US2374961A - Core barrel - Google Patents

Description

B. w. SEWELL CORE'BARREL Filed Dec. 21, 1959 Q INVENTOR.

May 1, 1945.

ATTOR N EY.

Patented May 1, 1945 cons BARREL Benjamin W. Sewell, Tulsa, Okla., asslgnor to Standard Oil Development Company, a corporation of Delaware Application December 21, 1939, Serial 'No. 310,284

Claims.

The present invention relates to retractable core barrels formed to be dropped through the drill stem to a seat in a core bit and to take a sample of the formation. After a core has been taken, it may be sealed under the pressure of the formation and the core barrel withdrawn, leaving the drill stem and the drill in the bore hole.

It is an object of the present invention to provide a pressure core barrel which may be dropped down the drill stem and which will be latched in place when it is seated.

It is a further object of the present invention to provide a device having both an outer pressure barrel and an inner barrel so provided with latches that the inner-barrel may be unlatched and drawn within the pressure barrel before the pressure barrel is unlatched from its seat.

Another object of the present invention is to provide a pressure core barrel having upper and lower valves and arranged so that after it has been latched in, place in a drill stem the lower valve may be closed before the device is unlatched from the drill stem and the upper one maybe closed after it is unlatched from the drill stem.

. A further object of the. present invention is to provide a core barrel which may be dropped down a drill stem and which is locked in place when it strikes a seat at the lower end of the drill stem. The device i so arranged that, when a conventional type overshot attached to a wire line is dropped down the drill stem, it will fasten to a spear-shaped head on the upper end of the core barrel. A pull upwardly on the wire line will withdraw an inner barrel causing a. valve in the lower end of the'p'ressure barrel to close and'a continued pull will unlatch the device from the drill stem and then close a valve in the upper end of the pressure barrel; so effectively sealing a core in the barrel at the pressure of the formation.

Other objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawing in which Fig. 1 is a cross sectional view through a core drill with a preferred modification of the device of the present invention installed therein;

with conventional ilsh tail cutting edges 2-2 and a central passage 8. The lower portion of the central passage 3 in drill head I has a smaller diameter than the upper portion and forms a led e 4 within the passage.

Core bit head I isheld in threaded engagement with the lower end of a collar 5, the upper end of the collar being provided with threads (not shown) for engagement with a conventional tool joint. The lower end of the collar is provided with a ledgeb pierced by central passage 3. Lo-

cated on each side of central passage 3 are smaller passages 1-1 which also extend through both ledge .6 and the bit head. Collar I is also provided with circumferential grooves II and I6 10- cated. at a proper distance above ledge, as will hereafter be explained.

' Positioned within collar 5 is the pressure core barrel. An outer cylinder 8 having sufllcient wall thickness to resist a large plessure differential has arranged within it a concentric cylinder 9. The lower end'of cylinder 8 is upset to provide a threaded shoulder Ill towhich is attached cylindrical sleeve H which has an inwardly projecting shoulder l2 at itslower end. Sleeve It is provided with inwardly projecting stub shafts IS-l3. Mounted on the stub shafts for rotation within the space defined by shoulders l0 and I2 and the interior of sleeve II is a steel ball l4. Steel ball l4 is provided with a transverse circular opening adapted to receive inner cylinder 9. Shoulders l0 and I2 are suitably cut away to conform with the shape of steel ball l4 and,

Fig. 2 is a. cross sectional view along the line threads and attached thereto by mating threads is a cylindrical block 2!. Block 2| is in the form of a cylinder with outside portions of its upper end milled away to leave a circular shoulder 22 having ribs 23-23 joined thereto. Shoulder 22 is provided with'a central passage 25 and has its under-portion bevelled for reasons which will,

later appear. A passage 26 of smaller diameter than the interior of cylinder 8 extends longitudinally from the lower end of block 2| to the cutaway portions thereof and has a knife edge 21 formed on the lower end thereof. Attached to ribs 23-723 by means of rivets 28-28 are dog's 2929. The cylindrical block 2| is also provided with a laterally ofiset longitudinal passage 30 controlled by a needle valve 3| and when opened making connection with a lateral passage 32 provided with a plug 33 for the purpose hereafter specified. Access to needle valve 3! is provided by a slot 35 milled in block 2i.

Positioned within the pressure barrel is inner cylinder 9 provided at its lower end with a core catcher 3d and having a cylindrical valve head 36 attached to its other. end by means of suitable screw threads. The valve head is provided around its circumference with slots 37 below which is arranged a seat 38 for a ball valve 38. The upper end of the valve head is provided with a recess in which thrust bearings d! are arranged. A bolt 32 has its head 43 resting on thrust bearings dl, the bolt being held in place by a screw cap dd carried by the upper end of the valve head. A stud i is screwed into cap 65 which, in turn, is screwed to the upper end of bolt #32. Upon the upper face of cap 46 is arranged a disk of resilient material 3? which is of such dimensions as to form a seat for the knife edge 21 attached to the lower face of cylindrical block 2 i The stud 25 is screwed into a cylindrical block 48. The central portion of block 418 is provided with a slot 49 and attached within slot 49 by rivets 50-56 are dogs 5I5l. Block 48 is also provided with laterally projecting pin 52. Fitting slidingly over block 38 is a sleeve 53 provided with a spear head 5d and having its center portion provided with slots 55-55 and 55-51%. Slots 55 are so arranged that the upper ends of dogs 5! may extend outwardly through them when sleeve 53 is resting in its lowermost position in which the upper ends of slots 56 rest on pin 52.

outer sleeve 51 fits slidingly over cylindrical block 2!. The upper end of sleeve 5'? is provided with pins 58-58 which project into the slots St -55 of sleeve 53. Sleeve 5'! is additionally provided with slots 59-59 placed so that the upper ends of dogs 29-29 may extend outwardly through them when sleeve 51 is resting upon cylindrical block 2! in its lowermost position.

The above described device may briefly be said to comprise a heavy pressure barrel provided with valves at its upper and lower ends and an inner barrel slidingly arranged'within the pressure barrel. When the device is ready for taking a core, locking means lock the inner barrel against longitudinal movement with respect to the pressure barrel, its lower end protruding from the lower end of the pressure barrel and other locking means, in turn, lock the pressure barrel is the sole means for opposing the rotative force applied to the ball by springs 58-18 and hence the only means for retaining the opening in the steel ball in line with the axis of cylinder 8. In the upper end of the device, upper ends of dogs 29-29 and 5l-5l are momentarily retained inwardly in order to allow sleeves 53 and El to assume their lowermost positions, and are afterwards allowed to fall outwardly. When this occurs, relative longitudinal movement between cylinders ii and 9 will be prevented because cylinin the lower end of the drill stem provided with a core bit. The lower end of said inner barrel projects into the head of the core bit in order to receive a core. .When a core has been received by the inner barrel, a pull on the upper end of the device unlocks said inner barrel and rertacts it within the pressure barrel to allow the valve in the lower end of the pressure barrel to close. A continued pull on the upper end of the device next unlocks the pressure barrel from the drill stem and then closes the valve in the upper end of the pressure barrel to hermetically seal the core within the pressure barrel.

The device is prepared for taking .a core by having the longitudinal axis of the opening in steel ball ld'in line with the longitudinal axis of outer cylinder 8. the lower end of cylinder 9 being extended through the opening in steel ball Id and then projected a predetermined distance beyond it. It will be apparent that cylinder 9 der 8 is attached to block 2! while cylinder 5 is attached to block 48 through stud t5, and since block it rests on a face of block 2! it cannot move downwardly and upward movement is prevented by dogs 5l5l resting against that part or block M which forms shoulder 22.

With the inner and outer barrel locked together as described in the preceding paragraph, the device is ready to be lowered into a drill stem in order to take a core. A drill stem having at its lower end a collar and core bit head as shown in Fig. 1 may be in position in a bore hole with the cutting edges of the bit at the point in the hole at which it is desired to obtain a core. The core barrel may then be placed within the drill stem and allowed to fall under the force of gravity. If there is no obstruction within the drill stem, shoulder l2 will strike the ledge 6 of the collar and the device will then be locked in this position by dogs,2929 which fall outwardly and engage notch 55, as shown in Fig. 1. If there is a small obstruction between ledge and shoulder l2, shoulder 42 will rest on this obstruction and the device will be locked in position by engaging notch iii. In either event the lower end of cylinder 8 will project within passage 3 for the purpose of receiving a core. After the device has been locked in place, the drill stem may be rotated and drilling fluid forced down the drill stem and out through passages l-'l into the bore hole in the conventional manner. As the drill stem rotates, cutting edges 2--2 will cut a core which enters central passage 2 and hence cylinder 9.

It will be evident that the rotary movement of inner cylinder 9 will be independent of the rotary movement of the drill stem and the outer cylinder 8 because cylinder 9 is connected to these other members through the thrust bearings 4|. As the core enters cylinder 9, drilling fluid will be displaced upwardly through ball valve 39 and out through slots 31.

When a core of the desired length has been cut by the bit, the rotation of the drill stem may be stopped and an overshot attached to a wire line dropped down through the drill stem and allowed to engage with spear head 54. Since such overshots are conventional to the art, this device in itself forms no part of the present invention and, hence, is not illustrated in the drawing. An upward pull on the wire line attached to the overshot lifts sleeve 53 until the lower portions of slots 55 strike dogs 5|, pulling them inwardly, thereby unlocking cylinder 8 with respect to cylinder 9. A continued pull upwardly on sleeve 53 causes pins 52 to rest on the lower ends of slots. 56. transmitting the pull to stud 45 which retracts cylinder 9 within steel ball I4 and allows springs l8-l8 to rotate'the steel ball to to close off the lower end of cylinder 8. Continuing the pull on sleeve 53 causes the bottoms of slots 55 to strike pins 58 and pull sleeve 5'! upwardly to disengage dog 29 from notch I5. All the pull is now transmitted directly through block 48 to stud which causes disk 41 to seat against knife edge 21, sealing oil the upper end of cylinder 8 and allowing the forceto be transmitted to cylinder 8 in order to withdraw the entire device from the bore hole.

When the device is withdrawn to the surface of the earth with a core under formationpressure in'barrel 8, the gaseous components of the sample may be collected by removing plug 33 from block 2| and attaching a conduit from passage 32 to a suitable device for containing these components. Needle valve 3| may next be opened to allow the gaseous constituents to be withdrawn from the core barrel to the sample containerrtl ereby relieving the pressure in the core barrel. The core barrel may then be dismounted to obtain the core and the core barrel then reassembled and arranged to take another core in the manner previously described.

While I have disclosed a specific modification of the present invention it is obvious that various changes in the shape, size and arrangement of the parts may be made without departing fromthe scope of the invention. For'example, the number and shape of the locking dogs used in the device may be altered, other means may be used for withdrawing the gaseous constituents from the sample chamber and other types ofcore bits may be'used. I therefore do not intend to be limited to the above described modification.

I claim:

1. A retractable core barrel adapted to fit slidingly within a string of drill pipe and to be locked against longitudinal movement when it strikes a ledge at the lower end of saidstring of pipe comprising an outer casing, an inner casing fitting slidingly within said outer casing, means for sealing both ends of said outer casing in a pressure-tight manner, releasable means carried by said inner casing for looking it against longitudinal movement with respect to said outer casing, and releasable means carried by said outer-casing for locking it-against longitudinal movement with respect to said stringof drill pipe.

2. A retractable core barrel comprising a first cylinder, a second cylinder adapted to be concentrically arranged within said first cylinder, a

block adjacent an end of said first cylinder and connected to said second cylinder by means of a rod, a first sleeve arranged concentrically around said block, a second sleeve arranged concentriarranged within said outer cylinder, a first block attached to said second cylinder by means of a rod, a second-block directly connected with said outside cylinder, dogs attached to said first block and arranged to press against said second block to prevent relative longitudinal movement between said blocks, and dogs attached t said second block arranged for locking the device against longitudinal movement when it is positioned within a drill collar.

4. In a retractable pressure core barrel a cylindrical block provided with laterally extending pins and providedwith a slot, dogs arrangedin said slot and attached to said block, a sleeve arranged concentrically around said block, said sleeve being provided with a slot to correspond to each of said pins and dogs, and further provided with a spear head, asecond sleeve arranged concentrically around said first sleeve and provided with a plurality of longitudinal slots and with members which project within the slots provided in said rst-sleeve for said dogs.

5. A core b rel comprising a. tubular member, a core receiving chamber within said member in communication with the lower end of said memberby-nneans of a central passage, means arranged in said barrel to hermetically seal said core receiving chamber, and means mounted on said member to releasably anchor it to the lower end of a drill stem.

6. A core drill assembly including a core drill, and a drill collar connected thereto, a core barrel disposed within said assembly, means to anchor said core barrel releasably to said assembly, a central passage defined by said assembly adapted to receive a. core of theformation being drilled, a

chamber arranged in said barrel in communicamanner, and means mounted on said casing arranged to releasably anchor it to the lower end of a drill stem.

8. A pressure core barrel in accordance with claim 7 having the sealing means arranged to close the passage before the anchoring means is released.

9. A pressure core barrel comprising a casing having a central core receiving passage leading to 'its lower end and a. second passage provided with fluid communication between the upper end of said central passage and the exterior of said casing, means mounted on said casing arranged to releasably anchor it to the lower end of a. drill stem, means arranged in said casing to close the lower end of said central passage in a fluid tight manner, and means arranged in said casing to close said second passage in a fluid tight manner whereby said chamber is hermetically sealed.

10. A pressure core barrel in accordance claim 9 having the means for closing the central passage arranged to seal it before the anchoring means is released, and the means for closing the second passage arranged to seal it after said anchoring means has been released.

11. A core drill assembly including a core drill, and a drill collar, 9. core barrel disposed within said assembly, said barrel being provided with a central passage to receive a core cut by said drill, means mounted on said barrel to releasably anchor it to said assembly, means arranged in said barrel for sealing the upper and lower ends of said core receiving passage, said sealing means being arranged to close the lower end of said passage before said anchoring means is released.

12. A cdre drill assembly including a core drilland a drill collar, a core barrel disposed within said assembly comprising an elongated casing having a central passage extending to its lower end, said casing being arranged to be supported by said assembly, releasable means arranged on said casing to anchor it'to said'assembly against sample receiving position and to be within the casing in retracted position, means mounted on said member to aid in retracting it, and means mounted on said casing arranged to seal the lower end of said passage in a fluid tight manner upon the retraction of said member.

13. A wire line core barrel assembly comprising a casing having a. central bore, a tubularv member telescopically arranged in the bore of said casing for receiving a core, a means arranged at each end of said casing for sealing the ends of said bore in a fluid tight manner, and means mounted on said casing to releasably anchor it to the lower end of a drill stem.

14. A core drill assembly including a core drill and a drill collar, a core barrel disposed within said assembly comprising a first cylinder arranged to be supported by said assembly, releasable means arranged on said cylinder to anchor it to said assembly against upward movement, a second cylinder telescopically arranged in said first cylinder, said second cylinder being arranged to have its lower end extend below said first cylinder when in core taking position and to be within said first cylinder in retracted position,

means mounted on said second cylinder to cooperate in retracting it within said first cylinder, and means mounted on said first cylinder for hermetically sealing the ends thereof upon the retraction of said second cylinder.

15. A borehole tool arranged to be anchored to a drill collar and to be retracted by a wire line comprising a tubular member, a chamber within said member in communication with the exterior thereof by two outlets, means mounted on said member to anchor it to said drill collar, said anchoring means being arranged to be released by upward tension on a wire line attached thereto, means arranged on said tool for sealing each of said outlets in a fluid tight manner, said anchoring means and said sealing means being cooperatively arranged whereby one of said passages is sealed before the anchoring means is released, by tension exerted through said line, and the other passage is sealed after said anchoring means is released but before the tubular member is moved upwardly by continued tension exerted through said line.

BENJAMIN W. SEWELL.

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