US2076063A - Core barrel - Google Patents

Description

April 6, 1937. Q E BURT 2,076,063

CORE BARREYL Filed Nov. ,'23,v 1955 f /9 17" .3. N/ L Tg X5@ Sar l 2O A Patented Apr. 6, 1937 CORE BARREL Clarence E. Burt,

Baker Oil Tools, Inc.,

Los Angeles, Calif., assigner to Huntington Park, Calif.,

a corporation of California Application November 23, 1935, Serial No. 51,281

4 Claims.

This invention relates to oil well drilling tools and particularly peains to core barrels. i

Rotary core barrels for taking samples'or cores of formation to be penetrated by the well bore 5 are in general use. Thesecore barrels usually comprise an outer drill barrel fitted with a bit at its lower end, which barrel is revolved by the drilling stem to cut or form a core. Arranged within the drill barrel is a core recovery tube which passes over the core as the core barrel advarices through the formation, the core remaining in this core recovery tube when the drill barrel is removed from the bore. The drilling fluid is usually pumped downwardly through the drilling stem, thence between the drill barrel and the core tube to discharge at the bit. Prior core barrels have not been entirely successful due to the fact that it is extremely seldom that a true core of the entire formationpenetrated is recovered. In fact, the percentage of recovery has been small and has depended upon the character of formation being cored and the eiiiciency of the particular core barrel employed as well as the expertness of the driller.

It is the principal object of myinvention to provide an improved rotary core barrel capable of eiiectinga maximum recovery of a core from the formation penetrated by the core. barrel.

I accomplish this object by providing a core barrel having a drill barrel within which a core recovery tube is suspended. I utilize the drilling Iiiuid pumped downwardly to the bit to create a suction tending to evacuate the core recovery tube lfrom its upper end, and thereby creating a reduced pressure area within the core tube so that the differential pressure between the interior pressure in the core tube and the external pressure in the well bore will aid in projecting the core upwardly into the core tube and thus insure aSmaximum recovery.

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

Fig. i is a central vertical section of a core barrel constructed in accordance with my present invention.

Fig. 2 is a view in section and perspective of the water-jet pump portion of my core barrel.

Fig. 3 is a transverse sectional view taken on line III-III of Fig. l.

Referring more particularly to the accompanying drawing, I0 indicates a rotary core barrel 65 which comprises a drill barrel II fitted at its upper end with a sub I2 by means of which it may be (Cl. Z-72) connected with the lower end of a drilling stem. The lower end of the drill barrel I I isfltted with the usual bit I4 for penetrating into the formation when the drill barrel is revolved by the drilling stem to form a core I5.

Suspended concentrically within the drill barrel II is a core recovery tube I6, the lower end of which is fitted with the usual core trimmer shoe IIwhich also is provided with a suitable type oi core catcher I8. It will be noticed that the external diameter of the core recovery tube I6 is somewhat less than the internal diameter of the drill barrel II so that anannular space 4occurs therebetween through which the drilling iluid may travel from the drill stem to the bit I4.

The upper end of the core recovery tube I8 is tted with a two-part core tube head I9, consisting of a lower portion 20 and an upper portion 2l which are threadedly connected as illustrated. The upper' end of the core tube head I9 is conv20 nected to the sub I2 vby a suitable swivel connection 22, which enables the drill barrel I I to revolve relative to the core-tube I6 and its head I9. but which prevents relative axial movement therebetween.

It is intended that 25 when the core barrel here disclosed is in' operation, that the drill barrel II revolve so that it will advance into the formation, while the core tube I6 will advance axially with the drill barrel 'so that it will pass over the core, but due to its swivel connection with the drill bar-` rel, it will not revolve.

lFixed by welding or any other suitable connection within the tubular lower portion 2li loi the core tube head I9 is a strainer body 23, which" is hollow and cylindrical. At its'lower end the interior of thisk strainer body 23 is formed with a restricted passageway 24 having a valve seat 2l at the point where it joins the interior of the body 23. A ball valve 26 is adapted to seat on this seat 25 to prevent the passage of iiuid downwardly into the upper end of the core tube. The lower end of the' strainer body 29 below the restricted passageway 24 terminates in a strainer It will be noticed that the strainer head -23 is provided with vertical, channels 28 extending from its upper to its lower end, so that fluid from within the core tube I6 may pass upwardly through the strainer 21, and thence upwardly past the' strainer head 23 through the channels 29, which channels will occur between the interior periphery of the lower portion 2l! of the core tube head I9 and the strainer head 23. Likewise, iluid from the core tube may passupwardly through 55 the restricted passageway 24 by unseating ,the valve 26 into the interior of the strainer head 23. Radial ports 29 are formed through the sides of the strainer head 23 between the channels 23, which ports register with similar ports 30 formed through the wall of the lower portion of the .core tube head I9. Therefore, when iluid passes upwardly through the restricted passageway 24 by unseating the valve 26, it will then pass into the interior o1' the strainer head 23 and may discharge through the ports 29 and 30 into the annular space between the core tube and the drill barrel.

Arranged concentrically within the core'tube head I9 above the strainer head 23 is a nozzle 3|, the lower end of which iits in a counterbore 32 formed within the upper end of the strainer head 23. The upper end of the nozzle rits within Athe bore 34 oi' the upper end of the lower portion 20 of the core tube head I9. A gland 35 is threaded into the upper extremity of the lower portion 2|l of the head I9 to secure the nozzle .3| in position.

It will be noticed that the diameter of the bore of thenozzle at its lower extremity agrees with the internal diameter of the strainer head 23, while the internal diameter of the nozzle at its upper extremity agrees with the internal diameter of the/gland 35.

It will therefore be seen that due to the/fact that the upper portion 2| of the core tube head I9 is hollow, cylindrical and open-ended, that drilling fluid pumped downwardly through the drilling stem will pass into the upper end of the core tube head I9 and then must pass downwardly through the nozzle 3| and thence outwardly through the ports 29 and 30 into the annular space between the core tube and the drill barrel. It may pass downwardly through this annular space and discharge at the bit in the usual manner.

I utilize the drilling iluid to create a suction in the upper end of the core tube to partially evacuate the latter and thereby create a differi ential pressure between the interior of the core tube and the exterior thereof. This differential in pressure aids in projecting the core upwardly into the core tube so that a maximum recovery of the core will be edected.

It will be noticed that the nozzle 3| is in the form of a Venturi tube so that when the drilling uid passes downwardly therethrough, its velocity will be increased. Small oriiices 36 are formed through .the wall of the nozzle 3| just below its restricted throat so that the iluid passing downwardly through the nozzle will create a suction through these orices 39. Due to the fact that there is an annular space within the core tube head I9 surrounding the nozzle and communicating with the orifices 36, whichannular space communicates with the interior of the core tube at its upper end through the channels 28, the suction created through the orifices 38 will draw the uid in the core tube I8 upwardly and discharge it through the oriilces 36 into the drilling fluid stream. In other words, there will be an evacuating action tending to evacuate the core tube and reduce the pressure therein to a pressure under that in the surrounding well bore. It is obvious that the differential in pressure will tend to force the core upwardly into the core tube.

What I have done in effect is to provide a water-jet pump with its suction communicating with the interior of the cor'e tube at its upper and thence downwardly through the core tube to wash the same out before commencing coring operations.

After the washing action has, been complete,

the ball valve 26 is dropped downwardly throughthe drilling string where it will iind its seat on the seat 25. The drilling string is then revolved and suiiicient weight is employed so that the drill barrel II will advance through the formation, cutting `an annulus therein and forming the core I5, which will be in alignment with the core recovery tube I6, so that it will project thereinto.

While the drilling is going on, drilling fluid under considerable pressure is continuously pumped downwardly through the drilling string to lubricate the bit I4. This drilling iluid will pass downwardly through the upper portion 2| of the core tube head I9 and thence pass through the nozzle 3| and discharge through the ports 29 and 30 to the annular space between the core tube and the drill barrel. It will, of course, travel downwardly through this annular space to discharge at the bit. During the passage of the drilling fluid through the nozzle 3|, its velocity will be accelerated due to the Venturi shape of the nozzle 3| and will create a suction through the oriilces 3B, tending to create a partial vacuum in the space surrounding the nozzle 3| which is in communication only with the upper end of the core tube. This-will, of course, tend to evacuate the upper end of the core tube and will reduce the pressure therein to a'pressure lower than the pressure in the surrounding well bore. The diierential in pressure will tend to force the core upwardly into the core tube and insure a maximum recovery thereof.

It is obvious from the `foregoing that I have provided a rotary core barrel which is lcomparatively simple in construction and operation and which will be effective in obtaining a maximum core recovery of the formation penetrated.

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 invention as defined in the appended claims.

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

1. A rotary core barrel including a drill barrel adapted to be connected to the lower end of a drill stem in a manner where circulating iluid pumped downwardly through the drillstem will enter the upper end of the drill barrel, a core tube mounted within the drill barrel, a central nozzle member arranged within the drill barrel with its upper end in the line of flow of iluid from the drill stem and its lower end in'communication with the space between the drill barrel and the core tube, said nozzle having oriilces therein in communication with the interior of the core tube whereby the ilow of iiuid through said nozzle will create a suction through said oriilces tending to evacuate the core tube.

2. A rotary core barrel including a drill barrclldlptedtobeconnectedtothelonrend of a drill stem, a core recovery tube suspended in said drill barrel, there being an annular space between the exterior of the. corey tube and the interior of the drill barrel, a rotary connection between the upper end of the core tube and the drill barrel enabling fluid from the drill stem to be pumped therethrough into the annular space between the drill barrel and the core tube but not into the upper end of the core tube,

a nozzle incorporated in said connection through which the uid must pass, said nozzle having orices in communication with the interior of the core tube whereby the flow of fluid through the nozzle will create a suction through said orifices l5 tending to evacuate said core tube.

3'. A rotary core barrel including a drill barrel adapted to be connected to the lower end of a drill stem, a core recovery tube mounted therein, a swivel connection suspending said 20 core tube Within the drill barrel, said swivel connection including a. nozzle in the form ofa Venturi tube through which uid pumped downwardly through the drill stem must the lower end of said nozzle being in communication 25 with a space between the exterior of the core bular membersuspended within said outer` tu- 10 l bular member in a manner permitting the outer tubular member to rotate relative thereto, the upper end of the inner tubular member being closed to the flow of fluid pumped downwardly through the drill stem into the upper end of the outer tubular member, anozzle in the form of a Venturi tube Within the upper end of the outer tubular member through which the ow of iluid from the' drill stem must pass, said nozlzle having oriiices formed therein in communication with the inner tubular member whereby a. ow of fluid through the nozzle will create a suction through said orifices tending to evacuate said inner tubular member.

` CLARENCE E. BURT.

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