EP1731708B1 - Sledgehammer drilling apparatus and method - Google Patents

Description

The present invention relates to a device for drilling, in particular by means of a countersunk hammer, and a drilling method, in particular for overlay drilling.

Drilling devices referred to as countersink drills have a rotary percussion drill head which is lowered into the wellbore. Other designations include "in-hole hammer" and "DTH hammer" ( down-the-hole hammer ).

For the purposes of this application, overlay drilling is understood to mean a drilling method in which a pipe lining the borehole, at least in the region of the bottom hole, is carried along.

In the German Offenlegungsschrift DE 43 10 726 A1 is a drill pipe with countersinking drill head described in which by means of an air distributor compressed air as flushing medium from the outside inwards to a central part of the crown of the drill, and the drill cuttings is conveyed through a centrally located in the drill string passageway. This known device also has in the area of the hammer on a downwardly open skirt through which the enriched with cuttings compressed air is fed into the air manifold.

From the German patent DE 42 25 806 C1 is a drill bit for a large hole drilling known, with a large hole is made by a rotationally driven drill pipe. In rocky rock, a drill bit is lowered eccentrically into the drill pipe with a downhole hammer. The drilling insert has a drilling tool with a shank, on the rear end of the down-hole hammer with a piston exerts blows. The deep hole hammer is braced by means of two wedge elements, which in turn are supported by rollers with vertical axes against the drill pipe in the same.

From the international application WO 97/00371 A1 there is known a countersink drilling apparatus in which the cuttings are removed through at least one opening on the face of the drill and through the hammer.

In the US patent application US 2005/0103527 A1 describes a double-walled drill pipe, the inner tube is formed as a tube through which the cuttings are transported upwards, while drilling through the gap between the inner and outer tube of the drill pipe drilling mud down.

In the international patent application WO 02/081856 A1 a drill head is described in which the flushing medium is conveyed from the inside out to the edge of the crown of the drill, and the drill cuttings from a central part of this crown to the periphery of the drill head.

It has been found that the known drilling devices on the one hand have a high demand for flushing fluid, on the other hand provide in some applications partly insufficient drilling depth, unsatisfactory drilling speed or only a small borehole diameter.

It is therefore an object of the invention to propose a drilling apparatus and a drilling method which have an increased efficiency, ie, for example, with less flushing fluid requirement or faster provide a greater drilling depth or a larger borehole diameter.

This object is achieved by the drilling apparatus and the drilling method according to one of the independent claims.

In a first aspect, the drilling apparatus according to the invention comprises a countersinking drill head with a percussion drill bit, a drill pipe with a conveying channel for the drill cuttings and at least one irrigation medium supply channel, irrigation medium supply, and a gasket for sealing the drill tube against the wellbore opening, wherein the gasket is disposed at a constant distance from the hammer during drilling.

In another aspect, the invention provides a overburden drilling apparatus having a percussive hammer bit with a percussion drill bit, a drill pipe having a drill channel for the cuttings, and at least one irrigation medium supply channel, a purge medium supply, and an overlay tube.

The features of the invention in these two aspects are preferably combined with each other.

In one embodiment, a ring is preferably mounted above an air distributor around the drill pipe, preferably against that on which at least one, preferably a plurality of disks are arranged as a seal. Preference for this purpose by smaller plastic discs spaced-apart rubber discs whose outer diameter corresponds to the inner diameter of a superposition tube. The stack of rubber and plastic discs is preferably held together by two smaller diameter steel discs bolted together. In the axial direction, the sealing arrangement of the discs and a ring carrying the discs is preferably fixed by a lock ring and / or a flange.

This measure ensures that the flushing medium pressure losses are reduced by joints in the rock. One additional pressure loss due to increasing borehole volume during drilling is avoided. As a result, the flow rate of the energy transfer medium required to operate the percussion hammer is sufficient to act as a rinse medium for the drill bit after leaving the hammer, largely independently of the nature of the pending rock (water, fractures).

Furthermore, the invention provides a method of overburden drilling in the air lifting method. In this aspect, the drilling method according to the invention comprises supplying the flushing fluid in particular peripherally for discharging the cuttings at least over a predominant part of the drilling depth, and the entrainment of a superimposed pipe arranged adjacent to the pending rock. It is preferred if the overlay tube does not rotate relative to the upcoming rock or slower than a centrally located drill pipe for the supply and removal of the flushing fluid.

In a preferred embodiment, the drilling method according to the invention further comprises the sealing of the drilling sole against the hole opening, and in particular the entrainment of the seal. The seal rotates relative to the pending rock at a rate of at most that of the drill pipe, and preferably at least that of the overlay pipe.

A spin percussion method is preferred which comprises supplying energy by means of an energy transfer medium to a downhole hammer while rotating the hammer.

Figur 1

eine erfindungsgemäße Bohrvorrichtung im Längsschnitt;

Figur 2

eine erfindungsgemäße Bohrvorrichtung im Querschnitt;

Figur 3

einen erfindungsgemäßen Plugg im Querschnitt;

Figur 4

eine Übersichtsskizze einer erfindungsgemäßen Bohrvorrichtung;

Figur 5

eine weitere erfindungsgemäße Bohrvorrichtung ausschnittsweise im Längsschnitt.

Further advantageous embodiments and details emerge from the dependent claims, the following description and the attached drawings. The claims are to be understood as a non-limiting attempt to describe the invention in general terms. Show it:

FIG. 1

a drilling device according to the invention in longitudinal section;

FIG. 2

a drilling device according to the invention in cross section;

FIG. 3

a plug according to the invention in cross section;

FIG. 4

an outline sketch of a drilling device according to the invention;

FIG. 5

a further drilling device according to the invention in sections in longitudinal section.

In the exemplary embodiment according to FIGS. 1 and 2, the drill pipe 1 comprises a drill pipe 2 with a central delivery channel 3 and an air channel 4 arranged at its periphery. At the lower end of the drill pipe 2, a connecting piece 5 is welded into which a countersunk hammer drill head 6 from below is screwed with its central connector 7, which has a compressed air supply opening 8, through which the Senkhammer drill head 6 is supplied to drive his percussion drill bit 9 with compressed air. The diameter of the percussion drill bit 9 is greater than that of the drill pipe 2 and also larger than the diameter of the drill bit In the connecting piece 5, a conveying channel section 10 extends from the centrally arranged conveying channel 3 of the drill pipe 2 obliquely downward to a lateral inlet opening 11. Furthermore, an air duct section 13 extends from the peripheral air duct 4 of the drill pipe to a central region of the connecting piece 7th of the drill head.

The percussion drill bit 9 is driven to blow by compressed air from a compressor unit located adjacent the well bore in the example, while it is rotated by the drill string 1. The percussion drill bit has a central pilot crown 9a and a ring crown 9b surrounding it. Pilot crown 9a and ring crown 9b are detachably connected to each other by means of a bayonet connection. The ring crown 9b is rotatably connected via a Casingschuh 15 with a superposition tube 12, which is thereby pulled along in the course of drilling. The compressed air flowing back from the borehole bottom to the borehole opening acts as flushing medium, assisted by water present in the borehole or additionally supplied, and holds in the central conveying channel 3 a flow velocity of more than 30 m / s, preferably 70-80 m / s, sufficient to convey the cuttings , in particular about 75 m / s upright.

In the embodiment of FIG. 1, the drill bit 9 further has a feed channel 41 for the compressed air 42 flowing from the hammer 6 into the drill bit 9, a feed passage 43, a discharge passage 44, a bypass 45 and a discharge passage 46 for the return compressed air 47. Drilling elements 50a, 50b of the pilot or annular crown are arranged on the end face of the crown 9. The ring crown 9b is by means of the holding elements 51, 52, 53 on the one hand releasably coupled to the pilot crown 9a, on the other hand rotatably connected to the Casingschuh 15, so that the ring crown 9b is able to entrain the Casingschuh 15 together with the superimposed pipe 12 welded thereto. The overlay tube 12 thereby does not rotate or substantially slower than the drill bit 9, depending on the frictional resistance of the borehole wall and on the crown exerted torque.

For compressed air supply for a 457mm (18 ") Imlochhammer and a drill pipe with 200 mm outer and 125 mm inner diameter serve compressors 60 with 30 to 80 m ³ / min flow rate, preferably 50 to 70 m ³ / min capacity, with Increasing depth and grain size of the cuttings corresponding to larger air flow rates are used.

The borehole is lined, at least in the region of its sole, beyond the hammer 6, with the overlay tube 12. About the connector 5 as a seal Plugg 18 is set (Figure 3), which rests tightly on the overlay tube 12 and the drill pipe 2 and in the course of drilling with the drill pipe 2 moves down. This Plugg 18 includes in the illustrated embodiment, three rubber discs 20 which are supported by two plastic discs 22 of smaller diameter spaced from each other. Preference is given to one or two to five rubber discs, which are separated from one another by a correspondingly smaller by one number of plastic discs. The stack of rubber and plastic discs is held on both sides by steel discs 24 of the same diameter as the plastic discs 22, and six threaded through holes 26 in the discs threaded bolt 28 together with nuts. The disk stack is arranged and fixed by means of bolts 32 on a mounting ring 30 which is rotatably pushed onto the drill pipe 2 and fixed in the axial direction by a lock ring 34 welded to the drill pipe 2. By this arrangement, the mounting ring 30 rotates not or only slowly with the drill pipe 2, while the rubber discs 20 abut against the inner wall of the overlay tube 12. Opposite the upcoming mountains, the sealing discs of the Plugg 18 rotate at a speed at least that of the overlay tube 12 and smaller than that of the drill pipe 2.

In an alternative embodiment, an inflatable tube ring ("packer") is arranged on the mounting ring instead of the disc stack.

For example, a 711 (28 ") x8 mm tube with an inside diameter of 695 mm is fitted with the Plugg rubber discs 20. The rubber, steel and plastic discs of the Plugg 18 each have a thickness of 15 mm. As shown in FIG. 3, these disks are attached to a bronze ring 30, which in turn is rotatably pushed onto the drill pipe 2 with an outer diameter of 200 mm and secured in the axial direction by a lock ring 34.

Above the connecting piece 5, a drill collar 36 (see Figure 4) is arranged to dampen the impact of the hammer 6 upwards and so to lead down. This drill collar 36 is, for example, as part of the drill pipe 2 with an outer, with lead poured coat educated. The plug 18 is disposed above or preferably below the drill collar 36.

In the example described above, the overlay pipe is a continuous pipe string, which is continuously supplemented in the course of drilling and can remain in the hole after completion of the hole. In an alternative of the drilling device, the strand is not supplemented over the Plugg out, but completed with an example, frustoconical lid piece upwards. In this case, alternatively, the cover piece is designed as a seal, so that the plug is dispensable. The lid piece closes against the drill pipe rotatable tight.

In a further embodiment (FIG. 5), a downwardly closed jacket tube 14, which is preferably double-walled, is arranged below the lateral inlet opening 11 around the hammer 6. Towards the top, this jacket tube 14 extends in this example to the upper edge of the connecting piece 5, wherein for the lateral inlet opening 11, a passage 15 is formed in the jacket tube 14. As a result, the flushing medium is forced to flow through the jacket tube 14 narrowed circumferential space (outer hatched area in Figure 2) between the jacket tube 14 and overlay tube 12. Because of the restricted free cross-section, the flow velocity at the hammer level increases to values that ensure purging of the cuttings.

In the drilling method according to the invention, the drill bit 9 is rotated while passing through the drill pipe 2 for transmitting a hammering action to the rotary drill bit 9 to the hammer 6, an energy transfer medium, for example a portion of the purge medium, is supplied; with the drill bit 9 an overlay tube 12 and a seal 18 between the overlay tube 12 and the drill pipe 2 is carried along; and the cuttings are discharged through the drill pipe 2. The overlay tube may be continuously added to the wellbore orifice at its top end, or terminated at the top after the seal is installed. In the former case, the overlay tube can remain in the well after completion of the hole or be removed again. The embodiment in the latter case has the advantage that the frictional resistance of the entrained overlay tube remains independent of the drilling depth, and thus in this respect sets no significant limit.

The drilling methods according to the invention have the advantage that by entraining the plug 18 close above the air distributor connection piece 5 for the deflection of the flushing medium, and by carrying an overlay tube 12, reliably a sufficient pressure gradient between the borehole bottom and well opening is established to blow out the cuttings On the one hand, the flushing medium can not escape into fractures of the upcoming mountains, on the other hand, the volume to be pressurized remains constant and comparatively low in the course of drilling.

In a further preferred embodiment, the passage cross-section for the cuttings-enriched flushing fluid in the region of the hammer is restricted, if necessary by a jacket tube surrounding the hammer, such that it is at most ten times the internal cross-section of the conveying channel of the drill pipe (internal hatched area in Figure 2), on the other hand, preferably not less than that, in particular at least four times as large, and more preferably six to eight times as large, so that even coarse cuttings can pass.

It is preferred to make overlay pipe, drill pipe delivery channel and optional jacket tube circular cylindrical. In this case, the three lengths (see Figure 2) give A = outer diameter of the hammer or mandrel around the hammer, nB = one and a half to four times, preferably two and a half to three, inside diameters of the irrigation fluid delivery channel above the air distributor and C = Inner diameter of the overlay tube, when assembled into a geometric figure, a pointed or in particular right-angled triangle with the sides A, nB and C.

These measures ensure that the drill cuttings are blown past the hammer into the drill pipe.

The optional jacket tube is preferably single-walled or double-walled and has a passage or a recess which connects the inlet opening of the air distributor with the space surrounding the jacket tube. Furthermore, the jacket tube closes at its upper end against the drill pipe or the air distributor, at its lower end against the hammer.

This ensures that the flushing fluid enriched with cuttings at a sufficiently high speed around the casing pipe to the inlet opening of the air distributor flows to accelerate the cuttings to its ascent rate.

In a preferred embodiment, the drilling process is performed in a first section, at a relatively large diameter borehole, using such a jacket tube; after reaching a certain hole depth, a second drill section with a smaller hole diameter and without the jacket tube, or with a jacket tube smaller outer diameter is continued. In the upper, further well section can then be installed, for example, a barrier piping. In this way, the entire bore with largely the same components and thus space-saving and cost-effective.

Claims (20)

1. A DTH-hammer drilling device, comprising:

   a down-the-hole-(DTH-)hammer drilling head (6) with a percussion drill bit (9);

   a flushing medium supply device (60); and

   a drill pipe (2) with a waste conduit (3) for the cuttings and at least one supply conduit (4) for the flushing medium,

   characterized by

   a downwardly closed sleeve tube (14) arranged around the hammer (6).
2. The DTH-hammer drilling device according to claim 1, further comprising a seal (18) for sealing the borehole against the borehole opening.
3. The DTH-hammer drilling device according to claim 2, wherein the seal (18) for sealing the borehole against the borehole opening is arranged at a fixed distance from the drilling head (6).
4. The DTH-hammer drilling device according to one of claims 1 to 3, wherein the sleeve tube (14) is formed double-walled.
5. The DTH-hammer drilling device according to one of claims 1 to 4, further comprising a casing tube (12) mutually rotatably connected to the drill bit (9).
6. The DTH-hammer drilling device according to claim 5, wherein in a region of the hammer (6), a free cross sectional area within the casing tube (12) is at least as large, preferably at least four times as large, and in particular six to eight times as large as a free cross sectional area of the waste conduit (3) for the cuttings.
7. The DTH-hammer drilling device according to claim 5 or 6, wherein the casing tube (12) and the sleeve tube (14) have circular-cylindrical shape.
8. The DTH-hammer drilling device according to claim 7, wherein an outer diameter A of the sleeve tube (14), an n-fold inner diameter n·B of the circular-cylindrical waste conduit (3) for the cuttings, and an inner diameter C of the casing tube (12) fulfill the condition that a triangle with sides A, n·B and C is right-angled or acute-angled, wherein 1,5<n<4, preferably 2,5<n<3.
9. The DTH-hammer drilling device according to one of the preceding claims, wherein the waste conduit (3) for the cuttings is surrounded by the supply conduit (4) for the supply medium.
10. The DTH-hammer drilling device according to one of the preceding claims, wherein the seal (18) comprises at least one, preferably two to five, particularly three spaced apart rubber disks (20).
11. The DTH-hammer drilling device according to claim 10, wherein two to five, particularly three rubber disks (20) are separated by plastic disks, respectively.
12. The DTH-hammer drilling device according to claim 11, wherein a diameter of the plastic disks (22) is less than a diameter of the rubber disks (20).
13. The DTH-hammer drilling device according to one of claims 10 to 12, wherein the disks (20, 22) are arranged on a mounting ring (30) rotatably arranged around the drill pipe (2) .
14. A percussion drilling method, comprising:

    rotating a drill bit (9); and

    supplying an energy transfer medium through a drill pipe (2) to a hammer (6) for transmitting a percussive action onto the rotating drill bit (9);

    characterized by

    carrying along a sleeve tube (14); and

    flushing away cuttings around the sleeve tube (14) and through the drill pipe (2).
15. The drilling method according to claim 14, further comprising compressing air for providing the energy transfer medium.
16. The drilling method according to claim 14 or 15, wherein the flushing away of the cuttings is effected at least partly by the energy transfer medium after its percussive action.
17. The drilling method according to one of claims 14 to 16, wherein the cuttings are blow-lifted through the drill pipe (2) with a speed of at least 50 m/s, preferably more than 60 m/s.
18. The drilling method according to one of claims 14 to 17, further comprising dragging a casing tube (12) along with the drill bit (9).
19. The drilling method according to claim 18, wherein a first drilling section is carried out with the sleeve tube (14) arranged between the hammer (6) and the casing tube (12) for drilling a larger diameter first borehole section, and a second drilling section is carried out without the sleeve tube (14) for drilling a smaller diameter second borehole section.
20. The drilling method according to claim 18 or 19, further comprising carrying along a seal (18) between the casing tube (12) and the drill pipe (2).

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