US1853239A - Double casing perforator - Google Patents

Description

April l2, 1932. p, L. SHULL 1,853,239

DOBLE cAsING PRFORATOR Filed Feb. 23, 1928 2 Sheets-Sheet 2 Patented Apr. 12, 1932 UNITED STATES PATENT oEFlcE y DANIEL L. SHULL, OF BAKERSFIELD, CALIFORNIA, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, vT SH'ULL PERFORATING COMPANY, A CORPORATION OF NEVADA DOUBLE CASING PIERFOlt'ATOIRv Application led February 23, 1928. Serial No. 256,178.

My invention relates to oil well equipment and more particularly to casing perforators.

After an oil well has been drilled, a casing called the water string is inserted therein, and there is extended into this water string a casing known as the oil string. For straining gravel and sand from the inward seeping oil which might injure the oil pump, the oil string is provided with a screen pipe which extends through the oil sands. The screen pipe i's either formed prior to installation of the oil string or else the oil string is perforated, at the level of the oil sands, after installation by a perforator provided for this purpose. It is sometimes desirable to perforatethe water string also, as when the water string has been cemented olf below the oil bearing strata which it is desired to drain, and it is inconvenient or impossible to raise the lower end of the water string to this strata.

It is an object ot my invention to provide a novel casing perforator, adapted to perforate one or more casings.

Since those perforators now in use are not adapted to give the operator a positive indication of the completion of the perforation he oftentimes continues the operation until the perforations are in the form of long slits which materially weaken the casing and decrease the efiiciency of the straining action.

It is another object of my invention to provide a perfor-ttor of the class described which will give a positive indication to the operator when the casings have been perforated.

It is sometimes necessary to perforate not only the two casings but also cement around the water string before communication is established between the oil string and the oil bearing strata.

It is a further object of my invention to provide a perforator of the class described in which the cutting member has a long throw so that it may cut out through the formation adjacent to the outer casing.

It is a further object of my invention to provide a perforator in which the cutter can be moved into cutting position at any time it is desired and which will not move Fig. 2 is an enlarged vertical section of theperforator of `my invention with the cutter in retracted position.

Fig. 3 isa view indicated by the line 3-3 of Fig. 2.

Fig. 4 is a view indicated by the line 4--4 of Fig. 2.

Fig. 5 is a vertical section similar to Fig. 2 except that the cutter is released and in cutting position.

Fig. 6 is a vertical section of part of the body portion of my perforator showing the position of the cutter at the completion of the perforation.

Fig. 7 is a vertical sectional view of the cylindrical sleeve of the trip cage of my invention indicated by the line 7 7 of Fig. 4.

Fig. 8 is a view indicated bythe line 8--8 of Fig. 7

Referring to the drawings and particularly to Fig. 1, a well 11 has been drilled by apparatus supported upon a derrick 12 and an outer casing or water string 13 has been inserted in the well and cemented oil'l at its lower end as indicated at 14. The upper end of the casing 13 is provided with a casing-head 15 forming a tight fit between the water string 13 and an oil string 16 which is extended inside the water string. When it is desired to permit oil to flow into the oil string 16 at a level above that at which the water string is cemented ofl", as at an oil stratum 17, a perforator 18 of my invention is attached to the lower end of a jar 19 and associated weight 20, and lowered on a cable 21 through t-he oil string 16 into the position shown in Fig. 1.

The jar and weight mechanism may be of the conventional type well known in the art,

comprising two interlocking links 22 with n. ram or weight 23 attached to the upper link.

The rforator 18 includes a body 24 cylindrical 1n cross-section, as illustrated in Figs. 3 and 4, with a coupling 25 at its upper end adapted to threadedly receive the lower end of a link 22 of the jar mechanism 19. The lower end of the body 24 has a cylindrical hub 26 of lesser diameter than the body 24, and this hub is provided with external threads 27 for a purpose to be described later.

Formed diametrically in the body 24 and with its axis parallel to the axis of the perforator 18 is a cutter slot 28 having a vertical', an inclined, and an arcuated wall, as indicated by the numerals 29, 30 and 31 respectively in Figs. 2, 5 and 6. At right angles to the cutter slot 28 a cam slot 32 extends through the body 24, this cam slot comprising a portion 33 and a portion 34 substantially parallel to the vertical portion 29 and the inclined portionl 30 of the cutter slot 28.

Positioned in the cutter slot 28 is a cutter 35 non-rotatably mounted on a cutter shaft 36 slidably disposed in the cam slot 32, the cutter shaft 36 being of a length which prohibits its projection outside the body 24 at any position in the cam slot 32 for obvious reasons. The cutter 35 comprises a blade portion 37 with an arcuated lower edge 38 and a cutting edge 39, and a plate portion 40. The plate portion 40 is provided with a flat edge 41 at approximately a right angle with the blade portion 37 and an arcuated portion 42 of downwardly inclined teeth 43, and the whole cutter 35 is so mounted on the cutter shaft 36 as to permit substantially the entire edge 41 of the plate 40 to bear against the vertical portion 33 and the inclined portion 34 of the cam slot 32 when the cutter 35 and shaft 36 are properly rotated.

The external threads 27 of the cylindrical hub 26 at the lower end of the body 24 are adapted to screw into internal threads of a hollow cylindrical sleeve 44 of a trip cage 45. Threadedly secured in the lower end of the sleeve 44 is an end plate 46 with a central cylindrical bore 47 through which a trip shaft 48 is adapted to slidably extend. Re'- tained in threaded engagement with the upper end of the trip shaft 48 as by a lock nut 49 is a trip plate 50 with an arcuated slot 51 formed therein, as illustrated in Figs. 4 and 8. Threadedly secured to the trip late 50 in the arcuated slot 51 is a pin 52 wliich extendsinto a groove 53 formed by two lips 54 and 55 projecting inward from the cylindrical sleeve 44. The lip 55 has an inclined portion 56 extendingr toward and beyond the lip 54 and the lip 54 ends a short distance above this inclined portion 56 as clearly illustrated in Fig. 7. Pivoted to the interior of the cylindrical sleeve 44 immediately under the lower end of the lip 54 is a gate 57 whose lower end 58 is adapted to engage the inclined portion 56 vof the lip 55 when the gate 57 4is in a vertending to retain the gate 57 in a vertical or closed position is a flat spring 59 attached to the lip 54 as by a screw 60. An o ning 61 in the cylindrical sleeve 44 permits thee gate 57 to swing open to allow the pin 52 to move out of the roove 53 and also permits the operator to set t e pin 52 back in the groove 53 at the conclusion of the' operation. Supported on the trip late 50 is an operatin pm 62 which is slidab y disposed in a cylin rlcal bore 62a in the body 24 to the cutter slot 28. The operating pin 62 is provided with a hub 63 at its lower end and a head 64 at its upper end, both of which are of greater diameter than the bore 62' so that the movement of the pin 62 in the bore 62* is limited.

Threadedly secured to the lower end of the trip shaft 48 is a cylindrical stop member 65 slidabl disposed in a cylindrical sleeve 66 which is t ireadedly attached. at its lower end to the spring-retaining sha''t 67. Disposed between the cylindrical stop member 65 and the spring-retaining shaft 67 in the cylindrical sleeve 66 is a coil spring 68 which acts as a shock absorbing member for the pin 52 in the top of the groove 53 during the downward passage of the perforator 18 in the casin'g 16. It should be obvious that the trip shaft 48 is free to rotate relative to the springretaining shaft 67. Attached as by screw to the spring-retaining shaft 67 are flat springs 70, here shown as four in number, adapted to frictionally and resiliently engage the inner surface of the oil string 16.

The operation of my invention is as follows:

The cutter 35 is placed in the osition shown in Fig. 2, and the pin 52 is p aced in the groove 53, and the apparatus with its associated jar 19 and weight 20 is lowered on the cable 21 into the oil string 16 to the level at which it is desired to perforate the casings. During the downward travel of the perforator 18 the pin 52 is retained in the top of the slot 53. The spring 68 absorbs the shocks caused by any irregularities in the casing which might prove detrimental to the pin 52.

When the apparatus is at that level at which it is desired to o erate the cutter 35, the cable 21 is subjecte to an upward pull. Because of the engagement of the flat springs 70 with the casing 16 this causes a relative movement between the body 24 and the spring-retaining shaft 67 so that the springretaining shaft 67, the trip shaft 48, and the trip plate 50 move downward relative to the body 24 and the cylindrical sleeve 44 until the pin 52 contacts the inclined portion 56 of vthe lip 55 in the groove 53. The continued upward pull on the cable 21 causes the pin 52 to move downward on this inclined surface 56, through the swing gate 57 as indicated by the dotted lines 71 of Fig. 7 and into ltical or closed position. Bearing against and the position shown by the dotted lines 72 of thel same figure. After the passage of the pm v52 the gate 57 is closed by the pressure of the flat spring 59 to prevent the entrance of `the pin 52.

tive to the body 24 and the sleeve 44 so that it engages the operating pin 62 and causes it to move the cutter 35 into the position shown in Fig. 5.

As the weight is raised and dropped by the cable21 the .cutting edge 39 of the cutter blade 37 is forced into the casing 16. Each successive blow on'the perforator 18 causes the cutter to move upward relative to the body 24 in the cam slot 32. Because of the inclined portion 34 of. the cam slot 32 this relative movement forces the cutter blade 37 further into the casing 16. The teeth 43 of the plate portion of the cutter 35 engage the innner surface o f the casing 16 to retain the'blade portion 37 in proper cutting position. The pounding act-ion is continued until both casings and the formation immediat-ely adjacent vare perforated. It should be noted that because of the fact that the cutter 35 is operating through a circular swing the cutter blade 37 has an exceptionally long throw so that any cement or non-porous formation adjacent to the outer casing can also be perforated.

When the cutter blade 37 has finished the perforation, the cutter shaft 36 will be at the top of the inclined portion 34 of the cam slot 32. At this time the body 24 and associate j ar 19 and weight 20 will drop until the eutter shaft 36 reaches the top of the vertical portion 33 of the cam slot 32, thus giving the operator a positive indication of the completion of the perforation.

The perforator 18 is then pulled upward, the cutter shaft 36 sliding in the inclined portion 34 of the cam slot 32 and removing the cutter blade 37 from the perforation. The frictional engagement of the flat Springs 70 with the casing 16 causes the spring-retaining shaft 67, the trip shaft 48 and the trip plate 50 to move downward relative to the body 24 until the pin 52 is in the position shown by the dotted lines 72 of Fig. 7 when the whole apparatus moves upward as a unit. The downward movement of the trip plate 50 relative to the body 24 permits the operating pin 62 to assume the position shown'in Fig.

2 so that the movement of the cutter shaft 36 in the inclined portion 34 of the cam slot 32 may continue until the cutter 35 assumes the position shown in Fig. 2 in which it offers no resistance to the upward movement of the perforator. This upward movement of the apparatus is continued until that level is reached at which another perforation is made. The cutter 35 is moved into operating position in this .second location by simply lowering the Weight 20. The fiat springs retain the trip plate 5'0. in the same position while the body 24 is lowered" until the trip plate 50 causes the operating pin 62 to move the cutter 35 into cutting position. Thereafter the operation is identical with that already described.

IVh'en the perforator 18 has been removed from the casing` 16, the gate 57 is moved into an open position in the opening 61 in the cylindrical sleeve 44 and the pin 52 is moved into the groove' 53. The perforator is then ready to again be lowered into a Well.

While the preferred form ofv embodiment of my invention above illustrated and described is fully capable of fulfilling all ofthe purposes primarily stated, I do not Wish to be limited to it, for it isr to be understood that my invention may be embodied in various other forms, all coming within the scope of the claims which follow.

I claim as my invention:

1. In a casing perforator, the combination of: a body; cam slots formed in said body,

said cam slots comprising an inclined and a vertical portion; a cutter mounted in said body on a shaft between said-cam slots, said cutter being adapted to permit said body to drop when said shaft is in said vertical portion of said cam slots following the cutting operation; and Ameans for moving said cutter along said inclined portion of said cam slots.

2. In a casing perforator, the combination of: a body; cam slots formed in said body, said cam slots comprising an inclined and a vertical portion; a shaft supported between said cam slots; a cutter adapted to cut two strings of easing mounted on said shaft, said cutter being so formed as to permit said body to fall the length of said vertical portion of said cam slots when the perforation is completed; and means for so moving said shaft along said inclined portion of said cam shafts as to cause said cutter to perforate said casings.

3. In a casing perforator, the combination of: a body; cam slots formed in said body, said cam slots comprising an inclined and a vertical portion the vertical port-ion being arranged above the inclined portion; a cutter shaft extending between said cam slots; a cutter mounted on said cutter shaft between said cam slots, said cutter being adapted to complete the perforation of two strings of casing while said cutter shaft is in said inclined portion of said cam slots; releasing means for moving said cutter into operative position; locking means for preventing the functioning of said last named means until said body is moved upward relative to said releasing means; and means adapted to so frietionally engage said casing as to permit the upward movement of said body to be relative to said releasing means.

4. In a casing perforator, the combination of: a body; cam slots formed in said body, said cam slots comprising an inclined and a vertical portion; a. cutter shaft extending between said cam slots; a cutter mounted on said cutter shaft between said cam slots, said cutter being adapted to complete the perforation of two strings of casing while said cutter shaft is in said inclined portion of said cam slots; a pin adapted to move said cutter into operatingr position; a plate adapted to actuate said pm; a pin and groove mechanism so associated with Said plate as to prevent the actuation of said pin until said body is moved upward relative to said plate; and spring means associated with said plate, said spring means being adapted to cause said body to move upward relative to said plate when said body is moved upward in said casino'.

5. In a casing perforator, the combination of a body, cam slots formed in said body, said cam slots comprising an inclined portion and a vertical portion thereabove, a cutter mounted in said body on a shafft between said cam slots, said cutter including a blade portion having a cutting edge and a plate portion having an arcuate surface providing pipe engaging means, the cutting edge and the pipe engaging means of said cutter being adapted to engage the pipe to be perforated to determine the position of engagement of the cutting edge of said cutter with the pipe, and means for initiating movement of said cutter along said inclined .portion of said cam slot.

6. In a casingperforator, the combination of a body, a cutter supported by the body, said cutter including a blade portion having a cutting edge and a plate portion of arcuate surface thereabove for frictionally engaging the pipe to determine the position of engagement of the cutting edge with the pipe, means for pivotally supporting the cutter, and means for moving the pivotal support of said cutter outwardly as the body is dropped relative to said pipe to cause the cutter to be thrust outwardly from the body.

7. In a casing perforator, the combination of a body, a cutter supported by the body, said cutter including a blade portion having a cutting edge and a plate portion providing means for engaging the pipe to determine the position of engagement of the cutting edge with the pipe, means for pivotally supporting the cutter, means for moving the pivotal support of said cutter as the body is dropped to cause the cutter to be thrust outwardly from the body, and means adapted to be actuated only during the first portion of the drop of said body to move the cutter so that the cutting edge of the blade portion and the engaging means of the plate vportion engi the pipe.

8. In a casing perforator the combination of; a body, a cutter mounted in said body and normally positioned within said body, means' for frictionally engaging a casing, means responsive to downward movement of said body relative to said frictional means for forcing said cutter outward from said body and through a casing, 'locking means for preventin such relative movement of said body, an frictional engaging means, and means responsive to upward movement of said body relative to said frictional engaging means for releasing said lockin means.

9. In a casing perforator the com ination of; a body, a cutter mounted in said body and normall positioned within the lower part of said bo y, means for ejectin said cutter laterally from said body where y it engagesthe casing, and means for forcing said cutter through said casing in response to downward movement of said body throu h a predetermined distance relative to sai casing, said means thereafter permitting further permitting further downward movement of the body with respect to the casing throu h an additional predetermined distance wit out further movement of said cutter through the casing.

10. In a casing perforator the combination of; a body, cam slots formed in said body having lower inclined portions and upper vertical portions, a cutter mounted in said body .between said cam slots and having means engaging with said slots, said means normally engaging the lower ends of said slots whereby said cutter is maintained within said body, means responsive to downward movement of said body relative to an enclosing casing for initiating movement of said cutter upward in said slots to engage it with said casing whereby further downward movement of said body relative to said casing forces said cutter along said inclined slots to project it through the casing and thereafter along the straight portions of said slots to permit relative movement of said body and cutter without further penetration of the cutter in the casing.

In testimony whereof. I have hereunto set my hand at Los Angeles, California, this 17th day of February, 1928.

A DANIEL L. SHULL.

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