FR2535780A1 - IMPROVEMENT WITH DOWNHOLE HAMMERS FOR SOIL DRILLING - Google Patents

Abstract

Device enabling to impart simultaneous rotating and striking motions to the bit of a drilling head, the drive force required for the latter motion being transmitted through liquid distributed through the drill pipes down to the drive elements arranged in the lower drilling head. The drive elemements are comprised of a turbine (16) supplied with said liquid and driving a hydraulic pump (17) which indirectly actuates, through a distributor (35), the hammer (22) which strikes the shank (27) of the bit (2). Said elements being distributed in two chambers sliding one on the top of the other, said sliding motion being used to stop the striking motion when the device is hanging and to start again the striking motion as soon as the device bears at the bottom of the drilling hole. The invention may be used for any deep drilling or for any drilling in rocky ground or even mellow or water-bearing ground.

Description

PT RFFCTION19EMFNT AUX P, / LARTEAUX-FOlnD -DE -TROU
FOR DRILLING DFS SOILS.

Deep exploration of the soil is generally carried out using a rotary drill bit which, made integral with the end of the tubes which are elongated in successive sections as the drill bit advances in depth , is driven by said tubes in their rotational movement, together with a pressurized liquid (generally charged with lubricating particles) and leads through these to the drill bit, in order to evacuate the pulverized rocks which go back to the surface started by said liquid between the wall of the borehole and the tubes,
In order to facilitate the penetration of the drill bit, it is sometimes animated simultaneously with an alternating percussion movement along its axis.

 Various means have been proposed for ensuring this complementary percussion movement of the head of the drill bit, without it being necessary to animate with such a movement the entire column of tubes which support it.

 According to a device described in patent No. 2,213.4 () 9 in the name of HALIFAX TOOL, this percussion movement is carried out by means of a mass maneuvered in the manner of a hammer acting on the drill bit and contained in the tette of drilling, said hammer being driven by an alternating movement by exclusively pneumatic means.

 Such an energy source has the disadvantage that it does not allow the use of such a device in drilling which requires the injection of mud, therefore practically in rock drilling and deep drilling or in a soft environment. . In fact, the hydrostatic pressure of the liquid loaded with mud contained in the borehole creates a back pressure at the level of the drill bit which is a function of the depth of the borehole, which imposes a very high air pressure to ensure the operation of the machine, whose performance is therefore poor compared to the energy expended.

 Likewise, the use of such a device is not possible in aquifers 5 in which the water table creates the hydrostatic back pressure which affects the performance of the device.

 We even note that in all circumstances, this device cannot be used in boreholes longer than 200 to 300 meters.

 In patent 2,271,378 of VSFSOJUZNY, the motive agent is in this case the liquid used to lubricate the drill bit at the same time as to evacuate the drilling mud, which makes it possible to avoid the disadvantage of the hydrostatic back pressure . But the machine described in this deposit, called by its author "Turbo-drilling machine", uses, as its name suggests, only the only rotary movement, which is much less effective in attacking rocks than when the movement rotary bit is combined with a percussion movement of this organ. So that to obtain a useful result, such a device requires a very high liquid pressure, hence a significant expenditure of energy.

 The device which is the subject of the present invention makes it possible to avoid each of these drawbacks. First of all, this device combines the percussion and rotation movements of the drill bit, which improves the energy efficiency compared to the last patent cited. But in addition, if the device which is the subject of the invention, as it will be described, does indeed include a hammer contained in the drilling head and periodically striking the tail of the drill bit, as is the case in the first patent cited, it will be noted that the fluid used to transmit the motive force necessary for the reciprocating movement of the hammer is essentially the same liquid which is sent inside the drilling tables to the drill bit to lubricate the working face and raise the drilling mud. that, thanks to this means, at the level of the drill bit, and therefore of its percussion member, the hydrostatic pressure of the liquid which rises the drilling mud is practically balanced at all times by the sole height of the liquid injected into the tubes which conduct it, liquid which is in this case used as working fluid thanks to its injection under pressure. The efficiency of such a device is therefore higher than the previous one, the driving energy being thus transmitted without appreciable loss.

 For this, the liquid injected under pressure into the. drilling column reaches a hydraulic turbine located in the drilling head itself, before being evacuated in the drilling to play the usual role of lubricant used there as a rising mud vehicle, This turbine thus set in motion drives a hydraulic pump which pressurizes a lubricating intermediate liquid, which is injected into the cylinder of a known device capable of generating the reciprocating movement of the hammer, said device also being contained in the drilling head, said intermediate liquid intervening in a closed circuit between the reservoir which contains it and the hydraulic pump which drives it, the assembly being contained in the device which is the subject of the present invention.

 The accompanying drawings, given by way of example only, show an embodiment of the device which is the subject of the present invention.

 Figure 1 is a schematic elevational view of the object of the invention.

 Figure 2 is a schematic view in diametrical vertical section of the same object.

 As shown (fig. 1) we see that the drilling head, which has at its upper end the conical screw 1 allowing its adjustment to the lowest drilling rod and at its lower end the drill bit 2, is constituted by a cylindrical body formed by two main parts 3 and 4 sliding between them along the central cylinder 5 (fig. 2) which guides them one on the other and which at the same time centers the lower part 4 in rotation by through the grooves 6 with which said central cylinder 5 is provided according to its external generatrices, at its part closest to the part 3, said grooves cooperating with the complementary grooved ring 7, the sliding of the two elements 3 and 4, the one with respect to the other, being limited by the stop 8 integral with the cylinder 5.

 The lower part 9 of said cylinder 5 is smooth at the level of its fitting fitted into the body 10 which forms the upper part of the element 4, the watertightness being ensured at this level by the O-ring 43.

 The outer skirt 11, with an outside diameter equal to the general outside diameter of the drilling head, envelops the upper part of the part 10, bored for this purpose, and slides thereon, the sealing at this level between these two parts 10 and 11 being obtained by means of the O-ring 12. The opposite parts of the skirt 11 and of the bottom of the bore of the part 10 are chamfered towards the outside, in reverse, so as to reject towards the outside, in their reciprocal sliding movement, the rock debris which could be placed at this level during the drilling work.

 The lower part 4 of a drill rod, in which the upper part 3 slides, is itself formed by two bodies 13 and 14 made integral with one another by final interlocking at 15 and made the same, together, integral with the part 10, in which the cylinder 5 slides.

 All the different bodies forming the device which are the subject of the invention thus being mutually adjusted, it can be seen that the upper part 3 is formed of a hollow cylinder which contains the hydraulic turbine 16 which controls the hydraulic pump 17, contained in the same alveolus. The cylinder 5 itself hollow, communicating the inner part of the upper body 3 with the intermediate body 13, which is itself also hollow and which contains the annular reservoir 18, which surmounts the lower body 14 which has a lower cylinder 19 , reamed so that a vacuum 20 is left between this cylinder 19 and the inner wall of the body 14.

 The cylinder 19 is also internally bored to receive a hydraulic percussion member 21 of known type carrying the hammer 22 and being able to slide freely inside the cylinder 19, being retained at its upper part by the shutter 13 of the cylinder 19, with interposition of the shock absorber spring 24.

 At the base of the lower body 14 is the drill bit 2 capable of sliding freely in the threaded bush 25 screwed into the lower part of the body 14. The drill bit 2 and this bush 25 each carry complementary grooves 26 which make it possible to drive the drill bit 2 in rotation, when the entire drilling head is entrained by the rods which carry it, at the same time as said drill bit can freely slide in said socket under the effect of the vibrations of the hammer 22 on the tail 27 of the drill bit, by means of the counterweight 28 interposed between the hammer 22 and the shank 27, and held between these two parts by the annular silentbloc 29, the outer ring of which is screwed tightly inside the body 19, the presence of this intermediate elastic piece making it possible to seal between the two chambers thus created: that 19 containing the percussion member, itself sealed with respect to the body 14 which contains it, and that containing the tail 27 of drill bit 2.

 Said tail 27 comprises the stop 30 which limits its downward movements.

 The threaded sleeve 25 is blocked by the fixed stop 31 and is drilled to present the conduits 32 which communicate with the annular conduit 20 through the chamber 33 and with the drill bit which itself presents the conduits 34 which open at its lower surface.

The assembly is completed by the distributor 35 and by the flexible tube 36 which connects the suction of the pump 17 to the reservoir 18, the flexible tube 37 which connects the pressure outlet of the pump 17 to the distributor 35, the flexible tube 3 which connects an outlet of the distributor 35 to the hydraulic percussion member 21, the tubing
flexible 39 which connects the return of the percussion member to the reservoir
18 and the tube 40 which directly connects the other outlet of the distributor
35 to reservoir 18.

The device which is the subject of the invention being thus constituted,
understands that the liquid, intended to lubricate the cutting front and to
raise the drilling mud to the outer periphery of the machine, will reach the drilling head through the raccor drilling tubes
dice with conical thread 1. This liquid will pass through the upper zone 3
of the device setting in motion the turbine 16 which will itself drive the hydraulic pump 17. Then this liquid will pass through the hollow cylinder 5, will pass through the central channel of the annular reservoir 18, will reach the peripheral channel 20 of the lower body 14 to enter the chamber 33, from where it will be injected up to the surface of the cutting front through 32 and 34, thus playing the role for which it is intended.

But the turbine 16 having been put into operation by this pressurized liquid and the pump 17 having been driven by it, the intermediate liquid, lubricant, contained in the reservoir 18, will be
sucked and discharged under pressure to the distributor 35, through the flexible tubes 36 and 37.

 It is then that, if the bit 2 does not bear to the bottom of the borehole, that is to say if it is not in the working position, for example during the descent of the machine into the borehole, the bodies 3 and 4 (fig. 1), which slide, relative to each other, on the cylinder 5, will be in their most distant position from each other, the body 4 being retained by the stop 8.

 Under these conditions the control lever 41 of the distributor 35, which remains constantly in contact with the lower surface of the cylinder 5, will be in the high position, which will have the effect (the distributor 35 playing the role of bypass) return the liquid delivered under pressure by the pump 17 directly to the reservoir 18 through the tube 40.

 But as soon as drill bit 2 is in the working position.

resting on the bottom of the borehole, automatically, by the simple weight of the drill pipes which carry the device which is the subject of the invention, the body 3 will approach the body 4 (fig. 1). Immediately the control lever 41 will be lowered, pushed by the cylinder 5, and the liquid delivered under pressure by the pump 17 will be immediately sent to the percussion member 21, through the tubing 38. So that this percussion member will immediately set in motion, transmitting its vibrations to the drill bit 2 via the suspended counterweight 28, at the same time as the rotation of the drill rods will entrain said drill bit in their rotary movement.

 Conversely, as soon as the drill rods reassemble the machine, the cylinder 5 will withdraw, letting the control lever 41 rise, which will have the effect of immediately stopping the percussion.

Although in this case still the injection of the liquid intended to stop the sludge can continue to clean the bottom of the borehole, without the drill bit working.

 It is therefore found that thus the drilling effect due to the rotary movement of the drill bit is considerably increased by the simultaneous percussion of this organ, which considerably reduces the energy necessary for the same result, the torque which must be developed for the rotation. decreasing due to percussion.

 It is also noted that only the drill bit 2 is set in vibratory movement, without this movement having repercussions on the whole of the device and the drill rods which carry it and whose inertia would reduce the yield.

 It is also noted that the percussion movement can never be transmitted to the drill bit 2 until it is in contact with the bottom of the borehole, which avoids the deterioration of the vibratory organs, as would happen if the vibrations could be transmitted while the drill bit is not pressing on the work surface.

 Finally, it can be seen that the useful pressure exerted on the percussion member is practically independent of the depth, except for head losses due to the length of the borehole, the hydrostatic pressure of the rised sludge or the aquifers traversed being practically balanced by the column liquids injected through the drilling rods, only the overpressure which is imparted to this liquid playing the role of motive force, regardless of the length of the drilling, under the conditions which have just been said.

 It is understood that the invention is not limited to the example which has been given of it, any variant considered to be equivalent cannot modify its scope.

 The device which is the subject of the present invention can be used for drilling in rocky ground to facilitate penetration as well as in loose or aquiferous ground, the continuous injection of the evacuation liquid, which can be maintained independently of the work of the drill bit, allowing the borehole to be kept always under pressure, in order to avoid landslides in this case.

Claims (8)

'CLAIMS 1) - Device constituting an improvement to drilling heads whose drill bit is driven by simultaneous movements of rotation and percussion, Characterized by the fact that the motive force necessary for the percussion movement with which the drill bit is driven is transmitted up to the drilling head by means of the liquid injected under pressure from the ground surface into the drill rods and which is also used for the evacuation of cutting waste, said pressurized liquid, which constitutes the means of transmitting the force drive to the drilling head, causing the percussion movement, indirectly, via a percussion member of known type, which works in a closed circuit, using a lubricating fluid not loaded with solid material, put under pressure by means of a pump driven by a turbine, itself set in motion by said liquid injected under pressure through the drill pipes, all of these different members are found contained in the drill head. 2) - Device according to claim 1, characterized in that the drilling head, which, at the end of the drilling rods, receives the primary liquid under pressure, essentially comprises two cylindrical bodies 3 and 4 aligned on the same axis and each constituted by the chamber or chambers necessary to contain the elements of the system, said bodies 3 and 4 sliding between them along their axis, the upper body 3 being made integral, by any known means or such as the threaded cone 1, with tubes drilling with which it is placed in communication, the lower body 4 carrying the drill bit 2 at its lower end and driving it.  30) - Device according to claim- 2,  Characterized by the fact that the bodies 3 and 4 slide between them along their axis, the lower body 4 being guided on the hollow cylinder 5 which is integral with the upper body 3 and which has at its upper part the longitudinal peripheral grooves 6 which cooperate with the complementary grooves 7 of the lower body 4 to entrain it in rotation while allowing longitudinal sliding along these grooves, the lower part of the cylinder 5 being smooth and ensuring the external sealing of the sliding thanks to the O-ring 43, the axial translational movement of the two bodies between them being limited by the stop 8 installed on the cylinder 5.  40) - Device according to claim 3,  Characterized by the fact that the bodies 3 and 4, sliding between them, guided by the hollow cylinder 5, together form a succession of chambers communicating with each other and through which the injected liquid coming from the drilling rods in order to lubricate the front of cutting is carried out to drill bit 2, said chambers successively containing the turbine 16, the hydraulic pump 17, actuated by it, the reservoir 18, containing the intermediate working fluid, lubricating and not loaded, the distributor 35 which controls the distribution under pressure of this intermediate fluid, and finally the hydraulic percussion member 21 of known type.  50) - Device according to claim 4,  Characterized by the fact that the turbine 16 is set in motion by the lubrication fluid of the working face which is conveyed under pressure through the drill rods, said turbine 16 actuating the pump 17 which pressurizes the intermediate motor liquid which drives the hydraulic percussion device 21 under the control of the distributor 35 of the "bypass" type, including the control arm 41, which, being kept constantly in contact with the base of the cylinder, allows the intermediate motor liquid to be conveyed to the percussion member 21 when the bodies 3 and 4 are closest to each other, the cylinder 5 then plunging as far as possible into the chamber contained in the body 4, and, conversely, returns said liquid to the reservoir 18 , thus isolating the percussion member, when the bodies 3 and 4 move away from each other, which has the effect of retracting the cylinder 5 relative to the body 4.  60) - Device according to claim 5,  Characterized by the fact that the drill bit 2, located at the lower end of the device is driven by the latter in rotation, the tail of said drill bit being provided with longitudinal peripheral grooves 26 which cooperate with the complementary grooves with which the part 25 is provided, made integral with the body 4, said grooves 26 allow tau the longitudinal displacement of the drill bit 2 under the effect of the percus' ston impressed by the hammer 22, driven by the percussion member 21, by means of the suspended flyweight 28 by the silentblock crown 29 which also seals between the chamber 33 in which the shank 27 of the drill bit moves and the sealed chamber 19 which contains said percussion member 21, the libretranslation movement of the drill bit 2 being limited by the stop 30.  70) - Device according to claim 6,  Characterized by the fact that the lubrication liquid from the cutting face is conveyed to the lower surface of the drill bit through the peripheral conduits 20 external to the intermediate chamber 19 which contains the percussion member 21, said conduits 20 opening out in Ia chamber 33 containing the tail 27 of the drill bit, from where the liquid is led to the lower surface thereof through the conduits 32, then 34, formed in the lower part of the tail of the drill bit.  80) - Device according to claim 7,  Characterized by the fact that the lower part of the tail of the drill bit, where the conduits 32 which lead the face liquid flow to convey it to the conduits 34 which the drill bit itself has, is conical, so that during the vibrations the conical surfaces in contact between said tail and the bush 25 which guides it periodically move apart, thus allowing the escape of pressurized liquid which diffuses between the drill bit and the lower surface of the device, ensuring permanent cleaning of this part mobile and preventing its scaling which could immobilize it.  90) - Device according to claim 8,  Characterized by the fact that a percussion member 21 of known type is suspended freely inside the intermediate sealed chamber 19 by means of the damping spring 24, said member being hydraulically connected to the distributor 35 through the upper wall of said intermediate chamber.  100) - Device according to claim 2,  Characterized by the fact that the metal skirt 11 with a diameter equal to the general outside diameter of the drilling head is made integral with the base of the upper body 3 so as to slide on the upper part, suitably bored, of the lower body 4, thus housing the grooves 6 which- secure the two bodies 3 and 4 and allow their axial translation, the lower edge of said skirt and the bottom of the bore receiving it being chamfered so as to reject the drilling debris outwards being able to reach this part of the device and impede its sliding, the sealing at this level being obtained by means of the O-ring 12.