classification: E21B37
IPC codes: B08B9, E21B4, E21B37, E21B41