US2912930A

US2912930A - Perforating assembly

Info

Publication number: US2912930A
Application number: US540424A
Authority: US
Inventors: Blake M Caldwell
Original assignee: WELOX Inc
Current assignee: WELOX Inc
Priority date: 1955-10-14
Filing date: 1955-10-14
Publication date: 1959-11-17
Anticipated expiration: 1976-11-17

Description

Nov. 17, 1959 B. M. CALDWELL 2,912,930

PERFORATING ASSEMBLY Filed Oct. 14, 1955 5L/7ZE M CifiWfd IN VEN TOR.

PERFORATING ASSEMBLY Blake Ml. Caldwell, Fort Worth, Tex., assignor, by mesne assignments, to WeLx, Inc., Fort Worth, Tex., a corporation of Delaware Application Gctober 14, 1955, Serial No. 540,424 4 Claims. (Cl. 1022tl) This invention relates to well perforating assemblies and particularly to means for providing a blank interval in such assemblies, which blank interval does not include explosive perforating units.

In the completion of wells drilled by the rotary method, it has long been the practice to perforate casing set in the well adjacent the producing formation for the purpose of providing ingress to the well from said formation. Such perforating formerly was done before the well was capped and while the heavy drilling mud was within the casing, and after perforating, the well was completed for production by removing the mud, running tubing into the well and capping same. More recently, however, the practice of running in the tubing, affixing the well head equipment, and replacing the drilling mud with clean fiuid, all prior to perforating, has gained considerable popularity in the field, and in this method the perforating assemblies used must be adapted to be lowered through the tubing until, upon emergence therefrom in the vicinity of the oil-bearing formation, the perforating can be accomplished.

Equipment for perforating wells completed in the aforementioned manner has now been devised and a particularly effective type of such apparatus is that wherein the assembly is arranged so that during the lowering of same through the tubing the perforating units are in vertical alignment with the axis of the tubing, but upon emergence of the assembly from the lower end of the tubing, said units are permitted to pivot to a horizontal firing position. Such apparatus is disclosed in Patent No. 2,543,814 of W. H. Thompson et al., dated March 6, 1951, and entitled Means and Method of Tilting Explosive Charges in Wells. An improvement upon the Thompson et al. patent, which patent does not provide for a retraction of the apparatus after emergence from the bottom of the tubing, resides in an application for United States Letters Patent, filed February 19, 1954, by Blake M. Caldwell and Joe P. Wier, Serial Number 411,349, entitled Tilting Charge Well Perforating Assembly. A further improvement upon such apparatus resides in an application for United States Letters Patent, filed October 8, 1954, by Blake M, Caldwell and Harrold D. Owen, Serial Number 461,236, entitled Well Perforating Assembly.

In such apparatus there is provided a firing head from which is suspended an elongated carrier, pivotally carrying shaped charges, the shaped charges being resiliently urged to horizontal position, but by interlock means normally being held in axial disposition with respect to the carrier. An explosive release means, such as a squib, abuts a detent on the bottom shaped charge and upon firing of the squib the bottom shaped charge is permitted to pivot to horizontal position, releasing the others so that they too may assume horizontal, or firing, position. Control means are provided in such apparatus whereby the shaped charges may not be fired in the event they are prevented as by well obstructions from attaining the described firing position.

Patented Nov. 17, 1959 The instant invention is concerned particularly with interconnecting means between the shaped charges suspended in the carrier. As previously stated, the charges in the aforementioned apparatus are interlocked the Quote the other and when the charges are pivoted to firing position and fired, a regular pattern of perforations is produced in casing and formation. This uniform spacing of perforations is normally desired but, frequently, it is necessary that an entire zone or zones of the formation not be perforated as, for example, where there is a shale streak at a given level or a piece of apparatus in the well which is not to be perforated.

It is, therefore, the object of this invention to provide explosive shaped charge apparatus of the characterabove described wherein groups of charges may be longitudinally spaced from each other, such spacing to be in such extent as to suit the exigencies of the particular job at hand.

In the accompanying drawings:

Figure 1 shows a side elevational view of a perforating assembly constructed in accordance with the invention set forth in the aforementioned application, Serial Number 461,236;

Figure 2 shows a partial side elevational view of the foregoing apparatus incorporating, however, the instant invention; and

Figure 3 shows the apparatus incorporating the invention after the release of the charges and the pivoting thereof to firing disposition.

In its general aspect, the invention comprises a firing head 10' supported by a conductor cable, not shown, which is suspended in the well from the surface. Carried by the firing head 10 is an elongated carrier 14 through which passes a detonating fuse 16, detonated by the firing head. Said detonating fuse passes adjacent shaped charges 18, which charges are pivotally mounted within the carrier and are resiliently urged to horizontal position, being fired by the detonating fuses. Said charges are, however, by means such as the detents 20 held interlocked in axial disposition with respect to the carrier. A release means which could be solenoid or other electrically operated stop means, but which is shown here as the explosive cartridge, or squib 22, is electrically connected through a suitable conductor 24 to the firing head 10 and abuts the detent Zfia of the bottom shaped charge. Upon firing of the squib, the bottom shaped charge is permitted to resiliently pivot to horizontal position. Pivoting of the bottom shaped charge releases the next shaped charge for similar resilient pivotal movement to horizontal position, and the process is repeated to permit each charge to assume firing disposition.

Electrical control means, not shown, are provided whereby the shaped charges may not be fired from the surface in the event they are prevented, as by well obstructions, from reaching a proper firing position. These control means are actuated by a plunger 30 connected to an upper release arm 32, which itself is provided with one of the detents 2t), for interlock with the uppermost shaped charge. Thus, upon firing of the squib and horizontal pivoting of the shaped charges, the release arm 32 is likewise pivoted urging the plunger Stl upward to permit firing of the shaped charges.

it is with the interlocking and plunger operating characteristics of the instant assembly that this invention is particularly concerned and, in essence, said invention resides in the arrangement whereby a blank interval is provided in the carrier, which interval is bridged by an elongated rod, which rod operates to release the upper shaped charges from interlock in response to the release of the lower shaped charges upon firing of the squib 22.

Detailed description of the general perforating assembly is set forth in the aforesaid application, Serial Number 461,236, and it is believed that the general description of said assembly set forth above sufficies but for the means establishing the blank interval. In this regard, and at a position within the assembly where a blank interval is desired, a tandem release arm 34 is pivotally afiixed to the carrier 14, which tandem release arm is adapted to pivot outwardly and upwardly as do the charges 18 under the urging of a resilient spring 36. An extension 38 of the release arm is adapted to interlock with the detent 20 of the next adjacent shaped charge 18 whereby, upon pivoting of the release arm, the shaped charge is, in turn, permitted to pivot and the assembly to operate in the manner previously described.

Pivotally affixed to the tandem release arm 34 is a clevis 40 into which is threaded a connecting rod 42, which connecting rod may be varied as to desired length through provision of the threaded collars 44. A clevis 46 is pivoted to a lower release arm 48 which, in turn, is pivoted to the carrier 14 and pivotally urged by the resilient spring 50 towards horizontal position. As with the tandem release arm, the lower release arm 48 is provided with an extension 52 which interlocks with the detent 20 of the lower adjacent shaped charge. If desired, the detonating fuse 16 and conductor 24 may be wrapped about the rod 42 as shown on Figures 2 and 3 to stabilize their positioning and prevent damage as by scraping against the casing or well wall.

Thus, it may be seen that through the instant inven- By these means is prevented the necessity, for example,

of more than one run into the hole when spaced zones of a formation must be perforated. Similarly, the invention avoids the well-known difficulties attendant upon the design and operation of apparatus suitable for firing a number of charges of a perforating assembly, moving the said assembly and firing other charges.

While there has been described what is at present considered a preferred embodiment of the present invention, it will be apparent to those skilled in the art that various modifications and chanegs may be made without departing from the essence of the invention, and particularly that the invention herein presented is adapted to various types and kinds of tools other than well perforating assemblies. It is intended to cover herein all such modifications and changes as come within the true scope and spirit of the appended claims.

I claim:

1. A well perforating assembly comprising: an elongated carrier; means for lowering said carrier into a well; an upper and a lower group of shaped charges pivotally mounted on said carrier, the shaped charges of each said group being interlocked in axial disposition with respect to said carrier; bridging means between said groups, said bridging means including an elongated rod and release arms connected thereto and pivotally mounted on said carrier, said release arm interlocking the lowermost shaped charge of said upper shaped charge group and the uppermost shaped charge of said lower shaped charge group; resilient means urging said shaped charges and said release arms to pivot from said axial disposition; release means maintaining said shaped charges and said release arms so interlocked, said release means including a conductor; a detonating fuse for firing said shaped charges; and means operable from the surface of said well for operating said release means to release said shaped charges and said release arms from interlock to V 4 permit pivotal movement from such axial disposition and for firing said detonating fuse.

2. A well perforating assembly comprising: an elongated carrier; means for lowering said carrier into a well; an upper and a lower group of shaped charges pivotally mounted on said carrier, the shaped charges of each said group being interlocked in axial disposition with respect to said carrier; bridging means between said groups, said bridging means including an elongated rod and release arms connected thereto and pivotally mounted on said carrier, said release arms interlocking the lowermost shaped charge. of said upper shaped charge group and the uppermost shaped charge of said lower shaped charge group; resilient means urging said shaped charges and said release arms to pivot from said axial disposition; release means maintaining said shaped charges and said release arms so interlocked, said release means including a conductor; a detonating fuse for firing said shaped charges; and means operable from the surface of said well for operating said release means to release said shaped charges and said release arms from interlock to permit pivotal movement from such axial disposition and for firing said detonating fuse, said conductor and said detonating fuse being wrapped about said elongated rod.

3. A bridging device for a well perforating assembly comprising: an elongated carrier member; an upper release arm pivotally mounted on said carrier member for movement between a position longitudinal and a position transverse of said carrier; a lower release arm pivotally mounted on said carrier member for movement between a position longitudinal and a position transverse of said carrier member; a connecting rod having its ends pivoted to said release arms on opposite sides of the pivot points of said release arms; resilient means urging said release arms to pivot from said longitudinal position to said transverse position; a lower shaped charge pivotally mounted on said carrier below said lower release arm; an upper shaped charge pivotally mounted on said carrier above said upper release arm; said shaped charges being longitudinally aligned with respect to the carrier and pivotable to positions transverse to the carrier; resilient means urging said shaped charges to pivot from said longitudinally aligned positions to said transverse positions; interlocking detents on said lower release arm and said lower shaped charge restraining said lower release arm in said longitudinal position, said detents disengaging upon pivoting of said shaped charge to release said lower arm for pivotal movement; and interlocking detents on said upper release arm and said upper shaped charge restraining said upper shaped charge in said longitudinally aligned position, said detents disengaging upon pivoting of said upper release arm to release said upper shaped charge for pivotal movement.

4; A bridging device for a well perforating assembly comprising: an elongated carrier member; an upper release arm pivotally mounted on said carrier member for movement between a position longitudinal and a position transverse of said carrier; a lower release arm pivotally mounted on said carrier member for movement between a position longitudinal and a position transverse of said carrier member; a connecting rod having its ends pivoted to said release arms at the sides of the pivot points of said release arms; resilient means urging said release arms to pivot from said longitudinal. position to said transverse position; a lower shapedcharge pivotally mounted on said carrier below said lower release arm; an upper shaped charge pivotally mounted on said carrier abovesaid upper release arm; said shaped charges being longitudinally aligned with respect to thecarrier'and pivotable to positions transverse to the carrier; resilient means urging said shaped charges to pivot from said longitudinally aligned positions to said transverse positions; interlocking detents on said lower release arm and said lower shaped charge restraining said lower release arm in said longitudinal po- References Cited in the file of this patent UNITED STATES PATENTS Kanady July 7, 1953 McKean Dec. 29, 1953 FOREIGN PATENTS France Mar. 11, 1953