US3110257A

US3110257A - Well perforating method and apparatus

Info

Publication number: US3110257A
Application number: US719255A
Authority: US
Inventors: Maurice P Lebourg
Original assignee: Schlumberger Well Surveying Corp
Current assignee: Schlumberger Well Surveying Corp
Priority date: 1958-03-05
Filing date: 1958-03-05
Publication date: 1963-11-12
Anticipated expiration: 1980-11-12

Description

NOV. 12, 1963 LEBOURG 3,110,257

WELL PERFORATING METHOD AND APPARATUS Filed March 5, 1958 2 Sheets-Sheet 1 MW i A 4' 60;

O O O W A 4 m May/me P. 1 ebou/ INVENTOR.

ATTORNEY Nov. 12, 1963 M. P. LEBOURG WELL PERFORATING METHOD AND APPARATUS Filed March 5, 1958 2 Sheets-Sheet 2 Mau/vce P leoar INVENTOR.

United States Patent 3,110,257 WELL PERFGRATING METHOD AND AlrARATUS Maurice P. Lehourg, Houston, Tex., assignor to Schlumherger Well Surveying Corporation, Houston, Tex., a

corporation of Texas Filed Mar. 5, 1958, Ser. No. 719,255 9 Claims. (Cl. -2-20) This invention relates to perforating apparatus and more particularly pertains to new and improved methods and apparatus including shaped explosive charges for perforating well casing.

Shaped explosive charges have been used with considerable commercial success in oil well operations known as Permanent Well Completions. In this application, a shaped charge perforating gun is lowered through production tubing of relative small diameter to a level of interest where it is used for producing perforations through the larger diameter well casing. Obviously, a small size and high penetrating power are desirable in perforating guns of this type.

It has been established that shaped charges generally do not provide optimum hole size and penetration when tired directly into a target. it has also been found that as the clearance, that is, the spacing between the charge and the target increases, the penetration increases to optimum point and then decreases with further increases in clearance. Hole size similarly may vary with the clearance.

Therefore, it is an object of the present invention to provide new and improved methods and apparatus including shaped explosive charges for perforating well casing which meet size and penetration requisites of Permanent Well Completion techniques.

it is another object of the present invention to provide new and improved orienting devices for a shaped charge gun which allows positioning of the gun in a well casing thereby to allow the hole size and penetration to be optimized.

A further object of the present invention is to provide a new and improved orienting device for a shaped charge gun in which a plurality of charges may be simply and reliably positioned with respect to the casing at a given clearance thereby allowing the charges to obtain optimum penetration at a plurality of spaced points.

Yet another object of the present invention is to provide a new and improved method of perforating well casing in which both direction and extent of penetration may be reliably established.

These and other objects of the invention are achieved by disposing, in a well casing of ferromagnetic, material, perforating means having a given perforating axis and orienting the perforating axis by a magnetic force acting on the well casing along magnetic axis in a longitudinal plane angularly disposed to longitudinal plane containing the aforesaid perforating axis with the planes extending in the same direction as the longitudinal axis of the casing. Apparatus constructed in accordance with the present invention therefore includes a support adapted to be disposed in the casing and magnetic means carried by the support which is attracted to the casing and thus brings at least a portion of the perforating apparatus into con tact with the inner wall of the casing. The magnetic means has a magnetic axis lying in a first plane extending in the same direction as the longitudinal axis of the casing. The perforating means included and carried with the support has a perforating axis lying in a second plane disposed at an angle relative to the first plane.

T he novel features of the present invention are set forth with particularity in the amended claims. The present in- Patented Nov. 12, 1963 "ice vention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a side elevational view of perforating apparatus embodying the resent invention shown in a well oasing below production tubing;

FIGS. 2A and 2B represent upper and lower portions, respectively, of apparatus embodying the invention in a view taken along lines ZAB-ZAB of FIG. 3 and shown partly in cross section;

FIG. 3 is a cross-sectional View taken along lines 33 of FIG. 2A;

FIG. 4 is a cross-sectional view taken along lines 44 of FIG. 2B;

FIG. 5 illustrates a modified form of the apparatus featuring the invention;

PEG. 6 is similar to H6. 1, however, it illustrates the invention as it may be employed in dual well completion;

FIG. 7 is a cross-sectional view taken along the lines 7-7 of FIG. 6.

in EEG. l of the drawings, perforating apparatus em bodying the present invention is shown disposed in borehole i6 having a well casing 11 and traversing earth formations i2, 13, -14. it is assumed that formation 13 is the one of interest to be perforated in a manner which will be more apparent from the discussion to follow.

The perforating apparatus comprises a conventional casing collar locator 15 to facilitate the positioning of the apparatus, a cylindrical orienting device 15 and a cylin drical perforating gun 16 suspended by an electric cable 1'7 in the Well casing elow the production tubing 18. Cable 17 together with a conventional winch (not shown) are provided for lowering the apparatus into a borehole to a level at which casing 11 :is to be perforated.

Referring now more particularly to H6. 2A and FIG. 2B, the orienting device 15 generally consists of a nonmagnetic cyL'ndrical body 26 such as nonmagnetic stainless steel having a coupling socket 21 at its upper end connected to collar locator 15' and having a stub mandrel 22 at its lower end connected to the gun 16. Body 20 is bifurcated to provide

side arms

23 and 24 separated by a longitudinal slot 25 of, generally rectangular configuration in transverse section (FIG. 3) that extends from the lower end of body 28 to a transverse wall 25a adjacent the socket 21. A central opening 26 in wall 25a is aligned with a central opening 27 in stub mandrel 22 and a tube 23 of electrically insulating nonmagnetic material, such as Bakelite, extends through the slot 25 and is received by the

openings

25 and 27. A rod 29 of the electrically conductive material extends through the tube 28 and projects from the upper and lower ends of the tube. An upper terminal 3% is connected to rod 29 and through cable 17 to a suitable source of current (not shown) at the surface of the earth by means of a conductor 30a and other conductors not shown. The lower end of rod 29 is connected via a terminal 31 to an electrical conductor 32 that extends to a detonator (not shown) for the perforating gun 16. Appropriate ground connections (not shown) complete the electrical circuit just described.

Magnets are employed in the present invention to bring the device 15 into attachment with the casing. Since the device is typically cylindrical and typically has a much smaller diameter than the inner diameter of the casing, a generatrix of contact exists between the device and the casing. The generatrix of contact is invariably generated by a certain imaginary line or axis extending lengthwise of the device and a line of contact along the casing. The imaginary line or axis along the device is a result of the magnetic means developing a resultant radial force of attraction and lies in a definitely located position in a plane which intersects the central axis of the device. As may be surmised, the poles of a magnet can be arranged in various ways so long as the magnets develop a resultant radial force of attraction along an imaginary line or axis along the device.

A magnetic arrangement, as shown in FIG. 3, includes elongated

permanent magnets

33 and 34 each having a generally U-shaped configuration in transverse cross section. The magnets are positioned in back-toback relation in the slot 25 between the side arms with the magnetic poles extending outwardly so that the magnets are positioned at 180. Between each of the poles lies an axis 33a, 34a (FIG. 3) which represent a resultant radial force of attraction. The axes lie in a plane M which intersects the longitudinal axis 35 of the body 20. The magnets may be of any suitable material, for example Alnico NoJS. The

magnets

33, 34 abut tube 28 and a suitable insulating and bonding nonmagnetic plastic, such as commercial Epon or any other suitable binder material, fills the space 36 between the

magnets

33, 34 and the tube and the space 37 between the poles of each magnet. The poles of

magnets

33, 34 and the filling material in space 37 are shaped to conform to the cylindrical outer configuration of body 20, as best seen in FIG. 3. The portion of apparatus embodying the invention, thus far described, is comprised of magnetic means having a resultant radical force of attraction lying in a plane M that extends centrally between the respective outward facing magnetic poles. This plane also intersects the longitudinal axis of the well casing 11 and extends in the same direction as the longitudinal axis.

The stud mandrel 22 has threaded radial bores 40 extending into it at 90 intervals (FIG. for receiving screws 41. Two of the bores are positioned in the longitudinal plane M extending centrally through the magnets and two of the threaded bores are positioned in a longitudinal plane P which is rotated 90 from the first-mentioned longitudinal plane. This allows the perforating unit 16 to be aligned in a longitudinal plane P rotated 90 from the longitudinal plane M for reasons which will become more apparent later.

Turning now to the perforating gun 16 (FIG. 2B), this portion of the apparatus may be constructed in a conventional manner. For example, shaped charge perforating apparatus of the type described in Patent No. 2,785,- 631 to A. Blanchard may be employed. Alternatively, the perforating gun may be constructed as disclosed in the copending application of Maurice P. Lebourg, Serial No. 510,129, filed May 23, 1955, and assigned to the present assignee. As contemplated for the present invention, the charges should be oriented in a selected manner. Preferably, their perforating axis should be positioned to lie in plane P (FIG. 3) which intersects and is at 90 relative to the plane M, although it will be apparent that in accordance with the teachings of the invention other angles may be suitably employed. The charges may be phased at a 180 with respect to each other although it will become apparent that other positionings may be suitably employed in accordance with the teachings of this invention. For purposes of illustration the gun, as disclosed in the Lebourg application, will be briefly described and further reference may be made thereto for specific details not presently shown.

Referring to FIG. 2B, the perforating gun 16 is comprised of a tubular housing 43 which is adapted to be coupled to stub mandrel 22 by means of the screws 41 and may be constructed of a frangible electrically conductive material, for example an alloy of aluminum. A plurality of shaped

explosive charge units

44 and 45 are mechanically supported within the tubular housing having their respective jet axes 46 and 47 inclined relative V to longitudinal axis 35 of the assembly and in longitudinal plane P. Each of the charge units includes a hollow cylindrical container 48 for an explosive material 49 having conical front recess fitted with a liner 50 and having a primer 51 at its rearward end.

A booster charge 52 for primer 51 of the lowermost charge 44 is associated with a blasting cap (not shown) to which electrical lead 32 is connected and a ground lead (not shown) is also provided to complete the circuit. A source of electric current (not shown) may be selectively connected to the leads to detonate the blasting cap and, in turn, ignites booster charge 52. The primer 51 is thus ignited and charge material 49 detonated thereby to form a perforating jet along the axis 46 in a known manner.

A cylindrical booster charge 53 has one end disposed in the path of material comprising the jet from charge 44 which is formed along axis 46. The other end of booster 53 is associated with the primer 51 at the rear end of charge material 49 contained by a housing 48 of charge unit 45. Consequently, the jet from charge unit 44 ignites the booster 53 which, in turn, ignites primer 51 and charge material 49 is detonated and its perforating jet is formed along axis 47. Although only two charges have been illustrated and described, obviously any number of additional charges may be suitably employed.

In accordance with the teachings of the invention, the

gun 16 is connected to the orienting unit 15 by means of screws 41 and threaded bores 40 so that the direction of fire is in a longitudinal plane P spaced angularly from longitudinal plane M containing the magnetic axes 33a, 34a.

'In operation the perforating apparatus is lowered through tubing 18 into the well casing 11 and one of the

magnets

33 or 34 will be magnetically attracted to the casing. The apparatus slides downward while maintaining magnetic contact with the casing until the zone where perforating to be accomplished is reached. Since the orienting unit 15 determines the position of the perforating apparatus relative to the casing, perforating unit 16 is positioned so that the axis 46, 47 of the perforating charges 44, 45 lie in plane P. It is obvious that regardless of the position of perforating apparatus on the inner wall of the casing, the charges will always be directed in a plane P which is at an angle of 90 relative to plane M.

The spacing between the gun body and the well casing along the jet axis as shown in FIG. 3, thus, will always be constant and equal for both sides and thus, the clearance can consequently be standard although a housing for perforating apparatus of minimum size is employed.

To assist the magnets in orienting the apparatus unstabilizing means, as shown in FIG. 5, may be employed. In this modification a pair of longitudinal ribs 55 are positioned in a longitudinal plane on opposite sides of the body in line with the plane P of the perforating axis. The ribs 55 are of generally triangular cross section in a horizontal plane and converge outwardly to present apices 56. If the ribs contact the casing 11, the assembly is unstabilized or unbalanced and will tend to rotate in either direction, for example, from the position shown in full lines toward the position shown in dotted-line construction. Thus, one of the magnets will readily bring the apparatus into engagement with the well casing with the charges directed in plane P.

FIGS. 6 and 7 illustrate the application of the invention to a dual well completion. As illustrated a portion of the well casing 11 extends through the zone 13 to be perforated and contains a nonmagnetic section 60 of a production tubing 61 which is packed-off by conventional packing means 62 and 63 from the zone to be perforated. A second production tubing 64 extends through the packer 62 to the zone to be perforated. When the apparatus is lowered into the casing 11 through the second production tubing 64, it afiixes to the casing in a manner previously described. Of course, it cannot attach to the nonmagnetic section. With the use of the invention the firing of the shaped charges is directed in a plane which does not intersect the production tubing section 60 and the plane of firing as indicated by arrows 65 will be spaced from the production tubing 6t).

Obviously, other forms of magnetic means may be employed in accordance with the invention. For example, a series of horseshoe magnets or bar magnets may be disposed in plane M in stacked vertical relationship with their legs alternating in direction and having a resultant radial force of attraction longitudinal and parallel to the longitudinal axis of the orienting body. Alternatively, instead of permanent magnets, electromagnets may be employed.

It will now be apparent that this invention has provided a method of perforating well casing in a reliable manner by positioning a magnetic orienting means with respect to a perforating means so that the magnetic means has a magnetic axis lying in a first longitudinal plane and in an angular relationship to a second longitudinal plane extending through the perforating means and lying in the plane of the perforating axis, positioning the means adjacent the zone to be perforated, orienting the plane of the perforating axis by magnetically attracting the magnetic means to the inner Wall of the well casing and firing the perforating means. It will also be apparent that suitable apparatus for perforating a ferromagnetic well casing has been provided which consists of an elongated support adapted to be disposed in the casing and having a longitudinal axis, a magnet means carried by the support for bringing at least a portion of the perforating apparatus into contact with the inner wall of the casing and having a resultant radial force of attraction lying in a first plane which extends in the same direction as the longitudinal axis of the support, and perforating means carried by the support having a perforating axis lying in a second plane which extends in the same direction as the longitudinal axis of the support where the second plane is disposed at an angle relative to the first plane.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

1 claim:

1. Perforating apparatus for use in well casing of ferro magnetic material comprising: an elongated support adapted to be disposed in the well casing and having a longitudinal axis, said support comprised of upper and lower coupling members and a bifurcated section joining said members, said members having means defining a bore extending longitudinally through said members, and a conductive rod disposed within said bore; insulating means covering said rod; U-shaped permanent magnet means disposed within said bifurcated section having magnetic poles facing outwardly and rear surfaces in back-to-back relation and abutting said insulating means, and having a resultant radial force of attraction disposed between the poles of the said magnet, said resultant radial force of attract-ion lying in a first longitudinal plane coinciding with the longitudinal axis of said support; a bonding material disposed Within said bifurcated section between said magnet means and said insulating means and between the poles of said magnet mews; and perforating means canied by said support including a plurality of shaped charges arranged to fire in different directions and defining therebetween an angular zone of non-firing; and means for detachably securing said perforating means to said support with said resultant radial force of attraction substantially bisecting said angular non-firing Zone.

2. Perforating appanatus for use in well casing of ferromagnetic material comprising: an elongated support adapted to be disposed in the well casing and having a longitudinal axis, said support comprised of upper and lower coupling members and a bifurcated section joining said members, said members having means defining a bore extending longitudinally through said members and a conductive rod disposed Within said bore; insulating means covering said rod; U-shaped permanent magnet means disposed within said bifurcated section having magnetic poles facing outwardly and rear surfaces in back-toback relation and abutting said insulating means, and having a resultant radial force 'of attraction disposed between the poles of the said magnet, said resultant radial force of attraction lying in a first longitudinal plane coinciding with the longitudinal axis of said support; a bonding material disposed within said bifurcated section between said magnet means and said insulating means and between the poles of said magnet means; and perforating means coupled to said support and including a plurality of shaped charges having forward end portions disposed along perforating axes which are aligned in a second plane intersecting said central axis, said shaped charges being arranged so that alternate forward end portions face in opposed directions relative to said central axis, said second plane being angul-arly disposed relative to said first plane at an angle of 99.

3. Well perforating apparatus comprising a perforating gun section and a magnetic gun orienting section in endwise longitudinal alignment, said orienting section having a generally cylindrical profile of sufficient diameter to include the longitudinally projected profile of said gun section, U-shaped permanent magnet means carried by said orienting section and having its opposite po-le faces terminating substantially at the cylindrical profile of said orienting section and symmetrically disposed With respect to a longitudinal plane of symmetry to develop a resultant radial force of attraction in said plane of symmetry, first and second groups of shaped charges carried by said gun section for firing in first and second directions, said gun section having an angular zone of non-firing intermediate said directions, and means for detachably securing said sections endwise in alignment, with said plane of symmetry substantially bisecting said angular non-firing zone.

4. Well perforating apparatus comprising a perforating gun section and a magnetic gun orienting section in endwise longitudinal alignment, said orienting sect-ion having a generally cylindrical profile of sufficient diameter to include the longitudinally projected profile of said gun section, Uashaped magnet means carried by said orienting section and having its opposite pole faces terminating substantially at the cylindrical profile of said orienting section and circumferentially spaced on one side thereof symmetrically with respect to a longitudinal plane of symmetry to develop a resultant radial force of attraction in said plane of symmetry, first and second groups of shaped charges carried by said gun section for firing in first and second directions which define an angular zone of non-firing intermediate said directions, and means for detachably securing said sections endwise in alignment, with said plane of symmetry substantially bisecting said angular non-firing zone.

5. Well perforating apparatus comprising a perforating gun section and a magnetic gun orienting section in endwise longitudinal alignment, said orienting section having a generally cylindrical profile or sufiicient diameter to include the longitudinally projected profile of said gun section, U-shaped magnet means carried by said orienting section and having its opposite pole faces terminating substantially at the cylindrical profile of said orienting section and symmetrically disposed with respect to a longitudinal plane of symmetry to develop a resultant radial force of attraction in said plane of symmetry, non-mag netic means disposed between said pole faces and shaped 7 to conform to said cylindrical profile, first and second groups of shaped charges carried by gun section for firing in first and second directions, defining therebetween an angular zone of non-firing, and means for cletachably securing said sections with said plane of symmetry substantially bisecting said angular non-firing zone.

6. Well perforating apparatus comprising a perforating gun section and a magnetic gun orienting section in endwise longitudinal alignment, said orienting section having a generally cylindrical profile or sufficient diameter to include the longitudinally projected profile of said gun section, U-shaped magnet means carried by said orienting section and having its opposite pole faces terminating substantially at the cylindrical profile of said orienting section and symmetrically disposed with respect to a longitudinal plane of symmetry to develop a resultant radial force of attraction in said plane of symmetry, first and second groups of shaped charges carried by said gun section for firing in first and second directions, defining therebetween an angular zone of non-firing of not more than 180, and means for detachably securing said sections endwise in alignment with said plane of symmetry substantially bisecting said angular non-firing zone.

7. Well perforating apparatus comprising a perforating gun section and a magnetic gun orienting section in endwise longitudinal aligment, said orienting swtion having a generally cylindrical profile of suflicient diameter to in clude the longitudinally projected profile of said gun sec tion, U-shaped magnet means carried by said orienting section and having its opposite pole faces terminating subst-antially at the cylindrical profile of said orienting section and symmetrically disposed with respect to a longitudinal plane of symmetry to develop a resultant radial force of attraction in said plane of symmetry, first and second groups of shaped charges earned by said gun section for firing in first and second directions, defining therebetween an angular zone of non-firing, means for detachably securing said sections with said plane of symmetry substantially bisecting said angular non-firing zone, and a firing circuit extending through said sections detachably connected at their junction.

8. The method of perforating a ferromagnetic casing in a zone below one tubing string set in the casing comprising the steps'of loading shaped charges into a perforating gun with two directions of firing spaced 'by an angular non-firing zone, securing endwise to said gun a U-shaped permanent magnet having its opposite pole faces spaced symmetrically with respect to a longitudinal plane substantially bisectin-g said angular non-firing zone, lowering the magnet and gun on a cable through the tubing string to said zone to develop a resultant force of attraction between said magnet and the casing in said zone acting in said plane of symmetry sufficient to secure said gun to said casing along a prescribed line of contact extending the length of said gun, and then supplying current through the cable to fire the shaped charges away from said line of contact.

9. In a dual Well completion in a well casing where a first production tubing extends through the casing to a lower production zone and a second production tubing extends through the casing to an upper production zone, the method of perforating the upper production zone comprising the steps of: positioning a magnetic orienting means having a resultant radial force of attraction in a longitudinal plane with respect to a perforating apparatus having different directions of firing defining an angular zone of non-firing so that the resultant radial force of attraction substantially bisects the zone of non-firing, disposing said means adjacent the upper production zone and below the second production tubing to orient the plane of the resultant radial force of attraction, and firing said perforating apparatus.

References Cited in the file of this patent UNITED STATES PATENTS 2,616,370 Foster Nov. 4, 1952 2,664,162 Howard et a1. Dec. 29, 1953 2,669,928 Sweetman Feb. 23, 1954 2,719,485 Bendar Oct. 4, 1955 2,729,494 Trowbridge Jan. 3, 1956 2,778,669 Goodwin Jan. 22, 1957 2,785,754 True Mar. 19, 1957 2,796,023 Abendroth June 18, 1957 2,853,944 Robertson Sept. 30, 1958 2,891,620 Bielstein June 23, 1959 FOREIGN PATENTS 211,094 Australia Nov. 8, 1956

Claims

3. WELL PERFORATING APPARATUS COMPRISING A PERFORATING GUN SECTION AND A MAGNETIC GUN ORIENTING SECTION IN ENDWISE LONGITUDINAL ALIGNMENT, SAID ORIENTING SECTION HAVING A GENERALLY CYLINDRICAL PROFILE OF SUFFICIENT DIAMETER TO INCLUDE THE LONGITUDINALLY PROJECTED PROFILE OF SAID GUN SECTION, U-SHAPED PERMANENT MAGNET MEANS CARRIED BY SAID ORIENTING SECTION AND HAVING ITS OPPOSITE POLE FACES TERMINATING SUBSTANTIALLY AT THE CYLINDRICAL PROFILE OF SAID ORIENTING SECTION AND SYMMETRICALLY DISPOSED WITH RESPECT TO A LONGITUDINAL PLANE OF SYMMETRY TO DEVELOP A RESULTANT RADIAL FORCE OF ATTRACTION IN SAID PLANE OF SYMMETRY, FIRST AND SECOND GROUPS OF SHAPED CHARGES