US3528515A - Rotary perforating tool and system for well perforation - Google Patents

Description

ROTARY PERFORATING TOOL AND SYSTEM FOR WELL PERFORATION Filed OC'. 2, 1968 M. A.'GARR|S0N 3 Sheets-Sheet 1 ggg Sept. 15, 1970 M. A. GARRlsoN ROTARY PERFORATINGATOOLAND jsYs'rEM FOR WELL PERFORATION Filed oct. 2, 1968- 5 Sheets-Sheet- 2 INVENTOR.r Marion A. Garrison @w @w m ATTORNEYS Sept. 15, 1970 M. A. GARRlsoN 3,528,515

ROTARY PERFORATING TOOL AND SYSTEM lFR WELL PERFORTYION Filed oct. z, 1968 s sheets-sheet s Il l FIG' INVENTOR.

Mar/'on A. Garrison '.27 Fla.` 9 l 28 United States Patent Olhce 3,528,515 Patented Sept. 1970 U.S. Cl. 175--78 10 Claims ABS'I'RAC'I` 0F THE DISCLOSURE Rotary perforating tool and system for wells having electrically powered drilling assembly lowered with elongated tube into well by flexible cable having insulated electrical conductors, tube holds said assembly against independent rotation, expanding means extending through openings in tube for securing and releasing tube at selected locations in well, pump means supplying fluid to the expanding means for directing said actions and lubricating a drill bit, a flexible shaft connecting drill ybit with the upper drill assembly, guide means for the flexible shaft, means for applying controlled pressure against bit while it is rotated, and means for maintaining said tube in a fixed position in well until bit is withdrawn from perforation.

This invention relates to a system of perforating well casings and adjoining structure by use of a perforating tool and to a perforating tool utilized in the performance of said system.

Wells frequently are drilled into various types of formation to obtain oil, gas and water, for example. It is the usual practice to line or encase the well bore with casing after the drilling has reached the total depth and this involves setting the casing, cementing and then perforating at one or more locations, which may be on the order of thirty to forty feet olf bottom.

Sometimes after wells have produced for a period of time, the formation adjoining the well bottom Abecomes clogged or lacking in suiiicient porosity to deliver a desired volume of flow into the well. Another condition which requires correction of well bottom features is the failure of the formation to produce uid in sufficient quantity at the selected level where there has been an indication of capability to produce the desired quantity at a somewhat higher or lower elevation. Under these circumstances, a length of the casing at the bottom of the well -will be sealed and it then becomes necessary to perforate the casing and usually some of the adjoining structural formation to obtain desired flow of fluid into the well at the newly established level above or below the point of sealing.

It has been a custom in the past to provide electric conductor cable extending into the well and gun-type or explosive-type perforators are carried on the lower end of such cable to the level where perforating is to be undertaken and the circuit controlling means at the surface is then operated to lire the explosive charges and thereby perforate the casing and adjoining formation. In many instances, the formations are seriously damaged by the high explosive charges used in such perforating operations. The present perforating system has been designed to utilize the conductive cable heretofore in use and to substitute a new type of perforating means for the explosive-type perforators and thereby attain the desired perforating of the:

lower end of the casing and associated formation without shattering effect or other damage to the structure.

The present invention includes both a novel system concept and a novel perforator tool concept which represents distinct departures from prior practices and utilize a number of innovations in attaining the casing and formation perforation. One of these comprises a novel type of perforating tool inclusive of a drill 'bit carried on a flexible shaft with provision for continuous rotation of the bit through a predetermined range of drilling movement followed by a withdrawal movement of the same degree as the extent of the penetration.

Another innovation involves the provision of an elongated tubular body which is supported by conductor cable and lowered into the lwell to dispose its lower end at a predetermined elevation with the elongated tube suspended in spaced relation to the well casing throughout its entire length and having at least one internal component arranged to extend through openings in the tubular body and engage a surface of the well casing so as to prevent rotation of the tubular body when the casing is so engaged. This arrangement leaves the internal components of the tubular body free to rotate within its enclosure and thus provide a drive for a bit mounted on a flexible shaft carried at a lower end of the string of such internal components.

It is an object of my invention to provide a simple, economical and efficient system for perforating a Well casing and adjoining producing formation to increase ow of formation fluids into the well.

Another object of my invention is to provide a drilling assembly of a novel character contained Within an elongated tubular body adapted to be lowered into a well by conductor cable so as to dispose the bottom of the assembly at a level of a producing formation and to provide the electric power requirements for the perforating operations by an electric motor contained within the tubular body and having the operation thereof actuating a drilll bit directed by control means at the surface.

A further object of my invention is to provide a novel type of pump in a` drilling assembly contained within a tubular body lowered into a well which is capable of circulating well fluid or other fluid to expand a contained locking device preventing rotation of the tubular body within the well fbore and supplying fluid to a rotating drill bit for the purpose of lubricating same and washing away cuttings produced by the bit.

'Other objects reside in novel details of construction and novel combinations and arrangements of parts, all of which will be set forth fully in the course of the following description.

The practice of my invention will be described with reference to the accompanying drawings illustrating typical structural embodiments adapted for performing the novel system of perforating well casings and adjoining structure. In the drawings, in the several views of which like parts bear similar reference numerals,

FIG. l is a vertical section broken at different elevations to illustrate a typical installation in which a drilling assembly is suspended within a well and has its lower end disposed at the level of a producing formation. The well is shown as having casing extending throughout its lengthwise extent and the portions of the drilling assembly disposed between breaks shown in the casing are designated A, B, C, D and E, respectively;

' FIG. 2 is an enlarged fragmentary vertical section of the A portion of the drilling assembly which as shown in FIG. 1 is the uppermost portion;

FIG. 3 is another fragmentary vertical section to the same scale as FIG. 2 and illustrating the structural features in the B section of the assembly;

FIG. 4 is a section taken along the line y4-4 of FIG. 2;

FIG. 5 is a fragmentary Vertical section of the C portion of the drilling assembly shown in FIG. 1;

FIG. -6 is another fragmentary vertical section of the portion of the drilling assembly shown at D in FIG. l;

FIG. 7 is a fragmentary vertical section of the portion shown at E in FIG. l which is the lowermost portion disposed at the level of a producing formation;

FIG. 8 is a section taken along the line 8 8 of FIG. 7;

FIG. 9 is a fragmentary partially *broken vertical section to the same scale as FIGS. 2 through 8 and illustrates a closed circuit hydraulic system which is used in the drilling assembly of the type depicted in FIG. 1 as an alternative for the open circuit hydraulic system of that assembly;

FIG. l() is a section taken along the line 10-10 of FIG. 2; and

FIG. 11 is a section taken along the line 11-11 of FIG. 9.

The practice of my invention will be described first with relation to the form of drilling assembly illustrated in FIGS. 1 through 8 and 10 in which an open circuit hydraulic system is provided for use of well fluid only. As shown in FIG. l, a well 21 has been shown as extending from the surface 22 to a lower producing formation 23 with the well bore encased by casing 24, and electric conductor cable 25 connected with means 26 at the surface controlling a circuit through said cable suspends a drilling assembly designated generally by the reference numeral 27 interiorly of the well casing in spaced relation thereto with a string of components comprising the drilling assembly being shown in the portions A, B, C, D and E of FIG. 1 in outline form and in complete detail in other figures of the drawings as will be specifically set forth in the following description. The conductor cable 25 carries electric current to the electric motor 30 driving a lower perforating tool 80 to provide the required drive therefor. This motor is a single phase motor and the circuit is completed by grounding the motor 30 to the drilling assembly 27 as shown at 31 in FIG. 2. This ground 31 is connected to the outer steel portion of the conductor cable 25 and therefore completes the electrical circuit. When the conductor cable has sufficient insulated conductors to handle three phases, a multi-phase motor may be used.

The structural arrangement shown in FIG. 2 includes an elongated body portion 32 secured by a top cover member 33 which is shouldered as shown at 34 and provides a seat for an internal threaded portion terminating in an annular flange 35 which seats against the shoulder 34 and suspends body portion 32 and a depending tubular portion 36 in the well bore. The electric conductor cable 25 is connected to and extends through the submerged top portion and forms a casing for the connector motor leads 25a and 25b which extend through the hollow portion of the tubular enclosure 36 and into the threaded neck and bore 30a of a motor 30. As will be best understood by reference to FIG. 10, a channel 37 is formed in the exterior wall of the motor assembly 30m and permits the leads to descend to the bottom of said motor as shown at the top of FIG. 3.

As shown in FIG. 3, a collar portion 40a extends downwardly from the base of motor 30 and an internal coupling `41 extends downwardly from the throat 40C within a compensating tube 42 having a protector 43 at its top and a plug 44 adjoining the protector. An elongated flexible tube portion 42a of tube 42 is contained within an annular bore 45 below the plug 44 and is filled with oil, its lower end connecting to the interior of a sealed housing of the adjoining gear reduction unit 40 while its opposite end is plugged. A spring coupling 50 connects the extended portion of coupling 41 with the input shaft '51 of the reduction gear assembly `40 and a Woodruff key 52 holds the coupled members against an unwinding action. The gear reduction unit 40 has a double oil seal assembly 53 at its upper end and a retaining ring 54 under the seal assembly 53 which is disposed at the upper end of a double ball bearing assembly 55 interiorly of the upper section 56a of the gear reduction housing 40. A compression tube 57 conducts oil from the compensating tube `42 to an outlet 57x lubricating the bearing assembly 55 and input shaft 51.

A pinion gear '60 is mounted on the lower end of input shaft 51 and drives an intermediate shaft 61 of the gear assembly which is connected at its lower end with an internal gear 62 which drives the output shaft 63 of the gear reduction assembly. In this arrangement, the shafts 51 and 63 are centered on the longitudinal axis of gear 62. Intermediate shaft 61 and output shaft 63 are each supported yfor rotation by ball bearing assemblies `64 and 65 and oil seals 66 are disposed below the lower ball bearing assembly 65 and secured by retaining rings `67 while an O-ring 68 is disposed in a recess in the outer wall of the lower section 56e of the reduction gear housing to confine lubricant flow in a manner to be subsequently described.

As shown in FIG. 5, the elongated tubular body 36 of drilling assembly 27 has a slotted portion 70 adjoining expanding means in tube 36 having an exterior portion arranged for movement through the slot 70 into frictional engagement with casing 24 to prevent rotation of tube 36 relative to casing 24. The expanding means shown in FIG. 5 comprises a slip body 71 of tapering cross section supported by a screw attachment with an adjoining portion of tubular body 36 and bearing against a slip carrier 73 on which a slip 74 is secured by cap screws 75. Slip pins 76 secure links 77 to a piston 78 mounted on a sleeve 79 on drive shaft 72. The sleeve 79 confines an elongated spring 83 in biasing relation to piston 78. Slip 74 as shown in FIG. 5 includes a plurality of jaws with teeth 74a on their exterior surface which are disposed at a common oblique angle to the longitudinal axis of slip 74 causing an expansion of said jaws when moved in one direction and a contraction by opposite movement. Because of the taper of body 71, slacking of cable 25 induces retraction of the slip jaws and spring pressure against piston 78 holds the jaws in retracted position until the next drilling cycle.

Piston 78 is hollow and confines the top plate 85 of a low pressure pump assembly 84 carried on driven shaft 72 and a top bearing 86 is provided for plate 85 which is connected to a lower plate 87 having a bearing 87a by screws 88 and the pump impeller 89 is disposed between said plates for rotation directed by a pump shaft 90 which is secured on driven shaft 72 by a key 91. Packing 92 is held against shaft 90 by a nut member 93 which is secured against unfastening by a lock nut 94. This provides a sealed arrangement for the internal bearing means permitting the hub of the piston to rotate independently of its outer portion.

Pump assembly 84 will by-pass fiuid within itself if the pressure reaches approximately 35 lbs. per square inch above the normal hydrostatic pressure within the well 21. The pump is driven by means of the sliding keys 91 in the keyway 72x of driven shaft 72. As pump assembly 84 is fastened fixedly -with the tubular portion 36, as shown at 82, it does not move up and down with the motor reduction gear unit 40.

A fiuid relief valve 96 comprising an upper hollow section 96a and a lower hollow section 96b has a threaded connection 97 with the lower end of shaft 72 which terminates at said connection. A keyed shaft 98 is fastened to the interior surface of upper section 96a by keys 98a and is held in driven relation by relief valve 96. A retaining ring 99 and washer 100 separate the hollow interior of section 96a from the hollow interior of section 96h which confines a spring 103, permitting elongation of the valve when the conductor cable raises, thereby exposing port to permit fiuid flow out of the cylinder above piston 78. Tubular portion 36 makes a threaded connection 101 with an exterior wall portion of a hollow chamber 102 in which the relief valve 96 is located.

A thrust type ball bearing assembly is mounted on shaft 98 below valve 96 and has an enlarged intermediate portion 111 of its exterior surface in close fitting engagement with tubular portion 36 and an O-ring 112 therein prevents fluid flow along the interior of said tube 36 past enlarged portion 111. Assembly includes an upper oil seal unit 113 and a lower oil seal unit 1114, secured by retaining rings 115 and 116, respectively. A plug 117 normally closes an opening by which a lubricant can be introduced into an interior space 118 for supplying the lubricant requirement of an upper ball bearing unit 119 and a lower ball bearing unit 120.

FIG. 6 illustrates an assembly 125 having a threaded connector 126 inserted between spaced threaded portions of tubular member 36, the lowermost of said sections having a plate 127 closing its hollow interior and supporting a hollow guide tube 128 which extends upwardly in enclosing relation to the lower end of keyed shaft 98 which has an internal coupling 129 with a exible shaft 130.

FIG. 7 illustrates the perforating assembly of perforating tool 80 which includes an extension of guide 128 being supported within tubular portion 36 by another plate 132 supported from its inner wall surfaces and having a welded connection with guide 128. The lower end 36x of tubular portion terminates in a threaded connection 133 with an elongated body 134 having an internal bore 135 extending from the lower end of shaft at its top to a bottom side outlet 136 in a curved path. Preferably, the body 134 is formed by two castings providing the required shaping and held as an integral body by screws 137.

The lower end of flexible shaft 130 is part of a stretch of flexible shaft shown at 138 extending through curved bore 135 which acts as a guide therefor. A drill bit 139 is carried at the lower end of flexible shaft and extends outwardly beyond outlet 136 to perforate the well casing '24 and associated producing formation 23. Flexible shaft 138 has an internal passage 140 (FIG. 8) preferably lined by plastic tubing which delivers a lubricant to the drill bit while operating and also provides a sufficient ow to wash cuttings from the perforation being formed. A casing shoe 141 secures the headed ends of lower screws 137 against damage during drilling and is held on body 134 by cap screws 142.

For some operating requirements, it will be advantageous to provide a closed circuit lubricating system in the drilling assembly and a closed circuit system of this type has been illustrated in FIGS. 9 and ll. The lubricant circulation and pumping and distributing features include different structural arrangements than those shown in FIGS. 5 and 6 and described hereinbefore and have been given different reference numerals. Structure shown above and below the closed circuit hydraulic system of FIG. 9 is identical with that shown in FIG. 5 and has been given the same reference numerals as in FIG. 5.

The closed circuit hydraulic system 144 illustrated in FIG. 9 has a piston 145 mounted on a lower portion of shaft 72 andy the piston encases the top plate 146 of a pump assembly and a bottom plate 147 is spaced therefrom. A top bearing 148 is provided for plate 146 and a lower bearing 149 is supported adjacent plate 147. The plates are secured by screws 150 and an impeller 151v on shaft 72 rotates in the space between plates 146 andl147. Packing 152 is secured in a nut 153 at the lower end of bearing 149 and a lock nut 154 seats on nut 153 to maintain its established locked position.

A threaded connector 155 is disposed between spaced sections of tubular portion 36 and has an internal passage 159 through which lubricant is elevated into the hollow interior of impeller 151 and thence into piston 145. In this system, it is necessary to conserve oil and it is bypassed through a passage 161 in the shaft 158 and out of a port when the conductor cable or wire line 25 lifts the tool, thereby uncovering port 160 and flows into the piston relieving pressure above the piston, allowing the piston to be raised to the top of its stroke when a lifting force is exerted by cable 25.

System 144 has a flexible reservoir 162 of soft, resilient oil-proof material which is exposed to the hydrostatic pressure in the well 21 by being located outside the housing 163 of system 144. Reservoir 162 will expand and contract sufciently to accommodate 'the displacement flow of the piston which actuates the slip 74, and also permits a moderate amount of leakage. As the piston which drives the bit into drilling contact moves down, the oil below same is displaced into the reservoir 162 through ports 159 located in the cylinder near the lower end of same. When the assembly is lifted by wire line 25, the valve 156 opens to allow the oil above the piston to be displaced as stated above. A ball bearing assembly is mounted on shaft 158 below the pump assembly 84 and comprises upper and lower oil seals 164:1 and 164b, respectively, and upper and lower bearings 165 and 166, respectively.

A lower pump assembly is provided to circulate well Huid to the bit and is of small volumetric output. This pump has an upper plate 171 secured on shaft 158 by a nut .172 and lock nut 173 and a screen member 174 is disposed between upper plate 171 and lower plate 175 having a passage 176 for delivery of screened well fluid into a lower distributing chamber 177 of the pump. Screen member 174 and associated lower plate 175 extend across the entire interior of tubular portion 36 with openings 178 or ports in portion 36 permitting intake of well fluid through screen member 174, thence through passage 176 into the interior portion of chamber 177 under the pumping action of rotor 185 (FIG. l1).

The arrangement of the bottom closure of chamber 177 is the same structural arrangement as shown in FIG. 6 and connects in turn with a perforating tool of the type shown in FIG. 7. Consequently, reference numerals shown in FIG. 6 have been applied to the bottom plate 127 and guide structure 128 shown in FIG. 9. A slight gap 179 is provided between the top of guide member 128 and the lower end of shaft 158 which permits the well fluid within chamber 177 to pass into an internal passage 181 in the pump rotor 180 and thence into keyed shaft .130 to which the flexible shaft 138 of the perforating tool is connected.

It will be apparent that the well fluid after screening to eliminate solids which might block internal passages through which the uid is conducted is delivered to the drill bit of the perforating tool in sufficient volume to provide the desired lubricating effect and to remove cuttings from the bit, while the lubricant circulation through the remainder of the closed circuit hydraulic system 144 is a clean lubricant which is conned and circulated 1taihrough the closed circuit without contamination by well i uid.

Again referring to FIG. l in which the entire drilling assembly is shown as being in an operati-ve position within an oil well 21, said assembly is shown in portion A and the related view, FIG. 2, as having an upper member providing connection with electric conductor cable extending into the well from a surface location outside of same and with control means at the surface for controlling the operation of an electric circuit through and inclusive of said conductor cable. An electric motor is disposed in the upper body portion 32 within an elongated tubular body 36 which extends throughout substantially the entire length of drilling assembly 27, the lower portion of which is disposed in a perforating position at the bottom of well 21. Motor 30 is connected in driving relation to an input shaft 51 which as shown in FIG. 3 extends into a gear reduction unit 40 and another output shaft 63 extends downwardly from the lower end of the gear reduction unit in coupled relation to a driven shaft 72. The tubular body 36 is apertured or slotted as shown at 70 in FIG. 5 and an expanding locking device has a slip portion 74 and associated carrier and linkage which assist the expansion and contraction movements of the slip -body through the slot 70 into gripping engagement with the well casing 24.

A sleeve 79 surrounds shaft 72 in supporting relation to the slip assembly which is fastened to tubular portion 36 by screws or other suitable fastening means. A low pressure pump assembly 84 is mounted on shaft 72 below the slip assembly and has an upper piston which is driven by the electric motor-reduction gear unit. The piston is subjected to pump pressure and well fluid pressure and is the means which controls the expanding and closing movements of the slip assembly. When the slip is expanded into contacting relation with the well casing, rotation of the elongated tube member within the well is prevented but the internal components of such assembly are rotated to accommodate the perforating tool in a manner which will be described hereinafter.

A pump unit is carried on shaft 72 immediately below piston 78 and directs the ow of well fluid admitted into the interior of tubular member 36 by the slotted openings 70 and circulates such flow downwardly through a hollow portion of the shaft and into the bore of a connecting flexible shaft is a part of the perforating tool assembly. In the operation of the drilling assembly, provision is made for lowering the internal components a predetermined distance during one perforating cycle and after completion of which, the assembly is again raised by actuation of the conductor cable to dispose it in the operative position to resume the next drilling cycle.

The perforating tool assembly 80 as shown in FIG. 7 incldes a tubular body extending downwardly from plate 132 in encompassing relation to keyed shaft 130 which is connected to the flexible shaft 138 extending through a curved internal bore in the elongated body 134 and which carries a drill bit 139 at its lower end extending through a bottom side outlet 136. The guide 128 prevents excessive bending or twisting of tlexible shaft 138 within it and within the bore 135 while the bit 139 is being rotated and drilling a perforation through the well casing or adjoining formation. It also is essential that the bit and exible cable be held against twisting during the following retraction stage of the cycle and the pumping pressure exerted against piston 78 and associated components is continued in the same degree until the bit is completely retracted and resumes the position shown in FIG. 7. At that stage of the operation, the conductor cable is pulled, allowing the relief valve 96 to move upwardly on shaft 72, exposing the opening 95 which it normally covers, thereby allowing confined well fluid to pass out of shaft 72 relieving pressure on the top of piston 78 and the resulting upward movement retracts slip 74, allowing it to return within the enclosure of tubular body 36 so that the entire assembly is elevated a distance equivalent to the maximum extension of bit 136 in the drilling action to establish a new position for operating in the next drilling cycle.

I claim:

1. A system for drilling perforation holes in a bordering surface of a well bore at a producing formation level, comprising an electric conductor cable supported at the surface and maintained in a depending position within the well bore, means at the surface for controlling an electric circuit through said cable, an elongated tube suspended by said cable in the well bore at a selected elevation below the surface, an electrically powered drilling assembly means for drilling the perforation holes, the electrically powered drilling assembly means being suspended by said cable interiorly of the tube and secured by the tube against independent rotation, pressure responsive expanding means extending through openings in the tube for selectively securing and releasing the tube at selected locations in said well bore, and a pump means for supplying fluid pressure to the expanding means whereby to direct its securing and releasing actions.

2. A system as defined in claim 1, having means for limiting the output pressure of the pump means.

3. A system for drilling perforation holes in a bordering surface of a well bore at a producing formation level, comprising an electrical conductor cable supported at the surface and maintained in a depending position within the well bore, means at the surface for controlling an electric circuit through said cable, a drilling assembly supported by the conductor cable for rotation in a depending position in the well bore and including an elongated tubular enclosure for a drive assembly, and a perforating tool connected `with the drive assembly, said perforating tool being directed in a laterally directed drilling operation by rotation imparted by the drive assembly responsive to the control means at the surface, said drive assembly including an electric motor, pressure responsive means for selectively locking the tubular enclosure to the well casing at selected depths within the well, piston means connected to the perforating tool for applying pressure to the bit thereof during the drilling operation, and pumping means operable to selectively supply fluid pressure to the locking means and the piston means whereby to selectively lock the tubular enclosure to the well casing and apply pressure to the bit of the perforating tool.

4. A system as defined in claim 3, including second pumping means within the tubular enclosure for supplying uid to the drill bit to lubricate it and wash away cuttings from the perforation, and means for supplying said second pumping means with a fluid withdrawn from the well bore.

5. A system as defined in claim 3, having an open circuit hydraulic system including second pumping means within the tubular enclosure supplying liquid to the drill bit to lubricate it and wash cuttings away from the perforation, and means for supplying iiuid from the well bore to said hydraulic system.

6. A system as defined in claim 3, having a closed circuit hydraulic system including said rst pumping means for circulating clean lubricant through the system, and a second pumping means within the tubular enclosure for supplying fluid from the well bore to lubricate the drill bit and wash cuttings away from the perforation.

7. A system for drilling perforation holes in a bordering surface of a well bore at a producing formation level, comprising an electric conductor cable supported at the surface and maintained in a depending position within the Well bore, means at the surface for controlling an electric circuit through said cable, a drilling assembly in the well bore supported by the conductor cable and including an elongated tubular member containing an upper drive assembly inclusive of an electric motor, a gear reduction unit associated with the motor having concentric input and output shafts, pressure responsive expanding means extending through openings in the tubular member for selectively securing and releasing the tubular member at selected locations in the well bore, pump means operable by said motor for supplying tluid pressure to the expanding means whereby to secure the elongated tubular member at seletced elevations within the Well bore, and said pump means being also operable to circulate a lubricant fluid interiorly 'of said drive assembly, and a lower perforating tool having a flexible shaft connection with the output shaft of the upper drive assembly, said perforating tool having a drill bit directed in a laterally directed drilling operation by rotation of the output shaft responsive to the control means at the surface, a guiding mechanism for said flexible shaft, said drilling assembly including means for measuring the travel of the conductor cable while the perforation is being cut by said bit, said expanding means being operable to continue to hold the guiding mechanism of the perforating tool against movement while the bit is withdrawn from the perforation, means delivering a lubricant uid in induced flow through the exible shaft to said bit, piston means responsive to said pump means and connetced to said perforating tool for applying a controlled pressure against the bit while it is rotated, and means for returning the conductor cable to the same starting position at the beginning of each cutting cycle.

8. In combination with a system for drilling perforation holes in the bodering surface of a well bore wherein a drilling assembly depends in said well bore from an electric conductor cable supported at the surface, said drilling assembly including an elongated tubular member containing a drive assembly and a perforating tool, the improvement which comprises:

pressure responsive expanding means mounted on said tubular member for engaging said well bore whereby to secure said tubular member at selected depths in the well; and selectively operable pump means for supplying fluid pressure to said expanding means whereby to selectively operate said expanding means. 9. The invention recited in claim 8, wherein: said tubular member has at least one slot therein for receiving said expanding means; and said expanding means comprises:

jaw means slidably mounted in said slot to be selectively movable away or towards the axis of said tubular member, said jaw means being for engaging said well bore; and a tapered actuating mechanism mounted along the axis of said tubular member in sliding contact with said jaw means, said actuating mechanism being operable in response to the fluid pressure of said pump means to move said jaw means into engagement with said well bore.

10. The invention recited in claim 8, including pressure responsive means connected to said perforating tool for applying pressure to the bit thereof during the drilling operation, said pressure responsive means being responsive to the iluid pressure of said pump means.

References Cited UNITED STATES PATENTS 2,516,421 7/1950 Robertson 175-78 2,539,047 1/1951 Arutunofl 175-78 X 2,558,452 6/1951 Mennecier 175-78 2,631,821 3/1953 Caldwell 175--78 ERNEST R. PURSER, Primary Examiner U.S. C1. X.R. 175--99

Images