US2896913A

US2896913A - Apparatus for drilling lateral openings in well bores

Info

Publication number: US2896913A
Application number: US615157A
Authority: US
Inventors: Charles D Holmes; Howard H Holmes
Original assignee: ANGLEDRILL CORP
Current assignee: ANGLEDRILL Corp
Priority date: 1956-10-10
Filing date: 1956-10-10
Publication date: 1959-07-28
Anticipated expiration: 1976-07-28

Description

July 28, 1959 Filed Oct. 10. 1956 a Mam I I! 1/ I 11/ I III c. HOLMES ETAL //A X W/ APPARATUS FOR DRILLING LATERAL OPENINGS IN WELL BORES 5 Sheets-:Sheet -1 INVENTORS, CHARLES D. HoLMLs it HqwArao H HOLMES JT TO Y July 28, 1959 c. D. HOLMES ETAL- APPARATUS FOR DRILLING LATERAL OPENINGS IN WELL BORES Filed Oct; 10, 1956 5 Sheets-Sheet 3 FIG. IL,

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7. a 7. h m w 8 l I. /d I I I! WII/l/lZ/Jlll/ll ff/l /r flfl fl i 07 5 5 T 7 4 ITB H 4 6 6 8 9 1 7 ml HFQAMMI/L ATTORNEY July 28, 1959 c. D. HOLMES ETAL APPARATUS FOR DRILLING LATERAL OPENINGS IN wsu. BORES Filed Oct. 10. 1956 5 Sheets-Sheet 4 i a k/ 64 INVENTORS CHARLES D HOLMES & HOWARDHHOLMES BY flTTOR/VEZY July 28, 1959 C. D. HOLMES ETAL APPARATUS FOR DRILLING LATERAL OPENINGS IN wzu. BORES 5 She ets-Sheet 5 Filed 00ft. 10, 1956 Flo. l8.

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Illllllll INVENTORS. C HARLES D. HoLmcs & HOWARD H, HOLMES United States Patent 2,896,913 Patented July 28, 1959 APPARATUS FOR DRILLIN G LATERAL OPENINGS IN WELL BORES Charles D. Holmes and Howard H. Holmes, Tulsa, Okla,

assignors to Angledrill Corporation, Tulsa, Okla, a corporation of Oklahoma Application October 10, 1956, Serial No. 615,157

Claims. (Cl. 25-16) This invention relates to boring or drilling apparatus, and more particularly to apparatus for use in the forming of lateral openings in an oil well bore, or the like.

An important object of the invention is to provide apparatus for drilling lateral openings in the rock or sand stratum containing the oil, such openings being formed substantially at right angles to the larger main well bore.

A further primary object is to provide apparatus of the above-rnentioned character, the use of which will greatly increase the oil output or yield of an old or sluggish well, due to the formation of a desired number of the lateral openings above-referred to.

Another object is to provide apparatus of the above character which may be used equally well in old or new oil wells, gas wells, distillate wells, water wells, or any other types of disposal or input wells.

An additional object is to provide a unitary and selfcontained drilling apparatus, adapted to be lowered bodily into the well and positioned at the desired elevation, and containing power and gravity operated means for causing a plurality of drilling elements to penetrate their way deeply into the rock or sand of the well substantially at right angles to the axis of the well bore.

A further objectis to provide in drilling apparatus of the above-mentioned character, novel guide and supporting means and relatively movable power and gravity operated boring ordrilling means engaging the guide means during the operation of the apparatus.

A particular object is to provide in an apparatus of the above-mentioned character novel flexible drive shaft means for the several drilling bits, and novel means for guiding the flexible drive shaft means longitudinally into and from proper drilling relation with the main well bore.

Still another object is to provide apparatus of the abovementioned character which is compact and simplified in construction, easy to assemble, disassemble and maintain, reliable and eflicient in operation, and relatively economical to manufacture.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout same,

Figure 1 is a fragmentary central vertical longitudinal section, parts in elevation, through a top portion of the drilling apparatus embodying the present invention.

Figure 2 is a companion central vertical longitudinal section taken at right angles to Figure 1, through the same portion of the apparatus.

Figure 3 is a horizontal transverse section taken on line 3-3 of Figure 1.

Figure 4 is a similar section taken on line 4-4 Figure 1. 1

Figure 5 is a similar section taken on line 5-5 of Figure 1.

Figure 6 is a fragmentary central vertical longitudinal section similar to Figure 1, through a next lowermost portion of the apparatus.

Figure 7 is a companion central vertical longitudinal section through the apparatus shown in Figure 6 and taken at right angles thereto.

Figure 8 is a horizontal transverse section taken on line 8-8 of Figure 6.

Figure 9 is a further fragmentary central vertical longitudinal section, similar to Figures 1 and 6, through a next lowermost portion of the apparatus.

Figure 10 is a companion central vertical longitudinal section of the portion of the apparatus shown in Figure 9, taken at right angles thereto.

Figure 11 is a further companion longitudinal vertical section, parts in elevation and parts broken away, taken substantially on line 11-11 of Figure 10.

Figure 12 is a horizontal transverse section taken on line 12-12. of Figure 9.

Figure 13 is a similar section taken on line 13-13 of Figure 9.

Figure 14 is a fragmentary central vertical longitudinal section similar to Figures 1, 6 and 9, through the lowermost portion of the apparatus.

Figure 15 is a companion fragmentary central vertical longitudinal section, parts omitted, taken at right angles to Figure 14.

Figure 16 is a horizontal transverse section taken on line 16-16 of Figure 14.

Figure 17 is a similar section taken on line 17-17 of Figure 14.

' Figure 18 is an enlarged fragmentary vertical section taken substantially on line 18-18 of Figure 9.

Figure 19 is a fragmentary central vertical longitudinal section taken on line 19-19 of Figure 18, parts omitted.

Figure 20 is an enlarged fragmentary sectional view through one drill bit and associated elements taken substantially on line 20-20 of Figure 14.

Figure 21 is a fragmentary central vertical longitudinal section on a greatly reduced scale through a well bore having the apparatus disposed therein and showing the entire apparatus in side elevation, the view being partly diagrammatic.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 20 designates an elongated cylindrical exterior casing or tube, forming a housing for the remainder of the apparatus, and adapted to be lowered bodily lengthwise into an oil Well bore or the like. At its upper end, Figures 1 to 3, the casing 20 receives an annular sleeve 21, rigidly secured therein by screws 22 or the like. A pair of diametrically opposed generally longitudinal rods 23 have their lower ends rigidly secured as by Welding to the top of the sleeve 21, and extend for a short distance beyond the adjacent ends of the casing and sleeve, as shown. A flat mounting or adapter plate 24 is rigidly secured as by welding to the ends of the rods 23, and the plate 24 has a large opening 25 at its center, and a number of circumferentially spaced openings 26 near its periphery for receiving bolts or the like, as will be further described.

The lower end of the casing 20, Figures 14, 15 and 17, has a cylindrical cap 26 suitably rigidly secured therein and provided in its end wall with a plurality of fluid escape openings 27. A tubular socket element 28 is rigidly secured as by welding to the cap 26 centrally thereof, and the usual anchor 29 for engagement with the bottom of the well bore is provided, and has screwthreaded engagement within the element 28, as shown.

A rigid transverse suspension plate 30 is positioned within the casing 20 directly below the sleeve 21, Figures 1 to 3, and the opposite end portions of the suspension plate engage the bottom of the sleeve 21 at diametrically opposite points, as shown. An eye-bolt 31 is received by a central opening 32 in the suspension plate 30, and the eye-bolt carries positioning nuts 33, above and below the plate 30, and a lock nut 34. The lower nut 33 is spaced slightly from the bottom of the plate 36 so that the eye-bolt 31 is freely swiveled and may turn upon its longitudinal axis within the opening 32. A hoisting cable 35 is suitably secured at 36 to the eye-bolt, and by means of this cable the entire apparatus may be raised and lowered in the well.

A pair of diametrically opposed longitudinal screwthreaded suspension rods 37 are provided, Figure l, and have their upper end portions adjustably held within openings 33 of the suspension plate 36, by means of adjusting nuts 3%, above and below the suspension plate. The lower ends of the suspension rods 37 have screwthreaded engagement within screw-threaded openings of a cross plate 49, and this cross plate has a central opening receiving a downwardly directed screw 41, Figures 1 and 2. The screw 41 has screw-threaded engagement within the upper flange of the casing of an electric drive motor 42, and the plate 46 is held by the screw 41 tightly against the upper flange or end of the motor casing. The motor 42 is preferably a generally conventional three phase 440 volt A.C. submersible motor. Any other suitable electric motor may be employed, if found desirable, instead of the particular motor 42. The motor 42 has a splined armature or drive shaft 43 at its lower end, Figure 1. The lower end or flange 44 of the motor 42 is rigidly secured as at 45 to the upper end wall 46 of an elongated cylindrical tubular housing 47, of considerably smaller diameter than the outer casing 20. The tubular housing 47 with the motor 42 is disposed eccentrically of the outer casing 20, Figures 4 and 5, and the tubular housing 47 extends lengthwise of the casing 20 below the motor 42 for a substantial distance, and has its lower end terminating at 48, considerably above the longitudinal center of the outer casing 20. The lower end of the tubular housing 47 is open. The motor 42 and the tubular housing 47 are bodily movable as a unit lengthwise of the outer casing 20, as will be further explained.

A central relatively short longitudinal drive shaft 49 carries a splined head 56 at its top end, engaging and driven by the armature shaft 43. The lower end of the drive shaft 49 is connected by means of a universal joint 51 with an input shaft 52 of a spur gear box 53. The gear box 53 is cylindrical and is fixedly secured within the tubular housing 47 near and below its upper end. The gear box or transmission 53 is provided at its lower end with three driven or

output shafts

54, 55 and 56, adapted to turn in the same direction and at the same speed as the single drive shaft 49 and input shaft 52. The gearing within the gear box 53 is conventional spur gearing, and need not be described in detail.

A corresponding number of spaced generally longitudinal inclined drive shafts 57 are provided below the gear box 53, and the upper ends of the shafts 57 are connected with the three

output shafts

54, 55 and 56, through the medium of universal joints 58. The upper ends of the shafts 57 preferably have slotted connections at 59 with the universal joints 58, to allow limited endwise movement of the shafts 57, if necessary. The three drive shafts 57 are inclined with respect to the longitudinal axis of the casing 29 as shown in Figure 7. The lower end portions of the shafts 57 extend exteriorly of the tubular housing 47, the latter being provided with a large side opening 60, extending from a point 61 near its longitudinal center, toward and through its lower end. The

lower ends of the drive shafts 57 are connected with universal joints 62, and these universal joints are directly connected with upper bearing assemblies 63, to be described in detail hereinafter. It may be seen that the lower ends of the shafts 57- and the universal joints 62 are disposed outside of the tubular housing 47 and in the 4 space between the outer casing 20 and the eccentrically arranged tubular housing 47, Figure 8.

A long arcuate mounting plate or shoe 64 is fixedly secured by any suitable means to the inner face of the outer casing 26, at one side of the same, and extends lengthwise of the casing 20 from a point 64', near the top of the motor 42, to a point adjacent the top of cap 26, as shown at 64a, Figures 14 and 15. The mounting plate 64 forms a support for guide means for the motor 42, upper bearing assemblies 63 and other associated elements of the apparatus.

This guide means comprises three elongated substantially cylindrical tubular guide members 65, arranged in spaced parallel relation longitudinally of the shoe 64 and fixedly secured thereto as by welding. The tubular guide members 65 are thus mounted bodily upon the inner surface of the arcuate shoe or.mounting plate 64, and they extend continuously throughout a major portion of the length of the mounting plate 64 and have their lower ends terminating a substantial distance above its lower end, as shown at 66, Figure 9. Each guide member 65 is provided throughout substantially its entire length and in its forward or inner side with a continuous longitudinal slot 67, and these slots all face or open in the same direction and do not converge toward the center or longitudinal axis of the outer casing 20, Figures 8 and 12.

At its upper end, and adjacent its side nearest the mounting plate 64, Figure 4, the motor 42 is provided with an upstanding bracket or lug 68, rigidly secured thereto, and having an opening for the reception of a screw 69, which screw has screw-threaded engagement within a screw-threaded opening of a cylindrical slide 70, in turn slidably mounted within the central slotted guide member 65, as shown. The shank of the screw 69 extends movably through the slot 67 of the particular guide member 65. By this means, the motor 42 is anchored against lateral swaying within the casing 20 and is positively guided during its movement with the tubular housing 47 and associated elements lengthwise of the casing 20. When the apparatus is in a horizontal position, as during transportation, the weight of the motor 42 and associated elements is held off of the tubular guide means 65 by the slide 70 and associated elements abovedescribed. The motor is thus positioned free from contact with the outer casing 20, and the novel guide means enables the motor to be suspended Within the space afforded by the outer casing 20 for movement lengthwise of the outer casing.

At substantially lower points upon the fixed guide members 65, the three upper bearing assemblies 63 are slidably received therein, Figures 10 and 11. This is adjacent the lower ends of the shafts 57, as previously stated. The universal joints 62 at the upper ends of the bearing assemblies 63 and also the lower end portions of the inclined shafts 57 project through the slots 67, Figures 7 and 8, but clear and do. not contact the guide members 65.

Each upper bearing assembly 63 comprises a cylindrical casing or tube 71, slidably received within one tubular guide member 65. Adjacent the bearing assemblies 63, Figures 9 to 11 and 18, the previously mentioned side opening 60. ofthe tubular housing 47 is covered by a flat cover plate 72, which extends for substantially the lengths of the bearing assemblies, and the cover plate 72 is rigidly secured to the tubular housing 47 as by welding or the like, Figure. 12., A pair of opposed parallel longitudinal angle bars 73 are rigidly secured, as by welding, to the outer face of the cover plate 72, in opposed relation, as shown. Each tube 71 has a longitudinal radial fin 74 rigidly secured thereto and projecting laterally thereof. The fins 74 are parallel, and the two outermost fins 74 lie adjacent the inner faces of the upstanding webs of the i angle bars 73, Figure 12. The webs 74 and angle bars ceiving transverse bolts 76, as shown. The bolts 76 thus serve to prevent the bearing assemblies 63 from turning upon their longitudinal axes, while allowing them to move in unison lengthwise within the guide members 65. The radial fins 74 of the casings or tubes 71 project through the slots 67 of the guide members. The bolts 76 also serve to transmit the entire weight of the motor, housing 47 and associated elements through the angle bars 73 to the upper bearing assemblies 63, so that the latter will be forced downwardly by gravity during the operation of the apparatus.

Each upper bearing assembly 63 further comprises a rotary shaft 77, having its upper end operatively connected with one of the universal joints 62. Each shaft 77 is journaled for rotation within a pair of ball bearings 78, arranged in spaced relation inside of the tube 71, Figure 19. Below the lower bearing 78, each rotary shaft 77 has an enlarged cylindrical portion 79 integral therewith, and preferably journaled within a graphite-bronze bushing 80, or the like, within the tube 71 near its lower end. The enlarged portion 79 has a square bore 81, receiving a relatively short square driving element or pin 82, which is slidable lengthwise somewhat within the square bore 81. The lower end of the tube 71 is screw-threaded for receiving a screw-threaded cap 83 having a central bore 84, and a lateral port 85 leading therefrom and opening through the side of the cap for a purpose to be described.

A lower cylindrical end portion 84a of each square pin 82 is received within one end of a cylindrical coupling: sleeve 84, the opposite end of which receives the upper end portion 84b of a flexible drive shaft 86. The end portions 84a and 84b are soldered or sweated within the coupling sleeve 84' to assure a firm driving connection. Each flexible drive shaft 86 is housed within a casing or sheathing 87, which is also flexible, although stiff enough to be capable of transmitting a substantial axial thrust or pushing force, when properly supported against lateral bending. The entire sheathing 87 is enclosed within a flexible tubular braided covering or envelope 88, which may be formed of metal, glass rovings, plastic, or other suitable materials. The purpose of the braided cover 88 is to transmit pulling or tensile forces axially of the flexible drive shaft 86. The shaft 86 is freely rotatable within the sheathing 87 and this sheathing and the braided cover 88 do not rotate, and the former is employed to transmit pushing forces while the latter transmits pulling forces. The upper ends of each sheathing 87 and braided cover 88 are secured by soldering or the like at 89, Figure 19, to a reduced portion 89' of the cap 83.

The slotted guide members 65 are screw-threaded at 90, Figure 9, adjacent their lower ends and coupled by nuts 91 with the upper ends of substantially rigid, fixed guide or locator tubes 92, disposed in the lower portion of casing 20 and forming continuations of the slotted guide members or tubes 65. The flexible drive shaft assemblies including shafts 86, sheathings 87 and braided covers 88 extend slidably through the guide members 65 and through the locator tubes 92, and have relatively close fits therein so that they cannot bend or buckle when subjected to a thrust or pushing load in the downward direction.

Each tube 92 is shaped and gradually curved to form a; generally longitudinal portion 93 which is straight, and a curved elbow portion 94, as shown. The lower ends of the elbow portions 94 are cylindrical and straight for a.

short distance, as at 95 in Figure 20. These straight: terminal portions 95 of the guide tubes 92 terminate flush. with the inner surface of the outer casing 20, Figure 20,. and in registration with openings 96 formed through the: outer casing 28, adjacent the lower ends of the guide tubes. The lower end portions 95 of the three guide tuba: 92 are at slightly different elevations, Figure 14, and their" terminal portions 95 are preferably spaced 120 degrees circumferentially of the casing 20. To render the tubes- 92 fixed relative to eachother, they are soldered to the;

, 6 mounting plate 64 and to each other as at 97 and 98 respectively, Figures 14 to 16. a

With particular reference to Figure 20, the lower end of each flexible drive shaft assembly carries an enlarged tubular head 99, containing a pair of ball bearings 100. The lower ends of each casing or sheathing 87 and the companion cover 88 are secured by soldering at 101 to a reduced neck 101' of the head 99. It is thus seen that the head 99 in effect is part of the flexible shaft assembly, and the head is freely slidable axially within the straight tube portion 95. The head 99 does not rotate during the operation of the apparatus and neither do the sheathing 87 or braided cover 88.

Iournaled Within the bearings 100 for rotation and extending axially through the head 99 is a spindle 102, having its rear end secured by soldering at 103 to the lower end of the flexible drive shaft 86. Forwardly of the head 99, a rotary diamond drill bit 105 is fixedly secured to :the spindle 102 for rotation therewith by a set screw 106, Figure 20. The bit 105 rotates with the spindle 102 and flexible drive shaft 86, as should be obvious.

Each drill bit 105 has a diagonal compressed air or fluid port 107 opening through its forward end and leading to an axial air port 198 formed in the spindle 102. The port 108 leads rearwardly to a transverse port 109 in the spindle, opening radially into a small annular passage for air 110, surrounding the spindle and between it and the sheathing 87 and the neck portion 101, Figure 20. The air passage 110 communicates directly with a larger annular passage 111, between the sheathing 87 and flexible shaft 86 and extending throughout the entire lengths of the latter, upwardly to the upper bearing assemblies 63. The annular passages 111 of the flexible shaft assemblies lead to annular spaces 112 within the caps 83 at the lower ends of the bearing assemblies 63, Figure 19, and

the passages 112 are between the flexible shafts 86 and the bores 84 of caps 83. Each cap 83 has a lateral port '85 formed therethrough, as previously described, and suitable elbow fittings 114 are connected within the ports :85 and lead to short vertical hoses 115, having their lower ends connected with a common header or manifold 116, having an air or fluid inlet 117, adapted for connection with a compressed air supply line or the like, not shown. The interiors of the sheathings 87 are preferably coated with a suitable cement-like composition to render them substantially air or fluid tight so that the compressed .air or the like may be transmitted from the manifold 116, through the flexible shaft assemblies to the ports 107 of the drill bits, during the operation of the apparatus, for cleaning away the cuttings of stone and for cooling the bits.

In actual practice, it is contemplated having an upper tubular casing section somewhat similar to the casing section 20 and bolted to the adapter flange 24 of the lower casing section. This upper casing section has been omitted from the drawings, for the purpose of simplification, and may actually be dispensed with in the apparatus if preferred. When employed, the upper casing section will :house a suitable source of compressed air or fluid to be supplied by means of a flexible hose, not shown, to the inlet 117 of manifold 116, Figures 9 and 10. The upper casing section may also contain other required accessory units, as for example, a suitable source for a flowing liquid coolant for an external cooling coil 118 of the motor 42, Figures 1 and 2. The cooling coil 118 may be omitted from the apparatus, if preferred, but where used, the liquid coolant from the above-mentioned source may pass into the coil 118 through an inlet nipple 119, by way of a suitable hose, not shown. The upper casing section and the accessories contained therein, when used, will move bodily into the well bore along with the lower casing section 20, and will form therewith a continuous or unitary assembly. When the upper casing section is not used, the compressed air, liquid coolant, etc. may be supplied to the apparatus by any other suitable means above ground, or otherwise.

Operation With the various parts of the apparatus assembled, as shown in the drawings, the suspension rods 37 are adjusted lengthwise in order to have the plate 30 contacting the bottom of the sleeve 21 when the bits 105 are positioned substantially as in Figure 20 or flush with the outer face of the casing 20.

The entire apparatus, as shown in Figure 21, is now lowered into the well bore by means of the cable 35, which is connected above ground with suitable poweroperated winding and unwinding means, not shown. The apparatus may be lowered into the well bore until the anchor 29 contacts the bottom of the well, or until the apparatus is positioned at a desired elevation within the well bore, above the bottom of the well. It should be mentioned here that in the case last mentioned, where the apparatus is suspended somewhere above the bottom of the well, the suspension cable 35 will be attached to the upper flange 24, instead of to the eye-bolt 31, and the electrical cable to the motor 42, not shown, will be attached to the eye-bolt 31, as will be more fully described.

Assuming first that the apparatus is resting upon the bottom of the well, the cable 35 will be connected with the eyebolt 31, as shown and described. In order to cause the drill bits N to now drill the desired lateral openings radially of the well bore, Figure 21, the electric motor 42 is started for imparting rotation to the flexible drive shafts 86, through the medium of shaft 49, gearing 53, inclined shafts 57 and the shafts 77 and square pins 82 of the upper bearing assemblies 63. This will cause the three drill bits 105 to rotate at the desired speed simultaneously.

The suspension cable 35 which, up to now, has been taut for supporting the weight of the motor 42 and connected elements is slackened, and the weight of the motor, tubular housing 47 and all parts carried thereby will be transmitted as a thrust or pushing force through the flexible shaft sheathings 87, the lower ends of which will push upon the head 99, Figure 20. This thrust force will now drive the bits 195 which are rotating into the rock to form openings or passages at right angles to the well bore, and to a depth limited only by the length of the apparatus between the upper bearing assemblies 63 and the tops of the guide tubes 92, which length may be varied through relatively wide limits, as found desirable. Obviously, the greater this length is, the greater will be the extent of possible movement of the drill bits 105 radially outwardly from the casing 29 and into the oil bearing rock, because the extent of downward movement of the upper bearing assemblies 63 will be determined by the location or elevation of the coupling nuts 91 and the bottoms of the slots 67, Figure 9. The design of the apparatus is such that the unsupported weight of the motor 42, housing 47 and associated elements is sufficient to cause a proper feeding of the drill bits Hi5 into the rock or sand. It is thus seen that the apparatus operates to this extent by gravity, for automatically feeding the drill bits radially into the rock, at right angles to the well bore. If, for any reason, it should become desirable to lessen the weight of the motor 42 and associated elements during the operation of the apparatus, this may conveniently bedone by tightening or tensioning the cable 35 a desired amount.

In the event that one drill bit 105 should encounter greater resistance to drilling than the other hits, the entire weight of the motor and associated parts will be momentarily transmitted as thrust behind this particular bit to meet and overcome the increased resistance. After the particular drill bit has cut through the material causing this resistance, and the resistance against the three bits is again substantially equal, the thrust or push behind the three bits due tothe weight of the motor and related parts will again automatically be equalized upon 8 the three bits so that the latter will continue their Work uniformly and with maximum speed.

In connection with the above mode of operation, the upper bearing assemblies 63 and the flexible drive-shatft assemblies operate smoothly through the slotted guide. members 65 and the lower guide or locator tubes 92. The outside diameters of the tubes 71, flexible shaft assem: blies and head 99 are all substantially equal, and only slightly less than the inside diameters of the cylindrical guide members 65 and the tubes 92. With this arrangement, the flexible shaft assemblies may be pushed longitudinally through the members 65 and tubes 92 without any kinking, buckling or bending, and as previously stated, this pushing or feeding action due to the weight of the motor and the parts which move therewith is transmitted through the sheathings 87. When the drill bits are being withdrawn from the lateral bores which they have formed, this is accomplished by pulling the cable 35 upwardly and thereby elevating the motor 42, tubular housing 4-7 and associated elements, which will cause the elevating of the bearing assemblies 63 within the guide members 65, since the assemblies 63 are connected directly with the tubular housing 4-7, Figures 10 and 12. As the bearing assemblies 63 are thus pulled upwardly within the guide members 65, the flexible shaft assemblies connected with their lower end, Figure 10, will also be pulled upwardly through the tubes 92 and guide members 65 to retract or withdraw the drill bits and return them to positions such as shown in Figure 20. This retracting or pulling force for withdrawing the drill bits is transmitted through the flexible shaft assemblies by means of their outer braided coverings 88, and this is the purpose of the coverings 88. The flexible shafts 36 and the push ing sheathings 87 are thus relieved by the coverings 88 of any appreciable pulling or tensile stress, which they are not designed to withstand. When the drill bits 105 are thus retracted to their starting positions, Figure 20, the suspension plate 3i) will have again come into contact with the bottom of the sleeve 21, Figure 1. At this time, further lifting with the cable 35 will raise the entire apparatus bodily from the well bore, the motor 42 being of course shut ofl to stop the rotation of the drill bits.

When the apparatus is used without the anchor 29 hottoming in the well, as for drilling additional groups of lateral openings in the well bore at closely spaced but different elevations, or when the oil bearing stratum is considerably above the bottom of the well, the suspension cable 35 will be attached to the flange 24, rather than to the eye-bolt 31, as previously mentioned. At this time, the cable 35 could also be attached to the top of the upper casing section, not shown, for the accessory units of the apparatus. With this arrangement, the outer casing 20 may be suspended at any desired elevation in the well bore. The electrical cable, not shown, leading from above to the motor 42 is now attached securely to the eye-bolt 31, to support the weight of the motor, tubular housing 47 and associated parts. This is a special electrical cable, capable of carrying the necessary load suspended by the eye-bolt, and such reinforced cables are readily available upon the market. The electrical cable extends upwardly with the cable 35 to another winding and unwinding means above ground, not shown, and through this means the necessary relative vertical move ment between the motor 42 and associated parts and the outer casing 20 may be obtained, while the apparatus is suspended in the well bore. This relative longitudinal movement between the motor and outer casing 20 is what causes the desired feeding of the drill bits into the rock at right angles to the well bore and the retracting of the drill bits, in the manner above-described in detail with the apparatus resting upon the bottom of the well. By elevating the outer casing 20 step by step a slight amount after each drilling of three lateral openings with the three drill bits, any desired number of closely spaced lateral openings may be drilled, radially of the well herein a relatively small or relatively large area of the latter. Each time that the motor, housing 47 and associated parts are allowed to descend by gravity within the casing 20, three of the desired radial openings are drilled simultaneously in the rock and these openings will be spaced 120 degrees apart, circumferentially of the well bore and they will be at slightly diflerent elevations, due tothe arrangement of the tube portions 94, Figure 14. It is entirely practical with the apparatus as above described to drill openings at right angles to the well bore for as much as ten to fifteen feet or more into the rock, and as previously suggested, this distance can be increased to any practical degree by lengthening the apparatus in the region or portion between the coupling nuts 91 and bearing assemblies 63, in the elevated positions of the latter.

An additional desirable feature of the apparatus is its ease of assembly and disassembly above ground. With the drill bits 105 fully retracted inside of the tube portions 95, which may be accomplished through the medium of the nuts 39, it is merely necessary to remove the screws or the like securing the long shoe 64 to the outer casing 20, and the entire assembly inside of the casing 20, including the locator tubes 92 which are anchored to the shoe 64 will slide longitudinally out of the outer casing, it being also necessary first to remove the sleeve 21. Once this major separation of parts has been accomplished, the internal elements of the apparatus, such as the motor 42 and associated parts will be all readily accessible for servicing.

It is to be understood that the form of the invention herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described our invention, we claim:

1. Apparatus for drilling substantially horizontal openings in a substantially vertical well bore comprising elongated substantially rigid guide means, said guide means being curved and having portions extending substantially at right angles to the well bore, means connected with said guide means for positioning the same at the desired elevation within the well bore, a drive motor supported independently of the guide means within the well bore and movable longitudinally of the guide means and well bore and having an output shaft, gearing connected with and driven by said output shaft and having a plurality of driven shafts, a substantially tubular housing secured to said motor and receiving said gearing and extending for a substantial distance below the motor longitudinally of the guide means and having a side opening, a plurality of inclined shafts connected with and turned by the driven shafts of the gearing and extending through said side opening and exteriorly of the tubular housing, a corresponding number of bearing assemblies engaging the rigid guide means and shiftable lengthwise thereof and having rotary parts connected with and driven by said inclined shafts, and a corresponding number of flexible drilling shaft assemblies including drill bits engaging the rigid guide means and movable lengthwise thereof and restrained against buckling and twisting thereby and being elongated and extending throughout a major portion of the length of the rigid guide means, said drilling shaft assemblies including rotary parts connected with and driven by said first-named rotary parts of the bearing assemblies.

2. Apparatus for drilling substantially horizontal openings in a substantially vertical well bore comprising an outer tubular casing engageable within the well bore, means connected with said casing for positioning the same at the desired elevation Within the well bore, a plurality of substantially tubular guide elements secured within the casing adjacent the side wall thereof and extending longitudinally of the casing for a substantial length of the latter, each guide element having a longitudinal slot "10 formed therethrough throughout a major'portion of its length, each guide element including a curved portion arranged near the lower end of said casing with a section of the curved portion extending substantially at right angles to the well bore, a drive motor positioned within the casing near the side thereof opposite the guide elements, said slots of the guide elements facing the motor, means for suspendingly supporting the motor within the casing for movement longitudinally of the casing and guide elements, a slide carried by the motor and engaging within one guide element and having a part extending through the slot of such guide element, whereby the motor is restrained from lateral swaying and smoothly guided lengthwise of the casing, a flexible drive shaft assembly disposed within each tubular guide element and being elongated and shiftable axially Within the guide element, drill bit means carried by the lower end of each flexible shaft assembly, upper bearing assemblies disposed within the tubular guide elements for longitudinal movement and connected with the tops of the flexible shaft assemblies and having rotary parts and radial elements projecting through the slots of the tubular guide elements, rotary means driven by said motor and connected. with and driving said rotary parts of the upper bearing assemblies, and rigid means interconnecting said radial elements of the bearing assemblies and motor, whereby movement of the motor longitudinally of the tubular casing will cause a corresponding movement of the flexible drive shaft assemblies.

3. Apparatus for drilling substantially horizontal openings in a substantially vertical well bore comprising an outer tubular casing engageable within the well bore, means connected with said casing for positioning it at the desired elevation within the well bore, a plurality of generally tubular elongated substantially rigid guide elements secured within said casing and extending longitudinally thereof near the side wall of the casing, each guide element having a longitudinal slot formed therethrough, each guide element including a curved portion near the lower end of said casing with a section extending substantially at right angles to the well bore, upper bearing assemblies mounted within said rigid guide elements and movable lengthwise thereof and having radial connecting parts projecting through said slots, power operated rotary driving mean-s disposed within said casing and being independently supported therein for movement lengthwise thereof, means connecting said radial connecting parts of the upper bearing assemblies with said driving means, whereby movement of the driving means longitudinally of the rigid guide elements will cause a corresponding movement of said upper bearing assemblies longitudinally thereof, said bearing assemblies having rotary parts connected with and turned by the driving means, and a plurality of elongated flexible drilling shaft assemblies including rotary parts having drill bits engaging slidably within said tubular rigid guide elements and being shiftable longitudinally thereof and having corresponding ends secured to said upper hearing assemblies for movement therewith, the weight of the driving means when released forcing the upper bearing assemblies downwardly through said tubular guide elements to thereby push the flexible drilling shaft assemblies and drill bits axially through said sections of the guide elements which extend substantially at right angles to the well bore, the drill bits then forming the substantially horizontal openings in the well bore.

4. Apparatus for drilling a plurality of substantially horizontal openings substantially simultaneously in a substantially vertical Well bore comprising relatively stationary guide means including a plurality of substantially tubular elongated guide elements having portions which are curved so as to provide sections of the guide elements extending substantially at right angles to the axis of the well bore, means connected with the guide means for positioning the guide means at the desired elevation within the well bore, a motor mounted for movement longitudinally of the guide means, means supporting the motor independently of the guide means, gearing connected with and driven by the motor and bodily movable therewith relative to the guide means and having a plurality of driven rigid shafts, a corresponding number of elongated rigid bearing assemblies longitudinally movably mounted within said substantially tubular guide elements and having rotary parts connected with and driven by said driven shafts, and a corresponding number of elongated flexible drill shaft assemblies longitudinally movably mounted within the guide elements and including rotary parts carrying drill bits, the rotary parts of the flexible sh-aft assemblies connected with and driven by the rotary parts of the rigid bearing assemblies, the flexible drilling shaft assemblies adapted to move longitudinally through the substantially tubular guide elements in unison with the rigid bearing assemblies.

5. Apparatus for drilling a plurality of openings in a well bore substantially at right angles to the axis of said bore comprising a plurality of elongated substantially tubular rigid guides including sections which are curved so that parts of the guides extend substantially at right angles to said bore, means connected with said guides for positioning them at the desired point within the well bore, a drive motor supported independently of said guides and movably engaging the last-named means and having a single armature shaft, gearing connected with and driven by said armature shaft and including a plu-- rality of separate driven output shafts, a corresponding number of rigid bearing assemblies engaged within said guides and shiftable lengthwise thereof, rotary shafts journaled within said bearing assemblies and having corresponding ends connected with said output shafts and turned thereby, a corresponding number of flexible drive shaft assemblies engaging within said elongated guides and movable lengthwise thereof and having rotary parts connected with and driven by said shafts of the bearing assemblies, and a drill bit connected with the rotary part of each drive shaft assembly for drilling said openings substantially at right angles to the axis of the well bore when the flexible shaft assemblies are fed longitudinally in one direction through said guides.

References Cited in the file of this patent UNITED STATES PATENTS 1,804,819 Spencer et al May 12, 1931 2,044,648 Stevens June 16, 1936 2,198,016 Rogers et al. Apr. 23, 1940 2,516,421 Robertson July 25, 1950 2,558,452 Mennecier June 26, 1951 2,631,821 Caldwell Mar. 17, 1953 2,644,669 Curtis et al. July 7, 1953 2,646,252 Hylbak July 21, 1953 2,678,804 Lebourg May 18, 1954 2,693,342 'Lynes Nov. 2, 1954