US3724568A - Core drill latch - Google Patents

Core drill latch Download PDF

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Publication number
US3724568A
US3724568A US3724568DA US3724568A US 3724568 A US3724568 A US 3724568A US 3724568D A US3724568D A US 3724568DA US 3724568 A US3724568 A US 3724568A
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Prior art keywords
core
position
drill
piston
spindle
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Expired - Lifetime
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H Koepke
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MINDRILL Ltd
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MINDRILL Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B25/00Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors
    • E21B25/02Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe

Abstract

A core barrel inner tube assembly, having a latching mechanism which can latch the assembly into the drill string to prevent upward movement of the assembly relative to the string as it is lowered down a drill hole and which can be released by the application of drilling fluid pressure to allow normal operation during drilling.

Description

United States Patent 1 91 Koepke CORE DRILL LATCH [75] Inventor: Horst Koepke, East Coburg, Australia [73] Assignee: Mindrill Limited, Preston, Victoria,

Australia 221 Filed: Dec. 6, 1968 21 Appl. No.: 781,743

Foreign Application Priority Data Dec. 6, 1967 Australia ..30,828/67 US. Cl ..175/247 Int. Cl ..E2lb 9/20, E21b 25/00 Fieldjof Search .......175/237-239, 244,

1 51 Apr. 3, 1973 Primary ExaminerDavid H. Brown Attorney-Woodhams, Blanchard and Flynn [57] ABSTRACT A core barrel inner tube assembly, having a latching mechanism which can latch the assembly into the drill string to prevent upward movement of the assembly relative to the string as it is lowered down a drill hole and which can be released by the application of drilling fluid pressure to allow normal operation during drilling.

6 Claims, 5 Drawing Figures V) 43 &j%

77 7 Z 2 42 J I i CORE DRILL LATCH BACKGROUND OF THE INVENTION In core drilling, a tubular drill string having an annular drill bit is employed and the core produced by the bit is received by an inner tube located in the outer or drill string tube and this inner tube and its associated mounting is known as a core barrel inner tube assembly.

It is desirable in order to avoid damage to the core that the inner or core receiving tube be mounted in the drill string in such a way that it can remain stationary while the drill string rotates during drilling and that means be provided to signify when the core barrel is full or when it jams in any way during drilling. This can be achieved by suspending the core receiving tube from a spindle by means of a bearing and mounting the spindle and the inner tube within the outer casing for axial movement therein against spring loading on the spindle, the arrangement being such that when the core barrel is filled or if it jams during drilling, the inner tube and spindle assembly rises against the spring pressure and cuts off or restricts supply of drilling fluid to the bit through ports in the spindle thereby to cause a rise in pressure in the drilling fluid circuit which serves as a warning signal to the operator.

A core lifter is disposed at the bottom end of the the bottom when drilling is completed. In one type of core barrel, the core lifter may normally be disposed around the lower end of the inner tube so that it does not interfere with the core passing into the tube during drilling and is only' exposed to the core when the inner tube and spindle are raised. One particular core barrel incorporating all of the features outlined above is fully described in our prior Australian Patent Application No. 11787/66, the core lifter in that case being in the form of a split frusto-conical ring which is closed by engagement with a tapered seat in the outer drill tube when the whole drill string is lifted after a drilling operation.

It has been found that the whole purpose of having a core lifter of the type which is normally shielded by the inner tube is often defeated by the fact that conditions frequently arise which cause the core lifter to be exposed prematurely. One such set of conditions occurs when the barrel is being lowered or dropped down a drill hole and the upward forces caused by water in the hole act in the same manner as the upward forces on a full length core to cause the inner tube to retract and expose the core lifter. The present invention enables prevention of this occurrence by quite simple modifications to the barrel.

SUMMARY According to the invention there is provided a core barrel inner tube assembly having latching means thereon to latch said assembly into a drill string to prevent upward movement of the assembly relative to the drill string, said latching means being releasable by application of fluid pressure.

The inner tube assembly according to this invention may thus be latched into the drill string to prevent upward movement of the assembly relative to the string as it is lowered into a drill hole. When the string is positioned in the hole and drilling fluid is applied, the assembly is unlatched and is free to rise in the string under the influence of upward forces in the normal way.

Preferably, the latching means: comprises a hollow spindle, latching elements mounted on the spindle and movable between a latching position and a nonlatching position, and a piston slidable within the spindle between a first position in which it locks the latching elements in the latching position and a second position in which said latching elements are freed to move to the non-latching position, movement of the piston from the first position to the second position being brought about by the application of the fluid pressure.

In order that the invention may be more fully explained one particular embodiment thereof will now be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS:

In the drawing FIG. 1 is a vertical section through part of a core barrel having a spindle modified in accordance with the present invention and shows a piston within the spindle in a raised position;

FIG. 2 is a cross-section on the line 22 in FIG. 1;

FIG. 3 is a cross-section on the line 3-3 in FIG. 1;

FIG. 4 is a vertical section similar to FIG. 1 but shows the piston within the spindle in a lower position; and

FIG. 5 is a cross-section on the line 55 inFIG. 4.

The drawing shows part only of the upper end of a non-wire-line type core barrel inner tube assembly. As is normal, the spindle 11 is slidable within the outer casing 12 of the core barrel. Spindle 11 comprises upper and lower members 13, 14 which are connected by screw threads at 16 and locked together by an internally threaded locking ring". The outer casing 12 comprises upper and lower tubes 18, 19 screwed to one another at 21. Spindle l 1 is biased against upward movement relative to outer casing 12 by a helical compression spring acting between the upper end of the casing and the upper end of the spindle (not shown). The lower end of spindle 1 1 has an internally threaded spigot 22 on which a hanger bearing 23 is mounted and retained by a retaining pin 24 which screws into the spigot. Hearing 23 supports a core lbarrel inner tube as sembly 26. Inner tube assembly 26 is of conventional construction and only its upper end is shown in the drawing. Its lower end comprises the inner core receiving tube of the barrel.

Spindle 11 has a central bore 27 which receives a piston 28 with a tight sliding fit. Piston 28 has a tubular upper end enclosing a central bore 29 and has a solid bottom end 31. A little above the solid bottom end 31 of piston 28, a cross pin 32 extends diametrically through its tubular part to engage at its ends a pair of longitudinal slots 33 machined in the spindle to permit sliding movement of the cross pin therein when piston 28 is raised and lowered with respect to the spindle.

A hole 34 is drilled diametrically through spindle 11 and receives a pair of steel latch balls 36, the outer end of hole 34 being reduced in diameter, for example, by peening, to prevent the balls passing out fully through these ends. The upper end of piston 28 has a pair of circular recesses 37 formed at diametrically opposite locations at its outer periphery and the lower solid end 31 of the piston has a bore 38 drilled through it to receive a pair of detent balls 39 which are biased outwardly by a helical compression spring 41.

When piston 28 is in its raised position shown in FIG. 1, detent balls 39 are forced outwardly by spring 41 into engagement with a pair of holes 42 in the wall of spindle 11 to provide a detent action which holds the piston in this position. When the piston is held in this raised position, the whole spindle and piston assembly is prevented from moving upwardly with respect to the outer casing by contact of latch balls 36 with an outwardly and downwardly sloping frusto-conical shoulder 43 on outer casing 12. Shoulder 43 is formed by the lower end of the upper tubular member 18 of the outer casing. Thus the spindle and inner core receiving tube cannot rise within the outer casing when piston 28 is held in its upper position.

Before the drill string is lowered into the hole the piston 28 is moved to its upper position and the core barrel inner tube assembly is positioned on the drill string. The drill string is then lowered into the hole and with the piston thus held in its'upper position by the detent balls 39. The core barrel assembly is prevented by the engagement between the latch balls 36 and the shoulder 43 from moving upward under pressure from fluid in the hole. On arrival at the bottom of the hole, water under pressure is pumped down the drill string into the interior of spindle 11 and acts on piston 28 so as to overcome the detent action of balls 39 and move the piston downwardly relative to the spindle to the position shown in FIG. 2. This allows the latch balls 36 to fall back into recesses 34 and so enables the spindle and inner tube assembly to rise in normal fashion when the core receiving tube is full or becomes jammed. The movement of piston 28 relative to spindle 11 also brings a pair of openings 44 in the piston into line with holes 42 in the spindle thus allowing drilling fluid to pass to annular passage 46 between the upper end of the inner tube assembly 26 and the outer casing 12 whence it passes in normal fashion down to the bit. A

V groove 47 is formed in the lower end of piston 28 to through the drill string from a first position in which it locks the latch element means in said latching condition to a second position such that the latching element means is freedto adopt the non-latching condition.

2. A core drill according to claim 1, wherein the drill string includes a drill tube provided on its inner surface with a downwardly facing abutment adapted to be engaged by said latching element means.

3. In a core drill of the type having a core barrel inner tube assembly which must, during drilling, be capable of upward movement within a drill string, comprising the improvement wherein said assembly comprises a hollow spindle, latching elements mounted in the spindle and movable between a latching position and a nonlatching position, and a piston slidable within the spindle between a first position in which it locks the latching elements in the latching position and a second position in which said latching elements are freed to move to the non-latching position, the piston being movable from the first position to the second position by the application of drilling fluid down through the drill string on commencement of a drilling operation.

4. In a core drill according to claim 3, wherein said latching elements are balls carried in openings in the peripheral wall of the spindle and adapted, when in the latching position, to project outwardly therefrom, and the piston is provided with recesses which, when the piston is in the second position, are aligned with said openings to allow the balls to retract into the recesses thereby unlatching the assembly.

5. In a core drill according to claim 4 and further comprising detent means adapted to hold the piston in the first position but to be released on the said application of the fluid pressure. 7 p

6. In a core drill according to claim 5, wherein said detent means comprises spring-loaded balls carried by the piston and adapted to engage in ports provided in the wall of the spindle when the piston is in the first position, and the piston is provided with fluid passages which, when the piston is in the second position, are aligned with said ports to provide a passage for drilling fluid through the assembly.

Claims (6)

1. In a core drill of the type having a core barrel inner tube assembly which must, during drilling, be capable of upward movement within a drill string, the improvement comprising latch element means movable between a latching condition for latching the assembly to the drill string to prevent said upward movement of the assembly and a non-latching condition permitting said upward movement, and a locking member movable by the pressure of drilling fluid applied down through the drill string from a first position in which it locks the latch element means in said latching condition to a second position such that the latching element means is freed to adopt the non-latching condition.
2. A core drill according to claim 1, wherein the drill string includes a drill tube provided on its inner surface with a downwardly facing abutment adapted to be engaged by said latching element means.
3. In a core drill of the type having a core barrel inner tube assembly which must, during drilling, be capable of upward movement within a drill string, comprising the improvement wherein said assembly comprises a hollow spindle, latching elements mounted in the spindle and movable between a latching position and a non-latching position, and a piston slidable within the spindle between a first position in which it locks the latching elements in the latching position and a second position in which said latching elements are freed to move to the non-latching position, the piston being movable from the first position to the second position by the application of drilling fluid down through the drill string on commencement of a drilling operation.
4. In a core drill according to claim 3, wherein said latching elements are balls carried in oPenings in the peripheral wall of the spindle and adapted, when in the latching position, to project outwardly therefrom, and the piston is provided with recesses which, when the piston is in the second position, are aligned with said openings to allow the balls to retract into the recesses thereby unlatching the assembly.
5. In a core drill according to claim 4 and further comprising detent means adapted to hold the piston in the first position but to be released on the said application of the fluid pressure.
6. In a core drill according to claim 5, wherein said detent means comprises spring-loaded balls carried by the piston and adapted to engage in ports provided in the wall of the spindle when the piston is in the first position, and the piston is provided with fluid passages which, when the piston is in the second position, are aligned with said ports to provide a passage for drilling fluid through the assembly.
US3724568A 1967-12-06 1968-12-06 Core drill latch Expired - Lifetime US3724568A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4494615A (en) * 1981-10-23 1985-01-22 Mustang Tripsaver, Inc. Jarring tool
EP0198406A1 (en) * 1985-04-11 1986-10-22 Eastman Christensen Company An improved hydraulic inner barrel in a drill string coring tool
EP0293355A1 (en) * 1987-05-13 1988-11-30 DIAMANT BOART Société Anonyme Device to control the bolting of a core drilling machine
US20040216927A1 (en) * 2001-05-23 2004-11-04 Andrew Beach Inner core barrel head assembly for core tube within a drill string
US9151129B2 (en) 2011-08-01 2015-10-06 Groupe Fordia Inc. Core barrel assembly including a valve

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4553613A (en) * 1983-09-09 1985-11-19 Norton Christensen, Inc. Hydraulic lift inner barrel in a drill string coring tool

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2220554A (en) * 1936-02-08 1940-11-05 Shell Dev Device for recovering cores from boreholes
US2330155A (en) * 1942-05-11 1943-09-21 Reed Roller Bit Co Coring apparatus
US2682388A (en) * 1953-02-13 1954-06-29 Winter Weiss Co Drill for forming solidified core piles
US2978032A (en) * 1957-07-26 1961-04-04 Robert P Hanna Whip stock locking and releasing apparatus
US3126064A (en) * 1964-03-24 miller
US3225845A (en) * 1961-02-17 1965-12-28 Joy Mfg Co Core barrel assembly

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126064A (en) * 1964-03-24 miller
US2220554A (en) * 1936-02-08 1940-11-05 Shell Dev Device for recovering cores from boreholes
US2330155A (en) * 1942-05-11 1943-09-21 Reed Roller Bit Co Coring apparatus
US2682388A (en) * 1953-02-13 1954-06-29 Winter Weiss Co Drill for forming solidified core piles
US2978032A (en) * 1957-07-26 1961-04-04 Robert P Hanna Whip stock locking and releasing apparatus
US3225845A (en) * 1961-02-17 1965-12-28 Joy Mfg Co Core barrel assembly

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4494615A (en) * 1981-10-23 1985-01-22 Mustang Tripsaver, Inc. Jarring tool
EP0198406A1 (en) * 1985-04-11 1986-10-22 Eastman Christensen Company An improved hydraulic inner barrel in a drill string coring tool
EP0293355A1 (en) * 1987-05-13 1988-11-30 DIAMANT BOART Société Anonyme Device to control the bolting of a core drilling machine
BE1000529A4 (en) * 1987-05-13 1989-01-17 Diamant Boart Sa Device control lock core survey.
US20040216927A1 (en) * 2001-05-23 2004-11-04 Andrew Beach Inner core barrel head assembly for core tube within a drill string
US7314101B2 (en) * 2001-05-23 2008-01-01 2Ic Australis Pty Ltd Inner core barrel head assembly for core tube within a drill string
US9151129B2 (en) 2011-08-01 2015-10-06 Groupe Fordia Inc. Core barrel assembly including a valve

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GB1191548A (en) 1970-05-13 application

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