US3212580A

US3212580A - Casing perforator

Info

Publication number: US3212580A
Application number: US271389A
Authority: US
Inventors: Ottis W Frogge
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-04-08
Filing date: 1963-04-08
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19

Description

Oct. 19, 1965 o. w. FROGGE CASING PERFORATOR Filed April e, 1965 PWC-3.3

FIG. 4

QTTIS vv. FROGGE INVENTOR.

G 2 F AH 4.. IVA. mm [ULI x @nlllnw I J e IMNTV United States Patent O 3,212,580 CASING PERFORATOR Ottis W. Frogge, P.O. Box 8183, Oklahoma City 14, Okla. Filed Apr. 8, 1963, Ser. No. 271,389 s Claims. (Cl. 16s-55.3)

The present invention relates to oil field tools and more particularly to a casing perforator.

It is desirable in many oil wells to increase the oil recovery therefrom by perforating the casing and simultaneously perforating the cement surrounding the casing to open up a channel into an oil bearing formation through which the oil may enter the casing.

The prior art reveals a plurality of different types of casing perforators. A popular type perforator presently used preforms a casing perforating action by the use of explosive charges which forces a bullet-like projectile outwardly through the casing Wall.

The above mentioned bullet-type projectile perforators perform this function but the apertures formed in the casing wall, the surrounding cement and the oil bearing formation is relatively small and consequently easily plugged. After perforating the casing of an oil well, it is usually advisable to acidize or fracture the formation to open up the channels thus formed for the entrance of oil or gas into the casing.

It is, therefore, the principal object of the present invention to provide a casing perforator which will perforate the casing wall and surrounding cement and form an opening therethrough of substantal size.

Another object is to provide a tool of this class which is provided with antifriction means so that the casing perforating act may be more easily accomplished.

Another object is to provide a casing perforator which may be run on the end of a tubular string or on a wire line.

Another object is to provide a tool which, when connected with a tubular string, provides means for circulating fluid downwardly through the tubular string and tool.

Still another object is to provide a tool which may be indexed while still in the hole to perforate a plurality of horizontally aligned apertures spaced 120 apart.

Yet another object is to provide a casing perforator which remains in inoperative position while going in the hole and which may thereafter be tripped for performing the casing perforating action and, after perforating the casing, may be reset in neutral or inoperative position for the removal of the tool.

The present invention accomplishes these and other objects by providing an elongated body having a casing perforating blade slidably carried for vertical movement with respect to the tool and including antifriction means for vertical movement of the tool during the perforating action.

Other objects will be apparent from the following description when taken in conjunction with the accompanying single sheet of drawings, wherein:

FIGURE l is a vertical cross-sectional view of the tool, partly in elevation, and illustrating, by dotted lines, the casing perforating action;

FIGURE 2 is a fragmentary vertical cross-sectional view taken substantially along the line 2--2 of FIG. l;

FIGURES 3 and 4 are horizontal cross-sectional views, to an enlarged scale, taken substantially along the respective lines 3-3 and 4-4 of FIG. 1; and,

FIGURE 5 is a fragmentary vertical cross-sectional view, partly in elevation, of an alternate embodiment of the depending end portion of the device.

Like characters of reference designate like parts in those figures of the drawings in which they occur.

3,212,580 Patented Oct. 19, 1965 In the drawings:

The reference numeral 10 indicates the device, as a whole, which is cylindrical in general configuration and includes a body portion 12 and guide means 14. The reduced upwardly disposed end portion of the body 12 is provided with a tool joint 16 for threadedly connecting the body to an adapter 17 which is in turn connected to the depending end of a tubular string or a wire line, neither of which is shown. An elongated longitudinal cutter or blade carrier slot 18 is formed in the tool intermediate its ends. The bottom of the slot 18 extends downward and inwardly from the outer surface of the upper end of the body terminating in an abrupt end or shoulder 20 spaced above the depending end of the body. A bearing groove 19, coextensive with the slot 18, is formed in the body 12 in communication with the slot 18 and perpendicular to its longitudinal axis thus defining a substantial T-shaped opening 22 when viewed in horizontal cross section (FIG. 3) for the purposes which will presently be apparent.

As shown in FIGS. 1 and 2 the slot 18 is parallel to the longitudinal axis of the body 12 and opens outwardly of the body throughout its length. The T-shaped bottom portion of the slot extends diagonally with respect to and intersects the longitudinal axis of the body.

Adjacent its respective end portions and diametrically opposite the cutter opening 22 the body is provided with a transverse recess or socket 24 for journaling an antifriction roller 26 on a bearing equipped horizontal axle 28. The rollers 26 are provided with an arcuate or bulging periphery, preferably having a contour conforming to an arc of the inner periphery of the casing to be perforated. The function of the rollers is to reduce the frictional contact between the body 12 and the easing wall during the casing perforating act as more fully described hereinbelow.

A cutter or perforating knife 30 comprising a blade portion 32 and a T-shaped base portion 34 is cooperatively received slidably by the T-shaped opening 22. The blade portion 32 is formed of hardened material having parallel side surfaces and outwardly convergent upper and lower surfaces defining a sharpened edge or tip 36. The relative size or length of the knife 30, with respect to the opening 22, is such that the knife edge 36 lies inwardly of the circumferential plane of the body 12 when the knife is in its lowermost retracted position. A keeper plate 37, having a dove tail-shaped base 37A cooperatively received by a similarly shaped groove extending transversely across the opening 22, removably maintains the knife 30 in place.

The guide means 14 includes a tube member 38 of selected diameter, preferably relatively small when compared with the body 12, which is threadedly connected at its upper end to the depending end of the body. An enlarged nut 40, having a tapered and threaded exterior, is secured to the depending end of the tube 38. A conventional spring equipped wiper unit 42, having upper and lower collars 42A and 42B, respectively, slidably surrounds the tube 38. The lower collar 42B is cooperatively threaded for engagement with the nut 40.

A mandrel or plunger 44 is slidably received for vertical movement through the lower end portion of the body 12 by an aperture 46 so that the mandrel 44 normally extends downwardly below the lower end of the body a selected distance. A flattened surface or groove 45 formed on the mandrel 44, intermediate its ends, cooperates with a set screw 48 and permits vertical movement of the mandrel. The upper end of the mandrel 44 normally is positioned against the knife 30 when the latter is in its lower or retracted position. A plurality, preferably three, vertical grooves or slots 50 are formed ...n in the upper end portion of the periphery of the tube 38 in 120 spaced relation. A spring urged pin 52, extending through the wall of the uppermost collar 42A, engages the slots 50 to index the tool as is more fully explained hereinbelow.

In order to provide fluid circulation through the device 10 the body 12 is centrally bored at its upper and lower ends, as at 54 and 55. The bore 55 communicates with the bore of the tubular member 38. The body 12 is further provided with vertical extending diametrically opposing channels or slots 56 on its opposing sides, spaced 90 with Irespect to the knife slot 22, and communicating at their respective upper and lower ends with the bores 54 and S5 by horizontal or transverse bores 57 and 5S, respectively, which intersect the respective central bores `54- and 55 thus permitting fluid circulation through the tool.

An alternate embodiment of the guide means is illustrated in FIG. for use when running the device on a wire line wherein the depending end of the tube 38 is provided with a ring :or washer 60 rigidly secured, as by welding, to the periphery of its -depending end portion. In this embodiment the nut 40 is not secured to the tube 38 but loosely surrounds the latter. The depending end portion of the nut 40 is counterbored to receive the ring 60 thus permitting rotation of the nut 40 with respect to the tube 38. The nut 40, ring 60 and depending end portion of the tube 38 are transversely line drilled, as at 61, for the purposes more fully explained hereinbelow.

A tubular member 64, having a reduced depending anchor end portion 66, is secured to the depending surface of the nut 40, outwardly of the ring 60, by a collar 68 welded to the nut. The wiper collar 42B, the threaded portion of the nut 40 and the tube 38 are similarly transversely line drilled, as at 70, for the purposes more fully explained hereinbelow.

Operation When the device is to be used with a tubular string the adapter 17 is connected to the depending end of the latter and the device is lowered into the hole and casing 72 with the wiper unit 42 threadedly connected to the nut 40. The device is positioned at a selected depth within the casing 72 and the tubing string rotated to unscrew the wiper unit from engagement with the nut 40. The spring members of the wiper unit frictionally engage the inner surface of the casing thus holding the wiper unit stationary while the nut is unscrewed. To insure that the parting action of the nut 40, from the wiper unit collar 42B, is easily accomplished a pair of cooperating shoulders 74 are formed on the respective meeting surfaces or shoulders of the nut 40 and collar 42B, which prevents tight engagement of the threaded connection. After the wiper unit has been released from the nut 40, the body 12 is lowered wherein the tube 38 slides downwardly through the wiper unit. The upper collar 42A of the wiper unit, during this action, contacts the depending end of the mandrel 44 lifting the latter so that its upper end holds the cutter 30 stationary with respect to the casing 72. Downward movement of the body 12 with respect to the cutter 30 gradually moves the cutter radially outward of the body and positions the sharpened edge 36 of the cutter in contact with the inner wall of the casing. During this action the rollers 26 contact the inner wall of the casing opposite the cutter 30. The weight of the tubular string may then be used to further lower the body 12 thus forcing the cutter outwardly through the casing wall by the inclination of the cutter opening 22. The rollers 26 reduce the frictional resistance between the body 12 and the casing wall. At the upper limit of its movement within the opening 22 the cutter 30 projects outwardly through the casing Wall forming an opening therein of substantial size and similarly penetrates any cement 74 surrounding the easing and if the original bore hole is positioned adjacent the Casing, the cutter 30 penetrates the sand or oil bearing formation 76. The cutter is withdrawn from its casing penetrating position by upward movement of the body 12. A conventional weight indicator at the surface of the earth indicates when the device has completed its casing perforating action and is released from contact with the casing.

After forming one opening in the casing, the tubing string is rotated until the spring-loaded pin 52 contacts the next groove 50, thereafter the body 12 is again lowered to engage the cutter 30 with the casing at a new position. After perforating a selected number of holes in the casing, the tool may be withdrawn from the well, or, if it is desired to perforate the casing at a deeper position, the body may be rotated to engage the collar 42B with the nut 40 to prevent actuation of the cutter 30 during the downward movement. After perforating the casing it is sometimes desired to circulate fluid through the device which may be accomplished by the bores and channels disclosed hereinabove.

When it is desired to run the device 10 on a wire line, the adapter 17 is connected to the depending end of conventional cable tool jars, or the like, not shown, which are connected in a conventional manner to the wire line. In this arrangement the alternate embodiment, disclosed by FIG. 5, is used wherein a shear pin 78 is inserted into the bore 70 thus preventing rotation of the wiper unit 42 with respect to the nut 40. The device 10 is lowered into the well until the anchor 66 contacts the bottom of a hole or a bridge placed therein. Further downward movement of the tool by its weight or the cable tool jars, shears the pin 78. The device is then moved up within the casing to a selected location. The casing is then perforated in the manner disclosed hereinabove for use with the tubing string with the exception that downward movement of the body 12 to perform the perforating action, is obtained by jarring on the upper end of the body with the conventional cable tool jars. When the alternate arrangement, illustrated in FIG. 5, is used with a tubular string, the tubular member 64 and anchor 66 are normally omitted and a pin 80 is inserted into the transverse bore 61 thus locking the nut 40 to the tube 3,8 so that the wiper unit may be unscrewed from the nut 40.

An important feature of the operation of the device is that downward movement of the body 12 changes the thrust applied to the body to a thrust of the cutter in a lateral right angle direction with respect to the longitudinal axis of the body. This results in a thrust ratio of approximately 12 to l applied to the cutter. The cutter is forced outwardly through the casing wall in a punching action rather than a casing ripping action which eliminates vibration of the casing and a resulting loosening or rupture of the bond between the cement and the outer surface of the casing. This is desirable for the reason that if the cement bond is broken subsequent treating of the oil bearing formation, through the perforations, as by acidizing, results in a loss of the effectiveness of the acid by the circulation of the acid up and down the outer wall of the casing.

It is desirable that the side of the body containing the slot and cutter be positioned as closely as feasible to the inner wall of the casing to be perforated. To accomplish this the rollers 26 are formed in pairs, each pair having different diameters than other pairs so that a pairl of the rollers may be used which will contact the inner wall of the casing and position the cutter side of the body close to the inner wall of the casing.

Obviously the invention is susceptible to some change or alteration without defeating its practicability, and I therefore do not wish to be confined to the preferred embodiment shown in the drawings and described herein,

further than I am limited by the scope of the appended claims.

I claim:

1. A casing perforator adapted to be lowered into a cased well, comprising: an elongated body havingy a fluid passageway therethrough, said body having a slot parallel to the longitudinal axis of the body and opening outwardly of the body throughout its length, the bottom portion of the slot being T-shaped and extending diagonally with respect to and intersecting the longitudinal axis of the body; antifriction means carried by said body on that side opposite the T-shaped slot; a cutter having a blade portion normal to the longitudinal axis of the body and having a T-shaped base portion cooperatively received slidably by the slot and permitting downward movement of the body relative to the cutter when the latter is posi tioned against a casing wall; a tubular member connected with said body in depending relation; a casing engaging frictional wiper surrounding said tubular member and releasably engaged with the lower end thereof; and a mandrel slidably carried vertically by the depending end of said body and engageable with the upper end of said wiper upon downward movement of said body and holding said cutter stationary with respect to the casing as said body is lowered, whereby said cutter blade is moved transversely of said body into an extended position outwardly of the body during continued downward movement of said body.

2. Structure as specified in claim 1 in which said antifriction means includes: a pair of horizontal axles carried by said body adjacent its respective end portions on that side opposite said cutter, a roller journaled by each said axle, said rollers each having a peripheral surface projecing outwardly of the cylindrical plane of said body and cooperatively contacting an arc of the inner wall of a casing for holding that side of said body having the slot adjacent the inner wall of a casing to be perforated.

3. A casing perforator, comprising: an elongated vertically disposed body having a threaded upper end for connection with a tubular string; an elongated tube member of reduced diameter with respect to said body and connected with the latter in depending relation, said body having an elongated longitudinally disposed slot parallel to the longitudinal axis of the body and opening outwardly of the body throughout its length, the bottom portion of the slot being T-shaped in horizontal cross section and extending diagonally with respect to the longitudinal axis of said body, from a point adjacent the periphery of the body at its upper end portion to a point intersecting the longitudinal axis of the body at its lower end portion; a T-shaped cutter slidably received by said slot, said cutter having a blade portion normal to the longitudinal axis of said body and adapted to penetrate a casing; antifriction means connected with the respective end portions of said body opposite the elongated slot; wiper means mounted on the depending end portion of said tube and releasably connected thereto permitting vertical sliding movement of the latter with respect to said wiper means; and a mandrel extended vertically through the lower end portion of said body and communicating with the lowermost portion of said slot for holding said cutter stationary with respect to the casing to be perforated when the mandrel is urged upwardly by contact with said wiper means as the body is moved downwardly, whereby said cutter blade is moved transversely of said body into an extended position during continued downward movement of said body.

4. Structure as specied in claim 3 in which said body is provided with a socket adjacent its respective ends on that side opposite the cutter slot and in which said antifriction means includes a substantially barrel shaped roller within the respective socket, horizontal axles connected with said body journaling the respective said roller, a peripheral portion of each said roller projecting outwardly of the cylindrical plane defined by said body in rolling contact with the inner wall of a casing and holding that side of said body having the slot adjacent the inner wall of a casing to be perforated.

5. Structure as specified in claim 4 in which said wiper means includes upper and lower collars loosely surrounding said tube, a plurality of outwardly bowed spring members frictionally contacting the inner surface of a casing and interconnecting said collars in vertically spaced relation, said lower collar having a threaded bore, and a nut having a threaded exterior secured to the depending end of said tube for threadedly engaging said lower collar.

References Cited bythe Examiner UNITED STATES PATENTS 1,125,513 1/15 Graham 166-55.3 1,841,500 1/32 Shull 166-553 2,152,008 3/39 Yarbrough 166-55.3

CHARLES E. OCONNELL, Primary Examiner.

Claims

1. A CASING PERFORATOR ADAPTED TO BE LOWERED INTO A CASED WELL, COMPRISING: AN ELONGATED BODY HAVING A FLUID PASSAGEWAY THERETHROUGH SAID BODY A SLOT PARALLEL TO THE LONGITUDINAL AXIS OF THE BODY AND OPENING OUTWARDLY OF THE BODY THROUGHOUT ITS LENGTH, THE BOTTOM PORTION OF THE SLOT BEING T-SHAPED AND EXTENDING DIAGONALLY WITH RESPECT TO AND INTERSECTING THE LONGITUDINAL AXIS OF THE BODY; ANTIFRICTION MEANS CARRIED BY SAID BODY ON THAT SIDE OPPOSITE THE T-SHAPED SLOT; A CUTTER HAVING A BLADE PORTION NORMAL TO THE LONGITUDINAL AXIS OF THE BODY AND HAVING A T-SHAPED BASE PORTION COOPERATIVELY RECEIVED SLIDABLY BY THE SLOT AND PERMITTING DOWNWARD MOVEMENT OF THE BODY RELATIVE TO THE CUTTER WHEN THE LATTER IS POSITIONED AGAINST A CASING WALL; A TUBULAR MEMBER CONNECTED