US2422031A - Hydraulic well drilling device - Google Patents

Description

June 10, 1947. E. MERTEN 2,452,031

HYDRAULIC WELL DRILLING DEVICE Filed June 19,- 1944 3 Sheets-Sheet 2 Invznfor: Euqzn- Mel-fen June 10, 1947.

E MERTEN HYDRAULIC WELL DRILLING DEVICE 3 Sheets-Sheet 3 Filed June 19, 1944 Fig. u

lnvemor: Eugen Mel-fen Patented June 10, 1947 TED STATES PATENT o Fri-cs HYDRAULIC WELL DRILLING DEVICE iEugen Morten, Houston, Tex, assi gnor :to shell Development (Jumpany, San Francisco, ,Calif., .a corporation of Delaware Application June 19, 1944,'Serial No.'540,9'89

.The present invention pertains'to the drilling of Wells, exploratory lboreholesrand therli'ke, and "relates more particularly ito an improved hydraulic drilling device.

.Botlrrotary tools ian'drcablet-tools of the percus- It is thereforman object cof this invention to i provide :a drilling device especially adapted 'for "drillinggat anydesirable depth, through extremely :hardformations; the: impact actionzofitheconsiderable'mass vof thepresent'drilling device being efiectivein'cracking thin formations orvlayers of .r'ha'rdyrook. Sincethisimpact-action is notdependent onithe :degree of sharpness of the drill bitgthe'necessityvof replacing-worn out bits is i re- .duceditoaaiminimmn sandra,rapid rate ofipenetra- 'tioirinto eitherthin or tthickrhard formationsis 1 achieved.

it is also an :object.zofithisxinvention'to :provide a hydraulic drilling system wherein the reciproeating action of a: percussion" typesbit iszoontroll'ed b avaive responsive.to idiffierentialipressures generatecli'hy the fiowrof a; *hydrauliciorpressure *fluid through the bit.

It is .also *an obj ect Oflthisxl'IlVEIltiOIl "tdprovide "arhydrauiic "drilling device of'tthe percussion type capaib-le of :.operating with :a variable downward stroke, :which :is =.indenemient .of the rphysical dimensionsaoithe ireciprocatingmembers involved, :wherehy :the'rnecess'ity 0f rigorously maintaining the;;dr'i11ing device sat acritical distance from the Thottom of therhoiesis eliminated'rwithoutiimpairthe efficiency of =1 the rep erations.

It: i also ian-iobject tof': thiSliIlVEIltiOiItO :provide ioiidriliiirg systemra'vh-ich combines-the grinding "acation ofi-the rotary :tooi' wit'lrithe reciprocating :or impactingractioirof thecoahle toolgand thus poszsesses'xthe advantages of-1both driilin'g methods.

Ibis-also; ans-object of this i invention *to provide 'a' drilling system"whereins arotary land are'ciprocatingiinotion .isiirnnarted ito the 'bit .by rhydraulic lmeans bysupplying to the hit an actuatins tream of--:a pressure liquid thronghsa drill string rsuch -as used --inrotary systems.

It is also an object of this ii ivQlllliQ litfilpl'fl i lfi '9 Claims. (Cl. 2554.4)

suitable -:f or use "with the 2 a drilling system z-adapted to drill boreholes hav- :ing a :diameter:largerthanthat of the-rdrill bit used inadrilling.

It is also an object of this;invention-toprovide aidrilling systemwherein a nangerouslyworn condition of '1 the drill'iibitais indicated to the mperator byra rise in the pressure of the hydraulic iflu-id,

andth e drillingis automatically stopped-by means positioned, within the bit.

i'I 'hese andother objects-iofithis invention will be Ill'ldBlStOfiid from the following description, "taken with reference to the attached @drawings, "wherein Fig, L1 i is a diagrammatic view in l vertical crosssection of a preferred embodiment-of the-present drilling device;

"Fig. 1A i519, fragmentany vie-W oba'modification of :the deviceotFig. 1;

:Fig. .2 is another view of a modificationof the device of-Fig. 1;

:Fig. :3 is. a diagrammatic view inwvertioalcrossssection -of another --embodiment of the "present 1 drilling 1 device;

Fig: 4 is: a similar viewof a-modifieation. ofithe device of Fig. 3;

Fig. 5 is :a horizontalcross-section view taken along line 55"of.Fig. 3; y

Figs. 6 and '7 are, respectively, an: elevation and a horizontal"cross-section view-of -a=idrill bit suitable :foruse' with the system of the: present inven- :Figs. 6A and :7 A are-similar views of anothernhit suitable for use with the system of the p1".esent invention;

:Figs. S-rand '9 .are similar 'views-,0f another bit system of 1 the present invention;

Fig. .10 is a view, partly in eross section, ofithe :presentidrilling deviceprovided-With aclutch arrangement for rotary application;

Ties; ll-and 12 areidiagrammatic views of-a ibi-t arrangementadaptedto prevent damage .to ,the .mechanism of the present drillingrdevice throiigh the wear of the drill bit;

1318 -2, diagrammatic :viewin vcross-section oi awvalve arrangement. adapted tomaintain the hydraulic-fluid of .thelpresent system within predetermined pressure and circulation volume ranges;

Fig. i 14 is -a view, partly1in-.eross-section, of a modification of the upper part of the. mechanism shown? inFigs. 1' and .2.

Ref,erring to the drawings Fig. :1 showsindia- ,grammaticirfor-m a preferred embodiment .of .the

A presenthydranlio :drilling device, all. conventional sage IS. A spider plate I3, having passages ISA therethrough, supports a plate or cap member I I within chamber I above the passage I6. Lateral ports 9 provide for fluid communication between the inside and the outside of the string I.

The drill stem together with elements I5 and I9 forms a. stationary piston member with regard to a movable cylinder member 5, having a central bore 7 adapted to fit slidingly about said piston, said cylinder being suitably closed at the top and at the bottom, as shown at 2 and Packing elements may be provided between the piston and cylinder members as shown at 3 and I7. The lower par-t of the cylinder 5 may be integral with, or may have attached thereto, a cutting element or a drill bit having any desired number of cutting blades 21, such for example as a, fishtail bit.

' Carried within the piston I 5 between the transverse plates I3 and I9 is a movable valve member 8, having a cup-shaped hollow upper portion 4A and, if desired, an elongated stem member I8 depending therefrom. A very small-diameter channel I2 is in fluid communication between the space 4 within the hollow valve portion 4A and the space outside of said valve, The size and shape of the member 8 and of the channel I2 are selected so that the outer orifice or orifices of said channel are at the level of a constricted part of the flow passage through the piston when the cup member 4A abuts the cap member I I, for example, as shown in Fig. 1, for purposes to be described hereinbelow. The piston passage I6 is provided with seat I4 for the valve member 8, which is adapted to close said passage when moved into its lowermost position as shown in Fig. 2.

Exhaust means, such as a passage 25, are provided for flushing into the borehole the fluid from the space within the cylinder.

A pin or finger member, such as a. spring 2I is provided within the lower portion of the cylinder 5 in register with the stem I8 of the valve, being supported for example by means of a Web structure 23.

The operation of the present drilling device is as follows: a hydraulic fluid is forced under pressure downwards through the drill string I, the valve 8 being at that time in its lowermost position against the seat I4. The central passage I6 being thus closed, as shown in Fig. 2, the fluid passes through the ports 9, and the pressure developed within the bore or space I above the piston forces the cylinder 5 upwards with regard to the stationary piston I5-I 9 thus raising the bit 21.

As the moving cylinder comes to the upper limit of its stroke, the pin or spring means 2I strikes the valve 8 and raises it until it comes in contact with the cap II. The passage I6 being thus open, the hydraulic fluid flows therethrough from the drill string I, and also from the space I of the cylinder, and out into the borehole through the passage 25. The cylinder 5 moves down by gravity, impacting the blades 21 against the bottom of the borehole. As the downward motion of the cylinder begins, the yieldable means 2 motion of the movable member.

4 previously compressed against the valve 8, expands to its full non-stressed length, thereby still remaining in contact with said valve during a short initial period of the downward stroke. This maintains the valve 8 pressed against the cap II during said initial period, and permits the flow of the fluid through the piston to create, by the Venturi effect, a pressure difierential between the relatively restricted passage I6 and the space above and below. The reduced pressure within the restricted passage is transmitted, through the channel I2, to the space 4 within the cup-shaped valve, whereby said cup is firmly held by said pressure-differential or suction-cup efiect, against the cap member II during the downward stroke.

As the bit strikes the bottom of the borehole, and the downward motion of the cylinder 5 is stopped, the rate of the fluid flow through the passage I6 is decreased, no more fluid flowing from the space I, The differential pressure holding the valve 8 up is thus decreased; and the valve drops down on the seat I4, closing the passage I6, whereafter the upward stroke of the cylinder is repeated.

Instead of the construction shown in Fig. l, the cup-shaped valve member 8 may be formed without the depending projection I8, as shown in Fig. 1A, In this case, the low pressure prevailing under fluid flow conditions in the relatively constricted passage I3B is applied by means of a small communication passage or channel I2A to the inside of the cup 8A, which is thus maintained pressed, by the relatively higher pressure in space I5A, against the cap IIA during the downward The operation of the device of Fig. 1A is in all other regards: identical with the operation of that of Fig. 1.

It will therefore be seen that the valve structure of the present hydraulic drilling device has the advantage of not requiring any spring means for holding said valve in position, the holding effect being provided by pressure differential means, and. all difiiculties usually encountered in adjusting valve springs for properly timed operation under conditions of varying pressures being thereby eliminated. The great advantage of the present system resides however in its ability to operate with a variable length stroke. It will be seen that with the arrangement shown, valve 8 will close and thereby reverse the direction of the stroke whenever the bit hits the bottom of the borehole and thereby arrests the downward motion of the cylinder, whether or not the cylinder has at this moment reached the lower limit of its stroke, as determined by its position with regard to the stationary piston. The present variable stroke system thus eliminates the necessity of continuously and accurately correlating the level of the piston 65, that is, the length of the drill string, with the level of the bottom of the borehole or with the rate of penetration of the bit.

Fig. 2 shows a hydraulic bit similar to that of Fig. 1 and operating on the same principle, but provided with an additional spring 3!, which is compressed between the stationary piston and the bottom of the movable cylinder during the upward stroke of the latter. The spring 3| serves to accelerate the bit additionally to the elfect of gravity during the downward or impact stroke.

The bit of Fig. 2 is also provided with a valve 35, which serves to close the exhaust passage 25 through the bit when depressed downwards against the action of a spring 37, engaged between said valve and a spider 38 and tending to hold the valve up.

The operation oftlfiszv-alveis as follows: when the cylinder .5 is :aboutto reachlthe .end of .its

upward stroke, zthexspring 33 which corresponds to '.the:- spring :24 of :Fig. 1, lifts the upper :valve :8 *from-itsseat, openingthe passage I26. The valve -43 is pressed againstthe :cap H andactsttonompress first the. spring .33 and :then the springt3l, :thusclosing the lower valvex35. AsJthe cylinder reverses :its motion, the bit is. impactedagainst the formation by the triple client of .:gravity, of the spring 3.I,.and.of the hydraulic :pressure of .the .fluid passing through .passage I16 .and acting against the lower inner face 40 ofthe cylinder, whichis greaterthanthe upper innerlfacethere- 'oflby anarea equalto the cross-sectional:arearof :thetubular string I, said pressure acting at the sametime tohold the valve :35 closed'against the action of spring :31. a

As the bit hits the bottom, and the downward 'motion of .the cylinder'is arrested; the flowpf *fiuidthrough'the passage -lfizto thelower portion 332 of the cylinder ceases, the collapse of the differential pressure generated by said "flow-permits the valves to drop toits seat, closing the passage [6, and the fluid pressure applied throughthe .ports "9 to the upperportion l of :the cylinder startsanevwcycle byraising the cylinder. 'The :pressure .in the portion 132 of the cylinder below the piston is at that time relieved by :lluid leakage through a small-.bore channel or-passage 39 between the inside and the outside :of the cylindenwhichpermits the springz3'lto overcome saidpressure and to raisethe'valve-.35,..thus open- :ing :the passage .15 and allowing'the flui'dLfmm space "3.2 :to flow into .the borehole during the :2

upward stroke of the cylinder.

Although, as seen from the above,Fig..2adiffers :fromlFigzl by the inclusion of twoadditional-ele- .ments, namely the-spring 3| andthe valve 35, it is obviouslthatthe device oilFig. 1 'cantalso ybe modified by adding thereto only one of said ele- .ments.

Figs. 3 and 4 show bits similar in operation'to those orFigs. 1 and .2,'but inwhich the cylinder is stationary, being attached'tothe drill string,

whilethe bit is attached to a piston movable withinsaid cylinder.

The lowerportion of a drill stringfil 'forms or has affixed thereto anoutside.housingr53ywhich may be of a somewhat enlarged diameter asshown in the-drawing.

.Arranged concentrically with the ,outside'housing 53 :is an :inside housing .or cylinders, attached thereto by a lower flange 185, or by a spider or welov structure :55, orboth, said rspiderrserving as a top closure for the inner cylinder and the flange'fifi serving as bottom closure for 'botl'rhous- .ingsor cylinders. The inside cylinderewhasin its lower portion passages or openings 83 in communication Withthe space within the outside housing 53. Arranged for reciprocating action within the cylinder-80 is a piston 65, having \attached thereto a tubular inember orpiston rod 8!, whichppasses slidably through the flange 185 and carries attached to its lower end a bit =89. The piston rod has a bore iBZ openin-g at-the upper end tothe space-above thezpiston, and'in register at the lower end with a passage :9! through-the bit for exhausting the drilling or hydraulic fluid from the cylinder into the borehole. "Packing means Bl and 8! are provided to prevent loss of fluid during the reciprocating .action of the piston, as shown in the drawing.

The piston-.- 65, as seen fromFigs..3 .and 5,. has a plurality of laterally arranged axial passages 164 esurroundingsthecentral bore 82 of-thepistonrcd .andaopeninginto an annular openin 6.9. which ;f.orms a valvecseat for a valve structure adapted ;to :be closedwhen1 a valve ;member 1-13 :is seated thereon. I

.flhe hollow or: QupshaDed-VaIVe-member 1.3 has a central opening slidingly fitting around the aDiStOl'l rod 48 I, its. downward -.motion :alon l the rstemlbeinglimitedby.a stoprmember l9, aflixed stothexrrod 8. 1., and serving :as ea :closu-re :for :the -open-:end:.of the cup-shaped valve member when stheilatter-irs in its :lowermost posit-ion. .Aspring T5, positioned around the rod 8| within the hollow valve 1-3,;islikewise-supported bythe Stop or plate 11.9; and itendsito Fierce the valve :1;3;aga-inst :itsqseat 68. Small-diameter channels." are provided throu h the walls-of the :piston "todzfl'l -ior fluid communication between the'boreof said-rod "and the inside of the hollow valve.

Linkmembers Hare ainXedtothevalve-l? and apassqthrough theopenings 69 and 64, being connectedabovethapistonto a spideror web mem- ..her-63, having orifices Ii l said spider being. thus adapted to move together-with the l valve -13.

A powerful spring 5-9 is :held in compression between the piston-.55 and-the upper closure F55 .of'the inner cylinder. Pin or, finger means such :as. a stem, tappet or spring?51,;affiXed-t01-the' top closure of :the cylinder, qextend down-wards into ;the cylinder, concentrically and :within the spring-59.

The operationrof the variable stroke system of ,3is asfollows:

The spring '15 expands and forces :the :hollow --v-alve 13 against itsseatafifl, thus closing-themstonwfisagainstxfiuid flow. The pressurefluid sup- ..plied. from the. surface through-the string 51 en- .ters-thelower;portion:of the inner cylinder-.80 throughthe ports :83 and forces the piston- 65 upwards, compressing the springifi and helping the spring 15 to maintain the valve 13 closed --ag-ainst the seat .69. As the piston. 65 approaches .theupperlimit of its stroke, the :pinor spring 51 strikes the spider 76A and forces the valve 13 downwards. The hydraulic fluid flows :now ';through passages. 6.4;pistonrod bore 82 and passagerflvi into-the borehole, whilethepistomBBand the .bit .8.9 .travel downward under the effect of gravity and of the spring, 59.

Ihespringfil expands-and acts to maintain the valve769-l-3-aopen during the-initial moments-of this downward stroke. ,Asythe spider 63 moves downward .and out of-contact with spring .51, however; the tendency ofsthe valve l-3cto close .underithe actionof-spring T5 is counteracted by the :fact that, due to the Venturi effectalready :mentioned with regard .to Fig. 1, the pressure .within the relatively.constrictedcboreefl, .whichis applied to'the insidegof thehollow valve member --l5 thr.ough the ;.passages. l-l, is lowerth-anthe .pressure .in the. cylinder space. 66 outside said hollow .valvermember, :WhiChiS therefore L maintained limits-lowermost position againstthe effectof spring 15. by thepressure differentialthus created.

:As the .biteBS hits the bottom-0f the borehole, iandwthedownward motion of thepiston SB is arrestedpthelfiow rate through the space-6B and tubing BI decreases. The decrease of-rthe pressure =difierential .permits'the spring 15 to close the vvalve -6'9l3, .andlthe cycle is repeated.

It isobviousthatthe spring 5!);may, be omitted, in .-which case the downward stroke of the .bit is effected onlytunder the-action offgravity.

The. embodiment of Fig.4. diners from that of Fig. .3 in that the central axial flow passage through the piston H is provided with a closure or cover member H4, which is maintained in open position by a spring H9 positioned within the piston rod bore 82 and supported by means of a spider or rim member I20. The cover H4 has a small-diameter channel or orifice I I3 therethrough.

The hollow valve I23 is similar to valve I3 of Fig. 3, but has a small-diameter channel I21 in communication between the space within the hollow valve and the passage I24 through the piston. Passage I2! corresponds in its functions to passage I! of Fig. 3.

The space above the piston H5 comprises, besides the springs 5! and 59, identical to those of Fig. 3, also a pin or spring member I08 adapted to register with and to close the cover I I4 at the end of the pistons upward stroke.

The operation of the system of Fig. 4 is similar to that of Fig. 3, excepting that, upon the end of the upward stroke, the spring I08 closes the cover H4 and the piston and bit structure is then forced down by the combined effect of gravity, action of the spring 59, and pressure of the hydraulic fluid applied to the top of the piston. The hollow valve I23 is maintained in its open position during the downward stroke by the differential pressure existing between the space I29 outside the hollow valve, and the relatively narrow passage I24, the lower pressure within said. passage I 24 being applied to the inside of the hollow valve by means of the channel I21.

When the bit hits the bottom of the borehole, and the downward stroke is thus ended, the spring I5 closes the bell valve due to the collapse of the pressure differential. At the same time, a leakage of the fluid through the small-diameter channel H3 relieves the pressure in the space above the piston and permits the spring H9 to lift the closure I I4. The hydraulic fluid admitted through the string 5| to the space below the piston then moves the piston upwards, driving the fluid from the space above the piston into the borehole through the piston rod bore 82.

Figs. 6 and '7 show a tubular bit member IOI, which may be similar to the members 52'I of Figs. 1 and 2, or to members 8I--89 of Figs. 3 and 4, and which is provided with blade elements I04, similar to elements 25 and SI of said figures, respectively. In order to impart to this bit not only the reciprocating or impact action described above, but also a rotary or grinding action, the hydraulic liquid passages through the bit may be given, if desired, an arcuate or spiral form such as shown at I03 in Fig. '7, whereby the bit is rotated by the repelling force of the pressure liquid issuing therefrom. The twist of the passage I03 should be in such a direction as to produce rotation giving a tightening action on the threads connecting the bit to the drill string. It may be noted that this method, inoperative in conventional rotary drilling, where the bit drags at all times on the bottom of the borehole, is extremely effective with the present system, the rotating motion being imparted to the bit at such times as it is traveling upwards or downwards, and is therefore not in frictional engagement with the bottom of the borehole.

When it is desired to impart to the bit a rotary motion from the surface, for example by means of a conventional rotary table, driving the drill string, the cylinder and piston members shown in Figs. 1-4 may be provided with splines, keys, keyways and the like in order to prevent their rotating with regard to each other. Since, however,

it is difiicult to keep such splines and keyways well fitted under conditions involving a rapid reciprocating action in a medium such as water or especially drilling fluid, it has been found preferable to use for this purpose the arrangement of Fig. 10, which is shown especially in its application to the embodiments of Figs. 1 and 2, although a similar arrangement can obviously be used also for that of Figs. 3 and 4, as will be apparent from the following.

A collar or sleeve member I25 is slidingly fitted over the drill stem above the sliding cylinder 5A. A spring I28 has its upper end connected to a pin I2l affixed to the drill string, and its lower end connected to said sleeve member as shown at I22, being thus held in tension and tending to pull the sleeve upwards. The sleeve I25 has formed therein inclined or slanting slots I39, adapted to receive pins or fingers I31, aflixed to the drill stem. The lower rim of the sleeve member I25 has formed thereon an annular row of teeth I 3 I adapted for a gripping engagement with teeth I34 formed on the upper end of the reciprocating cylinder member 5A. A plurality of spring members I33 maintain a frictional engagement between the sleeve and the cylinder members, being attached to one, for example to the sleeve I25, as shown in Fig. 10, and dragging over the surface of the other, for example the cylinder 5A, on which a band of serrations I35 may be provided to improve the frictional grip.

In operation, when the bit is on the bottom and it is desired to switch from percussion to rotary drilling, the drill string is lowered as far down as possible, and is rotated in the proper direction, for example clockwise with the arrangement shown in Fig. 10. The pins or fingers I31 rotate with the string, while the sleeve I25, due to the frictional effect of the springs I33, lags behind, thus causing the fingers I3'I to travel to the other end of the slots I39, lowering the sleeve I25 and permitting the teeth I3I to engage the teeth I34, whereafter the bit may be rotated from the surface by means of the drill string. When it is desired to stop rotary drilling, the drill string is raised, disengaging the teeth, and the tension spring I23 pulls the sleeve I25 further up to protect the teeth from blows when the percussion or impact drilling is resumed.

If it is desired to make, by impact drilling, a hole having a diameter larger than that obtainable with a bit of a particular size used, this may be effected, for example, by welding two of the cutting elements I42, on opposite sides of the bit at a slight angle with regard to the axis of the bit, as shown in Fig. 7A. This causes the bit to be deflected towards the side of the element I40 on the downward stroke, and in the opposite direction on the upward stroke, said second deflection being however smaller because of the smaller speed during the upward stroke.

A similar result may also be achieved by locating the center of gravity of the bit away from the axis of the bit, that is, away from the line of action of the driving force. As shown in Fig. 8, this may be effected by means of an asymmetrical arrangement of the cutting blades, for example by omitting one of the blades of a regular fourblade bit, and by reinforcing the blade I I3 which is positioned on that side towards which the bit is deflected and which does therefore most of the cutting work.

Since the present system is adapted for uninterrupted operation throughout extended periods of time, it is sometimes advisable to provide it 9. with. an arrangement adapted to indicate; to." the driller that the drill. isworni beyond .alsafe point and to stop thezrecipro'catingaction. automatically beforedam'age is done to the present valve systern located above the bit. Figs. 11' and lz'show such an arrangement, wherein a bit I51, which may be of any of the types described hereinabove,

is provided withan axial passage I-53 and: a plurality of. radial o1: lateralpassages l52 in. communication therewith for exhausting or circulating the hydraulic or'drilling fluid. The. bit. has

formed. therein. in register with said passage l53= a well or cavity 156, in which a steel. plug: I 55 is held, for example by'brazing, spot welding. or: soft soldering. The plug IliThas a downwardly tapering. conical shape. and a diameter selected so that when, as shown in Fig. 12, the bitis worn beyond a safepoint, the direct hammering or pounding effect of the plug I51 against the bottom of the borehole resultsin detaching saidsplug.

from the copper, lead or other matrix retaining, said plugin the well I56, and in forcing it against the passage I53; which closes said passage and automatically stops the reciprocating action of the bit by interrupting the. flow of the hydraulic fluid.

Since the liquid throughput of the present bit issubject to considerable variations during each cycle, water hammer effects may sometimes occur in operation. To eliminate these effects, and at the same time to provide the proper volumeof circulating liquid. for flushing the borehole, a special valve may lee-provided whereby the fluid consumption of the bit. is regulated or heldv at a desired. value; This-valve may be mounted either in thewolkingcylinder of the present device, or in the drilLstring at any suitable distance above the bit. Fig..13. shows an enlarged section: I-lidof the drill'string H, which is provided with a port or. ports I69: A beam spring I6! is securely clampedto the wall of' the pipe section 563,- andrtends to maintain the port [69: normally closed. When the pressure differential between the inside and the outside of the pipe exceeds a maximum predetermined by the setting, or

strength of the spring I61, the valve I'H opens,

and'permitsa portion. of the liquid to by-passthe drill bit.

The workingcylinder. of the bit, or of the drill pipe; may also be providedwwith v additional ports Hi5, and the system maybe operated with these ports either open, or closed. by means of remov able plugs W3, depending on the volumeof the fluidwhichit is desired to circulate in the borehole.

During the drilling process, it may sometimes be desiredto move the bit up or down within-the borehole; for example for the length'of the kelly, without shutting off the circulation.

Inorder toenable the operatorsto do so without permitting the reciprocating action of the present system to start or to continue (which is dangerous when the bit is away from the bottom,

since the force of the blows is in such cases brought to bear ontheshoulder contact between the piston and the cylinder, with ensuing damage to theequipment the arrangement shown inFig. 14: may be used for the bits of the type: shown in Figs. 1 and Z.

The inside walls of. the upper portion of the:

reciprocatingrcylinder B are provided with rel'a tively shallow grooves lfi hhavinga longitudinal oraxial length greater thanthat of the piston I53. When. the drill stem MB is lifted until the piston. lEBdsstopped bycontact with the upper closure? shoulder of thecylinder, the grooves l8l provide-.a=-by-pass forthe hydraulic fluidaroundl saidvpiston; whereby no pressure rise is permitted-.tddevelopym the-space above the piston (5B,

-. as.describediwithiregardto Figs. 1 and 2, and the reciprocating action is not permitted to take place:

The same. result is obtained with regard to the r bits-of: the'type'shown in Figs. 3 and 4 simply by:- giving the; ports 8-3 a: vertical or axial length greater than' that oi the. piston. 65, whereby fluid is admit-ted to.:the-spaceabove the piston when therpistonais lint its lowermost position.

Lolaims asimy, invention:

1'; mhydraulio deviceadapted to be lowered 0211.8. drillsstring into a borehole for impacting. a drill bit again'st the. bottom thereof, said device comprisingicylindertan'd piston members, one of saiil members-beingattachedto said drill string.

and the other member being'attached to said drill bit: and movable. with. regardwto said string, and variable stroke: means for reciprocating the movable member, said: means comprising passage means for. admitting. a. pressure fluid from the drill string: tothe; cylinder member to one side 0tsaid pistongpassagemeans for exhausting the fluid: from-the cylinder on theother side of the pistbri;v apassage throughthe piston, said passage having'aurestricted. portion; a hollow cup-shaped valve adapted'to close saidpistonepassage to fluid flow during the upward" stroke of the movable member, a cap member aflixed to the piston memher. in register with the. open face of the cupshaped valve, pin meansaffixed to the cylinder.

memberradjacent: the passage means for exhausting the: fluid therefrom adapted to force said valve to an'openposition in contact with said cap member atthe end of saidupward stroke, and channelcmeans. throng-h the walls of the cupshaped' valve invcommunication between the restricted portion. of the piston passage and the closedspace. defined 'withinthe cup-shaped valve whenzsaidrvalve-is in contact withsaid cap member, whereby-said cup shaped valve is maintained inianzopen positionincontact with said cap member'bya a Venturi suction effect created by the fluid: flow-'throughsaid restricted portion of the piston. passage during. the downward stroke of thec'movablemember, and is released to a closed position by a decrease of said'fluid flow and of sa=i*d:suction effect occurring when the motion oi the movable. member-is arrested by the impact or therdri-lhbit againstth'e bottom of the borehole.

2; A: hydraulic device adapted to be lowered on: a drill strings into a borehole for impacting a drill: bit. against the bottom thereof, saidude vice: comprising; cylinder. and, piston members, oneioiisaid membersbieing attachedto saidrdri'll string and the other member being attached to said"dril-1'-bit and" movable with regard to said string, variable stroke means for reciprocating the movable member, said means comprising passage"meansfonadmitting a pressure fluid from the. drilrstringtb'the cylindermember to one side of saidpiston, passage means for exhausting the fluid from the cyl'i'nder on the other side of the piston, .a passage through the piston, said passage having a restrictedportion, a hollow cup-shaped valve.adapted-toclose said piston passage to fluid flow during the upward stroke of the movable member, alcupimember afiixed to thepiston member'in': register with the open face of the cupshapedzvalve, pin means aflixedto-the cylinder member adjacent the passage means for exhausting the fluid therefrom and adapted toforce said valve to an open position in contact with said cap member, channel means through the walls of the cup-shaped valve in communication between the restricted portion of the piston passage and the closed space defined within the cup-shaped valve when said valve is in contact with said cap member, whereby said cup-shaped valve is maintained in an open position in contact with said cap member by a Venturi suction effect created by the fluid flow through said restricted portion of the piston passage during the downward stroke of the movable member, and is released to a closed position by a decrease of said fluid flow and of said suction efiect occurring when the motion of the movable member is arrested by'the impact of the drill bit against the bottom of the borehole, a valve affixed to the movable member and adapted to seat against the fluid exhaust passage, spring means tending to maintain said valve open, yieldable means adapted to force said valve closed by contact therewith at the end of the upward stroke of the movable member, said valve being adapted to remain closed byfluid pressure within the cylinder against the action of said spring means during the downward motion of said movable member, and leakage means through the walls of the movable member adapted to relieve said pressure, whereby said valve is maintained open by said spring means during the upward stroke of said movable member.

3. A hydraulic device adapted to be lowered on a drill string into a borehole for impacting a drill bit against the bottom thereof, said device comprising a piston attached to said string and a cylinder adapted for reciprocation about said piston, said cylinder having the bit attached thereto, passage means for admitting a pressure fluid from said string to said cylinder above said piston, passage means for exhausting the fluid from the cylinder below said piston, a passage through the piston, said passage having a restrict ed portion, a hollow cup-shaped valve adaped to close said piston passage to fluid flow during the upward stroke of the cylinder, a cap member connected to the piston member above the cupshaped valve in register with the open face thereof, yieldable pin means aflfixed to the cylinder below said piston adapted to force said valve to an open position with its open face in contact with said cap member at the end of said upward stroke, and channel means in fluid communication between the restricted portion of the piston passage and the closed space defined within the cupshaped valve whensaid valve is in contact with said cap member,,,whereby said cup-shaped valve is maintained in an open position in contact with said cap member by a Venturi suction effect created by the fluid flow through said restricted portion of the piston passage during the downward stroke of the cylinder, and is released to a closed position by a decrease of said fluid flow and of said suction effect occurring when the motion of the cylinder is arrested by the impact of the drill bit against the bottom of the borehole.

4; The device of claim 3, comprising coil spring means disposed below the piston within the cylinder, said spring means being adapted to be compressed between the piston and the cylinder during the upward stroke of the cylinder and to expand during the downward stroke of the cylinder.

5.- The device of claim 1, having a clutch for imparting a rotary motion to the drill bit by means of the drill string, said clutch comprising a first annular toothed member fixedly connected to the drill bit member of the device, a second annular toothed sleeve member concentric with the drill string member of the device and adapted for sliding motion with regard thereto, pin and slot means connecting said sleeve and drill string members and adapted to translate a rotational motion of the drill string member into an axial motion of the sleeve member, whereby said toothed sleeve member is caused to engage the toothed member connected to the drill bit member, spring means frictionally connecting said sleeve and said drill bit members, and spring means engaged between said sleeve and said drill string members and adapted to urge said sleeve member away from said first toothed member.

6. The device of claim 1, having as fluid exhaust means an axial bore extending into the drill bit, radial passages in communication between said b'ore and the outside of the bit, an axial cavity in the body of the bit in register with said bore below said passages, a metallic plug in said cavity, and frangible means retaining said plug in said cavity, said plug being adapted to be pressed out of said cavity and into contact with said bore to close said bore by direct pounding against the bottom of the borehole when the lower part of said bit is worn out to the level of said plug.

'7. The device of claim 1, having radial port means in fluid communication between the inside and the outside of the drill string above said piston member, valve means adapted to close said ports, and spring means adapted to maintain said valves closed at fluid pressures within said drill string below a predetermined maximum.

8. A hydraulic device adapted to be lowered on a drill string into a borehole for impacting a drill bit against the bottom of the borehole, said device comprising a cylinder member and a piston member, one of said members being attached to the drill string and the other member being attached to the drill bit and being movable with regard to the drill string, and variable stroke means for reciprocating the movable member, said means comprising passage means for admitting a pressure fluid from the drill string into the cylinder member to one side of the piston member, passage means for exhausting said fluid from the other side of the piston member, a passage through the piston member, said passage having a restricted portion, a cap member rigidly connected to the piston member above said passage and coaxially therewith, a hollow cupshaped valve member adapted to close said passage to fluid flow during the upward stroke of the movable member, pin means carried by the cylinder member below said piston adapted to force the open face of said hollow valve member against said cap member at the end of the upward stroke, thereby opening said passage to fluid flow, and channel means through the walls of the cupshaped valve in communication between the restricted portion of the piston passage and the closed space defined within the cup-shaped valve when said valve is in contact with said cap member, whereby said cup-shaped valve is maintained in an open position in contact with said cap member by a Venturi suction effect created by the fluid flow through said restricted portion of the piston passage during the downward stroke of the movable member, and is released to a closed position by a decrease of said fluid flow and of said suction effect occurring when the motion of the movable member is arrested by the impact 13 of the drill bit against the bottom of the borehole.

9. A hydraulic device adapted to be lowered on a tubular string into a borehole for impacting a drill bit against the bottom thereof, said device comprising a cylinder and a piston, said piston being attached to the string and said cylinder being attached to the bit and movable with regard to thegstring, and variable stroke means for reciprocating the cylinder, said means comprising passage means for admitting a pressure fluid from the string to the cylinder above the piston, passage means for exhausting the fluid from the cylinder below the piston, an axial passage through the piston, said passage having a restricted portion, a cap member affixed to the piston co-axially with said passage, a movable hollow cup-shaped valve member adapted to close said piston passage to fluid flow during the upward stroke of the cylinder, said cup-shaped valve member having an open face in register with said cap member, pin means aifixed to the cylinder below said piston adapted to forcethe open face of the cup-shaped valve member into a position in contact with said cap member at the end of the upward stroke of the cylinder, thereby opening the piston passage, and channel means in 14 communication between the restricted portion of the piston passage and the space defined by said hollow cup-shaped valve member and said cap member when said members are in contact with each other, whereby said cup-shaped valve member is maintained in said position by a Venturi suction effect created by the fluid flow through said restricted portion of the piston passage during the downward stroke of the cylinder, and is released to a position closing the piston passage upon a decrease of said fluid How and said suction effect occurring when the motion of the cylinder is arrested by the impact of the bit against the bottom of the "borehole.

EUGEN MERTEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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