EP0605562B1

EP0605562B1 - Apparatus and method for removing drillhole debris

Info

Publication number: EP0605562B1
Application number: EP92920320A
Authority: EP
Inventors: Leland H. Lyon; Ernest C. Hinck
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1991-09-27
Filing date: 1992-09-16
Publication date: 1997-01-22
Anticipated expiration: 2012-09-16
Also published as: DE69217072D1; DE69217072T2; CA2119249A1; AU666500B2; JPH07502086A; CN1072988A; AU2656492A; KR940702580A; EP0605562A1; WO1993006334A1; CN1029700C

Abstract

A device (3) and method for removing debris from a drillhole (1), includes positioning a separator adjacent to a down-the-hole percussive drillhead, for removing water and other matter from the percussive fluid prior to the percussive fluid entering the drillhead. The water and other matter are ejected into the drillhole to remove the debris, and backflow of debris and water into the separator and drillhead is prevented, during periods when the percussive fluid flow ceases.

Description

This invention relates generally to rock drills and more particularly to pneumatically operated percussive drills of the type adapted to be inserted into a drill hole being drilled thereby and commonly known as "down-the-hole" drills or (DHD).
Many applications for down-the-hole drills require that fluids such as water and other matter be injected into the drill air supply to provide improved hole cleaning and stabilisation. Typically, the volume of liquids injected can range from about 2.0 gallons (7.57 l) per minute to about 15.0 gallons (56.78 l) per minute. When water is injected into the air flow for a DHD, an appreciable loss in penetration rate results for a given pressure. The decrease in penetration rate can range from 30% to 60%, depending upon the fluid injection rate and pressure. The loss in hammer performance associated with fluid injection adversely affects DHD production and in many cases causes the use of DHD to be unsuitable.
A down-the-hole separator to separate drilling mud into portions of different densities is known from US-A-4 688 650.
According to a first aspect of the present invention, there is provided a device for removing debris from a drill hole made by a fluid-activated, percussion, down-the-hole drill tool adapted to be suspended at its top end from a drill string having an axial bore, the device including an inlet for fluidly communicating with said drill string axial bore and for receiving a flow of a mixture of gaseous percussive fluid and other matter from said drill string axial bore;characterised by separator means positioned adjacent said top end of said tool for receiving a flow of a mixture of gaseous percussive fluid and other matter from said drill string axial bore, for separating and collecting in a bottom end of said separator means substantially all of said other matter from said gaseous percussive fluid and for thereafter transmitting said percussive fluid through said device to said tool, while simultaneously transmitting said collected other matter and at least some of said percussive fluid out of said separator means into the drill hole annulus, for removing said debris, and deflector means to deflect flow of the gaseous percussive fluid in said separator means and a passageway extending through said deflector means for communicating between said drill string axial bore and said top end of said tool to permit at least some of a percussive fluid mixture to bypass the deflector means.
According to a second aspect of the present invention, there is provided a method for removing debris from a drill hole, said drill hole being made by a fluid-activated, percussion down-the-hole drill tool adapted to be suspended at its top end from a drill string having an axial bore, the method being characterised by positioning a separator means between said top end of said drill tool and a bottom end of said drill string, injecting into said bore a flow of a mixture of a gaseous percussive fluid and other matter, transmitting said mixture down into said separator means in said drill hole, removing substantially all of said other matter from said mixture as a separate phase prior to said percussive fluid entering said drill tool, simultaneously ejecting said removed other matter from said separator means into said drill hole to remove said debris, and simultaneously preventing backflow of said debris from said drill hole into said separator when said flow of said mixture ceases, and simultaneously injecting into said drill tool at least some of said percussive fluid mixture prior to removal of said other matter to lubricate said drill tool.
For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-

Figure 1 is a longitudinal section of a cleaning device for use with a fluid-activated, percussion, down-the-hole drill tool,
Figure 2 is a horizontal cross-sectional view taken along line 2-2 of Figure 1,
Figure 3 is a horizontal cross-sectional view taken along line 3-3 of Figure 1 and
Figure 4 is a longitudinal section of a one-way valve with portions removed.

Referring to Figure 1 there is shown a drill hole 1, having a drill hole cleaning device 3 positioned therein. The cleaning device 3 has a top connector 5 connected by conventional means such as threads to the bottom end 7 of a drill string 9. A bottom connector 11 connects the device 3 by conventional means such as threads to a back head of a down-the-hole drill 13. Equivalently, the bottom connector 11 could connect to another member in the drill string 9, rather than the drill 13, so long as the device 3 is within the drill hole 1 and adjacent to the drill 13.
As is well known, a fluid is caused to flow through the drill string 9 to activate the drill 13. In this instance, the drill 13 is of the type known as a percussive down-the-hole drill activated by a pneumatic fluid such as air. Eventually, the fluid exits the drill head and moves up the drill hole to carry out debris from drilling. Debris from drilling can include particles of strata being drilled, water seeping into the drill hole, plus other matter introduced into the drill 13 via the drill string 9.
In order to increase debris removal, water may be injected into the fluid. Other matter, such as oil, may be injected for lubrication of the tool head. In addition, other matter, such as particles of rust or scale dislodged from the drill string interior may be carried by the fluid. Thus, the percussive fluid may be a mixture of air, water, oil and other matter, including solid particles.
As used herein, the term "percussive" refers to the type of drill that utilises a reciprocating piston to impart impact forces to a drill head to cause penetration of the strata, and does not refer to a rotary type drill that utilises a rotary grinding action to cause penetration.
Also, as used herein, the term "percussive fluid" refers to the pneumatic fluid that imparts the reciprocating action to the drill piston.
A longitudinal casing 15 is fastened, as by welding, to the top connector 5 and bottom connector 11 and defines a hollow vortex chamber 17 extending axially therebetween. A first inlet 19 at the top connector 5 fluidly communicates axially between a drill string axial bore 21 and the vortex chamber 17. A first outlet 23 at the bottom connector 11 fluidly communicates axially between the vortex chamber 17 and back head of the drill 13.
A deflector means 25 is sealingly fastened in the first inlet 19. As shown in Figures 2 and 3 in horizontal cross-section the inlet 19 is circular in outline, as is the deflector means 25, although other shapes of outline could be used. Referring again to Figure 1, the deflector means 25 includes a deflector plate 27 extending across the first inlet 19 in a plane that is transverse to, and perpendicular to, the longitudinal axial direction of the vortex chamber 17 and bore 21. This plane of the deflector plate 27 is referred to herein as a "radial" plane or direction. The deflector means 25 deflects flow of a mixture percussive fluid and other matter from a downward axial direction to a radial and tangential direction, as hereinafter described.
A hollow focus tube 29 below the deflector means 25 extends axially through the vortex chamber 17 and has a lower end 31 sealingly in contact with the bottom connector 11 and an upper end 33 terminating adjacent the deflector means 25 in a focus tube inlet 35. The focus tube 29 defines a first percussive fluid passageway 37 between the inner surface 39 of the casing 15 and outer surface 41 of the focus tube 29. The focus tube 29 also defines a second percussive fluid passageway 43 within focus tube 29 communicating axially between the vortex chamber 17 and first outlet 23.
A baffle 45 is connected to the lower end 47 of the focus tube 29 and extends radially into the first percussive fluid passageway 37 and ends spaced from the inner surface 39, to cause reversal of flow of percussive fluid as described hereinafter.
A collection gallery 49 is formed below the baffle 45 in the lower end 47 of the vortex chamber 17 for collecting other matter separated from the percussive fluid as hereinafter described. A collection gallery outlet 51 communicates between the drill hole bore and the inside of the collection gallery 49 to permit flow of the matter collected therein, plus some of the percussive fluid out into the annulus of the borehole 1. The outlet 51 can be a simple "T" shaped nipple having open passageways 53 therethrough. Although one outlet 51 is shown, a plurality of outlets, spaced circumferentially around vortex chamber 17 may be used.
The deflector plate 27 of the deflector means 25 has a cone-shaped upper surface 54 extending axially upwardly within the first inlet 19. As shown in Figures 2 and 3, the connector 5 has a plurality of apertures 55 therethrough which extend in a radial direction with respect to the axial direction of the chamber 17. The inlet 19 is circular in outline as viewed in horizontal cross-section, and the apertures 55 extend tangentially with respect to the inner surface 57 of the inlet 19 and communicate between the first inlet 19 and first fluid passageway 37. Sealingly suspended downwardly from the plate 27 is a hollow shield tube 59 telescoped axially over the focus tube inlet 35 and extending a sufficient distance to prevent entry of the percussive fluid mixture into the focus tube inlet 35 until after the percussive fluid mixture has passed downwardly the length of the vortex chamber 17 and reversed direction at the baffle 45. A single aperture 61 extends axially downwardly through the plate 27 to form a passageway communicating between the first inlet 19 and focus tube inlet 35 to permit at least some of the percussive fluid mixture to by-pass the deflector means, so as to permit as small amount of percussive fluid mixture to flow directly to the drill tool head for a purpose such as lubrication. It would be equivalent to provide a plurality of apertures instead of the single aperture 61.
Sealingly positioned in the first inlet 19 is a one-way flow valve 63 adapted for permitting only downward axial flow of the percussive fluid mixture therethrough. During flow of percussive fluid, the valve 63 is normally open. When flow of percussive fluid ceases, the valve 63 closes. The need for the valve 63 is because water and other debris from the borehole annulus backflows into the collection chamber 49 via open passageways 53 when fluid flow ceases. Such backflow accumulates in the chamber 17 and would rise up to the focus tube inlet 35 and thence flow into the drill tool, to cause damage to the drill when it starts operation again. This feature is important because, during periods when the operators are not working, the drill is left down in the drill hole.
With the valve 63 closed, percussive fluid is trapped inside the cleaning device 3, and as water and debris rise inside the vortex chamber 17, the percussive fluid becomes compressed until its pressure equals the backflow pressure, and backflow ceases. Any conventional one-way valve will suffice.
Figure 4 shows one embodiment of such valve 63, which includes a hollow tubular body 65, removably positioned on a shoulder 66 in the first inlet 19. An annular elastic seal 67 positioned in a groove in an outer surface of the body 65 sealingly contacts the inner surface 57 of the inlet 19. The body 65 is retained in place by a retainer ring 69 positioned in a matching groove 71, as is well known. Slidably positioned within the hollow body 65 is a hollow valve stem 73, which has a truncated conical upper end 75 extending axially upwardly towards axial inlet aperture 77 in the body 65. The body 65 has a seal seat 79 sloped downwardly therein and shaped to conform to the conical upper end 75. Positioned in the seat surface 79 is an elastic seal means 81 for alternate sealing and unsealing against the upper end 75. Annular elastic spring means 83 seated against a bottom flange 85 of the body 65 contacts the bottom end of the stem 73 and urges the stem 73 upwardly, so as to cause the upper end 75 sealingly to contact the seat surface 79 and seal 81. Thus, the valve 63 is normally closed to percussive fluid flow. Inside the stem 73 is a hollow inlet chamber 87 that communicates axially with the vortex chamber 17. A plurality of fluid passageways 89 extend through the wall of the stem 73, the passageways 89 being spaced around the perimeter of the conical surface 75.
In operation, percussive fluid acts upon the upper surface 75 to cause the stem 73 to move axially downwardly and lose sealing contact with the seal 81, thereby opening up a fluid passageway between the axial bore 21, inlet 77 and inlet chamber 87, via passageways 89. When percussive fluid pressure is zero, as when the drill is inoperative, the spring 83 urges the stem 73 into sealing engagement with the seat 79, thereby closing the valve 63. The elastic property of the spring 83 is preferably selected so that with a residual percussive fluid pressure greater than zero, and equal to, but not greater than the pressure inside the vortex chamber 17, with an inoperative drill, the valve will remain closed.
An acceptable alternative would be to position a one-way valve at the outlet 51 instead of within the inlet 19.
In operation, the mixture of percussive fluid and other matter flows axially downwardly into the first inlet 19, against the upper surface 54 and is deflected to a tangential and radial outward direction into the vortex chamber 17, to impact tangentially against the inner surface 39 of the casing 15. Thereafter, the percussive fluid mixture flows downwardly and circularly, in a vortex fashion, through the first percussive fluid passageway 37 of the vortex chamber 17, causing separation of at least some of the other matter from the percussive fluid mixture. Such separated matter flows downwards along the inner surface 39 of the casing 15 to the collection chamber 49. At the lower end of the chamber 17, the percussive fluid mixture strikes the baffle 45, reverses its flow to an upward direction, causing separation of more of the other matter from the percussive fluid mixture, and collection thereof in the collection gallery 49. The percussive fluid, with substantially all of the other matter now removed, flows upwardly along the outer surface 41 of the focus tube 29 toward the focus tube inlet 35; thereafter down the second fluid passageway 43, through the outlet 23, into the backhead 13 of the drill tool, and thence therethrough to the drill hole bore, as is conventional.
In operation, the present device in tests caused removal of a substantial amount of the other matter from the percussive fluid mixture, including water, oil and solid particles from the drill string interior. Such removal has resulted in dramatically improved penetration rate over those achieved without the removal of such other matter, while at the same time retained the benefits of debris removal due to the presence of the other matter in the bore of the drill hole.
In the percussive fluid mixture, water can be injected at the rate of between 0 and 15 gallons (56.78 1) per minute, air flow rate can be between 200 and 1100 standard cubic feet per minute (between 94.38 and 519.09 l/s) and air pressure can be between 100 and 300 pounds per square inch (between 689.5 and 2068.5 kN/m²).

Claims

A device (3) for removing debris from a drill hole (1) made by a fluid-activated, percussion, down-the-hole drill tool (13) adapted to be suspended at its top end from a drill string (9) having an axial bore (21), the device including an inlet (19) for fluidly communicating with said drill string axial bore (21) and for receiving a flow of a mixture of gaseous percussive fluid and other matter from said drill string axial bore; characterised by separator means positioned adjacent said top end of said tool (13) for receiving a flow of a mixture of gaseous percussive fluid and other matter from said drill string axial bore (21), for separating and collecting in a bottom end (49) of said separator means substantially all of said other matter from said gaseous percussive fluid and for thereafter transmitting said percussive fluid through said device (3) to said tool (13), while simultaneously transmitting said collected other matter and at least some of said percussive fluid out of said separator means into the drill hole annulus, for removing said debris, and deflector means (25) to deflect flow of the gaseous percussive fluid in said separator means and a passageway (61) extending through said deflector means (25) for communicating between said drill string axial bore (21) and said top end of said tool to permit at least some of a percussive fluid mixture to bypass the deflector means (25).
A device according to claim 1 and comprising a valve (63) in said separator means for sealing said separator means against backflow of debris into said separator means when flow of said gaseous percussive fluid ceases.
A device according to claim 1 or 2, comprising a top connector (5) for connecting the device (3) to the drill string (9) and a bottom connector (11) for connecting the device to a back head of the tool (13), the separator means having a longitudinal casing (15) extending axially between the top connector and the bottom connector and defining a hollow vortex chamber (17) and a first outlet (23) at said bottom connector (11) fluidly communicating axially between said vortex chamber (17) and the back head.
A device according to claim 3, wherein said deflector means (25) is arranged to deflect flow of said percussive fluid mixture from a downwards axial direction to a tangential outwards direction, to cause said percussive fluid mixture to impact tangentially against an inner surface (39) of said casing (15) and thereafter to flow downwardly through said vortex chamber (17), thereby causing separation of at least some of said other matter from said percussive fluid.
A device according to claim 4, wherein said separator means further comprises a hollow focus tube (29) below said deflector means (25), extending axially through said vortex chamber (17), having a lower end (31) sealingly connected to said bottom connector (11) and an upper end terminating adjacent said deflector means (25) in a focus tube inlet (35), said focus tube defining a first percussive fluid passageway (37) between said inner surface (39) of said casing and an outer surface (41) of said focus tube and a second percussive fluid passageway (43) within said focus tube, said second percussive fluid passageway communicating axially between said vortex chamber (17) and said first outlet (23); there being a baffle (45) connected to said lower end of said focus tube (29) in said first percussive fluid passageway (37) and spaced from said inner surface (39) of said casing, for reversing downward flow of said percussive fluid mixture into an upward flow towards said focus tube inlet (35), causing separation of more of said other matter from said percussive fluid mixture, and forming therebelow a collection gallery (49) for said other matter separated from said percussive fluid, and a collection gallery outlet (51) permitting flow of said other matter and at least some of said percussive fluid out of said collection gallery into the annulus of said drill hole to cause removal of said debris.
A device according to any one of the preceding claims, wherein said deflector means (25) comprises a deflector plate (27) sealingly connected to an inner surface (57) of said inlet (19), having a cone shaped upper surface (54) extending axially upwardly within said inlet (19), a plurality of apertures (55) through said deflector plate, said apertures, when viewed in horizontal cross-section, being tangentially disposed with respect to said inner surface (57) of said inlet and forming a plurality of percussive fluid passageways communicating between said inlet (19) and said separator means.
A device according to claims 5 and 6, wherein a shield tube (59) is sealingly connected to said deflector plate (27), said shield tube (59) extending axially below said deflector plate (27) and telescoped over said focus tube inlet (35) a sufficient distance to prevent entry of said percussive fluid mixture into said focus tube (29) until after said percussive fluid mixture has passed through the length of said first percussive fluid passageway (37).
A method for removing debris from a drill hole (1), said drill hole being made by a fluid-activated, percussion down-the-hole drill tool (13) adapted to be suspended at its top end from a drill string (9) having an axial bore (21), the method being characterised by positioning a separator means between said top end of said drill tool (13) and a bottom end of said drill string (9), injecting into said bore (21) a flow of a mixture of a gaseous percussive fluid and other matter, transmitting said mixture down into said separator means in said drill hole, removing substantially all of said other matter from said mixture as a separate phase prior to said percussive fluid entering said drill tool, simultaneously ejecting said removed other matter from said separator means into said drill hole to remove said debris, and simultaneously preventing backflow of said debris from said drill hole into said separator when said flow of said mixture ceases, and simultaneously injecting into said drill tool (13) at least some of said percussive fluid mixture prior to removal of said other matter to lubricate said drill tool.
A method according to claim 8, in which said percussive fluid is air.
A method according to claim 8 or 9, in which said other matter is substantially water.
A method according to claim 8, 9 or 10, in which said other matter is a mixture of solid particles from the axial bore of said drill string and water.
A method according to claim 8, 9 or 10, in which said other matter is a mixture of solid particles from the axial bore of said drill string, oil and water.
A method according to any one of claims 8 to 12, in which said water is injected at the rate of between 0 and 15 gallons (56.78 1) per minute.
A method according to any one of claims 8 to 13, in which the air flow rate is between 200 and 1100 standard cubic feet per minute (between 94.38 and 519.09 l/s).
A method according to any one of claims 8 to 14, in which the air pressure is between 100 and 300 pounds per square inch (between 689.5 and 2068.5 kN/m²).