US2643860A - Rotary drilling mechanism - Google Patents

Description

June 30, 1953 c. w. KOCH 5 3 v ROTARY DRILLING MECHANISM Filed May 22, 1950 4 Sheets-Sheet 1 3 INVENTOR.

C. W. KOC H June 30, 1953 c w, KOCH 2,643,860

ROTARY DRILLING MECHANISM Filed May 22, 1950 4 Sheets-Shet- 2 FIG.- 2.

INVENTOR.

C. W. KOCH BY 7M7 ATTORNEYS June 30, 1953 c, w KOCH 2,643,860

ROTARY DRILLING MECHANISM Filed May 22, 1950 4 Sheets-Sheet 3 FIG-3.

ATTORNEYS June 30, 1953 c. w. KOCH 2,643,860

Y .ROTARY DRILLING MECHANISM Filed May 22, .1950 1 '.4- Sheets-Sheet 4 &\ INVENTOR.

A T TORNE VS Patented June 30, 1953 ROTARY DRILLING MECHANISM Carl W. Koch, Phillips, Tex., assignor to Phillips Petroleum Company, a

ware

corporation of Dela- Application Ma y 22, 1950, Serial No. 163,350

13 Claims.

This invention relates to a mechanism adapted for use in the drilling of wells through earthen strata. In one of its aspects, it relates to a bottom hole rotary drilling mechanism. In an- ..other of itsaspects, it relates to a bottom hole drilling motor having balanced-torque counterrotating bits adapted to drill through an earthen formation. In still another of its aspects, this invention relates to a means for balancing the torque of counter-rotating bits in a bottom hole drilling mechanism. In yet another of its aspects, this invention relates to a pair of counterrotating bits adapted to have the torque necessary to rotate each, automatically balanced.

In recent years,;the quest for oil has led to the drilling of deeper and deeper wells into the earth. Today it is not unusual to drill wells from ,ten to fifteen thousand feet in depth and it is becoming common practice to drill exploratory wells to depths oftwenty thousand feet.

Asthe search for oil becomes more and more intensive, it is expected that the average depth of producing as well as exploratory wells will increase until wells having a depth of over twenty to thirty thousand feet will be common. In thedrilling of the greater majority of Wells, it is presently conventional to employ a rotary drilling rig having 'a tubular drill string which .rotates in the bore hole to force a drilling bit attached to one end of the drill string through the earthen formation. The cuttings formed by the drill bit as it penetrates the formations are removed from the well bore. by maintaining mud circulating within the bore. As the well progresses in depth, the drilling string becomes longer and longer and heavier and heavier, more and more of its weight must be borne by the drilling device and associated drilling lines since the weight or pressure imposed by the drill bit a suspended string of drill pipe approximately twenty-three to twenty-four thousand feet in length, made from the best grade of drill pipe presently available, will theoretically break of its .prevent rotation of the drilling motor.

own weight. Consequently, if wells twenty to thirty thousand feet deep are to be drilled, Ways must be found for drilling wells other than driving a shaft four miles or more in length.

One way to eliminate the above problem would be to provide a bottom hole drilling mechanism comprising a suitable motor adapted to drive a drill bit connected to the motor, and such meanshave been tried in the past. The assembly of th motor and drill bit is'lowered by means of a cable to the bottom of the bore hole, thereby eliminating the need for the long string of drill pipe. However, as can be appreciated, some means must be provided to prevent the drilling motor from rotating in the bore hole since the action of the drillitng "bit upon the earthen formation will induce a rotative torque upon the drilling motor. Ordinarily, there is provided as a sole means for preventing such rotation of the drilling motor, a rather complicated system of dogs which are attached to the motor and'which grasp the sides of the bore hole in an effort to Such efforts to prevent rotation of the drilling motor are ordinarily unsuccessful or impractical because of the enormous torque induced by the rotative bit andbecause, at various times, the dogs will encounter loose formations which do not permit them to grasp the sides of the bore hole firmly enough to prevent rotation of the drilling motor in the bore hole.

It has been further suggested by the prior art .that counter-rotating bits be employed in order to balance and cancel out the opposing torques applied to the motor turning such bits. As is obvious, the torque induced by each of the counter-rotating bits will vary from formation to 'formation and it is practically impossible to predict the torque which willbe necessary to beexerted on each bit as it passes through successive formations. Further, one bit will become dull before the other thereby varying the torque necessarily applied to each bit in order to maintain the drilling rate constant and the torques balanced.

It has now been found that the torque necessary to rotate counter-rotating bits can be automatically balanced and equalized by providing a means for extending or retracting one of the bits with respect to the other and, at the same time, varying the bite of one of the bits tochange its torque with respect to the torque necessary to drive the other bit. It has also been found be automatically regulated by providing a means for extending one of the bits wherein such means is actuated by any rotation of a normally stationary housing or casing associated with the counter-rotating bits. In such fashion, any unbalanced net torque of the counter-rotating bits which acts to rotate the housing associated with said bits is rebalanced.

It is an object of this invention to provide a rotary drilling mechanism suitable for use in the drilling of wells.

It is another object of this inventionrto'provide a rotary drilling mechanism having counter-rotating bits and a means foreffectively balancing the torque of such bits.

It is still another object of this invention to provide a means for balancing the'torque induced by the drilling bits of a bottom hole drilling mechanism.

Yet another object of this invention is to provide a rotary drilling mechanism adapted to drill through earthen formations which vary one from the other in their drillability without causing the drilling motor to rotate in the bore hole.

Still yet another object of this invention is to provide counter-rotating bits having'a means for automatically balancing the torque necessary to rotate each of the bits.

In order to even better understand this invention, it will be described in a particular preferred embodiment thereof as illustrated in the attached drawings. In the drawings, Figures 1, 2 and 3, when considered with each other, illustrate a preferred embodiment of the rotary drilling mechanism of this invention. Thus, Figure 1 represents the top portion of the drilling mechanism, Figure 2 represents an intermediate portion which attaches to that shown in Figure 1, while Figure 3 represents a lower portion of the drilling mechanism which attaches to the bottom portion of the section shown in Figure 2. Figure 4 is a cross sectional view'taken on the line 44 of Figure 1. Figure 5 is a cross sectional view taken on the line 5r-5 of Figure 2,

and Figure 6 is a cross sectional view taken on the line 6-6 of Figure 3.

In describing the embodiment illustrated in the drawings, consider that Figure l is superimposed above Figure 2 and that Figure 3 is placed below Figure 2, thereby illustrating the complete embodiment of the preferred drilling mechanism of this invention.

A motor I is provided within a fluid tight compartment defined by housing or casing2 and can be any type of positive-displacement, rotatingtype element fluid actuated motor. This motor I can be a gear-type, helical screw-type or other type of motor adapted to be driven by means of afiuid pressure applied to rotate its elements.

As shown, motor I has rotating screws or rotors 3 and 4 which are supported in parallel relationship by shafts 5 and 6 inserted in upper motor housing plate I and by shafts 8 and 9 inserted in lower motor housing plate I0. Upper and lower motor housing plates 1 and I6 ar spaced in a fixed parallel position and can be situated in grooves in housing 2 as shown. The plates should be provided at their external circumferences with a packing means (not shown) such as asbestos rope or rubber rings adapted to prevent the passage of fluids around the ends of the plates. Attached to the upper housing plate I is a fluid conduit comprising a nipple II which is extensible means such as a bellows.

which can be cylinders I3 and I4 which are adapted to contain pistons I5 and I6. The lower ends of cylinders I3 and I4 are closed by cylinderheads I! and I8. Cylinder head IT and I8 can be recessed at the surface facing pistons I5 and I6 and are adapted to receive conduits I9 and 20 in their opposite surfaces in a manner such that a fluid passageway is provided between pump 2| and cylinders I3 and I4.

Alternatively, cylinders I3 and I4 and pistons I5 and I6 can be replaced by other hydraulically As many individual hydraulically xtensible elements can be provided as is desired. Ordinarily, at least two joined to a housing I2, as shown. Situated'in v 7 housing I2 are a hydraulically extensible means and preferably three such elements should be employed.

The centrifugal type pump 2I is attached by means of pump shaft 22 to shafts of the rotating element 3 of motor I. Th discharge side of pump 2| can be connected by conduit 23 to conduits I9 and 20 in such manner that the fluid pumped by pump 2I i discharged into cylinders I3 and I4 between pistons I5 and I6 and cylinder heads I! and I8, respectively. Pistons I5 and I6 are adapted to reciprocate in cylinders I3 and I4, responsive to fluid pressure exerted by pump 2I and have piston rods 24 and 25, respectively, which extend through housing I2 to coact with a dog-extending mechanism described below. Pump 2I can be driven by other means than motor I such as by a fluid-actuated motor other than motor I or by an electrical motor.

As shown in Figure 1, a means for conducting an actuating fluid to motor I can comprise a hollow tube 26 which is attached by means of nipple 2? to the upper portion of housing I2 in such a manner that a fluid can be passed through passageway 28 which extends through tube 26, nipple 2! and housing I2 to discharge into fluidtight compartment or housing 2 and therein' cause the mud motor to be actuated. Annular groove 29 is formed between mud tube 26 and nipple 2'1 and is adapted to receive therein a cammed projection or lip 30, which extends from bushing 3|, as shown. Tube 26 and nipple 21 can be formed as one piece which can have, if desired, groove 29 formed therein. Referring to Figures 1 and 4, cammed projection 30 is shown as an annular lip extending from bushing 3I. The entire lower side of lip 30 is formed as an annular cam 32 which is-sloped along the lower surface of lip 30. Thus, cam 32 can be an annular ring whose thickness varies along its circumference and changes from a maximum thickness to a minimum thickness at point 32A of Figure 4.

Bushing 3I is rigidly attached to an annular gyration control frame 33 and is adapted to receive mud tube 26 in rotative relationship at its upper end. The lower portion of bushing 3I is likewise adapted to permit nipple 21 to rotate therein and is packed therefrom by means of packing 35 and packing ring 36. Surrounding bushing 3I is a collar 31 adapted to slideably reciprocate on the lower portion of frame 33. A thrust ring 38 can be interposed between collar 37 and piston rods 24 and 25 to provide for free rotation therebetween. Spring 39 surrounds gyrationcontrol frame 33 and is adapted to press against pring retaining shoulder 46 and collar 31. Pivoted in recess M of collar 31 is dog arm 42 which is also pivoted at its outer end in member 43 attached to dog 44. At the upper end of gyration control frame 33 is rigidly attached an upper support 45 having a dog arm 46 pivotly mounted therein. Th other end of dog arm 46 is likewise pivotly mounted in member 41 attached to dog 44.

A lifting lug 48 is attached to gyration control frame 33 at its upper end and is adapted to receive mud tub 26 in a rotative relationship. A bushing 49 is inserted in lifting lug 48 to serve as a packing ring for packing 56 and to receive mud hose 5| therein.

Thus, as shown in Figure l, a sub-assembly comprising mud tub 26, nipple 21 and housing I2 is adapted to rotate by means of bearings 52 with respect to another sub-assembly comprising mud hoser5I, bushing 49, lifting lug 48, gyration control frame 33, bushing 3| and packing ring 36.

Referring to Figure 2 a hollow cylindrical inner bit driving shaft 60 is rotatably mounted in the drilling assembly casing and can be received in lower motor housing plate I9. It can be adapted to conduct fluid discharged from motor I therethrough. Packing GI and packing ring 62 is provided, as shown, to permit shaft 60 to rotate in fluid-tight relationship with respect to lower housing plate ID.

A means is provided for motor I to rotate shaft 60. Although a preferred means is by suitable gearing as described below, it can consist of belts and pulleys or a combination thereof with gears. In the preferred form, rotative element 3 of motor I has a central shaft 8 extending through plate III and has drive gear 63 attached thereto. Coaoting with drive gear 63 is reversing gear 64 supported on shaft 65 which passes through support member 66 attached to gear housing El. The lower end of shaft 65 supports driving gear 69 and is further received in gear shaft support plate 68. Rotative element 4 of mud motor I is adapted to drive driving gear I9 through shaft 9 which is likewise received in gear shaft support plate 68, as shown. Driving gears 69 and I8 coact with driven gear II which is rigidly attached to inner bit shaft 60.

Inner bit shaft 60 extends through a lower hydraulic fluid reservoir I2 contained in a housing I3 and through a further housing I4, as shown in Figure 3. A drive gear I5 is rigidly attached to inner bit drive shaft 60 and is adapted to coact with reverse idler gears I6 and TI. Idler gears I6 and I! are, in turn, the driving gears for inner female ring gear I8. Female ring gear I8 terminates at its lower end as outer bit drive shaft I9 which extends through a bottom plat 89 attached to housing I4. An outer bit 8| is attached to outer bit drive I9. Outer bit 8| has cutting means disposed along its lower surface in a manner well-known to the art. Piston member 82 is adapted to permit ring gear I8 to-rotate therein by means of bearings 99. The piston member 82 can be keyed or fixed in a non-rotative relationship to housing I4 with which it is adapted to slideably coact along the surface 83 and is packed therefrom by means of packing 84. Thus, a hydraulic cylinder 85 is formed between piston member 62 and housing I4, as shown.

Bearing shaft 86 of idler gear 16 extends through housing I4, a shown, and has attached to its upper end a centrifugal pump 31 having a suction88 and a discharge conduit 89 connected to fluid passageway 90, as shown.

Although it is preferred that outer bit drive shaft I9 be driven by suitable gearing such as that just described by means of power supplied from inner bit drive shaft 60, outer bit drive shaft 19 can b rotated directly by motor I or by a second motor (not shown), operatively connected thereto by means of suitable gearing, belts and pulleys or combinations of the same. Further, pump 81 can be driven directly by motor I similarly to pum 2| or by means of any other rotative element in the drilling assembly. Also, pumps 81 and 2| can be driven by the same element and can be supplied with hydraulic fluid, such as oil, from a common source orreservoir (not shown) thereby combining reservoirs I2 and HA.

Inner bit drive shaft 68 is adapted to pass in slideable androtative relationship through outer bit drive shaft I9, packing 9| and packing ring 92 and to receive at its outer end inner bit 93 having mud passageway 94 therethrough. Inner bit 93 has a cutting edge along its lower surface adapted to drill through an earthen formation. One or more equalizing reamers 95 are pivoted in slots 96 of inner bit 93 and are adapted'to have their lower ends extended laterally from inner bit 93 as a result of the coaction of their upper ends 91 with the inner surfaces 98 of outer bit 8| when inner bit 93 is extended with respect to outer bit 8 I.

A fluid discharge passageway I96 is situated in housings I4, I3, 2 and I2 to thereby connect hydraulic cylinder 85 via conduit |0| to passageway I92 in nipple 21 and to discharge around valve I03 into annular groove 29. Valve I83 is a Dill valve which is a form of a tire core valve and can be the type shown in U. S. Patent 2,365,423 issued to Charles MacSporran. It is adapted to be opened by coaction of stem I04 with cam 32 when nipple 21 and the casing dependent therefrom as well as valve I63 is rotated with respect to cam 32. Thus, rotation of niplple 21 and valve I03 along the inclined surface of cam 32 causes stem I94 of valve I03 to be pushed down to unseat valve I93 or is raised to seatvalve I03 depending upon the direction of rotation of the nipple and valve with respect to the cam. In this fashion, the amount which valve I03 is opened is directly dependent upon the amount valve I03 is rotated along the surface of cam 32. Alternatively, valve I63 can be a screw-stem type valve, such as a needle or glove valve, and can have a gear attached to its stem which coacts with a female ring gear rigidly attached to frame 33 in such a manner that rotation of nipple 27 and the valve causes the valve stem gear to turn thereby opening and closing the valve in accordance-to the rotation of nipple 21. A discharge fluid passageway I II] is situated in nipple 21 and continues via conduit I I I and passageway I I2 in housings I2, 2, and I3 to discharge hydraulic fluid from groove 29 into lower hydraulic reservoir I2.

In operation, the drilling assembly shown in Figures 1, 2 and 3 is lowered into a bore hole until inner bit 93 and outer bit 8| are resting at the bottom of the hole. A fluid which can be drilling mud is pumped from the surface through mud hose 5| to the mechanism and passes through mud passageway 28 in mud tube 26, nipple 21, housing I2 and nipple II, into mud motor I wherein the fluid pressure causes elements 3 and. 4 to rotate in opposite directions. The mud is discharged from the mud motor through inner bit drive shaft 66 and mud passageway 94 in bit 93. Alternatively, the actuating fluid or drilling mud can be discharged from motor I through a. conduit (not shown) extending from motor I to a point outside the housing 2 such as laterally thereof or through plate 89' to impinge upon the bottom of the borehole near the counter-rotating bits. The rotation of element 3 causes drive gear 63, to rotate reverse gear 64 and drivinggearL-BS, which, in turn, .causesdriven gear'H to rotate inner bitdrive shaftzfifl. Rotating element l of mud pump l likewise causes drivinggear lli to rotate driven gear H inthesame direction as :..that .causedby. driving gear 59. Thus, the entire vdriving force of rotating elements 3 and A is applied toinner bit'driving-shaftfiil and, thence, toinner bite93.v .ln'rotating inner bit shaft 60,

drive gear which is attached thereto causes reverse idling gears vI6, and H to drive female :;ring.gear.l8 in a direction opposite to that of inner bit .shaft'tfi. Since female ringgear 18 is attachediby means of outer bit drive 19 to outer bit 4:81; the inner. bit shaft Sfiwill thereby cause outer 'bit 8| to rotate in a direction opposite to that of :inner bit 93.

.The rotation of element 3 of mud pump l causes pump 2| to discharge fluid from upper hydraulic '..l'6SB1VOiI HA into cylinders 13 and M thereby causing pistons l5 and Hi to push piston rods 24 1.. and 25 against thrust ring 38. thrust ring 38 and collar 37 are adapted-to slide the-bore hole.

Thence, since longitudinally upon gyration control frame 33,

,. the hydraulic pressure exerted through pistons 15 and 16 will overcome the force of spring 39 and cause collar 31 to slide along gyration control .frame 33,- thereby causing the lower portion of dog arm 42 to push dog 44 against the sides of uppereportion of dog 44 to push against the sides :lifting lug .48, bushing 49 andbushing 3! is forced drilling'assembly from the bore hole, the pumpof the bore hole. In this manner, the sub-assembly comprising dog 44, gyration control frame 33,

to remain in a non-rotative fixed position with respect to the "bore hole. This action also prevents any twisting of the mud hose 5 i.

When it is desired to remove the bottom hole ing ofdrilling mud or other fluid through mud hose 5! is ceased thereby stopping mud motor I :and pump 2!.

The hydraulic fluid in cylinders I3 and l4 drains through pump 2| into upper hydraulic fluid reservoir HA thus permitting spring 39 to force collar 31 downwardly. As a result, dog arms 42 and 3G retract dogs M into a position such that the assembly can be readily withdrawn from the bore hole without dogs 44 dragging along. the sides of the bore hole.

When the-bottom hole drilling assembly is in drilling-position at the bottom of the bore hole and bits8l and 93 are rotating in opposite directions, different earthen formations will be encountered which will cause the torque necessarily applied to each bit to maintain its individual drillingrate to become unequal whereby one bit willtend to rotate more easily than the other.

' When this happens, there is a tendency for the into fluid passageway 99 and cylinder 85.

unbalanced or net torque to rotate the entire bottom hole assembly. However, according to this invention, the unbalanced torque can be auto- .matically rebalanced by adjustment of the relative longitudinal extension of outer bit 8| with respect to inner bit 83. As shown in the drawings, the rotation of reverse idler gearlG by gear -15 and inner bit drive shaft 68 causes pump 81 farther into the formation with respect to inner bit 93. Inso advancing, surface 93 of outer bit 8| permits end 91- of equalizing reamer 95 to extend further laterally from bit 93thereby causing In so doing, dog arm E6 is likewise 1 pivoted between members 65 and 47 to cause the bore hole. As a result, the-.torque applied to inner bit 93 to maintain its cutting action decreases With respect to that of outer bit 8| When the torque which is necessary to rotate inner bit 93 decreases-sufiiciently, it will become less than that needed to rotate outer bit 8|. When this happens, the net torque rotatesthe entire housing of the motor assembly; comprising. housings l4, 13, 67, 2 and I2 as welLas nipple 2'! attached therctoso that valve N33 is rotated with respect to cam-32 which is held stationary bygyration control frame tSand dogs 44. As valve m3 is rotated, cam 32 depresseszstem. I04

.to permit hydraulicfluid to escape from cylinder 85 and passagewaysllllfl and 282 into passageways H8 and land thence into lower, fluid reservoirl2. .As a result, the fluid pressure in cylinder 85 decreases since the'pressure exerted by centrifugal pump 81 is proportional to'the' volume of fluid pumped. The decrease in fluid pressure in cylinder 85 permits piston member 82 to be raised by the force of the earthen formation pushing upwardly on outer bit Si. 7 In thus raising outer bit 8| with respect to innerbit 93, equalizing reamers' 95 are extended laterally from inner bit. 93,,to take a larger bite from the I formation. In so doing, the torques necessary of the inner .bit 'asdescribedabove.

to rotate the inner andouter bits will become equal.

Should inner bit .93 be extended too far with respect to outer bitlSi so that the torqueapplicable to the inner bit becomes larger than that required byzthe outer bit,- the resultant net torque will again rotate valve 103 along cammed surface 32 butin a direction. oppositetothat when the torque of the outer bit exceeded the torque Accordingly, the rotation of .valve L83 by the excessive torqueoi the-inner bit willucausestem I04 of valve I03 to rise and restrict the flow of hydraulic fluid through valvelB3. The decreased flow of hydraulic fluid permits pump 81 to build up the pressure inv cylinder 85 thereby advancing outer bit 85 withrespect toinner bit 93 to thereby again balance the. torque of the two bits.

It is to be notedithat idler gears 76 and H are adapted to drive innerring gear .78 and are .iurther .adaptedto .permityinner ring gear '18 to slide longitudinally with respectto the idler gears. Thus,'the.action.of the hydraulic. fluid in cylinder 85 insliding piston member 82 along surface 83 of housing 14 and concomitantly causing inner ring gear-l8 and outer bitdrive 19 to be advanced or retracted-does not disengage idler gears .lfi-and "H from inner ring gears 18'.

Thus, it is obvious. from the foregoing that any unbalanced torque exerted by either bit 81 respectively, so that more or less fluid :can be pumped by pump 81 with the" resultant decrease or increase in.pr.essure in cylinder 85 causing .outer bit 8| to retract or extend'into the formation thereby balancing the torque necessary to rotate .eachbit. .As bits 8! and 93 encounter formations that vary. one from the other in their case of drilling, the torque necessary to turn each bit willbe. adjusted to beequal by. auto- .matically varyingrthe. bite of bit .93 into the I function will be to prevent rotation of the gymtion' control frameand attached parts while the torques of the two bits are being adjusted. It

it thuslyobvious .thatdoggM-need notibe connot be of exceedingly heavy construction nor need they be constantly in the grasp of a hard bore hole wall as would be necessary if they were the only means for preventing rotation of the drilling motor due to unbalanced torques of the counter-rotating bits.

Although the foregoing description has related to a preferred embodiment of the drilling apparatus of this invention and, accordingly, has been rather specific in its terms, it is apparent that many departures can be made from such embodiment without departing from the concept of the invention. Thus, housings l2, 2, 6! and 14 have been described as separate elements although it is obvious that two or more of these can be integrally combined into a single housing or casing. Also, flange joints can be substituted for the screwed joints shown. I

Still further, although the operating means for moving collar 3! upwardly has been described as comprised of pistons and cylinders, the motive means for such collar can be a hydraulically extensible bellows attached to the top part of housing I2 in such a manner that the extension of the bellows will push thrust ring 38 and collar 3'! upwardly to extend dogs 44 into the formation. Also, cylinder 85 and piston member 82 can be replaced by a hydraulic bellows or a series of parallel bellows adapted to'push outer bit drive shaft l9 and outer bit 8| out and away from plate 80. In such case, it would be preferable to secure bearings 99 to a member sliding along the inner wall of housing 14 in order that female ring gear 78 could be held in proper alignment with idler gears 16 and H.

For the sake of simplification of the attached drawings and the description thereof, many bearings and packing glands as well as other minor features have been omitted. Although such bearings and packing glands are highly desirable and necessary in a commercially operable mechanism, they do not aid but rather they tend to confuse a proper understanding of this invention. It is obvious to one skilled in the art just where and how such bearings, etc. should be installed.

While the invention has been described in con nection with a present, preferred embodiment thereof, it'is to be understood that this description is illustrative only and is not intended to limit the invention, the scope of which is defined by the appended claims.

I claim:

l. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination, a cylindrical casing, a hollow tube attached 'bya nipple to one end of said casing to form a fluid passageway through said tubeand said nipple into said casing, said nipple and said tube having an annular groove at their juncture, a frame rotatably supporting said tube and said nipple, a plurality of dogs laterally expansible from said frame means of upper and lower arms and adapted to press against the walls of said bore hole when in an expanded position to prevent rotation of said frame, an annular lip extending from said frame into said annular. groove at the juncture between said tube and said nipple,

an annular cam depending from the lower surface of said lip, a screw-type fluid motor situated in a fluid-tight compartment in said casing, said compartment being connected to said fluid passageway in said tube and said nipple,

10 said motor being adapted to be drivenby fluid passing. into said fluid-tightcompartment from said tube and comprising a pair of oppositely rotating rotors, a'hollo'w inner bit driving shaft rotatably depending from said fluid-tight compartment containing said rotors and extending through the lower end of said casing, an inner drilling bit attached to's'aid inner bit driving shaft externally. of said casing, said inner bit comprising a cutting bit having a plurality of laterally expansible equalizing reamers pivotally mountedthereonfsaid inner bit further having a fluid passageway therein connecting internally to said inner bit drives'haft so that fluid discharged from'saidffluid motor will pass through said inner bit drive shaft and out, said fluid passageway in said-bit, a'means' for driving said inner bit drive shaft comprising a driven gear attached to said inner bit driving shaft, a driving gear coacting therewith to transmit rotative force from one of said rotors of said motor to said inner bit driving shaft, a second driving gear likewise coacting with said driven gear on said inner bit driving shaft, a reversing gear driving said second driving gear and being driven by a second rotor of said motor turning oppositely from the first said rotor through a third driving gear whereby said oppositely rotating rotors of said motor coact to drive said inner bit drive shaft, an outer bit adapted to rotate in an opposite direction aroundsaid inner bit and to be extended and retracted longitudinally with respect to said inner bit, said outer bit having an inner surface which coacts with the arms of said reamers so as to extend the'opposite cutting ends of said reamers laterally from said inner bit when said outer bit is retracted and to contract said cutting ends toward-said inner bit when said outer bit is extended, a rotatable outer bit driving shaft attached to said'outer bit and slidably extending through said casing, a means for rotating said outer bit driving shaft in a direction opposite to that of said inner bit shaft comprising a female ring gear attached to said outer bit drive shaft, a plurality of reverse idler gears slidably coacting with and rotatably driving saidfemale ring gear and being driven by a drive gear attached to said inner bit drive shaft whereby said inner bit drive shaft rotates said outer'bit drive shaft in an opposite direction-from its own rotation, a hydraulic piston attached to said female ring gear and forming a hydraulic cylinder with a portion of said casing, a-centrifugal pump driven by one of said reverse idler gears and adapted to pump fluid from ailower hydraulicreservoir in said easing into said hydraulic cylinder to thereby cause isaidpiston to extend said outer bit with respect to saidinner bit, a first fluid passageway from said hydraulic cylinder through said casing and through 'saidnipple to said annular groove between said tube and saidnipple, a valve in said passageway, said valve having a stem adapted to be pushed down to unseat said valve and being further adapted to coact with said annular cam so that rotation of said nipple and said casing by the unbalanced torque of said counterrotating bits will cause said'valve to become seated and unseated responsive to the rotation of said nipple and said casing to thereby regulate the flow of fluid'through said pump and said passageway, a second fluid passageway connecting said annular groove with said lower hydraulic reservoir, a means for'expanding said dogs against the walls of saidborehole'comprising a plurality of hydraulic cylinders actuated by hydraulic fluid from a pump driven by said mud motor, last said pistons having piston rods coacting with a collar slidably mounted on said frame, and pivotally mounted arms connecting said collar and said dogs so that when last said hydraulic pistons are actuated by fluid pressure, said piston rods push said collar along said frame to extend said dogs to grasp the walls of said bore hole.

2. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination, a cylindrical casing, a hollow tube attached by a nipple to one end of said casing-to form a fluid passageway throughsaid tube and said nipple into said casing, said nipple and said tube having an annular groove at their juncture, a frame rotatably supporting said tube and said nipple, a plurality of dogs laterally expansible from said frame and adapted to press against the walls .of said bore hole when in an expanded position to prevent rotation of said frame, an annular lipextcnding from said frame into said annular groove at the juncture between said tube and said nipple, an annular cam depending from theilower surface of said lip, a fluid motor situated in a fluid-tight compartment in said cas-' ing, said compartment being connected to said fluid passageway in said tube and said nipple, said motor being adapted to be driven by fluid passing into said fluid-tight compartment from said tube, a hollow inner bit driving shaft rotatably depending from said fluid-tight compartment and extending through the lower end of said casing, an inner drilling bit attached to said inner bit driving shaft externally of said casing, said inner bitcomprising a cutting bit having a laterally expansible equalizing reamer pivotally mounted thereon, said inner bit further having fluid passageways therein connecting internally to said inner bit drive shaft so that fluid discharged from said mud motor will pass down said inner bit drive shaft and out said fluid passageways in said bit, a means for driving said inner bit drive shaft comprising a gear train adapted to transmit rotative force from said motor to said inner bit driving shaft, an outer bit adapted to rotate in an opposite direction around said inner bit and to be extended and retracted longitudinally with respect to said inner bit, said outer bit having an inner surface which coacts with an arm of said reamer so as to extend the opposite cutting end of said reamer laterally from said inner bit when said outer bit is retracted and to contract said cutting end toward said inner bit when said outer bit is extended, an outer bit driving shaft attached to said outer bit and slidably extending through said casing, a means for rotating said outer bit driving shaft in a direction opposite to that of said inner bit shaft comprising a gear trainconnecting' said inner bit drive shaft with said outer bit drive shaft, a hydraulic piston attached to said outer bit drive shaft and forming a hydraulic cylinder with a portion of said casing, a centrifugal pump adapted to pump fluid from a lower hydraulic reservoir in said casing into said hydraulic cylinder to thereby cause said piston to extend said outer bit with respect to said inner bit, a first fluid passageway from said hydraulic cylinder through said casing and through said nipple to said annular groove between saidtube and said nipple, a valve in said passageway, said valve having a stem adapted to be pushed down to unseat said valve and being further adapted to coact with said annular cam so that rotation of said nipple and said casing by the unbalanced torque of said counter-rotating bits will cause said valve to become seated and unseated responsive to said rotation of said nipple and said casing to thereby regulate the flow of fluid through said pump and said passageway, a second fluid passageway connecting said annular groove with said lower hydraulic reservoir, a means'for expanding said dogs against the'walls of said bore hole comprising a hydraulic'cylinder and a piston actuated by hydraulic fluid and'coacting with said dogs so that when last said hydraulic piston is actuated by fluid pressure, said dogs are extended to grasp the Walls of said borehole.

3. A bottom hole drilling assembly adaptedto drill a bore hole comprising, in combination, a casing, a hollow tube attached to one end'of said casing, a frame rotatably supporting said tube and said casing, a dog laterally expansible from said frame and adapted to press against the walls of said bore hole to prevent rotation of said frame, an annular cam supported by said frame, a fluid motor situated in said casing, and adapted to be driven by fluid passing into said motor from said tube, a hollow inner bit driving shaft rotatably mounted in said casing and extending through the lower end of said casing, an inner drilling bit attached to said inner bit driving shaft externally of said casing, said inner bit comprising a cutting bit having a laterally expansible equalizing reamer pivotally mounted thereon, said inner bit further having a fluid passageway therein connecting internally to said inner bit drive shaft so that fluid discharged from said mud motor will pass down said inner bit drive shaft and out said fluid passageway in said bit, a driving gear means connecting said motor and said inner bit drive shaft to drive said inner bit drive shaft, an outer bit adapted to rotate in an opposite direction around said inner bit and to be extended and retracted longitudinally with respect to said inner bit, said outer bit having an inner surface which coacts with an arm of said reamer to extend and retract the opposite cutting end of said reamer laterally from said inner bit, an outer bit driving shaft attached to said outer bit and slidably extending through said casing, a gear means rotating said outer bit driving shaft in a direction opposite to that of said inner bit shaft, a hydraulic pressure actuated piston attached to said outer bit drive shaft, means for supplying hydraulic fluid to actuate said hydraulic piston to thereby cause said piston to extendsaid outer bit with respect to said inner bit, a fluid passageway from said hydraulic piston, a valve mounted on said casing and located in said passageway, said valve operatively contacting said annular cam so that rotation of said casing by the unbalanced torque of said counterrotating bits will cause said valve to become seated and unseated responsive to said rotation of said casing to thereby regulate the flow of fluid through said passageway, a means for expanding said dogs against the walls of said bore hole comprising a hydraulic piston actuated by hydraulic fluid operatively connected with said dogs to extend said dogs to grasp the walls of said bore hole.

4. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination, a casing, a frame rotatably supporting said casing, a dog laterally expansible from said frame,

13 an annular cam attached to said frame, a fluid actuated motor situated in said casingfan inner bit driving shaft rotatably mounted in and extending through one end of said casing, an inner drilling bit attached to said inner bit driving shaft externally of said casing, said inner bit comprising a cutting bit having a laterally expansible equalizing reamer mounted thereon, a means operatively connected to said motor for rotating'said inner bit drive shaft, an outer bit adapted to rotate in an opposite direction around said inner bit and to be extended and retracted longitudinally with respect to said inner bit, said outer bit having an inner surface which coacts with the arm of said reamer to extend and retract the opposite' cutting end of said reamer laterally from said inner bit, a rotatable outer bit driving shaft attached to said outer bit and slidably extending through said casing, a means for rotating said outer bit driving shaft in a direction opposite to that of said inner bit shaft, a fluid actuated piston adapted to extend said outer bit with respect to said inner bit, a fluid release means associated with said piston comprising a valve mounted on' said casing and operatively contacting said annular cam so that rotation of said casing by the unbalanced torque of said counterrotating bits will cause said valve tobecome seated and unseated responsive to said rotation of said casing with respect to said frame to thereby regulate the fluid pressure exerted against said piston, and a means for expanding said dog laterally from said frame.

5. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination, a casing, a fluid actuated motor mounted in said casing, a tube attached to one end of said casing and adapted to conduct fluid to said motor, a frame mounted in rotatable relationship with said tube and having attached thereto an annular cam, a plurality of laterally expansible dogs mounted on said frame, a hollow inner bit drive shaft depending from a fluid-tight compartment containing said fluid-actuated motor and extending from said casing to support an inner drilling bit attached to its outer end, a gear train driven by said motor and adapted to rotate said inner bit drive shaft, an outer bit drive shaft extending from said casing to support an outer bit attached at its outer end, said outer bit drive shaft being rotatably mounted around said inner bit drive shaft and being slidably mounted in said casing, a gear train driven by said inner bit drive shaft and adapted to rotate said outer bit drive shaft in,

a direction opposite to that of said inner bit drive shaft, last said gear train being furtherin a slidable relationship with said outer bit drive shaft, a hydraulic cylinder responsive to a fluid pressure exerted by a pump driven by bit is extended with respect to saidinner bit,

and an equalizing reamer pivotally mounted on said inner bit and having an arm which coacts with the inner surface of said outer bit to contract and extend the opposite cutting end ofv said reamer upon extension and retraction of said outer bit thus causing said inner bit to take a smaller or a larger bite from the walls of said bore hole to thereby balance the torques necessary to rotate said bits.

6. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination, a casing, a fluid actuated motor mounted in said casing, a tube attached to one end of said casing and adapted to conduct fluid to said motor, a frame mounted in rotatable relationship with said tube and having attached-thereto an annular cam, a plurality of laterally expansible dogs mounted on said frame, a hollow inner bit drive shaft rotatably mounted in said casing and extending from said casing to support a drilling inner bit attached to its outer end, a gear train driven by said motor and adapted to rotate said inner bit drive shaft, an outer bit drive shaft extending from said casing to support an outer bit attached at its outer end, said outer bit drive shaft being rotatably mounted around said in- .ner bit drive shaft and being slidably mounted in said casing, a gear train driven by said inner,

bit drive shaft and adapted torotate said outer bit drive shaft in a direction opposite to that of said inner bit drive shaft, last said gear train being further in a slidable relationship with said outer bit drive shaft, a piston responsive to a last said gear train, a piston in said cylinder 'by coacting with said cam mounted in said frame in such a manner that when an unbalanced torque between said inner and outer bits causes said casing and said valve to rotate with respect to said cam and said frame such rotation will cause said valve to be opened or closed to regulate the hydraulic pressure in said cylinder to thereby regulate the amount said outer fluid pressure and adapted to extend said outer bit drive shaft and said outer bit with respect to said inner bit, a fluid passageway from said hydraulic piston, a flow regulating valve mounted on said casing and located in said passageway, said valve being opened and closed by coacting with said cam mounted in said frame in such a manner that when an unbalanced torque between said inner and outer bits causes said cas ing and said valve to rotate with respect to said cam and said frame such rotation will cause said valve to be opened or closed to regulate the hydraulic pressure acting on said piston to thereby regulate the amount said outer bit is extended with respect to said inner bit, and an equalizing reamer mounted on said inner bit and having an upper arm which coacts with the inner to an annular cam;'a laterally expansible dog mounted on said frame, an inner bit drive shaft rotatably mounted in said casin and extending from said casing to' support an inner bit attached to its outer end, a means operatively connecting said motor and said inner bit drive shaft and adapted to rotate said inner bit drive shaft, an outer bit" drive shaft extending from said casing to support an outer bit attached at its outer end, said outer bit drive shaft being rotatably and slidably mounted in said casing, means for rotatingsaid outer bit drive shaft in a direction opposite to thatof said inner 'bitdrive shaft, a hydraulically expansible' meansadapted to extend said outer bit drive shaft andisaid outer bit with 1 respect to said inner bit, a flea-"regulating valve mounted-on said casing and operativelyconnected withlsaid hydraulically expansible means, said valvebeing opened and closedby coacting with said cam mounted in said'frame in such a manner that when an unbalanced torque between respect to said inner bit, and an equalizing reamerhaving an arm which coacts with the inner surface of said outer bit to contract and extend the opposite cuttin end of said reamer upon extension and retraction of said outer bit thus causing said inner bit to take a smaller or a larger bite from the walls of said bore hole to thereby balance the torque necessary to rotate'said bits.

8. A bottom hole drilling assembly adapted to drill a bore hole comprising, in combination; a casing, a fluid actuated motor mounted in said casing, a non-rotatable frame mounted in rotatable relationship with said casing and having attached thereto a cam, an inner bit drive shaft rotatably mounted in said casing and extending from said casing to support an inner drilling bit attached to its outer end, a means operatively connecting said motor and said inner bit drive shaft and adapted to rotate said inner bit drive shaft, an outer bit drive shaft extending from said casing to support an outer bit attached at its outer end, said outer bit drive shaft being rotatably and slidably mounted in said casing, means for rotating said outer bit drive shaft in a direction opposite to that of said inner bit drive shaft, a hydraulically expansible means operatively connected to and adapted to extend said outer bit with respect to said inner bit, a fluid flow regulating means mounted on said casing and operatively connected with said hydraulically expansible means and adapted to be opened and closed by coacting with said cam mounted in'said frame in such a manner that when an unbalanced torque between said inner and outer bits causes said casing and said flow regulating.

means to rotate with respect to said cam and said frame such rotation will cause said flow regulating means to be opened or closed to regulate the hydraulic pressure acting on said hydraulically expansible means to thereby regulate the amount said outer bit is extended with respect to said inner bit, and an equalizing reamer having an arm which ooacts with the inner surface of said outer bit to contract and extend the opposite cutting end of said reamer upon extension and retraction of said outer bit thus causing said inner bit to take a smaller or a larger bite from thewalls of said bore hole to thereby balance the torque necessary to rotate said bits.

9. A bottom hole drilling assembly comprising, in combination, a casing rotatably mounted in a non-rotatable frame, an inner bit drive shaft rotatably mounted in said casing and extending therefrom, an inner drilling bit attached to said inner-bit drive shaft, an outer bit drive shaft ro-' tatably and slidably mounted in and extending from said casing, an outer drilling bit mounted on: said outer bit drive shaft and adapted to rotate around said inner bit, means for rotating said outer and inner bits in opposite directions,

adjustable 'cutting meanspivotally mounted on; said inner bit for varying the bite of said inneri bit responsive toi the longitudinal extension of said outer-bit with respect to said inner bit, and

means for regulating the said longitudinal exten= sion of said outer bit comprising a hydraulic expansible means cooperating with'said outer bit to extend-it responsive to hydraulic pressure in said hydraulic means and a fluid pressure regulating means mounted on said casing and up eratively connected to said-hydraulic meanstto vary the pressure therein responsive to the rota tion' of said casing caused by unbalanced torque of the counterrotating said inner and outer bits.-

10: A drilling bit adapted to drill a bore hole. comprising an inner'bit, an outer bit rotating around said inner bit in 'a direction opposite therefrom and extensible longitudinally with re-v spect to said inner bit, an equalizing reamer com-.

prising a V-shaped member pivotally mounted tosaid inner bit at a midpoint of said V-shaped member, one arm of said V-shaped reamer coacting withan inner surface of said outer bit so that a retraction of said outer bitfrom the: formation". being drilled will cause the opposite cutting end 7: of said V-shaped reamer to'be"extendedlaterale., ly from said inner bittto thereby cause said inner bit to'take a larger bite from said formation.

11. A drilling 'bit adapted to drill'a bore hole comprising an inn-er bit, an outer bit rotating around said inner bit in a direction opposite i. therefrom, an extensible longitudinally with re-: spect to said inner hit, an equalizing reamer pivotally mounted to said inner bit; said reamer having an arm which coacts with an inner sur-" face of said outer bit so that a retraction ofsaid outer bit from the formation being drilledwill. cause the opposite cutting end of said reamerto Y beextended laterally from said inner bit to therebycause said inner bit to take a larger bite from said formation.

12; A drilling bit adapted to drill a bore hole comprising an inner bit, an outer bit rotating around said inner bit in a direction opposite therefrom and slidable longitudinally with re-' spectto said inner bit and an equalizingreamer comprising an inner bit, an outer bit rotating around said inner bit in a direction opposite therefrom and slidable longitudinally with respect to said inner bit andan equalizing reamer having'anupper arm and an opposite cutting edge, said reamer bein mounted on said inner bit so as to cause said inner bit to take a larger bite from said formation when said outer bit is retracted from the formation being drilled.

CARL W. KOCHQ.

References Citedin the file of this patent.

UNITED. STATES PATENTS Number Name Date 1,412,430 Verneuil Apr. 11, 1922 2,002,387 Bannister May 21, 1935 2,496,954 Prassel Feb. 7, 1950 Degner Oct. 31, 1950

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