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Publication numberUS2238609 A
Publication typeGrant
Publication dateApr 15, 1941
Filing dateApr 21, 1939
Priority dateApr 21, 1939
Publication numberUS 2238609 A, US 2238609A, US-A-2238609, US2238609 A, US2238609A
InventorsSewell Benjamin W
Original AssigneeStandard Oil Dev Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pressure core barrel
US 2238609 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

April l5, 1941. B. w. sEwELL 2,238,609

PRESSURE GORE `BARREL y Filed April 21, 195s :s sheets-sheet 2 i -18 z $49 2 7-90 vfag .a /91 g LA I Y April l5, 1941. B. w. sEwELl.A `2,238,609

` PRESSURE CORE BARREL FuedApril 21, 195s s sheets-sheetr s 8 2 7 www nn 4m 6.,67 7n WM 2 m 6 8. mw. @A l. 3 6. ..1 1H 7 .,M.. u\\\\\\ il In /W 7% F H 1. Ov. B. 8 @w m F 9 5 U 5. u E- Pu. WENN/M F F 2 8 ,8.88

, companying drawings in which- 'Patented Apr. 1s, i941` PRESSURE CORE BARREL w. seweu, ruin, om., minore Standard Oil Development Company; a -oorpo-` ration of Delaware application April ci, 1999, serial No, 26ans 19 Claims.

`The present invention is directed to a coring device for securing a core from a substratum under the pressureobtaining in the substratum.

The principal object of'the present invention is the provision of a-coring devicefof the character described including aa-longitudinal, retractable barrel' for receiving a core and means independ-Y end of'which is in threaded engagement with a cylinder I, the upper end of-'which is, `in turn, in Y entof said--barrelfor sealing the coreunderthef,

pressure of the formation from which -it was obtained, in which the means for sealing the lower end of the core is operated simply by raising the drilllstem.

additional object 'of-the 'present invention is the ,provision ofmeans of the character described in whichV is provided a valve for sealing off the lower end of the core barrel of such a i construction that during the c oring operation it is subjected to the flushing action `of the drilling fluid. l

, A further object of the present invention is the provision of afdevice of the character described including a core .barrel and a shell surrounding said barrel land normally xed for movement therewith in which means are provided for breaking the connection between these elements before the beginning of the coring operation.

Another object of the present invention is the threadedengagement Vwith a collar- 6 slidingly mounted on a section 1 Aof reduced diameter of a 4nipple 8 carried by a drill stem '9.' 'Iheins'ide` edge of the bottom end of collar 6 is beveled asV at Il to receiveisimilarly inclined faces of dogs II, each of which is'pivoted on a pin I2 in a lonlgitudirlalslot I3 in the wall of section 1 At `its -freeend each of these dogs carries a leafspring I4, the endcf whichfpresses againstthev inner i, face of ,sectionY 1 and normally tends to press the dogs inwardly .toward the center of section I out provision of novely means for breaking oil? a core from the formation from `which it is cut.

`Further objects and' novel features 'and fadvantages'ofv the present invention will appear from the following detailed-description of the ac- Figs. 1, 2 and 3 constitute together a side view, partly in quarter section and partly in-ha-lf section, of a coringdevice according to the present invention, said figures being arranged in sequence beginning at the bottom of the coring device;

Fig. 4 is a section .of the core barrel along the vplane at right angles to the -sectional view of Fig. 5 is a cross section on Fig. 3:

Fig. 6 Fig. l:

Fig.. 'I is a cross section along the-line BF-B of Fig. 1;

the line A.- of

1s a detailed viewfo: the vaivesnown in Fig.8 is a cross section along the'lineC-C of4 Fig. 1; and y Fig. 9 is va detail view of the core catcher. Referring to the drawingsv in detail, numeral I designates a conventional core drill head pro'- vided with conventional cone cutters 2 and with a centrall passage I. The core head is held in threadede'ngagement with a collar l, the upper of engagement with collar B. i

The inner face of each dog l I is provided with a ledge I5, the outer edge of which is turned up in the /formof a lip I6, said lip' being of such` configuration as to fit into an annular recess I1 provided on the undersurface of a head I8 carried by 4sleeve I9 slidingly mounted on a rod 20 which is provided at some distance from its end with a shoulder 2l to limit the movement of' sleeve I9 at that direction, and is provided with a nut I22 between which and the head I8 is arranged a helical spring 23 which normally forces sleeve I9 against shoulder 2|.

:The rod 21|4 is connected at its lower end with a- Acoupling 2l' to. which is also 'connected a rod 25 in alignment with rod 2|i,`which carriesiat its lower 'end through vconnections hereinafter described a barrel .26. f i

The lowerv end of the barrel 20 rests on a ledge 21 provided on the inner surface of a small tube 28 arranged in passage 3 and. threaded to the inner faceof the lower end of collar I,- lThe lower edge of tube 28 is serrated to form Acutting teeth in the conventional manner.

and the lower end of barrel 28, and is connected to the former by a shear pin 3| and to the latter by a shear pin` 32. In each case the end of the shear pin which is in the plug is carried bya ring of hard metal which is provided so as to l avoid the necessity of making the' whole plug of hardmetal which might cause some drilling difficulties if the plug should become lost in the hole.` VSincethe barrel 2l and tube 28 are rig' idly connected to each other and the latter is rigidly connected to collar I and the former to rod 20, it follows that, while pins 3l and I2 arein the position shown, theparts will remainr in the relationship shown.

Abovevthe cutting head the collar I is provided t on` its inner face witha shoulder 32 upon which rests a cylindrical valve head `Il which is con- A plug 29 having a central passage 30 is arranged inside of tube 23 through which rod 25 passes.

ried by a sleeve 35 which is also concentric with barrel 26. Sleeve 35 is of greater length than barrel 26 and carries at its upper end a cylindrical block 36 which has a central bore 31 Atits lower end, this central passage 31 is enlarged whereby an annular space 36 is formedbetween its inner face and the rod 25. A radial passage 39 connects space 38 with the exterior of the block. Ihe block is also provided with-a laterally offset longitudinal passage 46 controlled by a needle valve 4| and, when open, making connectionv with a lateral passage'42 provided with a plug 43 for the purpose hereinafter specied. Block 36 is provided with radially-extending longitudinal'ins 64 which space i t from cylinder 5.

Extending upwardly from block 36 is a. sleeve' 44 concentric with coupling 24, said sleeve nor-I mally having Ya smaller interior diameter than the outside diameter of coupling 2 4, but being reamed out to form a sliding fit for said coupling for a length defined by shoulders 45 and 46, whereby said coupling is permitted limited longitudinal movement within said sleeve for the purpose hereinafter specified.

At its upper end, sleeve 44 is provided wi `centric with the barrel 26 and is, in turn, carjecting into the space between the ribs. On these studs is journaled a steel ball 13 'which is provided with an interior passage 14 for the v receipt of barrel 26. Sleeve 65 is suitably rel cessed just above the cut-away portion 66 to receive a packing ring 15 which is of s uch configuration as to form a duid-tight seal with the surface of the ball13.v At either one of its journaled ends ball'13 carries a pinion'16 which is adapted to mesh with a rack 11 carried by the adjacent ribs 66. Each rack is secured to a rib by screws 18 working'in slots 18, said rack being laid against the side face of the rib, with its one edge projecting further laterally than the arcuate face of the rib, and is of such a length as to fit' between the lower end of cylinder 5 and shoulder 33 on collar 4. Thus, while each rack is secured to a rib which,in turn, is integral with sleeve 65, it acts as though it .were secured to collar 4, that is, it is capableof movement relative to sleeve 65 and, therefore,

` `relative to the pinions 16.

radially extending longitudinally arranged ins 41 which have inclined upper edges 48 adapted rto form a seat for'the beveled edge 49 of the inside edge lof the lower end of aforesaid section 1. Section 1 is also provided adjacent its lower end with an external inclined shoulder 56 which is adapted to abut against the beveled edge I6 on collar 6 for the purpose of limiting the relative movement of 'collar 6 and section 1. as hereinafter described. Rod 25 terminates an appropriately selected distance below the cylindrical block 36 in a carried by the upper end oi' the valve head.

The valvehead is provided around its circumference with slots 66. belowiwhich is arranged a seat 60 for a ball valve tl,v said seat being held in place by a ring 62. The lower end of' the valve head is connected to the barrel 26 by a Din 63.

The valve head bis composed of a sleeve 66 which has intermediate its ends a cut-out portion 66. The upper end oi'.the sleeve has in ternal threads 61 which engage threads onthe lower end of sleeve 66, and the remainder ofthe sleeve has an interior diameter equal to that of sleeve 66 which is slightly larger than the external diameter of barrel 28. The v/sleeve is provided with 'diametrlcally opposed longitudinal ribs 68 which have rounded'outer surfaces adapted to slldingly engage the interior of cylinder 6. Each rib is provided with a laterally extending shoulder 66 which are adapted to.

abutagalnst the lower end of vcylinder 6. :and

.with a shoulder 16 adapted to abut against shoulder 33 of collar 4. lSpaced 90 from the' ribs 66 are short ribs 1| which are used for spacing Purposes.

Each ofthe ribs 66 carries a ystud 12 pro- As previously stated, a feature of the present invention is the core catcher which is shown in detail in Fig. 9. As-can be seen by reference to this figure, the lower end of barrel 26 is pro'- vided with a circumferential series of spaced slots 68 and with a second series of these slots al spaced from the erst serie-s by bars s2'. Be-

low the latter sries of slots the inner face of the barrel is cut away to form seats 83. In each of these seats is set one end of a flat member 64 of spring steel which is then threaded through the successive slots 6| and 60 around the bar 82 with its free endpojecting into the barrel. The

arrangement of slots and bars is such that the/.fV

free end of each flat member is formed into a spring finger normally thrust into the interior of? the barrel. The plug 26 is provided with 1ongitudinal recesses 85 to receive these fingers. Likewise, the lower end of the barrel is provided with longitudinal grooves 66 to receive thesefingers when a core enters the barrel.

Before describing the operation of this device, a brief recapitulation of the relationship of the parts mayl be helpful. The core barrel itself is carried by the rod 20 and, until the oring operation begins, by the shear pins 3| and 32, the latter being connected t0 the barrel and the former being connected to the tube 26 which, in turn. is

rigidly connected to collar 4. Collar 4 is rigidly on reduced section 1 of nipple 8. In order thatthe rotary movement of drill stem 9 maybe transmitted to the collar 6, the latter is provided with a longitudinal key 81 which is seated in a slot 66 in reduced section 1. This slot is of suiiicient length to take care of relative longitudinal movement between collar 6 and section 1.

In order to prevent the return of collar 6 to the position shown after the desired longitudinal movement thereof has occurred, reduced section 1 carries dogs 66 which are pivoted on'pins 66, mounted in longitudinal slots 9| Ain section 8 and are spring-pressed outwardly by leaf springs 92. When in their outward position, the dogs are adapted to rest on the top of collar 6 after the latter has 4been moved downwardly the necessary distance and `to prevent the reverse movement of said collar. As will be apparent, the collar 6 is adapted to slide on the reduced section 1, its

' Y downward movement being limited by the shoulthe position shown are-dogs II which, in turn are held in position by the head I8 which, in effect.

l Ais carried by the barrel 26 which, in effect, is

carried by the collar 6. Accordingly, when the connection between the core barrel and the outer shell, namely the shear pin 3I, isbroken, the relationships shown in the drawings are automatically changed. i

. It will be understood that ln the use of this dei vice drilling mud must be circulated around-the core cutters. This mud flo-ws `down inside of the drill stern, down around rod 2'0 between fins 41, between the fins 64 of the cylindrical valve head 36, between sleeve 35 and cylinder 5 and down outside sleeve 65 to the bottom thereof which is at the top of the drill headwhich, in turn, is

provided with longitudinal passage 93 around its circumference, connecting its upper end with the cutter mountings.

The operation of the core barrel of the present invention is wholly automatic. With the parts in the position shown, the drill stem is lowered to the formation to be cored. When this formation is reached, the weight of the drill stem on the plug 29 first' shears pin 3l, which causes relative movement between the barrel 26 and the rest of the assembly for the distance permitted by the clearance between collar 24 and shoulder 45. This distance is made just exactly right to permit the head I8 to clear the lip I6 on each dog II, whereby each lip is forced by its spring III into the recess I1 provided in head I8 for that purpose.

The spring 23 insures a snugv fit between these elements.

Further pressure on the plug 29 shears pi-ns 32 and the coring operation is begun, the plug'29 being pushed up into the barrel by the formation core. As the core moves upwardly into barrel 26. the drilling mud in the latter is forced out through passage 33. When suiicient core has been cut, rotation of the drill stem is stopped and the drill stem is lifted. This causes spring fingers 84 t0 break off the core at that'point. At this time, the only point of the assembly connected directly to the drill stem is the core barrel 26, the rest of the assembly being free for relativemovement with respect to the core barrel by reason ofthe dogs lII having been pulled inwardly. Thus, with further upward mov/ement of the drill stem the core barrel is drawn upi wardly, the rest of the assembly resting on the formation until knife edge 53 comes into contact with its seat 52. i At this point, the'core barrel has been pulled upwardly a distance sufficient to clear the sleeve 35 to move upwardly, carrying ff with it. sleeve |55.A The movement of sleeve 65 relative to collar 4 causes the pinions 16 to run along the racks 11 and rotate the valve 13 suicient to seal off the lower end of the sleeve 35. this point the lower edge I0 0f the collar 6 has still not abutted against the shoulder 50 on section 'L make these abutting sections meet, places the ,spring 23 under compression, thereby tightening the seal between the knife edge and its seal and effectively sealing off the upper end of sleeve 35.

Upon further upward movement of the drill stem, therefore, the entire assembly moves upwardly. When the assembly arrives lat the surface, the collar 4 is unscrewed fromy the cylinder 5, exposing the lower end of sleeve 35. At this time, the dogs II are exposed by reason of the collar 6 having slipped down on section I and the dogs can be prized out of position by the application of a screw driver or other instrument tended to claim it as broadly as the prior art Further upward pull on the drill stem to to the notch shown at the other end, of the dog, or by any other expedient. The release of these dogs makes it then possible to slip out sleeve 35 in its entirety from cylinder 5.

The interior of the sleeve 35 is still under formation pressure. Plug 43 is removed and connection made with suitable sample collecting apparatus. Then needle valve 4I is opened and the pressure on the interior of the sleeve allowed to come down to atmospheric, any volatile constltutents contained in the sample passing oil' to the liquefaction or collecting apparatus for analysis. Upon the release of the interior pressure of the sleeve, the valve 13 can be `opened and the rod 25 is disconnected from coupling 24 and the barrel 26 is slipped out of the sleeve.

It will be understood that the device described `above simply represents-the preferred embodiment of the present invention. Manifestly, a great number of mechanical changes can be made therewith without departing from the scope of the present invention. Instead of the expedients relied upon in the device above described for limiting relative movements of parts, other expedient means can be employed. In short, the present invention is not to be limited by the above description of the accompanying drawings, but only by the appended claims in which it is inpermits.

I claim:

l. A device for securing a core from a subsuri face formation comprising a casing adapted to l be connected to a drill stem for rotation therewith, a core barrel carried within said casing capable of longitudinal movement relative thereto and adapted to assume a forward and a retracted position, means for normally holding said barrel in forward position, and means for releasing said last mentioned means at the beginningof the coring operation.

2. A device for securing a core from a subsurface formation comprising a lcasing adapted to be rotated by a drill stem and capable of longitudinal m vement relative thereto, a core barrel carried wi hin said casing capable of longitudinal movement relative thereto and adapted to assume a forward and a retracted position, means for normally holding said barrel in forward position and for holding said casing in fixed longitudinal relation with respect to said drill stem, and means for rendering said last mentioned means inoperative at the beginning 'of the coring operation.

3. A coring device comprising a casing adapted to be connected to a drill, stem for rotation therewith and for longitudinal movement relative thereto, a core barrel carried by said casing, a

4. A pressure coring device 'comprising an outer casing, an inner casing concentric with and spaced from said outer casing, a barrel mounted in said inner casing, a cutting head carried by said outer casing having cutters defining 4a'central passage in alignment with said barrel, and means for holding said outer casing, said. inner casing and said barrel in fixed longitudinal relationship, with the latter in communication with said central passage, comprising a shear pin adapted to be sheared at the beginning of the coring operation.

5. A device for securing a core from a subsurface formation comprising an outer casing adapted to be connected to a drill stem vfor rotation therewith, an inner casing concentric with said outer casing and mounted for limited longitudinal movement relative thereto, a core barrel concentric with said inner casing and mounted within said casing for limited longitudinal movement relative thereto, a cutting head carried by said outer casing having cutters defining a central passage in alignment with said core barrel, and a plug mounted in said passage and connected to said outer casing and said core barrel by shear pins and having its end projecting below 'the cutting 'head whereby, when the assembly is pressed against the formationto be cored under the weight of the drill stem, said pins are sheared and said barrel is freed for longitudinal movement relative to said outer casing.

6. A device for vsecuring a core from a subsurface formation comprising an outer casing connected to a drill stem for rotation therewith, means for normally holding said casing in xed longitudinal relationship with said drill stem, an inner casing concentric with said outer casing and mounted for limited longitudinal movement relative thereto, a Acore barrel carried by said inner casing and mounted for limited longitudinal movement relative thereto, means for normally holding said core barrel in a fixed longitudinal relationship with said outer casing, and.

' means actuated by the weight of the drill stem for disengaging said last mentioned means and simultaneously freeing said outer casing for longitudinal movement with respect to said drill stem and for connecting said barrel to said drill stem for longitudinal lmovement therewith.

7. A device. for securing a core from a subsurface formation comprising an outer casing adapted to .be rotated by a drill stem and capable of limited longitudinal movement relative thereto,4an inner casing concentric with said outer casing and capable of limited longitudinal movement relative thereto, a barrel mounted within said innencasing and capable of longitudinal movement relative thereto, said barrel being adapted to assume a forward and a retracted l position in said inner casing, means carried by said barrel for sealing off the upper end of said inner casing, when said barrel is in its retracted position, a cutting head carried by said casing having cutters defining a central passage in alignment with and in communication with the interior of said barrel, when it is in its forward position, a valve carried by the forward end of said inner casing and located between said cutting head and said barrel when the latter is in its retracted position, means for retracting said barrel after the completion of the coring operation, and means actuated by the retraction of said barrel for closing said valve.

8. A device for securing a core from a subsurface formation comprising anv outer casing adapted lto be connected to a drill stem for rotation therewith, an inner casing concentric with said louter casing, a core barrel slidingly mounted in said inner casing and capable of assuming a forward and a retracted position, a cutting head "r In) carried by said outer casing having cutters defining a central passage in alignment with and in communication with said barrel when it is in its forward position, a valve carried by said inner casing between said head andfsaid barrel when the latter is in its retracted position, means for,

moving said barrel from its forward position to its retracted position after the completion of the coring operation, and means actuated by the retraction of said barrel forl closing said valve.

9. A device for securing a core from a subsurface formation comprising an outer casing adapted to be connected to a drill stem for rotation therewith, an inner casing concentric with said outer casing and mounted for limited longitudinal movement relative thereto0 a barrel slidingly mounted in said inner casing capable of assuming a forward and a retracted position, a

Vcutter head carried by said outer casing having cutters,- deiining a central passage in alignment with and in communication with said barrel when it is in its forward position, a valve carried by the lower end of said inner casing ata point between said cutter head and said -barrel when the latter is in its retracted position, complementary means carried by the upper end of said barrel and the upper end of said inner casing for sealing the upper end of the latter when the barrel is in its retracted position, means for moving said barrel from its forward to its retracted position after the completion of the coring operation, and means actuated by the retraction of said barrel for closing the valve at the lower end of the inner casing.

10. A device for securing a core from a subsurface formation comprising a casing adaptedV to be connected to a drill stem for rotation therewith and for limited longitudinal movement relative thereto, a core barrel mounted within said casing for longitudinal movement relative to said drill stem, means carried by said drill'stem for normally holding said casing in fixed longitudinal relationship with said drill stem, and means actuated by the weight of the drill stem on the assembly for transferring said last mentioned means from the casing to the core' barrel, to thereby make said core barrel move longitudinally with said drill stem.

11. A device for securing a core from a subsurface formation comprising an outer casing for longitudinal movement relative thereto and .capable of assuming a forward and a retracted position, a cutter head carried by said outer casing having cutters dening a central passage in alignment and in communication withA said barrel when it is in said forward position, a valve carried by the lower end of said inner casing having a central bore for the passage of said core barrel and being adapted to be closed by the retraction of said core barrel into said inner casing, means severable by the weight of the drill stem on said assembly for normally connecting said barrel in forward position to'said cutter head, means for imparting longitudinal movement to said barrel relative to-4 said outer casing upon the severance of said connecting means. and means set into operation by said movement of said barrel for transferring the first mentioned means from said outer casing to said barrel to thereby make said barrel movable longitudinally with said drill stem.

12. A device for securing -a core vfrom a subsurface formation comprising an outer casing adapted to be rotated by a drill stem, 4an inner casing concentric with and spaced from said outer casing for the passage ofdrilling fluid, a core barrel slidingly mounted in said inner casing and adapted to assume a -forwardand a retracted positioma cutter head carried by said outer casing, having cutters defining a central passage in alignment with and in communication with said barrel when it is in saidforward position', a. rotatable valve mounted in the lower end of said inner casing at a point between said cutter head and said barrel when the latter is means actuated by the retraction of said barrel for closing the valve at the lower end of said inner casing.

17. A device according to the preceding claim lincluding means for holding said barrel in its retracted position.

18. A device for securing a core from a subsurface formation comprising an -outer casing adapted to be -connected to a drill stem for rotain its retracted position and having a central A bore adapted to receive said barrel when it is in its forward position, the walls of said inner casing being cut away adjacent said valve whereby the fluid circulating between said inner casing and said outer casing has access to said valve.

13. A device according to claim '7 including means for holding. the core barrel in its retracted position.

14. A device according to claim 8 including means for holding the core barrel in its retracted position.

15. A device according to claim 9 including means for holding the core barrel in its retracted position.

16. A device for securing a core from a` subsurface formation lcomprising an outer casing adapted to be connected to a drill stem for rotation therewith, an inner casing concentric with and spaced from said outer casing and in open fluid communication with said outer casing at both`of its ends, a core barrel having an open lower end and being slidingly mounted in said i inner casing at its lower end between said head and said barrel when the latter is in its retracted position, complementary means carried by the upper end of said barrel and the upper end of said l inner casing for sealing the upper end of said inner casing when laid barrel is in its retracted position, means for moving said barrel from its forward position to its retracted position aftery Y the completion of the coring operation, and

.tion therewith, an inner casing concentric with said outer casing and mounted for limited longitudinal movement relative thereto,ia core Vbarrel slidingly mounted in said inner casing and capable of assuming a forward and a retracted position, a, cutting head carried by said outer casing having cutters defining a central passage in i alignment and in communication with said barclosing said valve.

19. A device for securing a core from 'a subsurface formation comprising 'an outer casing adapted to be connected to a drill stem for rotation therewith, aninner casing in open uid communioatio'n with and concentric with said casing and mounted for limited longitudinal movement relative thereto, a core barrel slidingly mounted inl said inner casing and capable of assuming a forward and a retracted position, means carried by said barrel for sealing off the upper end of said inner casing 'when said barrel is in its retracted position, a cutting head carried by said outer casing having cutters denning a central passage in alignment and in communication'with said barrel when it is in its forward position, a valve carried by said inner casing between said head and said barrel'when the latter is in its retracted position, means for moving said barrel from its forward positionto its retracted position after the completion of the coring operation, whereby the upper end of said inner casing is sealed olf and further upward movement of said barrel causes said inner casing to move upwardly relative to said outer casing, andmeans operatively associated with said vinner casing and said outer casing for closing said'valve upon,reiative longitudinal motion between said casings.l

BENJAMIN W. SEWELL.

cooperating

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2494363 *Dec 23, 1944Jan 10, 1950Standard Oil Dev CoCore barrel
US2541785 *Aug 22, 1946Feb 13, 1951Texas CoCoring device
US2633336 *Dec 13, 1948Mar 31, 1953Reed Roller Bit CoCore drilling apparatus
US2734719 *Oct 11, 1951Feb 14, 1956 otway
US3035808 *Aug 30, 1956May 22, 1962Hydril CoPressure responsive valve
US3146837 *Dec 30, 1958Sep 1, 1964Jersey Prod Res CoSystem for obtaining trube core samples
US3207239 *Oct 31, 1961Sep 21, 1965Tiefbohr Mess Dienst Leutert &Apparatus for marking and for recovering oriented drill cores
US3207240 *Oct 31, 1961Sep 21, 1965Tiefbohr Messdienst Leutert &Apparatus for the drilling of and the protection of drill cores in deep-welldrilling operations
US3833074 *Dec 13, 1972Sep 3, 1974Inst Francais Du PetroleRemotely actuated device for surveying underground strata
US4256192 *Jul 6, 1979Mar 17, 1981Christensen, Inc.Pressure core barrel
US4272987 *Dec 3, 1979Jun 16, 1981Christensen, Inc.Pressure core barrel flushing system
US4356872 *Aug 21, 1980Nov 2, 1982Christensen, Inc.Downhole core barrel flushing system
US4552229 *Sep 9, 1983Nov 12, 1985Norton Christensen, Inc.Externally powered core catcher
US4950844 *Apr 6, 1989Aug 21, 1990Halliburton Logging Services Inc.Method and apparatus for obtaining a core sample at ambient pressure
DE3132436A1 *Aug 17, 1981Jun 9, 1982Christensen IncVorrichtung zum durchspuelen einer kernbohrvorrichtung
Classifications
U.S. Classification175/233, 175/245, 175/251, 175/253, 175/242, 251/250, 175/389
International ClassificationE21B25/08, E21B25/00
Cooperative ClassificationE21B25/08
European ClassificationE21B25/08