US2294521A - Removable plug for drilling strings - Google Patents

Description

Sept. 1, 1942.

` H. -V. ySTEADMAN E'lAL REMOVABLE PLUG FOR DRILLING STRINGS s sheets-sheet 1 Filed J'une 24, 1941 Figl l Ems E. Davs Bg #har A Hornzq Sept. l, 1942.

Filed June 24, 1941 Fig. lIl

H. v. STEADMAN 1-:r` AL y REMovABLE' PLUG" FOR4 DRILLING STRINGS s Sheets-sheet 2 2m www 3-O IH H mul 3o FQJY inventors: Hor-cz Vivian Sizadrnnn Ellis E. Davis,

Patentedfept. l, 1942 REMOVBLE PLUG FOR DRILLING STRINGS Horace Vivian Steadman and Ellis E. Davis, Tulsa, Okla., assignors to Shell Development Com-v pany, San f Francisco, Calif., `a corporation of Delaware Application June 24,'1941, serial No. .399,476

11 Claims. (ci. g55-72) The present invention relates to the drilling yof wells and pertains more particularly to drill string plugs or seals, which may be suitably placed in and removed from the drill string without the necessity of removing or raising the drilling equipment from the borehole.

In drilling wells by the rotary method, it is essential 4that a high ascending velocity of the drilling mud be maintained in order to remove the drill cuttings from the well. A high ascending mud velocity becomes increasingly important when the drill is making hole more rapidly, when the'cuttings become larger or denser, and especially when effecting the so-called well-cleaning operations preparatory to completing the well. For the purpose ofY increasing the ascending velocity of the mud fluid without overtaxing `the pumping equipment, it is generally the practice to apply reverse circulation, whereby the mud. iluid is pumped down the annular lspace between the drill string and'the casing or borehole and then passes up through the drill string. Due to the smaller space within the drill string the fluid passes upwards 'at a greater rate, thereby increasing the fluid carrying power for cuttings.

When employing this method of mud circulation, it is, usually necessary to enlarge the Water courses through the drill bit.

As mentioned above, it is'generally desirable to wash the wa11s-of the section of the borehole l" when this section of the bore-hole is thought to be` the producing zone, and it is expected to complete the well'andto put it on production. Heretofore, the washingwas accomplishedv by replacing the drill 'bit having enlarged water courses f with a plug or the like having small lateral jetting holes and then pumping the circulation medium down through the 'drill string and out through the jetting holes while rising and 'lowering the drill string to subject all or normally tion to provide means for eliminating the necessity of removing the drill string from the borehole while jet-washing the walls and removing the detritus accumulated after each washing.

It is another object to provide drill string plugging means insertable into and removable from said drill string by uid circulation through said string and v,capable of closing oil the watercourses through the drill bit while permitting iluid now from the drill string out-through jetting holes positioned arelatively short distance above the drill bit. Y It` is a further object to provide a simple, inexpensive, and eflicient well drill string plugging f device, which may be passed down the drill string to the desired position by means of fluid circulation. It is still another object to provide means for lowering and raising various tools in a string of invention has particular relation to certain novel ony a part of the borehole to thel jetting action. v

The detritus, which accumulates in the bottom of the borehole during jetting, is then 'removed by reverse circulation after reinstalling theirill bit. Frequently, and particularly after shooting a well with explosives, it is desirable to wash a section of the borehole several times and to remove the detritus washed down on the completion of eachv4 letting. Since each change to replace the drill bit with the jetting tool or vice versa requires withdrawing the entire drill string from the hole, the procedure of jet-washing the borehole l and removing the detritus several times is a timeconsuming and therefore costly operation.

It is, therefore, an object of the present invenfeatures of construction, operation, and-arrangement of parts, an example of which is given in this specification 'and illustration in the accompanying drawings, wherein: Y

FigureI is a view. partly in section, of a preferred embodiment of the present device as positionedY in a well drill string;

Figure II is a view similar to that of Figure I, showing the collapsed position of the present device in a well drill string during jet-washing of the borehole walls;

Figure III is a view similar tovthat of Figures I and II, showing the positionof the device just as flow is reversed to remove the device from the well drill string; i

Figure IV is an enlarged longitudinal cross-sectional view of the present device; y a

Figure V is an elevation of the present device as attached to a casing spear for plugging the' lower end of a drill string; and

Figure VI is a view, partly in elevation, showing the use of the present invention in combination with instruments for taking well cores.

Referring to Figure IV of the drawings, a preferred embodiment of the plugging device comprises a mandrel or stem I having threaded ends 2"and' 3, a lower hydraulic cup 5 coaxially and rigidly attached adjacentpne end of said mandrelk I, and an upper hydraulic cup 6 vcoaxially and slidably mounted on said mandrel I.- The cups 5 and 6 may be single, as shown, or mul- 2 tiple units and are adapted to withstand the fluid pressure imposed upon them. The lower hydraulic cup is upwardly flared; that is, it has a concave upper face 1, allowing pressure applied thereabove to expand it. The upper cup 5 has a concave lower face 5, opposing the face 1 of the lower cup 5. The cups maybe of any suitable design, and are made of -elastic or exible material such as, preferably, natural or synthetic rubber, or other suitable materials, for example, can-l vas, rubberized canvas, etc. The cups 5 and 5 are preferablyreinforced by protective metal rings Il within the axial bores II of said cups, and by a plurality of wires I2 attached at one end to said ,rings III and passing therefrom to and along or position. The cups 5 and 5 may be further rein-k forced by means of annular 4thimbles -or rings having tapered faces 2I `complementing and abutting the convex faces of said cups.

The lower cup 5 is rigidly held in place on the lower end of the mandrel I by means of a plug nut 25 screwed onto the threaded end 5 of the mandrel and abutting the annular thimble 2l on one side of the cup 5 and by means of a tubular follower v25 abutting the cup 5 and reinforcing ring I0 on the other side of the cup 5. The

plug nut 25 is suitably prevented from loosening by means of, fonexample, lock screws 30. Simi- -lar lock screws 5I or the like prevent movement of the tubular follower 25.

A nut 35 and lock nut 36 are screwed onto the other threaded end 2 of the mandrel I and constitute stop means against which the movable 4 cup 5 is preferably normally held by suitable resilient means, such as a coil spring 4|! surrounding the mandrel and acting between the stationary tubular follower 28 and a slidable tubular foltions for which the present device is adapted, the

l spring 45 or other resilient means is not absolutely necessary. When/the resilient means is omitted as for some purposes, it is preferable that some suitable spacer means be provided between the cups to stop movement of said slidable cup i toward the fixed cup 5 at a predetermined distance away from said fixed cup so that'the cups will be prevented from coming together in such a way as to prevent fluid from acting against. the concave facesf of the cups to expand them. In the preferred embodiment described above, the followers 26 and 4I, which project out fromthe concave faces of the cups', readily serve as stop means for this purpose. If desired, both cups 5 and 6 mayrbe xedly attached adjacent the respective ends of the mandrel I; however, for most purposes, greater efficiency and-facility of action -of the device is obtained when some auch resil- .ient means is provided.

l lower 4I similar to follower 25. For some operai vin connection with jet-,washing the borehole and depending thereinto a drill pipe'string 5I, to the lower end of which is attached a drill bit 53 having a water course or courses 54 passing therethrough. The lower section of the drill pipe string 5I is provided with lateral jetting holes 55 at a relatively short distance above the lower end of said string, and, preferably, with a non-nowrestricting stop means, such as a pin 51 bridging the bore of the string closely adjacent the lower end thereof. If desired, a special tube or pipe containing the ietting holes 55 andthe stop pin 51 may be inserted between the lower end of the drill string 5I and drill bit 53. Likewise. the shank of the drill bit 53 may serve as stop means A instead of any special means, if desired.

When it is desired to jet-washv the walls of the borehole after drilling with reverse circulation, the path of the circulationmedium is directed so that the nuid passes in the regular manner down through the drill string 5I out through the water courses 54 in the drill bit and up to the surface' through the annular space between the drill string 5I and the walls of the borehole 50.

l Ihepresent plugging device is then introduced into the'drill string and is forced down within the drill string by the pressure of thecirculation medium above it acting upon the lower and statlonary hydraulic cup 5, which is expanded against the walls of the drill string by said pressure, as shown in Figure I. The plugging device travels down ,through the drill string until the plug nut 25 on the lower end contacts the stop pin 51. At this point in the procedure, the spring 4l is still expanded and the upper cup 8 is positioned above the jetting holes or ports 55, as

shown in Flggure I. With a further increase in pressure of the rcirculation medium occurring when the device is stopped by the pin 51, the upper slidable cup I is forced downwards against the action of the spring 40,' thereby exposing the jetting ports 55 to the full 'force of the pressure of the circulation medium, as shown in Figure 1I. With thev water courses 54 in the -drill bit closed by the expanded lower cup 5 and with the jetting ports I5 exposed, the circulation medium flows at a high rate out through the small jetting ports" ycup 5 expands into sealing engagement with the drill string walls. On continued ow of circulation medium. through the water courses 54 and thejetting ports 55 into the drill string 5I below the cup 5 the plugging device travels up-kr ward to the-surface of well, where it inay be removed from the drill string. Reverse circulation may then be continued to" remove the detritus which hasiaccumulated inthe bottom of the borehole during the jet-washing.

Y tion of the above-described device. when used '75 Drilling maythen ,be resumed. or by again insetting and removing the plugging device the borehole -walls 'may be jet-washed and the detritus removed any number of times before resuming drilling without at any time having to remove the drill'pipe string yfrom the borehole. It may be i'eadily seen that according to the present invention the considerable time necessary for removing and replacing the drill string after and before each operation is obviated. Further, the present plugging device may be used in combination with various well tools for positioning said tools in a drill pipe string or tubing string and for removing'said tools thereffrom. Referring to Figure V,- one highly advantageous combination iswith a casing spear or similar inside gripping means. In the event that the formation pressures become suicient to displace the fluid'frorn the well, thereby causing a disastrous situation commonly known asa blow out, it becomesfnecessary to plug the drilling string in order to avoid hazard to the well, personnel, and farm land. To prevent such an occurrence, there may be inserted into the drill string and forced downward therethrough the combination of the plugging device of the present invention with means for grippingthe walls of the drill string, which means move into wall-grip 25 barrel. The lower end of the core barrel 90 is ping engagement upon'I upward movement thereof. For this purpose, the plugging device may be inverted, as shown, and the plug nut 25 replaced by any suitable inside wall-gripping means, such as, for example, a casing spear generally designated as 10. The spear 10 may, for example, comprise a mandrel 1| having lateral recesses 1.2 provided with downwardly diverging tapered faces 13, as shown in Figure V. Tapered slips 14 having horizontal teeth 15 on their outer commonly known as a pack-off rubber," aids in effecting a stronger seal against the high pressure differential across the plugging device. By means 5 of this combination of the plugging device with a casing spear, the drill string can be removed from a flowing well while maintaining said well under control. l

As a further example of one of the many uses l o i' the present invention, theplugging device may be used in connection with meansfor obtaining cores from a well. With the present device a core b arrel may be removed from the weil, the cores emptied from the core barrel, and the core barrel l reinserted into core-taking position without re- 2 0 of the plugging device by means of a coupling 9| containing', if desired, an upwardly-opening ball valve 92 or .the like, which provides a one-way passage for fluid flow from the inside of the core barrel 90 to the annular 'space outside the core taking, as shown in Figure VI, the tapered face 93 on the lower end of the core barrel 90 seats in a complementary tapered internal shoulder 96 of the core bit head 91., which is provided withA water courses 98 to allow circulation of drilling iiuid vertical sides are adapted to slide downwardly therethrough. The bit head 91 is attached to and outwardly on the tapered faces 13 intov Wall-gripping engagement upon upward movement of the mandrel 1|. Said slips 14 are held in slidable engagement with said tapered faces 13 by means of engagement of a key 16 and key way on each face 13 and slip 14, respectively, as shown in Figure V, or vice versa. It is often advisable when so using 'the plugging device to substitute, asshown in Figure V, a tubular mem-l ber 18 of rubber or like vmaterial for the sp1-ing A40 to assist the upper cup in sealing ofi the drill string as described below. If desired, instead of gripping means attached above, as shown, or below the plugging device, as just described, Aa dog- 'mechanism or the like may be carried between forces the combination assembly down to the de` sired position. By metering the amount of uid introduced into the drill string after the device is inserted, the position of the device is accurately known. 'When the' device reaches the desired l position, the pressure on the fluid above the device is released, allowing the full well pressure to act against the cup 5. The cup 5 is thereby expanded into sealing engagement with the walls of the drill string and caused to move slightly upward. The upward movement of the mandrel 1| carried by the plugging device causes the toothed slips 1I to be moved outwardly along the tapered faces 13 of the recesses 12 into engagement with the walls of the drill string. The plugging device is thus held in the |desired position within the drill string and thesealing action of the cup 5 prevents upward ow of well fluid through the drill string, thereby bringing the ,well under-control.

the lower end of a tubular member |00, which is in turn attached to the lower end of the drill string 5|. The tubular member 00 has a thickened portion |02 disposed so that, when the assembly of the plugging device and the core barrel is properly vpositioned for core taking, the lower cup 5 is within the thickened portion |02. The

thickened portion |02 is cut away to form vertical slots |03 allowing [fluid to by-pass the lower sition, as shown inv Figure VI, drilling iiuid is circulated down through the drill string 5| past 5 the upper cup 6 and through the slots |00 in the ,thickened portion |02 of the tubular member |00 past the lower cupi vand thence down through the annular space` |0| between the corebarrel 90 and the tubular member |00 and out through 55 the watercourses 98 in the core bit head 91 into the .borehole and up through the annular space between the tubular member |00 or drill string 5|J and the bore hole 50. The pressure againsty the lower cup 5 of the fluid passing downpast it holds the core barrel 90 in seated position in Coring proceeds with fluid circulation in this manner until the core taken the drill bit head 91.

,lls the core barrel v90. I' 'I'he core barrel 90 containing aV core held therein by means of catchers 95 and the plugging device attached thereaboveY` is then removed from the-tubular member |00l and drill string 5| by reversing the direction of fluid circulation. In addition to the imposition of fluid pressure against'the lower extremiiyof 7 the core barrel, the pressure of the fluid passing 5- the surface by ymeans of iluid circulation.

The tubular member 10, such as a rubber sleevev After removing the core barrel from the well and emptying the core therefrom, the assembly may be reinserted into the drill string and forced down through drill string 5I by yfluid pressure thereabove into position for taking another core.

Thus, it may be readily seen that. the use of the plugging device in combination with a core barrel oers the outstanding advantage of tak. ing an unlimited number of well cores without removing the drill string from the borehole after coring is started, thereby effecting a considerable saving of time and expense.

' It will be readily understood that thel drawings and description are illustrative onlyv of preferred embodiments of the present invention and that various modifications may be readily made without departing from the scope of the inventiom'.

as defined in the appended claims. Thus, for example, the plugging device may be used to advantage in combination with various tools other pand against the walls of the well pipe when uid flow is directed against their concave sides.

6. A well pipe tool adapted to pass to and from a desired position in a well pipe by fluid flow through said pipe, said tool comprising a mandrel, a hydraulic cup rigidly fixed coaxially on said mandrel adjacent one end thereof and having its concave side facing toward the other end than those indicated and, likewise, modifications Y may be made in the plugging device itself.

We claim as our invention: 1. A well pipe tool adapted to be moved within va well pipe by uid circulation, said tool comprisinga mandrel, and two opposed hydraulic,

adapted for limited slidable motion on said mandrel.

2. A well pipe tool adapted to be moved within a well pipe by fluid circulation, said tool comprising a mandrel and two hydraulic cups coaxially mounted on said mandrel and having their concave faces directed toward each other, one of said cups being rigidly fixed on said mandrel adjacent one end thereof, and the other cup being adapted for limited slidable motion on said mandrel.

3. A well pipe tool adapted to pass to and from a desired position in a well pipe by fluid flow through said pipe, said tool comprising a mandrel; a hydraulic cup` rigidly fixed coaxially on said mandrel adjacent one end thereof and of the mandrel, a second hydraulic cup slidably and coaxiallyi attached to said mandrel, the concave side of said second cup facing the concave side of said fixed cup, and resilient spacer means adapted to hold said slidable cup normally at a predetermined distance from said fixed cup.

'7. A well pipe tool adapted to pass to and from va desired position in a well pipe by fluid flow through said pipe, said tool comprising a mandrel, a hydraulic cup rigidly xed coaxially on said mandrel adjacent one end thereof and having its concave side facing toward the other end of the mandrel, a second hydraulic cup slidably and coaxially attached to said mandrel, thef concave side of said second cup facing the concave side of said' fixed cup, and resilient spacer means disposed between said cups and adapted to hold said slidable cup normally at a predetermined distance from said fixed cup.

8. A pressure shut-oil' device for well pipe strings, said device comprising a mandrel provided with gripping means adapted to engage the internal walls of said pipe upon upward movement of saidv mandrel, means to position said device within saidpipe by a downward fluid now, said means comprising an upwardly ilaring hydraulic cup coaxially carried by said mandrel, and means for engaging said gripping means with the pipe walls by `a reversal of said fluid flow, said means comprising a downwardly aring hydraulic cupcoaxially carried by said mandrel.

9. A pressure shut-off device for well pipe strings, said device comprising a mandrel prohaving its concave side facing toward the other end `of the mandrel, and a second hydraulic cup coaxially attached to said .mandrel and adapted for limited slidable motion thereon, the concave side of said second cup facing'the vconcave side of said fixed cup.

4. A well pipe tool adapted to pass to and from a -desired position in a' well pipe by uid flow through said pipe, said tool comprising a mandrel, a hydrauliccup rigidly fixed coaxially on said mandrel adjacent one end thereof and having its concave side facing toward the other mandrel,'a hydraulic cup rigidly fixed coaxially on said mandrel adjacent one end thereof and having its concave side facing toward the other end of the mandrel, and a second hydraulic cup coaxially attached'to said mandrel and adapted for limited slidable motion thereon; the concave side of said second cup Afacing the concave side t of said gated cup, said cups being adapted to exsaid barrel coaxially therewith, and means for vided with gripping means adapted to engage the internal walls of said pipe upon upward vmovement of said mandrel, means to position said device within said pipe by a downward uid flow, said means comprising an upwardly flaring hydraulic cup coaxially carried by said mandrel, means for engaging said grippingfmeans with the pipe walls by a reversal of said uid'flow,

said means comprising a downwardly flaring hydraulic cup coaxially carried by said mandrel,

one of said cups being fixedly attached to said mandrel and the other being adapted for limited slidable motion thereon, and a resilient-spacer sleeve lcoaxially carried by said mandrel between said hydraulic cups, said sleeve being adapted to be deformed into contact with the pipe walls by a motion of saidl movable cup toward said fixed cup.

10. For'use in coring operations in combination with a drill string having a core bit and an v internal axially segmented restriction above said bit, a coring tool comprising a core barrel adapted to seat within said bit, a mandrel, valved means for rigidly afllxing said mandrel above seating said barrel within said bit and for removing it 4therefrom by fluid circulation, said means comprising an upwardly flaring hydraulic i cup coaxially carried by said mandrel and adapted to register with said segmented restriction in the drill string when the core barrel is seated within the bit, a downwardly flaring hydraulic cup coaxially carried by said mandrel above said first cup, one of said-cups being xedly attached tothe mandrel and the other 'adapted for limited axial motion thereon, and resilientV spacer means for normally maintaining said cups at a small la'teral jet ports in its lower portion adjacentsaid bit, a mandrel having at its lower end an upwardly flaring 'hydraulic cup fixedly attached thereto and at its upper end a down- `wardly ilaring hydraulic cup axially-'slidable on said mandrel towardssaid ilxed cup, resilient means spacing said cups on said mandrel, said mandrel being adapted to be pumped .down the drill string by liquid circulation, stop means for arresting said mandrel adjacent the drill bit,

whereby said lower'cup is caused to close the bit opening and said upper cup is maintained above said lateral ports, means for slidingly forcing said upper cup on said mandrel to a position below said ports by applying hydraulic pressure within the drill pipe, and means to remove said mandrel to the surface by reversingthe direction of the liquid circulation.

HoRACE VIWANV STEADMAN. ELLIS E. Davis.

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