AU2020103040A4 - A reverse circulation drilling apparatus with a seal for an inner tube - Google Patents

A reverse circulation drilling apparatus with a seal for an inner tube Download PDF

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Publication number
AU2020103040A4
AU2020103040A4 AU2020103040A AU2020103040A AU2020103040A4 AU 2020103040 A4 AU2020103040 A4 AU 2020103040A4 AU 2020103040 A AU2020103040 A AU 2020103040A AU 2020103040 A AU2020103040 A AU 2020103040A AU 2020103040 A4 AU2020103040 A4 AU 2020103040A4
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Australia
Prior art keywords
inner tube
top cylinder
check valve
drilling apparatus
reverse circulation
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AU2020103040A
Inventor
Charles David Barden
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Epiroc Rock Drills AB
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Epiroc Rock Drills AB
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Priority to AU2020103040A priority Critical patent/AU2020103040A4/en
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Assigned to EPIROC ROCK DRILLS AB reassignment EPIROC ROCK DRILLS AB Request for Assignment Assignors: AIRDRILL HAMMERS AND BITS PTY LTD
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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B27/00—Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, baskets or buckets for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/10—Valve arrangements in drilling-fluid circulation systems
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/02—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells by mechanically taking samples of the soil
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B2200/00—Special features related to earth drilling for obtaining oil, gas or water
    • E21B2200/01—Sealings characterised by their shape
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B2200/00—Special features related to earth drilling for obtaining oil, gas or water
    • E21B2200/06—Sleeve valves
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B4/00—Drives for drilling, used in the borehole
    • E21B4/06—Down-hole impacting means, e.g. hammers
    • E21B4/14—Fluid operated hammers

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Soil Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Earth Drilling (AREA)

Abstract

A reverse circulation drilling apparatus comprises: (a) a top cylinder (120); (b) a check valve (130) located within the top cylinder (120) comprising a 5 check valve body (132) accommodating a check valve sealing means (135); and (c) an inner tube (140) for collecting cuttings formed during operation of the drilling apparatus. The inner tube (140) is detachably secured within the top cylinder (120) and has an outside surface (143) with at least one further sealing means (210) at least partially located within the top cylinder (120). Both the check valve sealing 10 means (135) and further sealing means (210) engage with a substantially smooth portion (145) of the outside surface (143) of the inner tube (140) to form a seal. The sealing means (135, 210) co-operate with the outside surface (143) of the inner tube (140) to substantially prevent air leakage past check valve (130) when the reverse circulation drilling apparatus is shut off. 15 vii all0

Description

vii all0
A REVERSE CIRCULATION DRILLING APPARATUS WITH A SEAL FOR AN INNER TUBE TECHNICAL FIELD
The present invention relates to a reverse circulation drilling apparatus with a seal for an inner tube. An inner tube is also known as a sample tube or a sample recovery tube.
BACKGROUND ART
The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
Reverse circulation drilling apparatus, such as down the hole hammers, comprise a downhole hammer housing which has a drill bit connected at one end. The hammer housing is connected to a drill string through a top/adaptor sub. A compressed air powered piston reciprocates within the hammer housing and impacts against the drill bit to cause fracture of a formation and generation of cuttings. The drilling apparatus includes a generally centrally located sample tube extending through bores in the hammer housing, piston and drill bit for collecting the cuttings via aperture(s) provided adjacent to the cutting face(s) of the drill bit. The sample tube, also called a sample recovery tube or an inner tube with the latter term generally being preferred in this specification, is connected at its upper end to an inner tube of the reverse circulation drilling apparatus.
As described in International Publication No. 96/04459, the sample tube is fixed with respect to the downhole hammer housing and both the piston and drill bit move with respect to the stationary sample tube. There is a sliding fit between the lower end of the sample tube and the drill bit to prevent blow-back from a lower piston chamber and to ensure that drilling debris does not enter the lower piston chamber. This would adversely affect drilling operations.
The bore through the centre of the piston is sufficiently large to provide a clearance with respect to the sample tube. Although there is no contact by the piston, the impact forces transmitted from the drill bit result in significant longitudinal and torsional loads being applied to the sample tube. In WO 96/04459, the sample tube is provided on its outside surface with a radial flange or projection intermediate its upper end, the flange or projection locating within recesses in an assembly - typically comprising a compressed air distributor and a check valve guide - which is fixed relative to the downhole hammer housing. The compressed air distributor is provided with a recess or counterbore portion within which the radial flange of the sample tube locates. The upper surface of the flange is flush with the upper level of the compressed air distributor and when the check valve guide body locates against this surface, the sample tube is held in place.
As further described in WO 96/04459, the radial flange and respective recess within the compressed air distributor are designed to secure and seal the sample tube with respect to the downhole hammer housing. However, because of the forces transmitted along the sample tube as a result of the operation of the drill bit, wear occurs which allows the sample tube to rotate within its mounting assembly. The rotation itself causes further rapid wear and, as a result, compressed air can leak from the centre of the compressed air distributor along the outside surface of the sample tube into the ?0 upper piston chamber. This will prevent the hammer from operating or, at worst, prevent its operation altogether.
WO 96/04459 addresses the wear issue by providing the sample tube projection with an irregular cross-section to prevent rotation of the sample tube with respect to a locating recess or other mounting means. Preferably, the projection has an elliptical cross section.
The Applicant's drilling apparatus is designed with a top loading inner tube and inner tube sealing arrangement that allows manual removal and insertion of the inner tube as required by a drilling apparatus operator. The sealing arrangement is distinct from that of WO 96/04459, particularly in that the Applicant's inner tube has some tendency to rotate during drilling apparatus operation, but has in common the feature that the projections are mounted on the outside surface of the inner tube. A problem encountered by the Applicant is that these projections impact and damage a lip seal of the check valve with removal-insertion cycles of inner tube(s). The higher the frequency of the removal-insertion cycles, the greater the wear. The problem is made worse if inner tubes are inserted or removed too forcibly. At the same time, damage to the check valve lip seal causes a less effective seal allowing air to pass the check valve when the hammer is off/not operational causing ingress of contaminants into the operational chambers of the hammer which can cause damage/increased wear to the hammer's internal components and, in severe cases, will not allow the hammer to operate.
SUMMARY OF INVENTION
An object of the present invention is to provide a reverse circulation drilling apparatus with a sealing arrangement for an inner tube that minimises or avoids the wear and operational problems such as those described above.
With this object in view, the present invention provides - in one embodiment - a reverse circulation drilling apparatus comprising:
(a) a top cylinder;
(b) a check valve located within the top cylinder and comprising a check valve body accommodating a check valve sealing means;
(c) an inner tube for collecting cuttings formed during operation of the drilling apparatus, the inner tube being detachably secured within the top cylinder and having an outside surface wherein said check valve sealing means and at least one further sealing means, at least partially located within said top cylinder, each contact with a substantially smooth portion of the outside surface of the inner tube to form a seal .
That is, the inner tube is not provided with an inner tube sealing flange or sealing projection(s) subject to wear in the substantially smooth portion.
The further sealing means conveniently comprises a rotary multi lip seal which is conveniently a substantially cylindrical sealing ring engaged within a groove formed in the top cylinder, or engaged within a groove formed in a sleeve seated inside the top cylinder, conveniently in the mid-portion of the top cylinder or assembly of components forming the top cylinder - the sealing ring acting radially inwardly on the substantially smooth portion of the outside surface of the inner tube to form a seal. The sealing ring is desirably provided with a plurality of lips to provide a more effective seal.
Advantageously, the inner tube is top loadable into the top cylinder without requirement for disassembly of the hammer. The inner tube is preferably a one-piece component. During loading or unloading (also known as assembly or disassembly) of the inner tube, the inner tube is manually pressed into the top cylinder, which may be a one-piece or multi-piece component, and through the check valve body.
The check valve sealing means may include a lip provided with a flexible sealing ring, such as an O-ring. Owing to the lack of projections on the portion of the inner tube that must pass the check valve sealing means during loading or unloading, the loading or unloading does not involve impact of sealing projections on the check valve sealing means, such as the lip seal, and leakage problems caused by resultant damage may conveniently be avoided.
In a further embodiment, the present invention provides an inner tube suitable for the reverse circulation drilling apparatus as above described comprising a generally cylindrical structure having upper and lower cylindrical portions with a central bore extending longitudinally through said upper and lower cylindrical portions and through which cuttings are recoverable for assay and having a drill bit end slidable into the central bore of a drill bit, wherein said upper portion is - with the typical exception of a groove proximate its end distal from the drill bit - ungrooved and substantially smooth. A smooth surface provides benefits in terms of improved sealing effect as well as faster and more cost effective production as a grooving process adds time to both manufacture and inspection.
The reverse circulation drilling apparatus, as above described, provides a seal arrangement for the inner tube which has improved ease of inner tube removal in not interfering with the check valve sealing means, providing more effective sealing - ideally avoiding causing a leak point in the reverse circulation drilling apparatus or hammer when shut off. Improved hammer performance is also achievable with the hammer having, for example, a sustained air lock when shut off underwater.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:
Figure 1 is an orthogonal view of an inner tube-top cylinder assembly of a prior art reverse circulation drilling apparatus being a down the hole hammer.
Figure 2a is a partial cross-sectional side view of the inner tube-top cylinder assembly of Figure 1.
Figure 2b is an end view A-A of the inner tube-top cylinder assembly of Figure 2a.
Figure 2c is a detail cross-sectional side view of part of the check valve lip seal of Figure 2b.
Figure 3 is an orthogonal view of the top cylinder of Figures 1 to 2b.
Figure 4a is a cross-sectional side view of the top cylinder of Figure 3.
Figure 4b is an end view D-D of the top cylinder of Figures 3 and 4a.
Figure 5 is an orthogonal view of the inner tube of Figures 1 to 2b.
Figure 6a is cross-sectional side view of the inner tube of Figure 5.
Figure 6b is an end view B-B of the inner tube of Figures 5 and 6a.
Figure 7a is an orthogonal view of the check valve body shown in Figures 1 to 2b.
Figure 7b is a cross-sectional side view of the check valve body of Figure 7a.
Figure 7c is an end view C-C of the check valve body of Figures 7a and 7b.
Figure 8 is an orthogonal view of an inner tube-top cylinder assembly of a reverse circulation drilling apparatus being a down the hole hammer of one embodiment of the present invention.
Figure 9a is a partial cross-sectional side view of the inner tube-top cylinder assembly of Figure 1.
Figure 9b is an end view A-A of the inner tube-top cylinder assembly of Figure 9a.
Figure 10 is an exploded orthogonal view of the inner tube-top cylinder assembly of Figure 8.
Figure 11a is an exploded cross-sectional side view of the inner tube-top cylinder assembly of Figure 10.
Figure 11b is an end view E-E of the inner tube-top cylinder assembly of Figure 11a.
Figure 12 is an orthogonal view of the inner tube of Figures 8 to 11b.
Figure 13a is cross-sectional side view of the inner tube of Figure 12.
Figure 13b is an end view D-D of the inner tube of Figures 12 and 13a.
Figure 14 is an orthogonal view of the inner tube of Figures 8 to 11a.
Figure 15a is a side sectional view of the inner tube of Figure 14.
Figure 15b is an end view B-B of the inner tube of Figure 14.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figures 1 to 4a, there is shown a portion of a prior art reverse circulation drilling apparatus 10, for example as available from Schramm Inc. under the model number AD660, including an assembly 15 comprising a top cylinder 20 within which is located a check valve 30 with check valve body 32 and an inner tube 40. Inner tube 40 has the same function as a sample tube or sample recovery tube which are alternative terms for the same component. Top cylinder 20 is connected to a hammer portion (not shown) which includes a piston reciprocable by a compressed air supply to operate a drill bit to form cuttings which are transferred from a formation cut by the drill bit (not shown) to inner tube 40. The cuttings are assayed to determine properties of the formation, for example an ore body.
Check valve 30 seals the air passage of the top cylinder 20 while the downhole hammer is not operating or shut off. Check valve body 32, as shown in Figure 2b, includes an annular groove 34 accommodating an annular lip sealing ring 35.
Top cylinder 20 is configured to allow top loading and unloading of the inner tube 40 into the assembly 15. Loading and unloading is typically done manually. Unloading of inner tube 40 is possible without disassembly of the drilling apparatus, this being an advantage of the illustrated design. In use, inner tube 40 longitudinally extends through a central bore including chambers 24, 26, 28 in the top cylinder 40. Inner tube 40 also longitudinally extends through the central bore of the check valve body 32.
As shown, the inner tube 40 is a generally cylindrical structure having upper and lower portions 44 and 46 with a drill bit end 49, an opposite or drill bit distal end 47 and a central bore 48 through which cuttings are recovered for assay. Upper portion 44 here has greater outer diameter than lower portion 46. Inner tube end 49 slides into the central bore of the drill bit (not shown). Upper portion 44 includes four grooves 44a each occupied by an O-ring. As such, while generally smooth, the inner tube 40 includes a non-smooth portion 440 formed by the grooves and O-rings 44a.
Sealing between inner tube 40, check valve 30 and top cylinder 20 is achieved by the clearance fit of the inner tube 40 in the circular top cylinder wall 27 defining chamber 26 such that the O-rings 44a contact, by acting radially outwardly, with top cylinder wall 27 although with a small risk of leakage; and the clearance fit of inner tube 40 within the circular inner wall 33 of the check valve body 32. The check valve lip sealing ring 35 forms a particularly important part of the sealing between inner tube 40, check valve 30 and top cylinder 20.
As described above, the inner tube 40 is top loading with the reverse circulation hammer having a configuration that allows removal and insertion of the inner tube 40 as required by a drilling apparatus operator. A problem encountered by the Applicant, as schematically indicated by Figure 2c, is that the O-rings 44a in rough portion 440 of inner tube 40 impact and damage, for example by rolling, the check valve sealing ring 35 when removing the inner tube 40 during removal-insertion cycles. The higher the frequency of the removal-insertion cycles, the greater the wear. The problem is made worse if inner tube 40 is inserted or removed too forcibly. At the same time, damage to the check valve lip sealing ring 35, for example by rolling, causes a less effective seal allowing air to pass the check valve 30 causing loss of power for the hammer and potentially preventing its operation altogether. Air leakage also occurs when the hammer is in a shut off condition.
It will also be apparent from the above that O-rings 44a themselves wear and, as these O-rings 44a form a part of the seal between the top cylinder 20 and inner tube 40, the same check valve sealing and hammer operational problems can be caused by O-ring ?0 44a wear as well.
Figures 8 to 11a show portion of a reverse circulation drilling apparatus 110 according to one preferred embodiment and which includes components in common with those described above. This similarity is recognised by numbering the components in the same manner except for the prefix of the numeral "1". Assembly 115 comprises a top cylinder 120 within which is located a check valve 130 with check valve body 132 and an inner tube 140. Check valve 130 has the same function as check valve 30 described above, i.e. of sealing the air passage of the top cylinder 120 while the downhole hammer is not operating or shut off. Check valve body 132, as shown in Figures 9a and 11a, again includes an annular groove 134 accommodating an annular lip sealing ring 135.
Top cylinder 120 is again configured to allow manual top loading of the inner tube 140 to form the assembly 115. Manual unloading is also possible with the loading/unloading operations being schematically indicated by the arrow of Figure 11a. Unloading of inner tube 140 is possible without disassembly of the drilling apparatus, this being an advantage of the illustrated design. In use, inner tube 140 extends through a central bore including chambers 124, 126, 128 in the top cylinder 140 as shown in Figure 13a. Inner tube 140 is also clearance fitted through the central bore of the check valve body 132.
Top cylinder 120 - as shown in Figures 8 to 13a - has a circular inner wall 127 defining chamber 126 (analogous to circular inner wall 27 defining chamber 26). Unlike the top cylinder 20 of Figures 1 to 2a and 3 to 4b, circular inner wall 127 of the mid portion 125 of the top cylinder 120 is provided, as conveniently shown in Figures 9a, 11a and 13a with an annular groove 129 in which is at least partially located a resilient plastic (here urethane) rotary seal 200 provided with a plurality of lips 210 to provide a rotary multi-lip seal by acting radially inwardly to contact the substantially smooth portion 145 of inner tube 140.
Again, the inner tube 140 - as shown in Figures 9a to 11b and 14 to 15b - is a generally cylindrical structure having upper and lower portions 144 and 146 with an outside surface 143 and a central bore 148 through which cuttings are recovered for ?0 assay. Upper portion 144 has greater outer diameter than lower portion 146. Inner tube end 149 slides into the central bore of the drill bit (not shown). Inner tube 140 also has an end 147 distal from the drill bit end 149. Unlike upper portion 44 of inner tube 40, upper portion 144 is - with the exception of the groove 141 proximate end 147 substantially smooth. The four grooves 44a each occupied by an O-ring of the upper portion 44 of inner tube 40 are absent leaving a substantially smooth portion 145. A smooth surface for inner tube 140 provides benefits in terms of improved sealing effect as well as faster and more cost effective production as a grooving process adds time to both manufacture and inspection.
Sealing between inner tube 140, check valve 130 and top cylinder 120 is achieved by the locational clearance fit of the inner tube 140 within the circular top cylinder wall 127 defining chamber 126 supported by the rotary multi-lip seal 200; and the clearance fit within the circular inner wall 133 of the check valve body 132. The check valve lip sealing ring 135 also acts on the smooth outside portion 145 of the inner tube 140 to provide sealing between inner tube 140, check valve 130 and top cylinder 120.
In providing sealing, rotary multi-lip seal 200 and inner sealing ring 135 co-operate, albeit at differing locations, to sealingly contact with the substantially smooth portion 145 of the outside surface 143 of the upper portion 144 of the inner tube 140. Such sealing is, in the case of rotary multi-lip seal 200, enhanced by the plurality of lips 210 gripping with the smooth inner tube surface portion 145. Air leakage past the check valve 130 is thereby substantially reduced or eliminated during hammer shut off.
It is noted that the sealing arrangement described with reference to Figures 8 to 15b, while providing effective sealing, does not tightly secure the inner tube 140, by a strong frictional engagement, within the top cylinder 140. That is the inner tube 140 is likely to have some tendency to rotate during drilling apparatus operation. Over time, the rotary multi-lip seal 200 causes wear on the smooth inner tube 140 which, as a consumable part, can be changed out at regular intervals during life of the hammer.
Modifications and variations to the reverse circulation drilling apparatus described in this specification may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed within the scope of the present invention.
Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers

Claims (5)

1. A reverse circulation drilling apparatus comprising:
(a) a top cylinder;
(b) a check valve, located within the top cylinder, and comprising a check valve body accommodating a check valve sealing means;
(c) an inner tube for collecting cuttings generated by the drill bit during operation of the drilling apparatus, the inner tube being detachably secured within the top cylinder and having an outside surface wherein said check valve sealing means and at least one further sealing means, at least partially located within the top cylinder, each contact with a substantially smooth portion of the outside surface of the inner tube to form a seal.
2. The reverse circulation drilling apparatus of claim 1, wherein said further sealing means comprises a substantially cylindrical sealing ring engaged within a groove formed in the top cylinder, or engaged within a groove formed in a sleeve seated inside the top cylinder, the sealing ring acting on said substantially smooth portion of the outside surface of the inner tube to form a seal.
3. The reverse circulation drilling apparatus of claim 2, wherein said sealing ring exerts radially inwardly acting forces on the substantially smooth portion of the outside surface of the inner tube to form a seal.
4. The reverse circulation drilling apparatus of claim 2 or 3, wherein said sealing ring comprises a plurality of lips to increase sealing engagement.
5. An inner tube suitable for the reverse circulation drilling apparatus as claimed in any one of the preceding claims comprising a generally cylindrical structure having upper and lower cylindrical portions with a central longitudinally extending bore extending through said upper and lower cylindrical portions through which cuttings are recoverable for assay and having a drill bit end slidable into the central bore of a drill bit, wherein said upper portion is - with the optional exception of a groove proximate its end distal from the drill bit - ungrooved and substantially smooth.
AU2020103040A 2020-10-27 2020-10-27 A reverse circulation drilling apparatus with a seal for an inner tube Active AU2020103040A4 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2020103040A AU2020103040A4 (en) 2020-10-27 2020-10-27 A reverse circulation drilling apparatus with a seal for an inner tube

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU2020103040A AU2020103040A4 (en) 2020-10-27 2020-10-27 A reverse circulation drilling apparatus with a seal for an inner tube

Publications (1)

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AU2020103040A4 true AU2020103040A4 (en) 2020-12-24

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Owner name: EPIROC ROCK DRILLS AB

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