US 3294163 A
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Dec. 27, 1966 M. P. LEBOURG ORIENTING AND PERFORATING METHODS AND APPARATUS 5 SheetsSheet 1 Filed Feb. 24, 1959 2468mM2468 3 5 7 9 l 3 5 7 9 Mdu/vce P Z @600 INVENTOR. 7
BYQ Al/ ATTORNEY Dec. 27, 1966 P. LEBOURG 3,294,163
ORIENTING AND PERFORATING METHODS AND APPARATUS Filed Feb. 24, 1959 5 Sheets-Sheet 2 52- Jlfl 5 Maur/ce P A 9600/ INVENTOR.
ATTORNEY Dgc. 27, 1966 M P. LEBOURG ORIENTING AND PERFORATING METHODS AND APPARATUS Filed Feb. 24, 1959 5 Sheets-Sheet 5 MOU/Vf f labour? INVENTOR.
* wwww ATTORNEY Dec. 27, 1966 M. LEBQURG 3,294,163
ORIENTING AND PERFORATING METHODS AND APPARATUS Filed Feb. 24, 1959 5 Sheets-Sheet 4 MOM/7C6 F. L eboury INVENTOR.
ATTORNEY Dec. 27, 1966 M. P. LEBOURG 3,294,163
ORIENTING AND PERFORATING METHODS AND APPARATUS Filed Feb. 24, 1959 5 Sheets-Sheet 5 3 i2 /Z //0 L [NTENJ/T) /flr? INDEXED POJ/T/O/VS Moor/re f. leou/y INVENTOR.
3,294,163 ORIENTING AND PERFORATING METHODS AND APPARATUS Maurice P. Lebourg, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a
corporation of Texas Filed Feb. 24, 1959, Ser. No. 795,099 4 Claims. (Cl. 1664) This invention relates to perforating sistems and more particularly to methods and apparatus for orienting the direction of firing of a perforating apparatus in one of a plurality of tubing strings in a borehole.
Multiple well completion techniques are concerned with the problem of obtaining independent production from a plurality of producing zones through a single borehole where the zones are spaced vertically from one another. In one technique of completion, after the borehole has been drilled and the casing set, each production zone is independently perforated and packed off, starting with the lowermost zone and ending with the zone nearest the surface of the earth. Tubing strings are then individually introduced through the packers to the various production zones, starting with a tubing string extending to the lowermost zone, another tubing string to the next higher zone and so forth until each producing zone is separated from one another by packers and opens into the lower end of a string of tubing.
In another technique of multiple well completion, after the borehole has been drilled, the tubing strings are positioned with their respective lower ends at each of the production zones involved and the entire borehole filled with cament so that each tubing string eifectively serves as a casing. Selective perforation of the various production zones may then be accomplished by apparatus disclosed in a copending application of the applicants S.N. 760,138, filed September 10, 1958, now abandoned in favor of a continuation-in-part application S.N. 816,993, filed May 29, 1959, now Patent No. 3,168,141. Briefly described, in aforesaid application, a perforating apparatus is provided with an orienting means arranged to cooperate and align with a special locating collar inserted in a preselected position in the tubing string. The perforating or firing axes (or axis) of the perforating apparatus are located with respect to the orienting means and collar so as to avoid perforation of adjacent, coextending tubing strings. While this apparatus is highly successful and satisfactory, it does require that the locating collar be positioned in the tubing string at the time the string of tubing goes into the well.
Therefore, it will be appreciated that in either of the above instances, an orienting system which may orient a perforating apparatus without the need of mechanical devices in the tubing string has a more universal appeal.
It is accordingly an object of the present invention to provide a new and improved method of orienting the firing axis of a perforating apparatus in awell bore.
Another object of the present invention is to provide a new and improved orienting means for use with perforating apparatus.
It is a further object of the present invention to provide a new and improved orienting means to orient the firing axes of a perforating apparatus.
Another object of the present invention is to provide a new and improved orienting means for use with perforating apparatus in a multiple well completion wherein the perforating apparatus in one string of tubing has a zone in which perforations are not produced, the orienting means permitting orientation of the zone relative to other coextending strings of tubing to prevent perforation thereof.
These and other objects of the present invention are achieved by lowering, into one of a plurality of tubing United States Patent Office with particularity in the appended claims.
10 of FIG. 9;
3,294,163 Patented Dec. 27, 1966 strings in a well, a perforator having at least one laterally extending zone in which perforations are not produced. Energy-emitting and detecting devices positioned at corresponding levels in the respective tubing strings provide signals representing energy transmitted between the devices in the respective tubing strings. One of the devices is positioned in the first tubing string and includes means rotatable in a predetermined relation to the perforator. Thus the detected signals are varied in accordance with the relative orientation of the rotatable means in relation 'to the other of said devices whereby the perforator may be oriented in accordance with the signals selectively to perforate only the first tubing string.
' In one embodiment of the invention, in a first tubing, a transverse beam of radiation from a radioactive source is oriented in a predetermined relatlonship to a perforator zone on a perforator, the zone being one in which perforations are not produced, while in another tubing, :1 radiation detector is provided. The beam of radiation and the aforesaid perforation zone are rotated relative to the first tubing string and the intensity of radiation received by the detector provides a direct indication of the relative angular position of the beam in relation to the detector thereby permitting orientation of the perforator.
In another embodiment of the present invention, in a first tubing, a source of radiation from a radioactive source is provided. In a coextending string of tubing, a radiation detector is encased by a rotatable isolation shield, the shield having an opening to admit radiation to the detector.
'The aforesaid opening is oriented in a predetermined rela- 'tion to the perforator zone of a perforator in which zone perforations are not produced. Rotation of the shield and opening relative to the other tubing string varies the intensity of radiation received by the detector and thereby provides a direct indication of the relative angular position of the opening. Thus, the aforesaid perforator zone may be oriented.
The novel features of the present invention are set forth The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:
FIG. 1 is an elevational view of an energy-emitting means together with a perforating apparatus in one string of tubing and an energy-receiving means in another string of tubing, the tubing being cemented in a borehole;
FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1;
FIG. 3 is a view in longitudinal cross section of the energy-emitting device taken along line 33 of FIG. 1 and drawn to a larger scale;
FIG. 4 is a horizontal cross-sectional view taken along line 44 of FIG. 3;
FIG. 5 is a horizontal cross-sectional view taken along line 5--5 of FIG. 3;
FIG. 6 is a view illustrated in a plane of the indexing slot system on the periphery of the indexing means;
FIG. 7 is a perspective vieW of a portion of the indexing slot system shown in FIG. 6;
FIG. 8 is a graph or log of the response of the energydetecting device as the energy-emitter and perforating apparatus of FIG. 1 is rotated;
FIG. 9 is an elevational view of a modified arrangement of the present invention wherein the energy-detecting device together with a perforating apparatus are disposed in one string of tubing, the energy-emitting device being in another string of tubing and the tubing string cemented in the borehole;
FIG. 10 is a view in cross section taken alon line 10- FIG. is a graph or log of the response of the devices:
shown in the embodiment of FIG. 14.
Referring now to the drawings, in FIG. 1, a borehole extends through earth formations 21 and 22, the formation 22 being the one selected for perforation. Tubings or conduits 23, 23' extend coextensively of one another and are cemented in borehole 20, the tubing 23 terminating shortly below the formation 22 and the tubing 23 extending downwardly through another formation of interest (not shown). It will be understood, of course, that it is desired to produce independently from separate formations at different levels and that, while only two tubing strings are illustrated, three or more tubing stringsv may be in the borehole in accordance with the teachings of the present invention as will hereinafter become more apparent.
A tool 24 is suspended in the tubing string 23 adjacent to formation 22 by means of an armored electrical cable 25. Cable 25 is spooled on a winch (not shown) which, in a customary manner, serves to raise and lower the tool through the tubing. Tool 24 includes a conventional cable head attachment and collar locator 27, a radiationemitting device 28, an indexing mandrel 29 and perforating apparatus 30 which are interconnected to one another to form a unitary assembly. Indexing mandrel 29 is slidably received within the central bore 31 (see FIG. 3) of an indexing centralizer 32 for relative rotation therebetween and for limited longitudinal movement. Centralizer 32 is provided with a plurality of outwardly extending spring arms 33 which frictionally engage with the inner wall of tubing 23 in a conventional manner. Arms 33 are attached by their ends to the centralizer in a conventional manner.
Perforating apparatus 30 may be any one of the presently known commercial types which is adapted to pass through tubing. For example, shaped charge perforating means 34, 34' may be disposed in a tubular housing 35 and suitably interconnected in a well-known manner either for successive or simultaneous detonation. The firing axes 36, 37 (indicated by the dotted line arrows in FIG. 2) of the perforating means 34, 34', that is, the
, axes along which the perforating jets travel, are preferably phased 180 from one another and lie in a longitudinal plane which intersects the central axis 38 of the tool assembly. With this arrangement there will be blind zones A and B on either side of the perforating axes 36,
37 in which perforations are not produced, the zones A and B extending longitudinally of the perforator 30. Obviously the perforating means may be arranged to fire only 'in one direction or can be aligned relative to one another in any preselected manner in harmony with the principles of the invention which will hereinafter become more apparent.
The radiation-emitting device 28 has a source of radioactivity 39 such as radium which emits gamma rays, the
gamma rays being collimated in a radial beam as shown by the arrow 40 in FIG. 2. If the beam of radiation or energy 40 is arranged perpendicular to firing axes 36, 37 then when the beam is directly towards or away from tubing 23', the firing axes 36, 37 will clearlyavoid perforation of the tubing 23.
To obtain an indication of the intensity of the beam of energy 40, an energy-receiving device 41 is suspended in tubing 23' at a level generally corresponding to the depth of the energy-emitting device 28 by means of a conventional spooling winch 42 and an armored electrical cable 43. Energy-receiving means 41 is, of course, complementary to the energy-emitting means 28 and, for example, a Geiger-Mueller counter or scintillation counter may be used to detect the gamma rays and provide an electrical signal in response to the intensity of the rays.
The signal provided by the receiving device 41 is received by a recorder 44, at the surface of the earth through the electrical cable 43. Recorder 44 is adapted to record variations in the intensity of radiation received by receiving device 41 for various angular positions of the beam of energy 40 with respect to tubing string 23 to produce an exemplary curve 47 (see FIG. 8) from which orientation of the beam 40 can be determined. Of course, a meter or other suitable indicating device may be employed if so desired.
Referring now to FIG. 3, the energy-emitting device 28 includes a tubular housing 50 connected at its upper end by screw means 51 and a coupling cylinder 52 to the lower end portion of the casing collar locator 27. The lower end of housing 50 threadedly receives the upper end portion of the cylindrical indexing mandrel 29 at 54. Fluid seals 55, 56 and 57 such as 0 rings for the abovedescribed connections provide a fluid-tight interior. Within the housing 50, a tubular spring finger clamping member 58 threadedly secured at 59 to the lower end of coupling 52 firmly secures a cylinder member 60 in a fixed longitudinal position in the housing 50. Cylinder member 60 and coupling 52 are prevented from relative rotation by means of a locking pin connection at 61.
Disposed in a longitudinally extending blind bore 62 in the upper end of the cylinder member 60 is the source of radioactivity 39, for example, radium, which is sealed in the bore by a plug member 64. The cylinder member 60 and plug member 64 are constructed of radioactivity absorbing material, for example, a heavy metal such as lead. To collimate the directed beam of energy 40 in a transverse direction relative to the housing 50, a passageway 65 is provided which extends between the radioactivity source 39 and the outer periphery of the cylinder member 60. The passage 65 is more accurately defined by the frustrum of a .pyramid having an apex located on the center line of the radioactivity source 39 and a rectangular base at the outer periphery of cylinder 60. The angle defined between the respective upper and lower surfaces 66, 67 and the side surfaces 68, 69 (FIG. 4) of the passage 65 effectively determines the beam width in longitudinal and transverse planes. The side surfaces 68, 69 which determine the beam width in a transverse plane have a relative small angle (FIG. 4), for example about 15. The tubular housing 50 is, of course, constructed of material such as steel which will pass the emitted radiation. A central bore 70 extends through the cylinders 52, 60 and mandrel 29 to provide a suitable passageway for electrical conductors 71 of the detonating system. Conductors 71 are connected between the perforator 30 and a source of power at the surface in a well-known manner.
Indexing mandrel 29 is provided with a slot system 73 while centralizer 32 is provided with a follower 76 extending into the slot system 73. Follower 76 is formed by a spring ring clamp 77 (see FIG. 3) received in an annular groove 78 in the upper end of centralizer 32, an opening 79 in the bottom of the groove 78 permitting a follower end 76 of clamp 77 to extend therethrough into slot system 73.
The indexing system hereinafter described is more completely detailed in the copending application filed on February 24, 1959, Serial No. 294,877, now Patent No. 3,154,147, assigned to the present assignee, however, the basic details so far as an understanding of the nature of the device is concerned is briefly as follows: Slot system 73 includes a plurality of identically arranged rectangular slots 74 equidistantly spaced about the periphery of the mandrel, the longitudinal slots being interconnected respectively by identically arranged slots 75 which are also rectangular (see FIGS. 5-7). Each of the longitudinal slots 74 extends between an upper terminal end portion 80 (FIG. 3) located above the lower end surface 81 of housing 50 and a lower terminal end portion 82, the spacing between terminal end portions 80, 82 being approximately 30 inches. Intermediate of the length of each slot 74, the upper bottom wall portion 83 of the slot is connected by an outwardly inclined bottom wall portion 84 to a raised bottom wall portion 85. Raised wall portion 85 and the lower bottom wall portion 86 of the slot form a downwardly facing shoulder 87. Hence, as the mandrel 29 moves upwardly relative to centralizer 32 from a lower position to an upper position, the follower 76 adjacent to bottom wall portion 83 is cammed outwardly by the inclined portion 84, follows over raised portion 85 and is resiliently returned to its initial position in lower portion 86 upon passing over shoulder 87.
Inclined slots 75 are connected between the lower portion 86 of one longitudinal slot below shoulder 87 and the upper portion 83 of an adjacent longitudinal slot. Each inclined slot 75 has, at its lower end, a bottom wall portion 88 which is connected by an outwardly inclined bottom wall portion 89 to a raised bottom wall portion 90. Raised wall portion 90 opens into a sidewall of the other longitudinal slot so that a shoulder portion 91 is formed in the sidewall. Hence, as the indexing mandrel 29 is lowered relative to the centralizer 32, follower 76 will engage shoulder 87 and be transferred into the inclined slot 75 and thereupon be cammed outwardly by the inclined portion 89, follow raised wall portion 90 and resiliently return to the upper portion 83 of a longitudinal slot upon pasisng over shoulder 91.
In operation, the tool 24 is assembled so that the firing axes 36, 37 are at right angles to the beam of energy 40 so that a zone in which perforations are not produced is in alignment with the beam of energy 40. The tool 24 is then lowered through the tubing 23, the weight being sufiicient to overcome the frictional drag of centralizer 32, to the level to be perforated. The energy-detecting device 41 is then lowered through tubing 23 to a corres onding level so that tool 24 and device 41 are adjacent to one another. Assuming the tool 24 and device 41 to be in an initial position as shown in FIG. 2, the beam of energy 40 or, more specifically, gamma rays emitted from the radiation source 63 in a beam defined between the walls 66, 67, 68 and 69 of passage 65 are directed towards the detector device 41 so that the intensity of radiation indicated by the recorder 44 is at maximum as shown by the point 94 on curve 47 which corresponds to an index position #1 on the log. In this position follower 76 lies in the upper portion of a longitudinal groove, the downwardly facing shoulder 81 of housing so abutting the upper shoulder 95 of centralizer 32. Upon recording of point 94 of curve 47 the operator raises the tool 24, e.g., approximately 26 inches so that the follower pin 76 now resides in the lower portion of the slot 74, the centralizer remaining stationary due to the frictional force of centralizer springs 3-3. The tool 24 is then lowered a corresponding distance of 26 inches so that follower pin 76 follows inclined slot 75 to the adjacent longitudinal slot, the tool being rotated 30 due to the camming action of the inclined slot 75 and follower pin 76. At index position #2 where the tool is now positioned, the intensity is recorded as a point 96 of the curve, the intensity being decreased since the beam 40 has been angularly displaced relative to the detecting device 41. Continued indexing in the above-described manner is carried out until the intensity at twelve indexing positions has been plotted on the log. The curve 47 therefore provides an indication of the intensity of the beam of radiation at various indexed positions, the minivmum point 97 of the curve indicating when the beam is pointed directly away from the device 41, the maximum points 94, 94a indicating when the beam is pointed 6 directly towards the device 41. Hence, the zone of the perforator in which perforations are not produced may be located with respect to the other tubing 23' so that perforator 30 may be fired with the perforations passing through the cement and the formations 22 but without perforating tubing 23'.
In the embodiment of FIG. 9, a source of radioactivity 98 is suspended in tubing 23' while the detecting device 41 is associated with perforator 30 in the tubing 23. More specifically, the detector 41 is fixed relative to the centralizer 101 and a tubular shielding member 102 having an elongated opening 103 therein is adapted to be rotated relative to the detecting device to obtain a selective sampling of radiation about the entire periphery of the device 41. Hence, the radiation received by the detector device 41 may be considered as a beam of energy 104 (see FIG. 10) directed towards the device 41. As shown in FIG. 11, detector 41 is threadedly secured in a bore 105 of a tubular extension 106 of centralizer 101. Tubular extension 106 is reduced in diameter to receive the tubular shielding member 102 and bearing means 107 near the upper end of member 102 rotatively secures the member 102 to extension 106. The lower end of shielding member 102 is threadedly secured to perforator 30 at 108, the upper end portion 109 of the perforator being spaced from the lower end portion 110 of extension 106 to receive an indexing device 111. A fluid seal means 112 is provided near the lower end of extension 106 to fluidly seal the member 102 and extension 106 relative to one another.
Shielding member 102 and the lower portion of centralizer 101 are coated with a heavy metal 114 to prevent passage of radiation therethrough except for the rectangular opening 103 located near the upper end of the member 102. Opening 103 has a narrow width between its sidewalls 115, 116 (see FIG. 10) to confine the radiation entering the opening to relatively narrowbeam width.
Positioned below detector 41 in bore 105 and separated therefrom by a spacer 117 is a solenoid coil 118. Below coil 118, a bore 120 of reduced diameter slidably receives an indexing cylinder 121 which is connected at its upper end to a solenoid armature 122. Cylinder 121 is resiliently biased in a direction away from coil 118 by a spring 123. Near the lower end of member 106, a transversely disposed pin member 124 extends into bore 120 to be received in an indexing slot system 125 in the periphery of cylinder 121. The lower end portion of cylinder 121 which extends beyond end portion 110 is provided with transversely disposed pin members 126, 127 extending at right angles to cylinder 121. A tubular camming member 128 secured to shielding member 102 is provided with generally triangular notches 129 in its upper end which form triangular fingers 130, the end portions of pin members 126, 127 being received within notches 129 and adapted to cooperate with fingers 130 (see FIG. 12).
The indexing pin 124 and slot system 125 which are arranged in a predetermined relation to notches 129 and fingers 130 will now be explained with reference to FIGS. 13A and 13B. Slot system 125 is generally N-shaped and comprised of longitudinal slots 125a, 125b, 1256, 125d spaced 90 from each other and inclined grooves 125ab, 125bc, 1250a, 125da connected between the respective upper and lower ends of the longitudinal grooves. Each of the upper ends of the inclined slots is offset slightly from the upper end of a longitudinal slot to form a pocket 132 to insure a one-way travel of the pin 124 in the slot system 125. The lower ends of the inclined slots are directly below the succeeding longitudinal slots and are also beveled to insure the one-way travel. Fingers 130 are six in number being spaced 60 from one another and arranged relative to the slot system 125 so that when indexing pin 127 is disposed in pocket 132, the apex of one of the fingers is longitudinally'aligned therewith while pins 126, 127 lie in a pair of oppositely opposed grooves 129.
In an operation of the indexing means, energization of solenoid coil 118 by a suitable power supply at the surface raises the cylinder 121, the indexing pin 124 and indexing slot system 125 thereby producing relative rotation between the cylinder 121 and shielding member 106. In an examplary cycle, when index pin 124 goes from an upper pocket 132 at A (FIG. 13A) to a lower position at B, the camming pin member 126 is raised and rotated to move from a position C between the cam fingers 130a, 13012 to a position D above the cam fingers 130 (FIG. 13B) and, before diseangagement with cam finger 13012 rotates the shielding member 106 through an angle of 30 relative to extension 106 (held against rotation by spring cage 48). In position D, the pin member 126 is located above and between fingers 130b, 130a so that when the cylinder 121 is lowered by the action of spring 123 upon the de-energizing of solenoid coil 118, the pin member 124 will be positioned in the notch 129a between the cam fingers 130b, 1300. Thereafter, if the solenoid coil 118 is again energized and de-energized, the indexing cycle above described will be repeated.
The operation of the apparatus described with respect to FIGS. 9-13 is substantially the same as the apparatus of FIGS. 1-8. That is, once the detecting and emitting devices 41 and 9 8 are positioned in the tubing, opening 103 which defines a beam of energy is rotated by the abovedescribed indexing means 111 and the intensity of energy received in recorded on the log. The beam of energy is, of course, oriented relative to the blind zone of the perforator. At a maximum value of intensity, the perforating axes 36, 37 are oriented so as not to intersect tubing 23' and the perforating means may be detonated.
Referring now to the embodiment shown in FIG. 14, an assembly 130 having perforating axes 36, 37 transverse to a beam of energy 40 as above described is disposed in a tubing 131 which is to be perforated. Tubings 132, 133 are coextending with tubing 131 and respectively receive identical detecting devices 41a, 411) which cooperate with the beam of energy 40 to provide an indication of the intensity of energy received. As shown in FIG. 15, devices 41a, 41b independently produce curves 134, 135 respectively forming a graph of the intensity received by the individual devices plotted against the rotational orientating of the beam of energy which is derived similar to the log of FIG. 8. A summation curve 136 of the curves 134, 136 indicates that at position #7 the directional characteristic bisects the center line between tubings 132, 133 so that perforating axes 36, 37 do not intersect the aforesaid tubings.
It should be readily apparent from the foregoing that the present invention sets forth novel methods of orienting an apparatus in a well having a plurality of coextending tubing strings.
Moreover, novel apparatus has been provided to orient a specific apparatus in one of a plurality of tubing strings in a well bore including energy-emitting and receiving devices arranged for positioning at corresponding levels in respective tubing strings to provide signals representing energy transmitted between said devices in said tubing strings.
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 and 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.
What is claimed is:
1. Apparatus for perforating one of a plurality of tubing strings in a well comprising: an elongated well perforator adapted for passage in a first tubing string and having perforating axes defining at least one zone extending longitudinally thereof in which perforations are not produced; means to frictionally engage the walls of said first tubing;
means coupled to said friction means and said perforator for rotating said perforator relative to said friction means through a plurality of angular positions in which the perforator is disposed at the same level in the well thereby to orient said zone relative to another of said tubing strings; energy-emitting and receiving devices arranged to be positioned at corresponding levels in the respective tubing strings diiferent from the level of the perforator to provide signals representing energy transmitted between said de= vices in said tubing strings with one of said devices being coupled to said perforator and said rotating means so that said one device is at the same level in the well at all of said angular positions of said perforator; and means to effect a beam of energy at said one device whereby said one device and perforator may be rotated to vary the detected signals in relation to the other of said devices to obtain a selective orientation of said perforator Zone.
2. Apparatus for perforating one of a plurality of tubing strings in a well comprising: an elongated Well perforator adapted for passage in a first tubing string and having perforating aXes defining at least one zone extending longitudinally there-of in which perforations are not produced; means to frictionally engage the walls of said first tubing; means coupled to said friction means and said perforator for rotating said perforator relative to said friction means through a plurality of angular positions in which the perforator is disposed at the same level in the well thereby to orient said zone relative to another of said tubing strings; radiation-emitting and radiation-receiving devices arranged to be positioned at corresponding levels in the respective tubing strings above the level of said perforator to provide signals representing the intensity of radiation transmitted between said devices in said tubing strings with one of said devices being coupled to said perforator and said rotating means so that said one device is at the same level in the well at all of said angular positions of said perforator; and means to collimate a beam of energy with respect to said one device whereby said one device and perforator may be rotated to vary the detected signals in relation to other of said devices to obtain a relative orientation of said perforator zone.
3. A method for orienting perforating apparatus in one of a plurality of pipe strings in a well comprising the steps of rotating said perforating apparatus through a plurality of angular orientations within said one pipe string, creating at the same level in the well for each of said angular orientations of said perforating apparatus a distribution of energy which characterizes the angular orientation of at least a second pipe string with respect to said one pipe string at such level, detecting said energy distribution at the same level in the well for each of said angular orientations of said perforating apparatus to obtain a signal at the earths surface indicative of said angular orientation, and rotating said perforating apparatus in said one pipe string to a position in prescribed relation to said angular orientation.
4. A method for orienting perforating apparatus in one ofa plurality of pipe strings in a well comprising the steps of rotating said perforating apparatus through a plurality of angular orientations within said one pipe string, creating at the same level in said well above the location of said perforating apparatus in said one pipe string for each of said angular orientations of said perforating apparatus an angular variation in energy to characterize the angular orientation of at least a second pipe string with respect to said one pipe string at such level, detecting said energy distribution at the same level above the location of said perforating apparatus for each of said angular orientations of the perforating apparatus to obtain a signal at the earths surface indicative of said angular orientation, and rotating said perforating apparatus in said one pipe string to a position in prescribed relation to said angular orientation.
(References on following page) 9 10 References Cited by the Examiner 2,875,347 2/1959 Anderson et a1. 2501()8 2,988,068 8/ 1961 True 166-55 UNITED STATES PATENTS 3,054,454 9/1962 Evans 1-66- 168 X 2/ 1939 Potts 255-28 1/131; Brons 5 CHARLES E. OCONNELL, Primary Examiner. Ennis Hare Exwmlne 7/1955 Herzoz 25043.5 C. O. THOMAS, D. C. BLOCK, D. H. BROWN, 6/1957 Abendroth 16655.5 X Assistant Examiners.