Wire line core barrel

Aug. 1, 1967 j. karich etal . 3,333,647

WIRE LINE CORE BARREL

Filed Nov. 27, 1964 6 Sheets-Sheet 1

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Aug. 1, 1967 j. karich etal 3,333,647

WIRE LINE CORE BARREL Filed Nov. 27, 1964 6 Sheets-rSheet 2

<img file="US3333647A_D0002.tif" />

J. KAR1CH ETAL

WIRE LINE CORE BARREL

Aug. 1, 1967

Filed Nov. 27, 1964

3,333,647

Sheets-Sheet 3

<img file="US3333647A_D0003.tif" />

Aug. 1, 1967

3,333,647

J. KARICH ETAL

WIRE LINE CORE BARREL

Filed Nov. 27, 1964

Sheets-Sheet 4

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<img file="US3333647A_D0005.tif" />

<img file="US3333647A_D0006.tif" />

INVENTORS

JOPA! PWS/CS/ AiBfXT F. P/c&amp;XO

<img file="US3333647A_D0007.tif" />

Aug. 1, 1967

J. KARICH ETAL

3,333,647

WIRE LINE CORE BARREL

Filed Nov. 27, 1954

Sheets-Sheet 5 /59 /58 /24 /Z7

757.

/4S /50 /281 /35 /36 /49 /40

<img file="US3333647A_D0008.tif" />

/56 '/44a.

/4Z /25 /44 /39 /42 /26 /48 /28 /38 /28 c /56 /33 /43 /444 &lt;/44d /3/ /3/ /32 /54 /56

INVENTORS yo//A/ /&amp;9J2/CA/ 4/.BCK7 K /^CACWtZ» /44 e /44^ /43 /44 /44i /29 /28a.

/56/ /39a. K /50 /6/ s/3$>

rfrroxt/fys

Aug. 1, 1967

Filed Nov. 27, 1964

J. KARICH ETAL

WIRE LINE CORE BARREL

3,333,647

Sheets-Sheet 6 /82b /82a /80b /78 /75 /7/

87/72 /73 /80

<img file="US3333647A_D0009.tif" />

/92 /93 '/93a /946 /9/ /95

794 /8Oa /74

84a /93c /94a

27c /70

84a /O /94c

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INVENTORS

JOHN KflR/Cf/

AiBiKT 7: P/CNAKD

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Arra/tN£ifs

United States Patent Office „ ., 3,333,647

Patented Aug. 1, 1967

3,333,647 WIRE LINE CORE BARREL

John Karich and Albert F. Pickard, Minneapolis, Minn., assignors to E. J. Longyear Company, Minneapolis, Minn., a corporation of Delaware 5

Filed Nov. 27, 1964, Ser. No. 414,218

Claims. (CI. 175—247)

This invention relates to the art of deep core drilling in earth formations and to improvements in wire line core barrel apparatus for recovering cores. More particulaly, ¹⁰this invention relates to new and novel apparatus for positively locking the latch elements of the core barrel inner tube assembly in a drill stem latch seat until the latch release member has been retracted through the use of an _lgovershot assembly; and additionally to new and novel valving means utilizable with the aforementioned apparatus so that core barrel inner tube assembly may be fluidly propelled to the bit end of the drill stem regardless of the drilling direction and thereafter provides an open fluid _QQbypass channel. Further this invention relates to new and novel valving means for an overshot assembly.

This invention has been made in order to provide water line core barrel equipment for overcoming problems of the nature set forth hereinafter which are encountered 25 in using core barrel equipment of the prior art. One of the problems encountered in using water line core barrel equipment of the prior art is that after substantial use, the axially and radially outward corners of the latch elements become worn as does the corners of the ledge 35 flange of latch seat of the drill stem against which the latch elements abut to normally preclude the core barrel inner tube assembly moving axially outwardly. As a result of this wearing, the latch elements will not always retain the core barrel inner tube assembly adjacent the 35 drill bit core during the time a core sample is being drilled.

Additionally with hydraulically propellable wire line core barrels of the prior art having fluid bypass channels that have at least a portion of the axial length thereof located within the confines of one of the elements of the 40 assembly, and a valve member movable between positions adjacent said location to open said channel when the assembly is in a core taking position and closing the channel to permit fluidly propelling the assembly to the bit end of the drill stem; at times due to drilling into pockets 45 having fluid, for example, water under high pressure, the back pressure will operate the latch release element to release the latches from the latch seat. That is with the prior art hydraulically propellable core barrel assemblies, the open fluid bypass channel adjacent the latch release 50 element has a restricted portion which is not of sufficient cross sectional area to permit the back flow of fluid without, at times, moving the latch release element to a latch releasing position. To increase the cross sectional area of a fluid bypass channel in such prior art core barrel as- 55 semblies would result in structurally weakening the assembly. In the present invention this problem is overcome by providing annular fluid bypass channel radially between the drill stem and the core barrel inner tube assembly, and a core barrel assembly valving member mov- 60 able between a position substantially forming a fluid seal with the drill stem and a position providing a clearance space of a transverse cross sectional area of about the same size as the cross sectional area between, for example, the major portion of the core barrel inner tube and ₆₅the drill stem to permit back flow of fluid without operating the latch release element, even when the assembly is in a latched operating position. Further the structure for providing the aforementioned valving action is much cheaper to manufacture than that of the prior art.

One of the objects of this invention is to provide new and novel apparatus for releasably, lockingly retaining the latch elements of a wire line core barrel inner tube assembly in a latched seated position. Another object of this invention is to provide new and novel means to constantly resiliently urge the latch elements and latch release element to a latch seated position.

A further object of the invention is to provide in a wire line core barrel assembly, new and novel mechanism for hydraulically propelling the assembly to the bit end of the drill stem; and upon the assembly latchingly engaging the drill stem, permitting fluid to readily bypass the assembly. Another object of the invention is to provide new and novel valving mechanism in a wire line core barrel assembly to permit fluidly propelling the assembly to the bit end of the drill stem regardless of the drilling direction, and which permits fluid to readily bypass the assembly when the assembly is being retracted through the drill stem. A still further object of this invention is to provide flexible annular members on a core barrel inner tube assembly and also on an overshot assembly to provide for hydraulically propelling the respective assembly to the bit end of the drill stem and to permit fluid bypassing the assemblies when they are being retracted.

Other and further objects are those inherent in the invention herein illustrated, described and claimed and will become apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the invention may be employed.

For purposes of facilitating the description of the invention, the term “inner” refers to that portion of the drill stem, or of the assembly, or an element of the assembly being described which in its position “for use” in the drill stem is located closer to drill bit on the drill stem than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumference, direction or diameter of the drill stem or other apparatus being described. The term “outer” refers to that portion of the drill stem, or of the assembly, or element being described which in its position “for use” in the drill stem is located closer to the mouth of the drill hole than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumference, direction or diameter of the apparatus being described.

The invention is illustrated in the drawings in which corresponding numerals refer to the same parts and in which:

FIGURES 1-3 one arranged above the other with the axial center lines aligned and lines A—A of FIGURES 1 and 2 aligned, and lines B—B of FIGURES 2 and 3 aligned, form a composite longitudinal section through the first embodiment of core barrel inner tube assembly of this invention and the drill stem when the assembly is in a latched core taking position;

FIGURE 4 is a fragmentary cross sectional view of an outer end of the first embodiment of core barrel inner tube assembly as it is being retracted through the drill stem, said view generally showing the same structure of the core barrel inner tube assembly as FIGURE 1, but in a retracted condition;

3,333,647 assembly being generally designated 10. Even though in FIGURES 1-3 the assembly 10 is illustrated generally in a horizontal condition, it is to be understood that it is utilized when the drilling direction is vertically downwardly or inclined downwardly sufficiently that the assembly will free fall to the bit end of the drill stem generally designated 11 in a manner described in U.S. Patent 2,829,868 to Pickard et al. The drill stem 11 is made up of sections of pipe coupled together and having an annular drill bit 12 mounted on the inner end thereof.

The portion of the drill stem attached to or extending below pipe section Ila is commonly referred to as the core barrel outer assembly and is provided for receiving and retaining the core barrel inner tube assembly, generally designated 10. The core barrel outer tube assembly is composed of a core barrel outer tube 18, a reaming shell 19 threadedly connected to the inner end of the tube 18, said shell having a hardened material such as diamonds (not shown) on the transverse outer reaming surface and on the annular drill bit 12 for drilling into earth formations from which the core sample is taken. The bit 12 is threadedly connected to the inner end of the reaming shell.

The outer end of the core barrel outer tube assembly includes a locking coupling 20 which connects said assembly to the adjacent pipe section Ila of the drill stem. At the opposite end of the coupling 20 from the aforementioned pipe section, a guide coupling 21 is threadedly connected. The inner end of the locking coupling in conjunction with the annular recess 21α of the guide coupling formed a seat in the guide coupling against which the detents or latch dogs 16 of the core barrel inner tube assembly are seated for removably retaining the assembly 10 adjacent the core bit. Also the inner end portion 20α which extends as a partial cylindrical surface in the recess 21α. The side face of this flange bears against a surface of the latch dog and causes said latch dog and other portions of the core barrel inner tube assembly to ⁴⁰ rotate with the drill stem when the latch dogs are in a latch seated position such as illustrated in FIGURE 1.

The opposite end of the guide coupling is threadedly connected to the outer end of the core barrel outer tube 18, the core barrel outer tube having an annular recess 18α to receivably mount a landing ring 23 in abutting engagement with the guide coupling (see FIGURE 2). As may be noted, the inner diameter of the landing ring is sufficiently smaller than the inner diameter of the remaining portion of the drill stem described heretofore to form a suspension shoulder in the core barrel outer tube. Since the core barrel outer tube is generally of a construction illustrated and explained in greater detail in U.S. Patent 3,120,282, issued Feb. 4, 1964, other than for the provision of the landing ring instead of a suspension flange and a substantially longer locking coupling, it will not be described in greater detail.

The core barrel inner tube assembly 10 includes a latch body 26 having a pair of latches 16 and a latch insert block 17 mounted thereon, a latch release tube 27 for retracting said latches, a core sample receiving tube 28, an inner tube cap 29 threaded into the outer end of the core barrel receiving tube, and a spindle 36 for connecting the cap to the inner end portion of the latch body for limited relative slidable movement. The core receiving tube has a replaceable core lifter case 31 threaded on the opposite end thereof and a core lifter 32 mounted in the core lifter case. The structure and function of the core lifter case and core lifter are generally of the nature set forth in U.S. Patent 2,829,868 and therefore will not be further described.

The cap 29 has a fluid passageway 34 that at one end opens to the interior outer end of the core receiving tube and at the opposite end to the annular clearance space between the core barrel inner tube assembly and the core

FIGURE 5 is a fragmentary view of an upper end portion of the first embodiment of the core barrel inner tube assembly being dropped through the drill stem to the bit end thereof, said view generally illustrating the same structure of the assembly as shown in FIGURE 1 but with the parts in a different relative position;

FIGURE 6 is a cross sectional view generally taken along the line and in the direction of arrows 6—6 of FIGURE 1 to show the relative positions of the latches releasably locked in the latch seats;

FIGURE 7 is a cross sectional view of the upper end portion of the second embodiment of the core barrel inner tube assembly of this invention as it is being fluidly propelled through the drill stem toward the.bit end thereof, the construction of the second embodiment of core barrel inner tube assembly axially inwardly of line E—E of FIGURE 7 being the same as the construction of the first embodiment axially inwardly of line B—B of FIGURE 2;

FIGURE 8 is a fragmentary view of the portion of the core barrel inner tube assembly of the second embodiment outwardly of line D—D of FIGURE 7 other than it illustrates the spear point valving mechanism of the core barrel inner tube assembly in the latched seated core receiving position; the solid line position of the flexible washer showing normal fluid bypass, and the dotted line position showing the flowing, thereof when fluid pressure is exerted in the opposite direction;

FIGURE 9 is a view similar to FIGURE 8 other than it illustrates the initial retraction of the valving mechanism, but prior to the time the latch release tube has moved sufficiently to retract the latches out of latching engagement with latch seat;

FIGURE 10 is a view similar to FIGURE 9 other than ----------------- . - it illustrates the relative positions of the elements at 35 of the locking coupling has an inwardly projecting nange outer axial end portion of the core barrel inner tube assembly at the time the latch release tube has been moved to a fully retracted position and the latch body move axially outwardly relative to said tube through the action of the coil spring;

FIGURE 11 is a cross sectional view generally taken along the line and in the direction of arrows 11—11 of FIGURE 7 to illustrate the flexible washer in a core barrel inner tube assembly fluid propelled position;

FIGURE 12 is a longitudinal cross sectional view, of the overshot assembly of this invention as it is being fluidly propelled toward the bit end of the drill stem;

FIGURE 13 is a fragmentary view of the structure of FIGURE 12 other than it illustrates the relative positions of the elements of the overshot assembly as said ₀₀overshot assembly is being retracted in the drill stem;

FIGURE 14 is a cross sectional view generally taken along the line and in the direction of the arrows 14—14 of FIGURE 12 to illustrate the flexible washer forming a fluid seal with the drill stem;

FIGURE 15 is a view similar to the upper end portion of FIGURE 7 other than it illustrates another embodiment of the valving structure and the mounting thereof;

FIGURE 16 is a cross sectional view illustrating the outer end portion of the first embodiment of the core barrel inner tube assembly in a “jammed” condition in a downwardly extending drill stem, the inner end portion of an overshot assembly used for lowering the core barrel inner tube assembly, and the inner end portion of a tube for releasing the pulling dogs from a spear point plug coupling condition; and

FIGURE 17 generally illustrates the same structure as FIGURE 16 other than showing the relative positions after the core barrel inner tube assembly has latched γθ in a core taking position such as illustrated more fully in FIGURES 1-3.

Referring now in particular to FIGURES 1-3, the first embodiment of the invention of the wire line core barrel inner tube assembly will now be described, said 75 barrel outer tube 18 that forms a part of the fluid channel

3,333,647 to permit fluid to bypass core barrel inner tube assembly when it is in core taking position such as illustrated in FIGURES 1-3. The cap 29 also includes an axially elongated bore 40 for receiving the inner end portion of the spindle 36. A grease fitting 41 is threaded into the opposite reduced end portion of the bore 40. A bearing 42 is mounted on the spindle in abutting engagement with the inner end of the bearing housing 38 which is also slidably mounted on said spindle and threadedly connected to cap 29; there being provided a coil spring 43 that at one end abuts against said bearing and at the opposite end against a nut 44 threaded on the inner end of the spindle. The spring 43 resilient urges the spindle towards the core receiving tube while retaining bearing 42 in abutting engagement with the bearing housing 38.

The bearing housing includes an outwardly extending annular flange for receivably mounting the thrust bearing assembly 46 in abutting relationship with the metal spacer washer 47. A pair of resilient shut off valve washers 48 are mounted on the spindle with a second metal space washer 49 intermediate washers 48. The shut off washer opposite the bearing 46 is mounted in abutting relationship with enlarged diametric annular member 39 which in turn abuts against a shoulder formed on the spindle. The outer end of the spindle is threaded into the threaded inner portion of the axially extending bore 50 of the latch body. A lock nut 51 is threaded onto the aforementioned end portion of the spindle to abut against the lower end of the latch body.

Referring to FIGURE 2 it is to be noted that the latch body has a diametric portion 60 of an outside diameter to fit within a centralizer ring 23 and a maximum diameter portion 26α to form with portion 60 a shoulder 61 seatable against said centralizer ring for supporting the core barrel inner tube assembly out of contact with the drill bit. Latch body portion 60 has an annular groove 58 for mounting an O-ring 59 that forms a fluid seal with the centralizer ring such as illustrated in FIGURE 2. To be mentioned is that all portions of the core barrel inner tube assembly axially inwardly of shoulder 61 are of diameters smaller than the minimum inside diameter of ring 61 in order that said portions may pass through the centralizer ring.

A plurality of circumferentially spaced, transversely extending outlet ports 56 are provided in the latch body to open to the bore 50 and to the annular space between the core barrel inner tube assembly and the core barrel outer tube axially inwardly of the centralizer ring 23 when said assembly is in a latched core taking position. A second plurality of ports 55 are formed in the latch body to at ₅₀their one ends open into the bore 50 and at the opposite ends of the annular fluid channel between the drill stem and the core barrel inner tube assembly, but on the opposite axial side of the centralizer ring from ports 56. The ports 55, ports 56, and the portion of the bore 50 intermediate said ports provide a channel to permit fluid bypassing the centralizer ring when the shoulder 61 is seated on said ring, the diameter of ports 56 being less than the axial height of the cylindrical portion of the centralizer ring.

A generally rectangular slot 67 is formed in the outer ₆₀reduced diameter portion of the latch body axially outwardly of ports 55 and has a through pin 68 extended therethrough and into appropriate apertures in the latch body for pivotally mounting the latch dogs 16 in side by side relationship. The diameter of the apertures in the latch dogs through which pin 68 is extended is slightly larger than the diameter of said pin in order to permit the bottom curved portions of said latch dogs moving into and out of engagement with the curved surface of the insert block 17 which is also mounted in a slot 67. A pin 66 is ₇₀extended through the insert block and into appropriate ‘ apertures in the latch body for retaining said block in said slot. The construction of the latches 16 is substantially the same as that described in U.S. Patent 3,103,981, granted Sept. 17, 1963 other than for the provision of apertures 75 β

for mounting rivets to attach springs and the differences noted hereinafter.

Mounted on the outer reduced diameter portion of the latch body for slidable movement between a position abutting against the shoulder 65 and a position axially spaced therefrom is the latch release tube 27. Tube 27 has a slot 70 radially opposite each of the latch dogs so that an outer corner portion of each latch dog may be extended therethrough to latchingly engage the latch seat 21α. A ) torsion spring 71 within slot 67 has one end of one leg bent to be retained in an aperture formed in the outer central portion of one latch dog, and the outer end of the second leg being bent to be retained in a corresponding position of the other latch dog, whereby it resiliently urges i the latch dogs to pivot about through pin 68 to extend through the respective slot 70 and to a position to latchingly engage the latch seat such as illustrated in FIGURE 1.

A right angle cut out 16α is provided in an outer corner I of one of the latch dogs and an oppositely faced cut out 16b of the substantially same size is formed in the other latch dog, the cut outs being located to form a generally rectangular, open ended slot when the latch dogs are spread apart to a latching position such as illustrated in FIGi URE 1. An axially elongated slot 74 is formed in the latch body on either side of the slot 67 to extend transverse thereto, the slots 74 having a cross sectional dimension substantially equal to the spacing between axially extending edges of the cut outs 16α, 16Z>. A through pin 75 is ¹ extended through the slots 74, and has its opposite ends mounting retained within opposed apertures in the latch release tube so as to be moved therewith. The diameter of the pin 75 is slightly smaller than that necessary to retain edges 16c of the latch dogs in abutting engagement with the peripheral wall of the guide coupling which forms the latch recess when the pin bears against opposite axial edges of the slots 16α, 16Z> as illustrated in FIGURE 1. The slots 74 extends axially inwardly sufficiently such that when the pin 74 abuts against the inner curved edges thereof, the pin is located slightly axially outwardly of the transverse edges of slots 16α, 16b and the inner annular edge of the latch release tube abuts against the shoulder 65. The axial length S of the slots 74 is sufficient so that when the pin 75 is moved outwardly to abut against the oppositely curved edges thereof, the latch release tube has fully retracted the latch dogs (see FIGURE 4). Thus the length of the slots 74 limit the amount of axial movement of the latch release tube relative to the latch body.

The outer end portion 26c of the latch body has a threaded aperture that opens to the rectangular slot 67 for threadedly mounting an elongated bolt 77 to extend axially outwardly of the latch body and centrally within the confines of the latch release tube. A transversely extending bar 78 is welded to the latch release tube in position to bear against the axially outermost surface of the latch body when the lower edge of the latch release tube seats against shoulder 65, the latch release tube having apertures of diameters to open on either side of said bar. The bar 78 has an aperture through which the bolt 77 is extended, there being provided a tubular guide 79 on the bolt which is also slidably extended through the aperture of the bar 78. The guide 79 has a flange at its outer axial end that bears against the head of the bolt 77, there being provided a coil spring 80 that at one end bears against said flange and at the opposite end bears against the bar 78 to resiliently urge the latch release tube to a position that its inner annular edge abuts against the shoulder 65. Accordingly through the provision of the bolt 77 which is attached to the latch body for movement therewith, the bar 78 which is attached to the latch release tube for movement therewith and the coil spring 79, the latch release tube is resiliently retained in a position relative to the latch body as shown in FIGURE 1 wherein through pin 75 is lo3,333,647 cated wthin the cutouts 16α, 16b of the latch dogs for locking said latch dogs in a latch seated condition.

A plug, generally designated 84, having an axially elongated transverse slot 86 is slidably mounted in the outer end of the latch release tube by a pin 87 secured in said tube and extended through said slot. The plug has a spear point 88 extending outwardly beyond the latch . release tube and a main body portion 85 to form a somewhat close sliding fit within the inner peripheral wall of the latch release tube, said main body portion having the aforementioned slot 86 formed therein and being integrally connected to the spear point.

The relative location of the pin 87, the slot 86 in the plug, and the axial dimension of the slot 86 are such that when the latch release tube abuts against the latch body shoulder 65, the pin 87 is a little outwardly of the inner transverse edge of the slot, and the inner surface 84α of the plug abuts against the head of the bolt 77. In this connection note that an injustment is provided in one direction due to the threading of the bolt 77 into the latch body.

The structure of the first embodiment of the wire line core barrel assembly of this invention having been set forth, the structure of the second embodiment of the wire line core barrel inner tube assembly, generally designated ICO, will now be set forth (see FIGURES 7-11). The assembly 100 is of the same construction as assembly 10 other than for the provision of the modified spear point plug and the structure mounted thereon. That is embodiment 100 includes a latch body 26, latch dogs 16 pivotally mounted thereon and a latch release tube 27 together with a plug generally designated 104 having a rectangular slot 105 through which the through pin 87 is extended to mount the plug for limited slidable movement relative the latch release tube. The slot 105 is located in the main body portion 106 of the plug, the outer end of the main body portion being integrally formed with a non-threaded intermediate diameter portion 107. Portion 107 in turn is integrally joined to threaded portion 108 and is of substantially the same diameter, portion 108 in turn being integrally connected to the minimum diameter portion 109. At the outer end of portion 109 there is integrally joined a spear point 110.

As may be noted, at the juncture of portions 106 and 107 there is formed a shoulder 111, the shoulder 111, the shoulder 11 being at the same elevation as the outer annular edge 27α of the latch release tube when the outer transverse edge of the plug slot abuts against pin 87. As a result the leather washer 112, which is approximately ₅₀the same axial thickness as the plug portion 107, extends generally radially in abutting relationship with the latch release tube to form a fluid seal between the plug and the inner peripheral wall of the drill stem. In this connection, it is to be mentioned that the outer diameter of the latch release tube and the outer diameter of the latch body is sufficiently smaller than the inner diameter of the drill stem to provide a fluid bypass channel between the core barrel inner tube assembly and the drill stem axially between the leather washer and the inlet ports ₆₀55 of the latch body.

In order to retain the inner annular portion of the leather washer in abutting engagement with the shoulder 111, a retainer nut 116 is threaded onto portion 108. A lock nut 117 is also threaded on portion 108 in abutting engagement with the retainer nut 116. The retainer nut has a beveled surface 116α (see FIGURE 8) that provides a radially extending annular surface 1166 having approximately the same outside diameter as the outside diameter of plug portion 106 for clampingly retaining the inner annular portion in a fixed position relative the plug. As a result of the provision of the beveled surface, there is provided a recess into which the outer annular portion of the leather washer may bend to the dotted line position of FIGURE 8 in order to permit a back flow of 75 being secured in apertures in the outer end of the tube 139.

fluid under pressure without causing the unlatching of the latch dogs in the event the drill bit cuts into a pocket of high pressure fluid. In this connection it is to be mentioned that other than the leather washer and the enlarged diametric portion of the latch body (same as 26α for the first embodiment), the maximum diameter of any portion of the core barrel inner tube assembly 10® inwardly of said enlarged diametric portion is not greater than the maximum diameter of any portion of assembly 100 outwardly of said enlarged diametric portion. Additionally, other than for the leather washer, the area of the portion of the fluid bypass channel 50, 55, 56 is substantially the same as the minimum area of the bypass channel at any axial location of assembly 100 axially outwardly of ports 55 and axially inwardly of ports 56 (see portion of the first embodiment) inwardly of lines A—A of FIGURES 2 and 3.

For retracting wire line core barrel inner tube assemblies, including the first and second embodiments described herein, the overshot assembly, generally designated 125, has been provided (see FIGURES 12-14). The overshot assembly 125 is generally cylindrical in shape and is made up of a main body 126 and a valving portion 127. The main body includes a generally cylindrical overshot body 128 that has an elongated slot 129 milled in the inner central portion thereof to form two spaced overshot body segments 128α. The transverse cross sectional area of each of the segments is similar in shape but the segments are located 180° relative to one another. The longitudinal length of the slot extends outwardly to the line 12§Z>. A pair of pulling dogs 131 are disposed in face to face relationship in the slot 129; and are pivotally mounted on the pin 133 which, extends through the overlapping hub portions of the pulling dogs, and is secured in the overshot body segments. A coil spring 134, which is seated on the pins 135 (there being one pin welded on the outer ends of each pulling dog), normally urges the outer ends of the pulling dogs apart, and thus urges the jaws together in a grasping posi40 tion while permitting expansion of the dog jaws to slide over the spear point of a core barrel inner tube assembly when the overshot body has been moved adjacent the bit end of the drill stem.

A frusto conical shoulder 136 formed on the inner . end of the overshot body aids in centering the overshot ^J assembly over the spear point, the inner surfaces of said shoulder being similarly shaped and slightly larger than the generally frusto conical portion inwardly of the spear point of the inner tube assembly to be retracted. When the spear point is retained between the jaws 135, the shoulder imparts stability to the entire core barrel inner tube assembly as the inner tube and overshot assemblies are retracted through the drill stem.

The overshot body is of a reduced diameter at 128c from a location a short distance inwardly of the outer ends of the latch dogs to the outer end thereof. An 'axial bore 138 is formed in the reduced diameter portion 128c from a location axially spaced from the line 128b to the outer end thereof.

An elongated tube is mounted on the reduced diameter portion 128c to have the inner annular edge generally coextensive with the line 128b and secured to the overshot body by shear pins 140. A bar 142 having a central aperture therethrough is welded into tube 139 similar to the welding of bar 78 to the latch release tube, the bar being located axially outwardly of the outer end of the overshot body.

The valving portion 127 includes a fitting 144 having an axially central, enlarged diametric portion 144α of a diameter to form a relatively close fit with the outer end . ¹ ’ of the tube 139. In order to mount the valving portion for a limited slidable movement relative to the tube 139, the diametric portion 144α is provided with the slot 145 through which a transverse pin 143 is extended, pin 143

3,333,647

Joined to the inner end of diametric portion 144a is a rod 144b that is threaded at the inner end, there being a washer 148 on said rod and a nut 149 threaded thereon to limit the inward movement of the washer. A coil spring 150 is provided on the rod such that the outer end abuts against the bar 142 and the inner end abuts against the washer 148 to resiliently urge the fitting to move to position that the pin 143 abuts against the outer transverse edge of the slot 145. A non-threaded intermediate diameter portion 144d is integrally joined to the enlarged diametric portion 144α to form an annular shoulder 154, the opposite end of portion 144d in turn being integrally joined to the threaded outer end portion 144e of the fitting. A retainer nut 157 (same construction as nut 116) is threaded on portion 144e to retain the flexible leather washer 156 is abutting relationship with the shoulder 154 in a manner that the leather washer of the second embodiment of the core barrel inner tube assembly is retained against the shoulder 111. Thus when the pin 143 abuts against the outer edge of the fitting slot 145, the washer 156 extends generally radially in abutting relationship with the outer annular end 139α of the tube 139 to at least substantially form a fluid seal with the drill stem.

A coupling element 158 is threaded onto the fitting portion 144e to have the inner end thereof abut against the retainer nut 157, the coupling element being generally tubular shaped and closed at its outer end by a cap portion 158α. The cap portion has an aperture formed therein for a wire line cable 159 to be passed therethrough and knotted or otherwise fastened.

A plurality of axially elongated, radially extending circumferentially spaced lands 1586 are joined to the outer surface of the coupling element to permit fluid bypassing the coupling element while at the same time form guides for the overshot assembly as it is moved through the drill stem. To be mentioned is that all portions of the overshot assembly other than for the washer 155 and the land 1586 are of maximum diameters relative to the inner diameter of the drill stem to provide an annular channel to permit fluid to bypass the overshot assembly in the drill stem.

When the valving portion is retracted relative the main body as illustrated in FIGURE 13, fluid flowing in an inward direction or the outward movement of the overshot assembly through the drill stem will cause the leather washer 156 to flex and thereby provide an open fluid channel from one axial end of the overshot assembly to the other, as will be more fully set forth hereinafter.

The structure of both embodiments of the wire line core barrel inner tube assembly and the overshot assembly having been described, the operation thereof will now be set forth. First the operation of the first embodiment of the core barrel inner tube assembly will be described.

For purposes of facilitating the description and operation of the inner tube assembly 10, it will be assumed that the drill stem is extended into a hole in a earth formation in a generally vertical downward direction and that the core barrel inner tube assembly is about to be inserted into the drill stem for continuing the taking of core samples. The core barrel inner tube is inserted into the outer end of the drill stem, the latch release tube beirig moved axially outwardly relative to latch body against the resilient action of spring 80 to a position such as illustrated in FIGURE 4 to first move the lock pin 75 out of the latch cut outs 16α, 16b and thence retract the latches. After the core barrel inner tube assembly has been moved into the drill stem sufficiently that the latch dogs are located in the confines thereof and no outward force applied to plug 84, the spring acting through bar 78 and bolt 77 causes the latch release tube to move inwardly relative the latch body to the position illustrated in FIGURE 5. In moving to this position, the beveled edges of the slot in the latch release tube permit the latch dogs to be moved apart about the axis of pivot pin 68 under the action of the torsion spring 71, the inner pe10 ripheral wall of the drill stem limiting the aforementioned pivotal movement of the latch dogs. However at this time the inward movement of the latch release tube toward the shoulder 65 is limited by the pin 75 abutting against the outer transverse edges 16e' of the latch dogs, the adjacent axial edges of the latch dogs not having moved sufficiently far apart to permit the lock pin 75 to move into the slot formed by cutouts 16α, 166.

When the core barrel inner tube assembly has moved in the drill stem to a position that the suspension flange 61 of the latch body seats against the shoulder provided by the centralizer ring, the outer corners of the latch dogs are opposite the latch seat in the drill stem. At this time, or upon slight rotation of the drill stem, the latch dogs pivot into the latch seat due to the resilient action of the spring 71. This pivotal movement of the latch dogs spreads the axial extending edges of cut outs 16α, 16b sufficiently that the pin 75 can move there between. Either through the action of gravity and/or in conjunction with the resilient action of spring 80, the latch release tube is then forced to move relative to the latch body to position pin 75 in the cut outs 16α, 166 as illustrated in FIGURE 1. The movement of the locking pin into the cut outs thereupon prevents the latch dogs being retracted from the latch seat until the time that the latch release tube has been moved sufficiently axially outwardly relative the latch body that the pin 75 is clear of the cut outs 16α, 166. Accordingly, even if the outer transverse corners along edge 16c of the latch dogs and/or the inner corner of the radially extending ledge of the latch seat against which edges 16c normally abut are worn slightly, the thus tapering of the surfaces due to wearing will not provide inclined surfaces whereby an outward pressure on the core barrel inner tube can force the latch dogs to a latch release position. As added insurance, the coil spring 80 resiliently urges the latch release tube to remain in a position relative the latch body such as shown in FIGURE 1.

Assuming now that the core barrel is filled with core and the shut ofi valve washers 48 have been compressed to provide a high pressure signal at the outer end of the drill stem, the drill stem is pulled axially outwardly. In the event the core is not broken, the core barrel inner tube will remain in position until the annular shoulder of the drill bit abuts against the core lifter case 31. This movement of the drill stem relative the core barrel inner tube and case 31 is permitted through the provision of the coil spring 43 and the bearing housing being mounted for limited slidable movement relative the spindle 36. Thus the force necessary to break the core is transmitted from the drill stem directly to the core lifter case.

To withdraw the core barrel inner tube assembly 10_; a conventional overshot assembly or the one illustrated’in FIGURES 12-14 is used. Assuming the overshot assembly is of a type to be lowered by a wire line cable and moves to the bit end of the drill stem through gravity, after the overshot jaws of the overshot assembly have clampingly coupled onto the spear point 88, the overshot assembly is retracted through the wire line. The initial retraction of the plug 84 will move it outwardly relative to the latch release tube to a position that the inner transverse edge of the slot 86 abuts against the pin 87. At that time further retraction of the plug will cause the latch release tube to also be retracted in the direction of the arrow 90 which results in the spring 80 being compressed but no movement of the latch body or the latch dogs takes place until the beveled edges of the slots 70 of the latch release tube abut against the diagonal edges of the latch dogs. At the time the aforementioned beveled edges bear against the latch dogs, the locking pin 75 has been moved by the latch release tube sufficiently outwardly from the inner curved edges of the slots 74 to be axially outwardly of the edges 16e of the latch dogs. Additional retraction of the latch release tube now forces the latch dogs to pivot about the latch pin 68 against the resilient

3,333,647

Fluid pressure acting against the outer exposed surface of the leather washer, the outer annular surface of the retaining nut 117, and the corresponding surfaces of the plug fluidly propel the assembly 100 to the bit end of the drill stem regardless of the drilling direction. At the time the assembly 100 has moved to a position that the latch body ledge flange abuts against the centralizer ring (same as that illustrated in FIGURE 2 for assembly 10), the latch dogs pivot outwardly to latchingly engage the latch seat. As a result of the latch dogs pivoting outwardly to a latching position, the locking pin 75 is free to move into the latch dog cut outs 16α, 16£>; and finally, the latch release tube under the resilient action of spring 80 (and/or gravity if the drilling direction is downwardly) moves inwardly relative to the latch body to abut against the shoulder 65 of the latch body. This inward movement of the latch release tube allows the plug 104 to move inwardly to abut against the head of the bolt 77 in the event it was previously spaced therefrom. Due to the provision of the elongated slot 105 and the fact that the latch release tube moves inwardly a substantially greater axial distance than any spacing between the adjacent surfaces of the head of the bolt 77 and the plug at this time, the plug in abutting against the bolt prevents further movement of the plug inwardly even though the latch release tube moves axially inwardly. As a result the outer annular edge 27α of the latch release tube moves away from the washer 112 a substantial axial distance as illustrated in FIGURE 8. Since the edge 27α no longer bears against the washer 112, The fluid pressure acting in the direction of arrow 124 causes the leather washer to flex inwardly to the position of FIGURE 8. As a result, an annular clearance space is provided between the leather washer and the inner peripheral wall of the drill stem substantially the same size as the main portions of the annular clearance space between the latch release tube and the corresponding inner peripheral wall of the drill stem. · . j .„ _ _I1UIU16 ____ .... Tn the event during the core taking operation, the drill the drilling direction 40 bit should extend into a high pressure pocket of fluid, the back pressure of said fluid would flow through the core bit aperture, thence through the annular clearance space between the core barrel inner tube and the drill stem, thence through the bypass channel provided by port 55, 56 and bore 50 and outwardly through the annular clearance space between the latch release tube and the drill stem. Due to fluid back pressure acting in a direction opposite the arrow 124, the outer annular portion of the washer 112 is flexed outwardly to a limiting position of . . - . . - r .1 ·--nut (see dotted line position of FIGURE 8) and thereby provides an annular clearance space adjacent the washer of substantially the same area as that of the solid line normal operating position illustrated in FIGURE 11. Due no substantial force component acting solely against the latch release tube and/or the valving member of sufficient strength to overcome the resilient action of the spring 80, this being in contrast to where the valving member, or 60 latch release member has a non-flexible enlarged portion that closes the clearance space between the core barrel inner tube assembly and the drill stem. Accordingly, no substantial movement of the latch release tube takes place and therefore the locking pin 75 prevents the latch dogs action of the torsion spring and thereby completely retract the latch dogs from the latch seat. The relative positions of the latch dogs, the outer portion of the latch body, the latch release tube, the plug 84 and associated structure when the latch release tube has been fully retracted relative the latch body are illustrated in FIGURE 4. In this connection it is to be noted that at this time the locking pin 75 abuts against the outer axial edge of the slot 74 to transmit the retracting force from the latch release tube to the latch body. Also after the core is broken the spring 43 will usually urge the bearing housing and the parts depending therefrom to move relative the spindle 36 to generally the position illustrated in FIGURE 2. The actual position depending on the spring characteristics and the weight of the core.

The operation of the first embodiment of the wire line core barrel inner tube assembly having been described, the operation of the second embodiment ICO will now be set forth. Since the construction of the second embodiment wire line core barrel inner tube assembly inwardly the line E—E of FIGURE 7 is the same as that inwardly of line E—E of FIGURES 1-3 for the first embodiment, that portion of the second embodiment has not been illustrated nor will the operation thereof be set forth. Likewise since the portion of the wire line core barrel inner tube assembly ICO intermediate line D—D and E—E of FIGURE 7 is the same as that between the same lines of FIGURE 5 for the first embodiment, the functions of this portion of the second embodiment will only be briefly referred to.

The second embodiment is hydraulically propellable, to the bit end of the drill stem regardless of the drilling direction, for example upwardly, downwardly, or at any angle relative to the horizontal. When the core barrel inner tube assembly 100 is to be fluidly propelled to the 35 bit end of the drill stem, it is inserted into the.outer end of said drill stem. After the assembly has been inserted m the drill stem and fluid pressure is exerted in an inwardly direction (arrow 124) in against the plug 104 and members 117, 112, or th- L.’¹' „ ’ is at an angle below the horizontal, the relative position of the elements at the outer end of the core barrel inner tube assembly are generally as shown in FIGURE 7. That is, the locking pin 75 abuts against the edges lee of the latch dogs and thereby prevents the latch release tube 27 moving relative to the latch body to a position to abut against the shoulder 65. However the coil spring 80 is resiliently urging the latch release tube to move to this ^P°After’ fluid under pressure has been pumped into the ₅₀ abutting against the beveled surface 116α of the retainer drill stem outwardly of assembly 100, fluid pressure act- ' --- -- ------ -ing against the valving portion 104, 112, 117 moves the valving portion so that the outer edge of the slot 105 abuts against the connecting pin 87, provided portion 104 ------has not already moved to this position. Now the inner ₅₅ to the aforementioned annular clearance space, there is axial surface of The plug is either abutting against the - _aPa,nst the head of bolt 77 or slightly axially spaced therefrom while the leather washer 112 has been moved to abut against the outer annular edge 27α of the latch release tube.. The outer annular edge of the latch release tube in conjunction with the shoulder 111 provides a sufficient supporting surface so that the outer annular edge portion of the leather washer does not flex inwardly to permit any subtubeTssemffiyTt the^ashe^In this connection it is to be ₆₅ from pivoting out of latching engagement with the latch noted that the outer diameter of the leather washer advantageously is of very slightly greater dimension than the inner diameter of the core barrel, inner tube assembly

1°12 may^be^a or^ffiei^m^er^a/a^long as ₇₀ a“Yydraulicany J„opeUable ^overshot^ asse^ it has sufficient rigidity to extend radially to form a fluid seal with the drill stem in the position illustrated m FIGURE 7 and will flex as illustrated in FIGURE 8 under normal fluid pressure when fluid is pumped into the drill stem during the time a core sample is being drilled. 71

Assuming that the core barrel inner tube has been filled with core and it is desired to retract the core barrel inner tube assembly 100 from the bit end of the drill fluidly propelled towards the bit end of the drill stem until the pulling dogs clampingly engage the spear point 110. Advantageously the overshot assembly used for retracting the core barrel inner tube assembly 100 is the 75 same as that described with reference to the overshot

3,333,647 assembly illustrated in FIGURES 12-14, the operation of which will be described hereinafter.

After the overshot assembly has been fluidly propelled to position to clampingly engage the spear point 110, the wire line is retracted to thereby retract the overshot 5 assembly and the valving member 104, 116, and 112. In the event that the inner transverse edge of the slot 105 is not abutting against the pin 87, the initial retraction of the overshot assembly moves plug 104 to such a position. If the overshot assembly is of a construction that ₁₀fluid bypasses it while it is being retracted, the leather washer 112 under the action of the relative motion to the fluid will cause said washer to remain in generally the condition illustrated in FIGURE 8. At this time further retraction of the plug 104 moves the latch release 15 tube axially outwardly relative to the latch body and thereby moves the locking pin axially outwardly from the latch dog cut outs to a position outwardly of the latch dog edges 16e. After the locking pin has been moved out of the cut outs, the beveled edges of the latch release 20 tube abut against the diagonal edges of the latch dogs to force them to pivot out of the latch seat; the latch release tube being movable relative to the latch body unit, the body pin 75 abuts against the inner edge of the slots 74. At this time the adjacent surfaces of the plug 25 and the head of the bolt 77 have been moved apart to relative positions such as illustrated in FIGURE 10. However it is to be understood that if assembly 100 is being retracted in a generally downward direction and/or depending on the characteristics of spring 80, it is possible 30 for the latch body to move relative the latch release tube until the locking pin abuts against the latch dog edges 16e and accordingly position the head of bolt 77 much closer the plug 106 than that illustrated in FIGURE 10. Further retraction of the overshot valve results in the 35 entire core barrel inner tube assembly being retracted through the drill stem while at the same time due to the flexing of the leather washer, fluid can bypass assembly 100 as it is being retracted in a manner corresponding to its bypassing the assembly during the core drilling opera- 40 iton.

The usage of the second embodiment of the core barrel inner tube 100 having been described, the operation of the overshot assembly 125 of FIGURES 12-14 will now be set forth. As previously indicated, the overshot as- ,_rsembly 125 is of a construction that is hydraulically pro- ’’ pellable to the bit end of the drill stem regardless of the drilling direction. When the core barrel inner tube assembly is first inserted in the drill stem and if there is no, or low tensional force being applied through the wire line 159 at the coupling element, the resilient action of the coil spring 150 acting through the rod 1446 will move the valving member relative tube 139 to a position that the outer transverse edge of the slot 145 abuts against the pin 143 such as illustrated in FIGURE 12. -At this time the flexible leather washer 156 is positioned to abut against the outer annular edge 139α of tube 139 while extending generally radially outwardly of the shoulder 154 of the fitting. As a result, the outer circumferential edge of the washer bears against the drill stem to at least substantially, if not completely, form a fluid seal therewith to prevent fluid under pressure bypassing the overshot assembly at this location in the direction of arrow 124. In the event the drilling direction is vertically downwardly, the spring 15» holds the tube 139 in abutting engagement with the leather washer as illustrated, ^b5the characteristics of the spring being such to accomplish this result. Fluid under pressure is pumped into the outer axial end of the drill stem to act against the outer annular surfaces of the coupling 158 and the exposed surfaces of the leather washer 156 to fluidly propel the ‘° overshot assembly through the drill stem in the direction of arrow 124. Upon the overshot assembly being moved adjacent the spear point of the core barrel inner tube assembly, the jaws 132 are forced apart to be passed 75 ¹⁴ over the spear point of the overshot assembly, and thence under the action of spring 134 move together to clampingly engage the spear point of the core barrel inner tube assembly that is to be withdrawn. Now the wire fine is retracted (moved in a direction opposite arrow 124) and thereby retracts the coupling element 158, the fitting 144 and the washer 156 relative the tube 139, the core barrel inner tube assembly being latched in position and thereby opposing the retraction of the tube 139 and the elements connecting the tube to the latch dogs. The initial retraction of the fitting moves it relative the pin 143 against the resilient action of spring 150 to a position that the inner transverse edge of the slot 145 abuts against said pin (see FIGURE 13). Further retraction of the wire line transmits the pulling force directly through the coupling element and fitting 144 to the pin 143 and thence to the tube 139 to retract the latch release tube, for example, in the manner described heretofore. To be noted is that the retraction of the fitting 144 relative the tube 139 moves the leather washer 156 axially outwardly of the outer, annular edge of the tube 139 and thereby provides a clearance space for the outer annular edge portion of the washer to flex inwardly such as illustrated in FIGURE 13. This provides an annular clearance space adjacent the washer to permit fluid bypassing the overshot assembly as it is being retracted. Accordingly fluid in the drill stem can readily bypass the overshot assembly during the retraction thereof; and if the core barrel inner tube assembly is of a construction to permit fluid bypassing it as it is being withdrawn, fluid is not forced out of the drill stem as the overshot assembly and wire line core barrel inner tube assemblies are being retracted.

Referring to FIGURE 15 there is shown a fragmentary outer end portion of a fluidly propellable core barrel inner tube assembly generally designated 17». The assembly 170 is of the same construction as assembly 100 other than for the differences noted hereinafter. The assembly 170 includes a latch release tube 27 together with a plug generally designated 171 that has a rectangular slot 177 through the main body portion 172. The inner transverse surface of the plug is flat such as illustrated for plug 104. A pin 87 connects plug 171 to the release tube 27. Plug 171 also includes a reduced diameter threaded portion 173 and a non threaded portion 174 of about the same diameter as portion 173 which integrally joins the main body portion to said threaded portion. At the juncture of portions 172, 174 there is provided a somewhat axially inwardly inclined, generally radially extending annular surface 175.

A flexible resilient member 178, such as a leather washer, having an inside diameter about the same as portion 174 is forced over portion 174. As may be noted from FIGURE 15, when the outer transverse edge of the slot 177 bears against pin 87, the flexible member 178 abuts against the tube 27 and at the outer peripheral portion forms a fluid seal with the drill stem.

An annular retainer 180 is threaded on portion 173, said retainer having an outer cylindrical surface that is substantially the same as the outside diameter as tube 27. The retainer has an annular frusto-conical surface 180α that is inclined radially outwardly and axially inwardly from the elongated axis of assembly 170, and has an annually frusto conical surface 1806 inclined radially outwardly and axially outwardly from surface 180α to provide a clearance space into which the outer peripheral portion of member 178 may be flexed. At the juncture of surfaces 180α and 1806 there is formed an annular ridge to bear against the flexible member radially outwardly of portion 174 to clamp said flexible member against the outer peripheral part of surface 175.

The plug also includes a spear point 182 that is threaded on the reduced diameter portion 173, said spear point having a main body portion 182α that has a cylindrical surface of a diameter substantially the same as the maxi3,333,647 immediate portion of the drill stem, for example, catching at a drill stem pipe joint. This frequently results in the core barrel inner tube assembly being prematurely released by the overshot assembly in a manner described 5 above; and as a result the core barrel inner tube assembly free falls and on reaching the bit end of the drill stem the abrupt stop will result in damage to either the outer tube assembly or the inner tube assembly. Applicants have through their invention of structure such as IO illustrated in FIGURES 1—6 have overcome this problem as will be described hereinafter.

The plug 84 has a minimum diameter portion 84e that at one end is integrally joined to the base of spear point 88 and at the opposite end to the minor base of 15 frusto-conical portion 84d. The diameter of reduced diameter portion 84e is such that when the jaws are clamping retaining the plug (such as in FIGURE 16) the edges of the jaws may abut against portion 84e, and at the same time dog edges 1946 will hold the release tube 192 against 20 inward movement relative dogs 194. Thus under normal core barrel inner tube assembly lowering conditions, the pulling dogs will support the weight of assembly 10, this resulting in the various part of the assembly 10 moving relative one another to a position such as illustrated in 25 FIGURE 4. That is since the overshot assembly supports the weight of assembly 10 (holds it against “free fall”) and plug 84 is slidingly attached to the latch release tube 27 by a pin in slot 86, the latch release tube and the structure depending therefrom will move relative the plug 30 such that pin 87 bears on the inner transverse edge of slot 86.

In the event during the lowering operation, assembly 10 should, for example, lodge on a pipe stem joint, the various members of assembly 10 are free to, and will under 35 gravity, move relative to one another to a position such as illustrated in FIGURE 5. In this connection note that plug 84 is free to, and does, move axially inwardly until surface 84α abuts against bolt 77 wherein the major base part of frusto conical portion 84d is located within 40 the confines of the latch release tube (see FIGURES 5 and 16). At the same time the inward movement of the overshot assembly relative assembly 10 is limited by inner shoulder 193c of the overshot body abutting on the outer annular surface 27c of the latch release tube whereby the ₄₅ jaws 194α are for the most part diametrically opposite reduced diameter portion 84e. Further the tube 27 can not at this time move further inwardly relative bolt 77 since pin 75 abuts against edges 16e of the latches 16. As a result jaws 194 still clampingly retain plug 84 and the 50 overshot release tube 192 still abuts against edges 1946.

Thus by retracting the overshot assembly with a wire line (not shown), the core barrel inner assembly 10 may be raised to dislodge it from a pipe joint.

When the core barrel inner tube assembly is latched in 55 position as indicated relative FIGURES 1-3, pin 75 moves down into slot 16α, 166 and the latch release tube moves downwardly relative bolt 77. Further the overshot body is free to move downwardly relative bolt 77 the same distance as the latch release tube. However, since plug 60 84 will abut against pin 87, tube 27 moves relative plug 84 such that the frusto conical portion 84d is located outwardly of the confines of tube 27 so as to force jaws 194α apart a distance greater than the maximum diameter of point 88 (see FIGURE 17). This results in the outer ends ⁶⁵ of the dogs 194 moving together sufficiently that release tube 192 moves axially inwardly relative thereto to prevent the dogs pivoting about pin 195. At this time the wire line (not shown) is retracted to retract the overshot assembly while leaving assembly 10 in a latched core receiving position.

Tube 192 may be of the same construction as that disclosed in the aforementioned U.S. Patent 3,120,252 (FIGURES 22, 23); or may be of the same construction other 75 than that the end wall 182 of said patent is eliminated.

mum diameter of retainer 180, an axially intermediate reduction diameter portion 1826 and a conical point. The spear point upon being threaded on plug portion 173 bears against the retainer to lock it in place, said retainer compressing the flexible member between it and the main body portion 172.

Due to the provision of the ridge formed by surfaces 180«, 1806, the flexible member is more firmly clamped in position than that obtained with, for example, assembly 100. Also since the spear point 182 and retainer are removable from the remaining portion of plug 171, the inside diameter of flexible member 178 may be substantial smaller than that of member 112 which has to be slipped over the spear point of plug 104. As a result, with plug 171, a greater annular portion of the flexible member 178 is located transversely inwardly of the outer circumferential surface of the latch release tube even though both of said members 112,178 have the same size outside diameter. Also due to the shape of surfaces 180α, 1806 and 175, the flexible member is more firmly held on the plug than member 112 on its plug. The operation of assembly 170 is the same as that of assembly 100; it will not be described.

Referring to FIGURES 16 and 17, there is illustrated the upper end portion of core barrel inner tube assembly 10, the lower end portion of an overshot assembly 191, and an overshot release tube 192. Since the overshot assembly may be of the same construction as that described in U.S. Patent 3,120,282, granted Feb. 4, 1964 (see FIGURES 22, 23) other than for the shape of the pulling dogs, the structure of the lower end portion of assembly 191 will be briefly described herein.

The overshot assembly includes an overshot body 193 having a pair of pulling dogs 194 pivotally mounted in a slot milled therein by a pivot pin 195 such that said dogs are oppositely faced. The outer end portion 193α of body 193 is of a sufficiently reduced diameter that the release tube may be slideably positioned thereon and abut against the outer transverse edges 1946 of said dogs when they are in a spear point clamping position. The dogs are resiliently retained in such a clamping position by a coil spring 197 that at opposite ends is positioned on pins 198 secured to the adjacent outer end portions of said dogs, i.e. on the ends opposite jaws 194α with pin 195 between spring 197 and the jaws. However in the event the frusto conical surface 84d of plug 84 is moved axially outwardly relative the jaws 194α of the pulling dogs when said dogs are clampingly coupled onto the plug 84, for example, through jarring or a hammering blow, the frusto conical portion 84d forces the jaws apart and causes the dogs to pivot about pin 195 such that there outer ends move more closely adjacent one another. If the drilling direction is at a sufficiently downwardly angle, the release tube 192 under action of gravity will move axially relative said dogs to a position that the dogs are prevented from returning to a clamping position (see FIGURE 17) even though the plug surface 84d has moved axially inwardly of said jaws. As a result the core barrel inner tube assembly is released from being couplingly attached to the overshot assembly. To facilitate the inward movement of the release tube 192 relative the pulling dogs, the interior, axially inner, surface thereof is beveled at 192α such as illustrated in FIGURE 16.

The aforementioned releasing is desirable when the core barrel inner tube assembly has been lowered to a position to engage the drill stem latch seats or said assembly is jammed in the drill stem and it has been decided to retract the overshot assembly without the core barrel inner tube assembly.

However in dry hole drilling in a downwardly direction, where it is desired to lower a conventional core barrel inner tube assembly through the use of an overshot assembly and release the overshot assembly from said core barrel inner tube assembly, at times the core barrel inner tube assembly will temporarily be “hung up” at an

3,333,647

An advantage of the second embodiment of the wire line core barrel inner tube assembly 10 over the first embodiment, is that the assembly 100 may be fluidly propelled to the bit end of the drill stem regardless of the drilling direction. A further advantage of the second embodiment of the wire line core barrel inner tube assembly and also of the overshot assembly 125 over that of the prior art is that there is provided means for resiiiently retaining the latch release tube and the valving member respectively in positions that a fluid seal is formed with the drill stem during the pump in operation.

As an example of the further construction of the washer 112, if it is to be used with a series of core barrel equipment wherein the drill stem inside diameter is 1¹¾^ inches and the washer is of leather, advantageously the washer has an axial thickness of approximately %₂, and outside and inside diameters of approximately 1% and 1 respectively. With this particular series, the outside diameter of the latch release tube would be approximately 1¹½) inches. Preferably the aperture in the washer through 20 which plug portion 107 extends is drilled rather than punched as punching breaks the grain structure and a punched washer when wet expands somewhat away from portion 107. Also a leather washer wears better if the grain side of the leather is toward the bit end of the drill 25 stem and the flesh side faces toward the pump end of the drill stem. However as previously indicated, flexible materials other than leather may be used.

As many widely apparently different embodiments of this invention may be made without departing from the 30 spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments herein.