US2012294A - Well tool construction - Google Patents

Description

7, 1935. J. c. WRIGHT ET AL: 2,012,294

WELL TOOL CONSTRUCTION Filed Jan. 4, 1933 2 Sheets-Sheet 1 Fig.2

3 7 fnuento rs J'ssg c. [m /1r @fvma W19 Aug. 27, 1935. J. c. WRIGHT ET AL 2,012,294

WELL TOOL CQNSTRUCTION Filed Jan. 4, 1933 2 Sheets-Sheet 2 fizz/6721073 JsQse C. Wright p rfo hr; 5. /-Pag5da/e Aiior y Patented Aug. 27, 1935 UNITED STATES PATENT OFFICE WELL TOOL CONSTRUCTION poration oi California Application January 4, 1933, Serial No. 650,132

3 Claims. (0]. 255-42) This invention relates to a. well tool construction and relates more particularly to a construction or combination for embodiment in well drills, well core drills, and the like.

The various classes of well drills in general use in the rotary method of well drilling are relatively slow in their cutting action or penetration of the earth formation, as they usually involve cutting parts at or adjacent their axes of rotation which move comparatively slowly during rotation of the drills and thus retard their cutting action. Core drills are employed in well drilling operations to obtain cores or samples of earth formations in the wells. Core drills usually embody a bit head'for making an annular cut in the formation, a barrel for receiving the core cut by the bit head, and core retaining means for retaining the core in the barrel. The core retaining means of a core drill is commonly placed adjacent or immediately above the bit head so that the length of the core receiving barrel is limited by the amount or length of the core that can be conveniently handled in one piece at the surface of the ground. Thus the usual core drills, while they do not have cutting parts adjacent their axes of rotation, are not capable of or adapted to penetrate the formation for any considerable distance without being pulled or withdrawn from the well, and therefore are not generally used as drilling tools or bits. Further, the amount of core or sample obtained by the core drill is limited by the length of the core receiving barrel and by the extent or length of a single core that can be conveniently handled at the surface.

It is an object of the present invention to provide a construction for embodiment in a core drill or in awell bit making an annular cut in a formation whereby the core drill or hit is capable of receiving and effectively handling a core or cores of great length so that the tool may be employed to penetrate or drill through the formation for a considerable or unlimited distance without requiring withdrawal from the well.

It is another object of the invention to provide a core receiving barrel for embodiment in or application to a core drill or 'well bitthat is adapted to efiectively receive and retain cores of great or unlimited length.

It is another object of the invention to provide a jointed or sectional core receiving barrel provided with a plurality of longitudinally spaced core retaining or supporting means whereby the barrel may be taken apart at the surface of the ground and sections of the core of convenient length will remain in the several sections or parts of the barrel.

It is another object of 'the'invention to provide a core retaining and supporting means em- 5 bodied in or provided on a member adapted to be connected between two parts or sections of a core barrel as a coupling for detachably connecting the sections of the barrel.

It is another object of the invention to pro- 10 vide core retaining and core supporting units of the character just mentioned that are extremely simple and inexpensive of manufacture and that are particularly effective and dependable in operation.

It is another object of the invention to provide core retaining units or coupling structures of the character mentioned that may be embodied in bits or core drills having a single body or barrel as well as in a coring outfit or core drill having 20 an inner barrel structure within the outer barrel or body for receiving the core.

It is another object of the invention to provide a simple compact core retaining or holding unit including an assembly of one or more 25 core engaging dogs, bearing means for the dogs, and means, for urging the dogs into engagement with the core which assembly is in the form of a unit that may be mounted or assembled with ease.

Other objects and features of the invention will be better and fully understood from the following detailed description of typical forms and applications of the invention, throughout which description reference is had to the accom- 35 panying drawings in which:

Fig. 1 is a side elevation of a well tool embodying the construction provided by the invention Fig. 2 is. an enlarged side elevation and partial vertical section of the tool illustrated in Fig. 1. a) Fig. 3 is an enlarged transverse detailed sectional view taken as indicated by line 3-3 on Fig. 2. Fig. 4 is an enlarged side elevation of one of the core engaging dogs included in the form of the invention illustrated in Figs. 1, 2 and 3. Fig. 5 is a bottom view of the dog illustrated in Fig. 3. Fig. 6 is an enlarged perspective view of one of the blocks for carrying the core engaging dogs. Fig. 7 is a transverse detailed sectional view of another form of core engaging or retaining unit, being a view taken as indicated by line 1-1 on Fig. 8. Fig. 8 is a side elevation and partial vertical section of the modified or alternate form of core retaining unit. Fig. 9 is an enlarged perspective View of one of the blocks included. in the form of core retaining unit illustrated in Figs. 7 and 8. Fig. 10 is a longitudinal detailed sectional view of another form of core drill embodying the present invention.

In accordance with its broader aspects the invention is adapted to'be embodied in or used in connection with bits and well core drills of various characters. The invention may be applied to or included in a bit or core drill having a single body or barrel, or in a bit or core drill having an outer tubular body and an inner core receiving barrel. Throughout the following detailed disclosure we will describe typical preferred forms of the invention embodied in a typical single barrel bit or core drill and in a typical double or two barrel core drill. It is to be understood that the present invention is not to be construed as limited or restricted to the specific forms or embodiments about to be described, or to use in connection with the particular classes of tools illustrated in the drawings, but is to be taken as including any features or modifications that may fall within the scope of the claims.

The tool illustrated in Figs. 1, 2 and 3 of the drawings, embodying one form of the present invention, includes generally, a bit head II) for making an annular cut in the formation, a sectional tubular body or barrel II carrying the bit head I0, and a plurality of spaced core retaining units I2 connected or assembled in the core receiving barrel II.

The present invention is not primarily concerned with the specific construction of the bit head Ill and we have illustrated a bit head of the character described and claimed in the co-pending application for Letters Patent of J. H. Howard and A. C. Catland entitled Bit head, Serial No. 650,131, filed January 4, 1933, including a tubular body or shoe I3 and cutting parts I 4 on the shoe. The shoe I3 of the bit head is provided at its upper end with suitable means for connecting with the core receiving barrel. The shoe of the particular bit head I illustrated in the drawings has a tapered screw threaded socket I5 in its upper end to facilitate connection with the barrel I I. The vertical or longitudinal opening I6 of the shoe I3 is adapted to pass the core or cylindrical part of the formation made by the cutters I4 upwardly into the barrel I I. The lower end portion of the opening I6 may be restricted as illustrated in Fig. 2 of the drawings so that the core has desirable clearance when received by the barrel II and so that the circulation fluid is discharged at an increased velocity about the core as it enters the bit head. The cutting parts It are in the nature of substantially radial blades projecting downwardly and outwardly from the lower end portion of the shoe I3. There is a suitable number of circrunferentially spaced cutting blades I4, each provided with a lower cutting edge II, a side reaming edge I8, and a core shaping or trimming edge I9.

The core receiving barrel H and the assembly of the barrel II and the core retaining units I2 are important features of the present invention. The barrel II is adapted to be attached to the lower end of an operating string of drill pipe, or the like, for example, it may be attached to a drill collar on the lower end of an operating string. In accordance with the invention, the barrel II is sectional, and may be of any suitable or desired length. The core receiving barrel II includes a plurality of elongate tubular sections 20. There may be any desired number of sections embodied in the barrel II, it being apparent that the length of the barrel is determined by the length and number of the sections 20 embodied in the structure. The tubular barrel sections 20 are of like diameter and are preferably of greater internal diameter than the bit head I 0 so that the core may pass into the barrel with clearance and without binding or jamming. It is a feature of the invention that the tubular barrel sections are detachably connected together and that the lowermost section 20 is detachably connected to the bit head IIl through the core retaining units I2 as will be subsequently described. Means is provided at the upper end of the barrel l I to facilitate connection with the lower end of the drilling string. In the particulancase illustrated in the drawings, a sub 2I is attached to the upper end of the upper section 20 of the barrel and is provided with a tapered threaded pin 22.

The core retaining units I2 are provided to retain and support the core within the barrel II. In practice, where thetool is used as a drilling bit in relatively soft earth formations, the circulating fluid under pressure passing downwardly through the barrel II may errode or wash away the softer parts of the core or formation that enters the bit head opening I6 and the barrel II so that only the harder or more resistant portions of the core remain in the barrel to be retained by the units I2 when the tool is withdrawn from the well. Where the tool is used primarily as a core drill for obtaining samples of the earth formation, the conditions of operation may be such that substantially the entire core is retained intact within the barrel I I and is supported and held in the barrel by the core retaining units I2. As the tool embodies only a single tubular body or barrel it is operable to obtain a core considerably larger in diameter than cores taken by the usual two barrel drills, and as the barrel I I may be of great length and is provided at spaced points with the core retaining units I2, a very long core may be taken if desired.

The core retaining units I2 are arranged or connected between adjacent ends of the several sections 20 of the barrel and one or more units I2 may be arranged or connected between the bit head Ill and the lower end of the lowermost bar rel section 20. In accordance with the form of the invention being described, the units I2 are in the form of couplings or connections for connecting the several barrel sections 20 and for connecting the barrel I I and the bit head I0.

The number of core retaining units I2 included in the tool depends upon the length of the barrel II or the number of sections 20 included in the barrel and upon the spacing of the units. The several core retaining units I2 may be alike in construction to simplify the assembly. Each unit I2 includes a tubular body having means at its opposite ends for connecting with adjacent portions of the tool assembly. The bodies 25 of the units I2 may resemble subs and may have comparatively heavy or thick walls. The openings 2B in the unit bodies 25 may be of substantially the same-diameter as the major portion of the bit head opening I6. In accordance with the broader principles of the invention, the bodies 25 of the core retaining units I2 may be connected to or with the adjacent ends of the barrel sections 20 in any suitable or practical manner. In the case illustrated in the drawings adaptor subs 28 are screw threaded on the lower end of the barrel sections 20 and are provided at their lower ends with tapered pins 2'! having comparatively coarse threads. The upper ends of the unit bodies 25 are provided with tapered sockets 28 having coarse threads for cooperating with the threads of the pins 21. The lower ends of the unit bodies 25 may be connected with the upper ends of the adjacent barrel sections 20 through lower adaptor subs 29. The subs 29 may be threaded to the upper ends of the barrel sections 20 in the usual manner and have threaded connections with the unit bodies 25. In the particular assembly illustrated in the drawings, a coarsely threaded pin 30 is provided on the lower end of each body 25 to thread into a. socket 3| in the upper end of an adaptor sub 29. From the above description of the bodies 25 of the core retaining units l2 and the typical means for connecting them in the barrel assembly, it will be apparent that the invention provides a simple sectional core receiving barrel in which the principal tubular sections 20 are connected together through the bodies '25 and suitable connecting members or adaptor subs One or more core gripping and retaining dogs 32 or sets of core retaining dogs 32 are provided on each unit l2. In the typical form of the invention disclosed in the drawings there are four sets of two dogs 32 carried by the body 25 of each unit I2. The core gripping and retaining dogs 32 are carried or supported by blocks 33 secured in openings or vertically elongated slots 34 in the walls of the bodies 25. Where the units l2 embody four sets of core retaining dogs 32 there are four circumferentially spaced vertically elongated slots. 34'provided in each body 25. The blocks 33 are rectangular or elongate and fill the slots 34. The blocks 33 may project slightly from the exteriors of the bodies 25 and may be securedin the slots 34 in any suitable manner, for example, they may be welded to the bodies 25. Two vertically spaced pockets or recesses 35 are provided in the inner side of each block 33. The recesses 35 may extend through the blocks 33 from one vertical side of a slot 34 to the other. The recesses 35 are shaped to receive the major portions of the gripping dogs 32 when the core is passing into the barrel I I and to effectively support the dogs 32 when the dogs are carrying the core. Each recess 35 has a downwardly and outwardly inclined upper wall 36 and a flat lower wall 31. A concaved cylindrically curved or rounded seat 38 joins the walls 36 and 31 of each recess 35.

The dogs 32 for retaining and supporting the core within the barrel H are pivoted in the recesses 35 and project from the interiors of the unit bodies 25 to engage and bite into the core. A transverse or horizontal opening 39 is provided in each dog 32 adjacent its lower end. Tubes 40 extend through the openings 39 and washers M are provided on the opposite projecting end portions of the tubes. The opposite ends of the tubes 40 may be spread or flared slightly to retain the washers 4| on the tubes and in engagement with the sides of the dogs 32. Vertical longitudinal cuts or slits 42 are provided in the lower ends of the dogs 32 to intersect the tube carrying openings 39. Torsional springs 43 are carried by or wrapped about the tubes 40 within the slits 42. One end of each torsional spring 43 is held in a reduced opening or socket 44 in a dog 32, while the opposite ends of the springs engage the walls of the recesses 35 whereby the springs 43 normally urge the dogs 32 into the openings 26 to engage the'core. Tangential openings 46 are provided in the unit bodies 25 and intersect the slots 34. Suitable pins 41 are arranged in the openings 46 to pass through the tubes 40 of the dogs 32 and pivotally support the dogs in the recesses 35. The pins 41 may have socketed or slotted heads threaded into the outer ends of the openings 46.

The dogs 32 each have a flat upper side 48 adapted to lie against the upper inclined wall 36 of a recess when the core is passing into the barreland has a flat lower surface 43 which is adapted to seat on the lower wall 31 of a recess when the dog is in supporting engagement with the core. The inner ends of the core engaging dogs 32 are cylindrically rounded or curved about their pivotal axes and bear or pivotally fit into seats 38. The seating of j the inner ends of the dogs 32 against the seats 38 and the engagement of the lower sides 49 of the dogs with the bottoms of the recesses 35 provides for the direct transmission of the weight of the core from the dogs to the blocks 33.

The outer ends of the dogs 32 which project into the openings 26 are shaped and proportioned so as to effectively cut or bite into the core. The outer end portions of the dogs 32 are reduced in thickness and the extreme ends of the dogs are bevelled to terminate in edges 50. During operation of the tool when the drill is passing downwardly into the formation and the core is being received by the barrel H, the pivoted dogs 32 engage the core and are held in the up and out positions, illustrated in Fig. 2 of the drawings, by the downward movement of the tool relative to the core. When the tool is raised to remove it and the core from the well, the sharpened outer ends of the dogs 32 bite into the core so that the dogs are pivoted downwardly through the relative movement between the barrel and core and thus bite into the core to retain it in the barrel and if necessary, to break it loose from the formation. In hard formations, it may be necessary to rotate the drill while raising it so that the dogs 32 make annular cuts in the core to assume their core retaining positions and/or to break the core loose from the formation in the bottom of the well bore. The washers 4| eifectively space the, opposite sides of the dogs 32 from the end walls of the recesses 35 and operate as thrust bearings or washers.

It is believed that the utility and operation of the tool illustrated in Figs. 1, 2 and 3 of the drawings will be readily apparent from the foregoing detailed description. In operation, the drill may be operated in the usual manner, that is, it may be rotated to cause the bit head I 0 to make an annular cut in the formation. The core cut by the bit head In passes into the barrel H as the tool advances through the earth formation. Where the tool is operated as a drill or bit, the circulation of fluid through the toolmay be such as to wash away or errode the softer portions of the core while the more resistant components of the core remain in the barrel ll. When the tool is used as a core drill for obtaining samples of the formation, the entire core may be received and retained with the barrel ll. During the passage of the core into the barrel II, the dogs 32 are in their up and out positions illustrated in Fig. 2 of thevdrawings so that they do not materially interfere with the core, but maintain engagement with the core through the pressure of the torsional springs 43. When the tool is raised or pulled upwardly the sharpened ends 50 of the dogs bite into the core causing the dogs to pivot downwardly in the recesses 35 and penetrate the core for considerable distances. The core may be broken away from the formation either by a straight up pull or by rotation of the tool during the up pull which causes the dogs 32 to make annular cuts in the core so that it may be broken from the formation at the lower core retaining unit I2. As the core barrel H may be extremely long a very long core may be obtained and the provision of the core retaining units l2 at longitudinally spaced points insure the proper retention and supporting of the core or sections of the core within the barrel. As the barrel ll provided with the core retaining units 12 is adapted to receive-and retain a core of unlimited length, the tool is operable to cut through the formation for an extensive distance and if desired, may be employed as a drilling bit as well as a means for obtaining samples of the formation in the bore.

When the tool has been withdrawn from the well and it is desired to inspect the core within the barrel II, the barrel ll may be taken apart either immediately above or immediately below the units l2, that is, the unit bodies 25 may be disconnected from either the adaptor subs 26 or 29 so that the portions of the core within the body sections 20 may be easily removed in lengths that may be conveniently handled. The tool involving only a single barrel and in being of moderate wall thickness is operable to obtain cores of large diameter. The core retaining units l2 in detachably connecting the adjacent ends of the barrel sections 20 provides for the quick and easy separation or disconnection of the barrel sections and insure the proper supporting of the core within the barrel at suitably spaced points. The core retaining units l2 are simple and inexpensive of manufacture, consisting of the simple tubular bodies 25 and the sturdy effective dogs 32 supported in the blocks 33. The springs 43 in being carried on the tubes 40 allow the assemblies of the dogs, tubes, and springs to be easily and quickly mounted in the recess 35 as units. It will be apparent that in some constructions and under certain conditions .it may be desirable to merely attach or retain the core retaining units I2 between connected parts of the barrel.

Figs. 7, 8 and 9 of the drawings illustrate a modified or alternate form of core retaining unit adapted to be connected or arranged in a core receiving tube or barrel in the same manner as the units l2 described above. The core retaining unit illustrated in Figs. 7, 8 and 9 of the drawings includes a body 55 and one or more core gripping slips 56 operable in the body.

The body 55 may be in the nature of a coupling or connecting member adapted to connect to.- gether parts of a well tool, for example, two tubular sections of a core receiving barrel. The unit body 55 may be similar to one of the bodies 25 described above, that is, it may be provided at its opposite ends with suitable connecting means. In the case illustrated, a. tapered screw threaded socket 51 is provided in the upper end of the body 55 while a tapered threaded pin 58 is provided on the lower end of the body. The longitudinal opening 59 of the body 55 may be of uniform cross section throughout its length. In accordance with this embodiment of the invention the body 55 is provided with one or more vertically elongated openings or slots 60. The particular form of the invention being described involves four core engaging slips 56 and four equally spaced slots 60 are provided in the walls of the body 55. A block 6i is provided in the outer end portion of each slot 60. The blocks 6| may be welded or otherwise attached to the bodv 55 and their exteriors may be substantially flush with the exterior of the body. The inner sides 62 of the blocks are inclined downwardly and inwardly to form surfaces for slidably supporting the slips 56. The outer portions of the slots 60 are of enlarged horizontal cross section so that shoulders 63 are provided in the side walls of the slots. The shoulders 63 are inclined downwardly and inwardly being of the same inclination as the inner sides 62 of the blocks 6|. The blocks 6! fit the slots 60 so that their inner sides 62 are spaced from the shoulders 63 to provide inclined key-ways 64 in the slip carrying portions of the slots 60. The provision of the inclined key-ways 64 makes the slip carrying slots 60 substantially T shaped in horizontal cross section.

The core engaging slips 56 are slidable vertically or longitudinally in the T shaped slots just described. There may be one slip 56 in each slot 60. The outer sides 65 of the slips 56 are inclined to slidably cooperate with the inner sides 62 of the blocks 6i and the slips are substantially T shaped in cross section having laterally projecting inclined keys 66 slidably fitting the key-ways 64. Upward movement of the slips 56 is limited by the upper ends of the slots 66' while blocks or bars 61 limit the downward movement of the slips. The bars 61 extend across the lower end portion of the slip carrying slots 60 and may be counter-sunk in the inner faces 62 of the blocks 6!. Screws 68 pass through openings in the blocks 6| and thread into the bars 61 to detachably retain the bars in position. The removable bars 67 prevent detachment or displacement of the slips 56 from the units and may be removed to take the slips 56 out of the slots.

The inner ends of the slips 56 are provided with I one or more upwardly inclined teeth or core biting parts 69. The slips 56 are proportioned so that they project into the openings 59 when in the extreme up positions illustrated in Fig. 8 of the drawings so that they are at all times in engagement with the core extending through the barrel and unit.

During downward passage of the tool into the earth formation the slips 56 are retained in their up positions through relative movement between the core and barrel. When the barrel is moved upwardly the slips 56 are held against upward movement through their engagement with the core and the inclined faces 62 and keyways 64 force the slips inwardly into tight gripping and holding engagement with the core. This engagement of the slips with the core is maintained during the removal of the tool from the well as the weight of the core supported by the slips retains the slips in their down and core holding positions. It will be apparent how the core retaining unit illustrated in Figs 7, .8 and 9 of the drawings may be readily embodied in various forms of core receiving barrels and how a plurality of these units may be connected between the several tubular sections of an elongate barrel of the class described above to act as detachable connecting means, as well as means for supporting the portions of the long core.

Fig. 10 of the drawings illustrates a form of the invention involving a core receiving means comprising core receiving tubular sections .arranged within the body or main barrel of the tool. The tool illustrated in Fig. 10 includes, generally, a bit head 10 for making an annular cut in the earth formation, a sectional bodv or barrel ll carrying the bit head 10, a

plurality of core retaining or catching units I2 interposed or assembled in the barrel II, and tubular core receiving sections I3 within the barrel II.

Any suitable form of bit head may be used in connection with the tool construction illustrated in Fig. 10 of the drawings. The bit head I0 is a typical core drill bit head including a shoe, I4 and cutting parts I5. The shoe I3 is tubular, and is provided at its upper end with a threaded socket IS. The cutting parts I5 are in the nature of blades projecting downwardly and outwardly from the lower end of the shoe I3. The cutting blades I5 are circumferentially spaced on the shoe I4 and are operable to make an annular cut in the formation to pass the core drill with clearance.

The body or barrel II is an elongate tubular structure carrying the bit head I0 and adapted to be attached to the lower end of an operating string of drill pipe, or the like. In accordance with the invention, the barrel II is sectional including a plurality of elongate tubular sections". The several sections II of the barrel II are connected together by the units I2, and the lowermost section 11 is connected with the bit head I0 by a unit I2, as will be hereinafter described.

The core catching or core retaining units I2 are assembled in the sectional barrel II and constitute means for connecting the several barrel sections 11. A core retaining unit I2 is connected between the adjacent ends of each of the several sections 1! and a unit I2 is arranged between the lower end of the lowermostsection I1 and the bit head I8. Each core retaining unit I2 includes a body I8 in the form of a sub that is adapted to connect together two members of the tool. The bodies I8 of the core retaining units are tubular, having central longitudinal openings I8 and are provided at their opposite ends with means for facilitating connection with other members of the assembly.

In the typical form of the invention illustratedin the drawings, the upper end of each body I8 is provided with a threaded socket 18a and a threaded pin 88 is provided on the lower end of each body. A sun or connecting member 8I may be provided on the lower end of each barrel section II. The connecting members 8| may have pins 82 threaded into the sockets 18a in the upper ends of the unit bodies I8. A connecting-member 83 maybe threaded on the upper end of each barrel section II and may be provided at its upper end with a socket 84 for receiving a pin 80. The threaded pin 88 of the unit body I8 on the lower end of the lowermost barrel section 11 may be threaded directly into the socket IS in the bit' head ID. The openings I8 on the unit bodies I8 are of considerably less diameter than the openings of the barrel sections 11 and the walls of the bodies I8 are comparatively thick.

One or more core retaining elements 88 is .carried by the body I8 of each unit I2.- The ments 86 are in the nature of pivoted dogs carried by blocks 81 arranged in slots 88 in the walls of the unit bodies I8. The blocks 81 may be welded in the slots 88 as illustrated in the drawings. Recesses are provided in the inner 'oted dogs carried by each unit body I8.

sides of the blocks 81 to carry the outer ends of the dogs 88. There may beone or more piv- In the speciflc construction illustrated, there a. pair of dogs on each block "and a plurality of blocks 81 on each unit body I8. The blocks 81 are spaced apart circumferentially on the v bodies I8, for example they may be spaced substantially apart as illustrated in the drawings. The core retaining dogs 86 and their mountings may be identical with the dogs 32 and the mountings for the dogs 32 described above, and reference may be had to the description of the dogs 32 to obtain a full understanding of the present embodiment of the invention. The core retaining dogs 86 project into the openings I8 of the unit bodies I8 and their inner core engaging ends may be. bevelled or sharpened.

The core receiving and holding sections I3 are provided to receive the core cut by the bit head I0 and to allow or provide for the circulation of circulating fluid downwardly through the tool into sockets 83 in the upper portions of the openings I8 of the unit bodies. The upper end portions of the sections I3 have sliding connections or telescopic engagement with the bodies I8. Enlargements or sockets 84 are provided in the lower ends, of the openings I8 to receive the upper end portions of the sections I3.

The form of the invention ilustrated in Fig. 10 of the drawings includes means for circulating the circulation fluid downwardly through the assembly or tool to discharge from the bit head I4. members BI and 83 are sufliciently large in diameter to provide annular spaces or passages 88 around the core receiving sections I3 which pas sages 88 form continuations of the passages 82. Longitudinal fluid passages 88 are provided in the unit bodies I8 to connect the openings or passages 86 in the connecting members on the opposite ends of the bodies. The passages 88 in the lowermost unit body I8 communicate with or discharge into an annular recess 88 in the upper end of the bit head shoe I4. Fluid discharge passages I08 are provided in the shoe I4 to communicate'with the recess 88 and discharge from the lower end of the shoe.

The tool illustrated in Fig. 10 of the drawings is adapted to be operated on the lower end of a string of drill pipe, or the like, and the bit head I8 makes an annular cut in the formation providing a core which passes upwardly into the The openings in the tubular connecting sections I3. During thepassage of the core into the tool the dogs 86 are in the retracted positions illustrated. When the tool is raised to break the core from the formation and to pull the tool from the well, the dogs 88 pivot downwardly to bite into the core so that the core may be broken away from the iormation and retained in the sections I6. After the tool has been withdrawn from the well, the threaded connections or joints at the lower ends of the unit bodies I8 may be released or broken and the various parts above these connections may be lifted 01! of both the inner sections 13 and the outer sections 11 below the disconnected joint. The core or sections of core contained within the sections 13 may then be removed by means of a plunger introduced into the lower ends ofthe sections. The tool illustrated in Fig. 10 of the drawings provides for the effective free passage of the circulation fluid to the bit head without in any way contacting with the core and is such that the core may be easily and quickly removed from the section 13 by disconnecting the parts of the barrel H at the core retaining units 78.

Having described only a typical preferred form of our invention, we do not wish to limit ourselves to the specific details set forth, but wish to reserve to ourselves any changes or variations that may appear to those skilled in the art or fall within the scope of the following claims.

Having described our invention, we claim:

1. In a well tool, a tubular body having a recess in its inner wall, a dog having a transverse opening, a tube extending through the opening, a spring carried by the tube, the assembly of the dog, tube and spring being adapted to be arranged in the recess as a unit, and a pin carried by the body and passing through the tube to plvotally support the dog in the recess, the spring reacting between the body and dog to pivot the dog inwardly.

2. In a well tool, a tubular body having a recess in its inner wall, a dog having a transverse opening, and a slot intersecting the opening, a spring in the slot carried by the tube, the

assembly of the dog, tube and spring being adapted to be arranged in the recess as a unit, and a pin on the body extending through the tube to pivotally support the dog in the recess, the spring reacting between the body and dog to pivot the dog inwardly.

3. In a well tool, a barrel for receiving a core and comprising a plurality of lengths of tubing, and means connected between the lengths of tubing'for retaining a core in the barrel, each of the said means including a tubular body having a slot in its wall, means at the opposite ends of the body for connecting with the barrel, a block fixed in the slot and having spaced recesses in its inner side, and a core engaging element pivoted in each recess and adapted to project from the interior of the body.

JESSE C. WRIGHT. JOHN B. RAGSDALE.

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