US2005989A - Core barrel - Google Patents

Description

2 Sheets-Sheet l C. E. BURT CORE BARREL Filed June 7, 1933 .1: ink

June 25, 1935.

IN V EN TOR.

A TTORNEYS.

Patented June 25, 1935 PATENT OFFICE CORE BARREL Clarence E; Burt, Los Angeles, Calif., assignor to Baker Oil Tools, Inc., Huntington Park, CaliL, a corporation of California Application June 7, 1933, Serial No. 674,655

6 Claims.

fitted at its lower end with a cutter head to.

penetrate the formation encountered. The cutter head cuts away an annular section at the bottom of the hole, leaving undisturbed a central section or core. This central section or core is received in a core tube disposed within the drill barrel. In penetrating hard formations, the receiving end of the core tube cannot be in advance of the cutter teeth of the cutter head for obvious reasons but this is not disadvantageous under these circumstances because the circulating fluid and the drilling action will not disintegrate the core as it is formed in such formations. However, the opposite is true in soft formations and consequently it is difllcult to obtain a true sample or 'core where the character of the formation varies because when penetrating soft formations with the receiving end of the core tube not in advance of the cutter head, the core is destroyed before it enters the core tube due to the disintegrating action of the drilling fluid and drilling action on the core. With prior equipment, therefore, considerable difiiculty has been experienced in taking a true core where the strata encountered are of both hard and soft formations.

Therefore, it is the principal object of the present invention to provide an improved core barrel which may be operated by a rotary rig and which is fitted with acore tube, the position of the receiving end of which will be automatically adjusted during operation relative to the cutter head of the drill barrel so that when soft formations are encountered, the core tube will penetrate into the formation in advance of the cutter to effect a full recovery and in hard formations retract to a positionto receive the core after-it is formed by the cutter head.

It is manifest that this will result in the recovery of a complete and accurate core of the formation penetrated regardless of changes in the ch'aracter thereof.

In practicing the invention 1- provide a core barrel which may be suspended from the lower end of a drill stem and operated by the rotation of the latter. The core barrel includes a drill barrel connected with the drilling stem at its upper end and fitted with a cutter head of any prcferred design at its lower end, the cutter head, of course, being designed to cut an annular section away at the bottom of the hole so as to form a central core. Arranged within the drill barrel is a core tube which is adapted to receive the core. The core tube is mounted in the drill barrel for reciprocable movement relative thereto. Operating means are also provided which constantly tend to maintain the lower end of the core tube in advance of the cutter head so that 10 when soft formations are encountered, the core tube will penetrate the same in advance of the cutter head to insure the recovery of a core. The means referred to include a mechanism for striking sharp blows to the upper end of the core tube intermittently during the operation of the barrel to advance the core tube into the formation. The position of the core tube, however, is adjusted automatically by the resistance it encounters in penetrating the formation so that in hard formations the cutter head'will be in advance of the core tube so that the latter will receive the core as it is formed.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a view of a core barrel embodying the preferred form of my invention, disclosing the same in a well bore with the drill barrel thereof in section.

Fig. 2 is an enlarged fragmentary view in vertical section showing, the mechanism with parts thereof in section which causes advancing and retraction of the core tube.

Fig. 3 is a view of the core tube, disclosing the manner in which it is connected to its operating mechanism.

Fig. 4 is an enlarged. view partly in central section through the drill barrel sub, disclosing the 40 manner in which the hydraulic cylinder is assembled therein.

Fig. 5 is an enlarged central sectional view through a portion of the core barrel and the upper end of the core tube, showing the connection between the core tube, the hydraulic cylinder arm the blow imparting mechanism.

Fig. 6 is an enlarged fragmentary view in central section through the lower end of the core barrel and core tube, disclosing certain features of construction.

Referring more particularly to the accompanymg drawings, l0 indicates a core barrel for use in obtaining samples of the formation to be penetrated in advance of drilling during the sinking I of a deep oil well.

This core barrel is what may be termed a rotary core barrel in that it is operated by rotation of the drill stem.

The core barrel 10 includes an outer drill barrel I I fitted at its upper end with a sub 82 by means of which it may be connected to the lower end of a drilling stem l4. At its lower end the drill barrel H is fitted with a drilling shoe l5, at the lower end of which is a cutter head I6. This cutter head may be of any preferred design capable of cutting an annular section away at the bottom of a hole so as to form an undisturbed cen tral section or core as the drill barrel advances through the formation.

Arranged within the upper end of the drill barrel Ii is a hydraulic cylinder ll. e upper end of this cylinder is fitted with a cylinder head i8 which is secured within the drill barrel sub i2 as most clearly illustrated in Fig. 4. Reference being had to this figure, it will be seen that the cylinder head I8 is formed with a cylindrical trunnion i9 fitting within a counterbore 26 in the sub l2. The outer periphery of the trunnion i9 is. formed with a peripheral groove 20. Latch pins 22 are threaded radially through thesides of the sub 12 and engage this groove 2! so as to latch the hydraulic cylinder into position within the upper end of the drill barrel. By removing the latch pins 22, the hydraulic cylinder ll may be readily removed from the drill barrel.

It will be noticed that the cylinder head H8 at the upper end of the cylinder H is formed with a circulating opening 23 which registers with a circulating opening 24 formed centrally in the drill barrel sub i2 so that circulating fluid pumped downwardly through the drill stem will enter the cylinder ll.

The lower end of the cylinder ill. as illustrated in Fig. 5, is fitted with a cylinder head 25 guided through which is a hollow piston rod 26. Reciprocably mounted in the hydraulic cylinder El and fixed on the piston rod 26 is a piston 21 of any preferred construction. The piston rod 26 projects through this piston and the upper end thereof is formed with a restricted port 28 so that a portion of the fluid under pressure entering the hydraulic cylinder through its upper head it will find its way into the piston rod 26 and discharge downwardly therethrough. The piston rod 26 is formed with discharge ports 29 at a point below the lower cylinder head 25 so that the circulating fluid passing through the piston rod 26 may discharge through the ports 29 into the drill barrel at a point below the hydraulic cylinder Hi. This circulating fluid passes downwardly through the drill barrel and discharges at the lower end thereso as to lubricate the cutting teeth of the head l6. Arranged within the drill barrel in is a core tube 30 which is mounted therein for reciprocable movement. The lower end of this core tube is fitted with a trimmer shoe 3!. The upper end of the core tube is fitted with a core tube sub 32 most clearly illustrated in Fig. 5. It will be noticed that this sub is provided with discharge ports 33 controlled by a check valve 36 which enables fiuid trapped within the core tube by the entrance of a core to discharge outwardly into the drill barrel through the sub 32 by means of the ports 33, but prevents the entrance of the circulating fluid in the drill barrel into the upper end of the core tube 36.

The core tube sub 32 is connected with the piston rod 26 through the medium of a percussion mechanism 35. There is a provision for a limited amount of axial movement between the piston 1011 26 and the core tube in order that the percussion mechanism 35 will be enabled to impart downward blows to the core tube as will be described, but, however, this connection enables the piston 21 in the hydraulic cylinder I! and the piston rod 26 to act as a yielding means constantly tending to advance the core tube downwardly relative to the drill barrel.

When hard formation is encountered, the fluid pressure in the cylinder I! is overcome so that the trimmer shoe of the core tube will be retracted with respect to the cutter head in order that the core will be formed prior to its entrance into the core tube. However, when soft formations are encountered, the fluid pressure in the cylinder ll will move the piston 21 downwardly and consequently advance the core tube relative to the drill barrel so that the core tube will be driven into the formation around the core prior to the forming of the latter by the action of the cutter head.

It is desired to point out, however, that during the rotation of the drill barrel and regardless of the position of the core tube with respect thereto, the percussion mechanism 35 constantly acts to impart a succession of rapid downward blows to the upper end of the core tube to aid in driving the same into the formation.

Reference being had to Figs. 2 and 5, it will be seen that the percussion mechanism 35 includes a percussion head 35 which is cylindrical in cross sectional area and of an external diameter somewhat less than the internal diameter of the drill barrel. Extending centrally downward from its upper end thehead is formed with a socket 37 into which the lower end of the piston rod 26 is reeiprocably received. Intermediate the lower extremity of the piston rod 26 and the lower end of the socket 31 is an expansion spring 38.

The percussion head 36 is formed with an elongated slot .39 which extends radially outward through the head 36 from the socket 31. The piston rod 26 is fitted with a radially extending pin &0 which projects into this socket to prevent relative rotation between the piston rod 26 and the head 36 and which likewise limits the longitudinal movement of the piston rod 26 with respect to the percussion head 36. That is to say, the piston rod will be enabled to reciprocate relative to the percussion head 36 a limited amount.

The lower end of the percussion head 36 is formed with a coaxial bore ll which extends upwardly from its lower end. Rotatably and reciprocably mounted in this bore ii is an anvil 62 which is formed as a part of the core tube sub 32. The anvil 32 is relieved intermediate its ends as at :33 and a pin (i l extends through the side of the head 36 into this relief so as to limit the axial movement of the anvil i2 with respect to the percussion head 36.

In the upper end of the bore 5! the percussion head is fitted with a hammer 65 which is adapted to engage the upper end of the anvil 12 so that when the percussion head 36 is reciprocated relative to the anvil Q2 and the core tube, the hammer 15 will impart intermittent downward blows to the upper end of the anvil 22. These blows, of course, will be transmitted to the core tube and tend to drive the core tube into the formation.

In order to obtain this action, the anvil 62 is fitted with a transverse pin'tle 38 just below the lower end of the percussion head 36. At opposite sides of this pintle are mounted cam rollers ll which are revolubly mounted on the pintle d6. These cam rollers engage an end cam 58 secured on the lower end of the percussion head 35. This end cam 48 is formed with two diametrically opposed high points as illustrated most clearly in Figs. 2 and 5.

Assuming that the core tube is held from reciprocable and rotatable movement relative to' the percussion head 36 and that the latter is re-- volved together with the drill barrel about the core tube, when the high points of the cams ride on the rollers 41, the percussion head 36 will elevate relative to the core tube and the anvil 42. When the high points pass the rollers, the fluid action on the piston 21 together with the action of the expansion spring-38 will cause rapid downward movement of the percussion head so that the hammer will strike a sharp blow to the upper end of the anvil 42. As there are two high points on the cam 48, two such blows will be struck during each revolution of the percussion head 36, and as this percussion head, as will be described, revolves in unison with the drill barrel, two downward blows will be imparted to the upper end of the core tube during each revolution of the drill barrel.

It is obvious, of course, from Figs. 2 and 5 that when the highpoints of the cam 48 are riding on the rollers that the hammer 45 will be spaced from the upper end of the anvil 42 to enable the hammer 45 to stroke the upper end of the core tube with considerable force. The force of the blow, of course, depends upon the fluid pressure and is accentuated by the action of the expansion spring 38.

In operation of the device, it is constructed and assembled as illustratedin the drawings and is made up on the lower end of a drill stem l4 and lowered thereby into the hole. When the cutter head is engaged with the formation, rotation is imparted to the drill stem l4 so as to cause the cutter head to penetrate into the formation, cutting an annular groove therein, forming a central core which passes into the core tube.

. During the operation of the drill barrel circulating fluid under pressure is forced downwardly through the drill stem l4 into the cylinder I1 and acts against the piston 21 to yieldingly force the core tube 30 in advance of the cutter head. As the lower end of the trimmer shoe 3| on the core tube is toothed, when it is engaged with the formation, it will not revolve with the drill barrel but will remain stationary.

During the period that the drill barrel is being rotated the percussion mechanism 35 will act to stroke intermittent downward blows to the upper end of the core tube to aid in advancing the same into the formation in advance ofthe cutter head I6.

A portion of the circulating fluid which is pumped downwardly through the drill stem M will pass through the restricted port 28 in the upper end of the piston rod 26 and discharge into the drill barrel through the ports 29 in the annular space between the periphery of the core tube and the inner periphery of the cutter head 16 so as to lubricate the cutter teeth of the latter. However, the relative areas of the rethe fluid pressure on the piston 21 and the action of the percussion mechanism 45 will be ineflective in advancing the core tube relative to the cutter head to any great extent so that the cutter head under these circumstances will form the core and the latter ,will enter the core tube as it is formed. However, in comparatively soft formations the fluid pressure on the piston 21 together with the percussion mechanism 35 will force the core tube downwardly relative to the drill barrel to a considerable extent and inasmuch as the core tube will penetrate into the formation in advance of the cutter head, the drilling action of the latter and the disintegrating action of the circulating fluid will be unable to disintegrate the core.

It is manifest that the core barrel which I have here disclosed will be very effective in taking a core through a formation in which the strata vary in degrees of hardness and that a reliable core will be taken through formation of varying characteristics.

While I have shown the preferred form of my invention, it is to be understood that various changes may be made in its construction by those skilled in the art without departing from the spirit of the inventionas defined in the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A core barrel comprising a drill barrel having a cutter head at its lower end to penetrate the formation to form a'core, a core tube disposed within the drill barrel and about which the drill barrel may revolve, said core tube being movable axially relative to the drill barrel, a plunger actuated by the pressure of drilling fluid in the drill barrel connected with the upper end of the core tube and exerting a constant down ward pressure thereon so as to urge the same downwardly relative to the drill barrel, and percussion means interposed in the connection between the plunger and the core tube for impart ing intermittent downward blows to the core tube during the operation of the drill barrel.

2. A core barrel comprising a drill barrel having a cutter head at its lower end, a core tube disposed in the drill barrel and capable of axial movement relative thereto, a hydraulic cylinder formed in the upper end of the drill barrel and open to the pressure of drilling fluid in the barrel, a piston in said cylinder, a connection between said piston and the core tube whereby pressure exerted against the piston in one direction constantly tends to move the core tube axially downward relative to the drill barrel, and percussion means for imparting intermittent downward blows to the core tube during the operation of the drill barrel.

3. A core barrel comprising a drill barrel, a

core tube mounted therein for axial movement relative thereto, yielding means constantly tending to advance the core tube axially relative to the drill barrel, said yielding means including percussion means for striking intermittent downward blows on the core tube operable upon rotation of the drill barrel.

4. A rotary core barrel comprising a drill barrel having a cutter head at its lower end adapted stricted port 28 and the piston 21 are suchthat to penetrate into formation to form a core, a

considerable pressure will be exerted downwardly on the piston so as to constantly tend to advance the core tube downwardly relative to the drill barrel.

In encountering hard formation the action of core tube mounted within the drill barrel for receiving a core thus formed, said core tube being mounted for axial movement relative to the drill barrel, hydraulic means associated with.

the core tube and constantly tending to advance the same coaxially of and relative to the drill barrel, and percussion means interposed between the hydraulic means and the core tube for striking intermittent downward blows to the core tube during the operation of the drill barrel.

5. A core barrel comprising a drill barrel having a cutter headat its lower end to penetrate the formation to form a core, a core tube disposed within the drill barrel and about which the drill barrel may revolve, said core tube being movable axially relative to the drill barrel, hydraulic means interposed between the drill barrel and the core tube and constantly tending to force the core tube downwardly relative to the drill barrel, said hydraulic means including a hydraulic cylinder axially immovable relative to the drill barrel, a piston in said cylinder, a connection between said piston and the core tube, and percussion means interposed in the connection between the piston and the core tube for imparting intermittent downward blows to the core tube during the operation of the drill barrel. e

6. A rotary core barrel comprising a drill barrel having a cutter head at its lower end adapted to penetrate into the formation to form a core, a hydraulic cylinder disposed within the upper end of the drill barrel, a cylinder head fitted to the upper end of the hydraulic cylinder, said head having a fluid passageway formed therethrough whereby fluid may pass through. the upper end of the drill barrel into said cylinder, cooperative latch means on the drill barrel and cylinder head for latching the latter in position suspending the cylinder in the drill barrel, a cylinder head on the lower end of said cylinder, a hollow piston rod projecting upwardly through the last named cylinder head into the cylinder, a piston in the cylinder secured on said piston rod, the upper end of said piston rod having a restricted port whereby fluid may pass downwardly through the piston rod, said piston rod being formed with discharge ports at a point below the lower cylinder head, core tube disposed in a drill barrel below the cylinder and connected with said piston rod whereby hydraulic pressure exerted on the upper end of said piston will tend to move said core tu'be downwardly relative to the drill barrel, said connection including percussion means operable upon rotation of the drill barrel to impart intermittent downward blows to the core tube.

CLARENCE E. BURT.

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