WO2008098052A2

WO2008098052A2 - Well perforating system with orientation marker

Info

Publication number: WO2008098052A2
Application number: PCT/US2008/053181
Authority: WO
Inventors: Jerry L. Walker; John H. Hales; Randall Moore
Original assignee: Halliburton Energy Services, Inc.
Priority date: 2007-02-06
Filing date: 2008-02-06
Publication date: 2008-08-14
Also published as: WO2008098052A3

Abstract

A well perforating system with an orientation marker. A well perforating system includes a perforating gun with a rotating perforating assembly and an orientation marker operative to indicate an azimuthal orientation of a perforating charge of the perforating assembly at a time of detonation of the perforating charge. The marker includes a portion biased by gravitational force to a vertically downward position as the assembly rotates. A method of indicating azimuthal orientation of a perforating charge at detonation includes: assembling the charge into a rotating perforating assembly of a perforating gun; attaching an orientation marker to the gun; permitting a portion of the marker to remain in a vertically downward position as a result of gravitational force acting on the portion, until the charge is detonated; and in response to detonation of the charge, fixing an orientation of the portion.

Description

WELL PERFORATING SYSTEM WITH ORIENTATION MARKER

TECHNICAL FIELD

The present disclosure relates generally to equipment utilized and operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a well perforating system with an orientation marker.

BACKGROUND

Well perforating systems have been previously developed for orienting perforating charges to shoot in predetermined azimuthal orientations relative to a wellbore. In many (although not all) cases, it is desired to direct the charges to shoot upward relative to a wellbore which is deviated from vertical.

Unfortunately, it is frequently difficult to later determine whether the desired azimuthal orientation of the charges was achieved at the time of detonation of the charges. In other words, it may be unknown whether the perforating charges were shot in the desired orientation relative to the wellbore. Thus, an accurate evaluation cannot be conveniently obtained to assess the effectiveness of the oriented perforating system.

Therefore, it will be appreciated that it would be desirable to be able to conveniently determine whether perforating charges are shot in desired orientations.

SUMMARY

In carrying out the principles of the present disclosure, well perforating systems and associated methods are provided which solve at least one problem in the art. One example is described below in which an orientation marker is included in the system, with the orientation marker having a portion thereof which seeks a low side relative to a perforating gun. Another example is described below in which detonation of a perforating charge fixes a position of the orientation marker, so that azimuthal orientation of the perforating charge at the time of detonation can be later determined.

In one aspect, a well perforating system is provided which includes a perforating gun with a rotating perforating assembly. An orientation marker is operative to indicate an azimuthal orientation of at least one perforating charge of the perforating assembly at a time of detonation of the perforating charge. The orientation marker includes a portion thereof which is biased by gravitational force to remain in a vertically downward position as the perforating assembly rotates.

In another aspect, a method of indicating an azimuthal orientation of at least one perforating charge at a time of detonation of the perforating charge is provided. The method includes the steps of: assembling the perforating charge into a rotating perforating assembly of a perforating gun; attaching an orientation marker to the perforating gun; permitting a portion of the orientation marker to remain in a vertically downward position as a result of gravitational force acting on the portion, until the perforating charge is detonated; and in response to detonation of the perforating charge, fixing an orientation of the portion.

In a preferred embodiment, an orientation marker may be used with any type of oriented perforating system that is used in deviated wells. The marker will accurately indicate the low side of a perforating gun at the time of detonation and, since the marker may also be oriented in a known position relative to the perforating charges, the orientation of the charges at the time of detonation will also be indicated. The marker can be easily read when a connector is removed from an end of the gun.

The marker can include a hollow tube or other enclosure with a ball inside. The enclosure and ball can be made of stainless steel. The enclosure may be formed in a ring with a brazed joint joining its ends. The ball is free to revolve around inside of the hollow enclosure.

The marker may be attached to a rotating internal perforating charge assembly within the gun. An axis of rotation of the charge assembly may be aligned with a center axis of the marker. The ball will always seek the low side of the marker (and thus of the charge assembly within the gun) due to the force of gravity. Alternatively, the marker may be attached to an outer tubular carrier of the gun.

When the perforating charges are detonated, the resulting pressure increase collapses the enclosure, compressing the enclosure against the ball. The position of the ball at the time of detonation is thereby preserved, and is easily visible when the gun is later disassembled. The orientation of the perforating charges relative to vertical at the time of detonation will correspond to the position of the ball relative to the enclosure.

These and other features, advantages, benefits and objects will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the disclosure hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a well perforating system and method embodying principles of the present disclosure;

FIG. 2 is a schematic partially cross-sectional view of a perforating gun which may be used in the system and method of FIG. 1;

FIG. 3 is an enlarged scale schematic partially cross- sectional view of an orientation marker as used with the perforating gun;

FIG. 4 is a further enlarged scale schematic cross- sectional view of the orientation marker;

FIG. 5 is a further enlarged scale schematic cross- sectional view of portions of the orientation marker;

FIG. 6 is a further enlarged scale schematic cross- sectional view of portions of the orientation marker; FIG. 7 is a further enlarged scale schematic cross- sectional view of portions of the orientation marker; and

FIG. 8 is a schematic cross-sectional view of an alternate configuration of portions of the orientation marker.

DETAILED DESCRIPTION

It is to be understood that the various embodiments of the present disclosure described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments .

In the following description of the representative embodiments of the disclosure, directional terms, such as "above", "below", "upper", "lower", etc., are used for convenience in referring to the accompanying drawings. In general, "above", "upper", "upward" and similar terms refer to a direction away from the earth's center relative to a wellbore, and "below", "lower", "downward" and similar terms refer to a direction toward the earth's center relative to the wellbore.

Representatively illustrated in FIG. 1 is a well perforating system 10 and associated method which embody principles of the present disclosure. In the system 10, it is desired to form perforations 12 extending vertically upward through liner or casing 14 and cement 16 lining a deviated wellbore 18 in order to provide fluid communication between an interior of the casing and an earth formation 20 surrounding the wellbore.

For this purpose, a perforating string 22 is conveyed into the casing 14. The perforating string 22 may be conveyed by any method, for example, using production tubing, wireline, slickline, coiled tubing, etc.

As depicted in FIG. 1, the wellbore 18 extends substantially horizontally in the formation 20. However, the wellbore 18 could be otherwise deviated or inclined relative to vertical in keeping with the principles of this disclosure. Indeed, any of the details of the system 10 and method described herein may be altered as desired without departing from the principles of the disclosure.

The perforating string 22 depicted in FIG. 1 includes at least one perforating gun 30. An example of a type of perforating gun which may be used in the system 10 is illustrated in FIG. 2 and described below, but it should be clearly understood that other types of perforating guns may be used for the perforating gun 30 in the system. In addition, any number or combination of perforating guns 30 may be used in the system 10 as needed.

Referring additionally now to FIG. 2, an enlarged scale schematic cross-sectional view of the perforating gun 30 is representatively illustrated, apart from the remainder of the system 10. The gun 30 is an example of one type of perforating gun which may incorporate the principles of the present disclosure. A similar perforating gun and variations thereof are described in U.S. Patent No. 6595290, the entire disclosure of which is incorporated herein by this reference.

The gun 30 includes perforating charges 32 mounted to tubular structures 34 in a gun carrier 36. The charge mounting structures 34 are preferably made from cylindrical tubing. For example, the structures 34 could be made of formed sheet metal, etc.

The structures 34 are rotatably supported in the gun carrier 36 by multiple supports 38. As depicted in FIG. 2, each of the supports 38 is connected to an end of at least one structure 34. Some of the supports 38 are connected between two of the structures 34.

This manner of rotatably supporting the multiple structures 34 at ends thereof prevents the charges 32 and structures from contacting the interior of the gun carrier 36. The charges 32 are thereby permitted to reliably rotate within the gun carrier 36, regardless of the combined length of the structures in the gun carrier.

Instead of the multiple charge mounting structures 34, the gun 30 could use a single charge mounting structure extending substantially the entire length of the gun carrier 36. In that case, the supports 38 would be attached periodically along the length of the structure. This would prevent the structure and/or charges 32 from contacting the interior of the gun carrier 36, while still permitting the structure and charges to rotate within the carrier.

Each of the supports 38 includes rolling elements or bearings 40 contacting the interior of the gun carrier 36. For example, the bearings 40 could be ball bearings, roller bearings, plain bearings, etc., or any other type of bearings. The bearings 40 enable the supports 38 to suspend the structures 34 in the gun carrier 36 and permit rotation of the structures.

Thrust bearings 42 are positioned between the structures 34 at each end of the gun carrier 36 and connector devices 44 attached at each end of the carrier. The devices 44 may be tandems (used to couple two guns to each other), a bull plug (used to terminate a gun string), a firing head, or any other type of device which may be attached to a gun carrier. As with the bearings 40 described above, the thrust bearings 42 may be any type of bearings. Furthermore, the bearings 40, 42 may be combined into a single bearing (as depicted in FIG. 3 and described below) or any other number of bearings.

The thrust bearings 42 support the structures 34 against axial loading in the carrier 36, while permitting the structures to rotate in the carrier. Although two of the thrust bearings 42 are depicted in FIG. 2, only one may be used at a lower end of the structures 34.

Any means may be used to rotate the charges 32 in the gun carrier 36. For example, an electric motor, a hydraulic actuator, gravity, or any other means may be used. The perforating gun 30 as depicted in FIG. 2 uses gravity to rotate the charges 32. However, it is to be clearly understood that it is not necessary for gravity to be used to rotate the charges 32 in keeping with the principles of the present disclosure.

The structures 34, the charges 32, and other portions of the gun 30 supported in the carrier 36 by the supports 38 (including, for example, a detonating cord 46 extending to each of the charges, and portions of the supports themselves) are parts of an overall rotating assembly 48. By laterally offsetting a center of gravity 50 of the assembly 48 relative to a longitudinal rotational axis 52 passing through the supports 38 (which is the rotational axis of the bearings 40), the assembly is biased by gravity to rotate to a specific position in which the center of gravity is located directly below the rotational axis. The assembly 48 may, due the construction of the various elements thereof, initially have the center of gravity 50 in a desired position relative to the charges 32. However, to ensure that the charges 32 are directed to shoot in respective predetermined directions, the center of gravity 50 may be repositioned, or the biasing exerted by gravity may be enhanced, by adding one or more weights 54 to the assembly 48.

On the left-hand side of FIG. 2, weights 54 are added to the assembly 48 to direct the charges 32 to shoot upward. On the right-hand side of FIG. 2, weights 54 are added to the assembly 48 to direct the charges to shoot downward. Of course, the weights 54 may be otherwise positioned to direct the charges 32 to shoot in any desired direction, or combination of directions.

The gun carrier 36 is specially configured to reduce or eliminate the detrimental effects of burrs (not shown) caused by the charges 32 when they shoot through the carrier. These burrs are well known to those skilled in the art. Burrs typically extend outwardly from the outer surface of a gun carrier surrounding an opening 90 (see FIG. 1) formed by a perforating charge 32. Burrs may cause a carrier to hang up on shoulders, etc. in a well, damage polished seal bores, etc.

The carrier 36 is provided with reduced wall thickness portions 60, which circumscribe each of the charges 32. The portions 60 extend circumferentially about the carrier 36 outwardly overlying each of the charges 32. Thus, as the charges 32 rotate within the carrier 36, they remain directed to shoot through the portions 60. A burr created by a charge 32 shooting through one of the portions 60 will remain below the outermost surface of the carrier 36, thereby preventing the burr from hanging up on, or damaging, anything else in a well.

Referring additionally now to FIG. 3, an end of the gun 30 is representatively illustrated. In this view, it may be seen how principles of this disclosure can be incorporated into the gun 30, so that the azimuthal orientation of the charges 32 at the time of detonation can be conveniently determined later, for example, after the gun has been retrieved from the well.

In this example, the gun 30 has an orientation marker 70 connected to one of the supports 38 (in this case, at a lower end of the gun) . However, it should be understood that the orientation marker 70 could be otherwise positioned, and could be connected to other components of the gun 30, in keeping with the principles of this disclosure.

As depicted in FIG. 3, a substantial portion of the marker 70 will rotate with the rotating assembly 48 about the axis 52. In other embodiments, a substantial portion of the marker 70 could be fixedly attached to the gun carrier 36, so that the marker rotates with the carrier independently of the assembly 48. For example, the marker 70 could be rigidly attached to an outer bearing housing 72, which could be in a fixed azimuthal orientation relative to the carrier 36. Thus, it will be appreciated that various configurations of the marker 70 and its attachment in the perforating gun 30 may be used without departing from the principles of this disclosure.

In FIG. 4, a more detailed view of the positioning of the orientation marker 70 relative to the support 38 and outer bearing housing 72 may be seen. In FIG. 5, a more detailed view of the orientation marker 70 itself may be seen.

Note that a notch or recess 74 is formed on the support 38. This recess 74 functions as an orientation reference for determining the relative azimuthal orientation between the marker 70 and the charges 32. Since the charges 32 are oriented in a known manner relative to the support 38, and the recess 74 provides an orientation reference between the support and the marker 70, it follows that the relative orientation between the marker and the charges can be conveniently determined.

A retainer 76 and resilient o-ring 78 are used to retain the marker 70 on the support 38. An enclosure portion 80 of the marker 70 is captured in a position between the retainer 76 and the support 38.

A further enlarged scale view of the enclosure portion 80 is illustrated in FIG. 6. In this view, it may be seen that the portion 80 is formed in a circular shape about an axis 82. Other shapes of the portion 80 may be used, if desired.

In this example, the axis 82 of the portion 80 is preferably aligned with the rotational axis 52 of the rotating assembly 48. However, such alignment is not strictly necessary in keeping with the principles of this disclosure.

A still further enlarged scale view of the portion 80 is illustrated in FIG. 7. In this view, it may be seen that another portion 84 of the marker 70 is contained within the enclosure portion 80.

As depicted in FIG. 7, the portion 84 is in the shape of a ball which is free to rotate within the enclosure portion about the axis 82. However, gravitational force will bias the portion 84 to seek a lowermost position relative to the portion 80.

Other shapes may be used for the portion 84 if desired, For example, a pendulum could be used instead of a ball, in which case the enclosure portion 80 could be disk-shaped, etc. Thus, it should be understood that the principles of this disclosure are not limited to any particular shapes of any components of the marker 70.

Note that the enclosure portion 80 does not completely surround the portion 84, since the portion 80 is not quite completely tubular in shape. Instead, an opening 86 is provided in one side of the portion 80.

This shape of the portion 80 has at least two benefits: it permits the portion 80 to be conveniently formed from a single piece of material which is "wrapped" about the portion 84, and it permits the portion 84 to be easily viewed from an exterior of the portion 80. However, use of the opening 86 is not necessary, and it is not necessary to view the portion 84 from an exterior of the portion 80.

For example, illustrated in FIG. 8 is an alternate construction of the portion 80 in which the portion is tubular in shape. In this example, a collar 88 is used to join the ends of the portion 80 after the portion 84 is installed therein. When installed on the support 38, the collar 88 can be received in the recess 74 to provide a positive relative orientation between the support and the portion 80.

In practice, the marker 70 would be installed as part of the perforating gun 30 as depicted in FIG. 3, prior to conveying the gun into the well. As the gun 30 is being conveyed and appropriately positioned for perforating the casing 14, the rotating perforating assembly 48 is free to rotate within the gun carrier 36.

During this process, the portion 84 is also free to rotate about the axes 52, 82. Gravitational force ensures that the portion 84 remains in a vertically downward position relative to the portion 80.

In the examples of FIGS. 3-8, the enclosure portion 80 rotates with the rotating perforating assembly 48. However, in other embodiments, the enclosure portion 80 could rotate with any other portion of the gun 30, such as the gun carrier 36 as described above.

When the perforating charges 32 are detonated to form the perforations 12, a sudden large increase in pressure is generated within the gun carrier 36. This pressure increase will cause the enclosure portion 80 to collapse or compress against the portion 84, thereby preventing further movement of the portion 84 relative to the portion 80. The position of the portion 84 relative to the portion 80 can be directly viewed upon retrieval and disassembly of the gun 30 if the embodiment of FIGS. 6 & 7 is used, or the position of the portion 84 relative to the portion 80 will be indicated by a bulge in the portion 80 where it overlies the portion 84 if the embodiment of FIG. 8 is used.

If the embodiment of FIGS. 6 & 7 is used for the enclosure portion 80, then the enclosure portion will also be forced against the recess 74, thereby forming an indentation on the portion 80, and indicating the relative azimuthal orientation between portion 80 and the support 38 (and, thus, the charges 32) at the time of detonation. If the embodiment of FIG. 8 is used for the enclosure portion 80, then the collar 88 will preferably be aligned with the recess 74, and the relative azimuthal orientation between portion 80 and the support 38 (and, thus, the charges 32) at the time of detonation will also be known.

In this manner, the relative azimuthal orientation between the portions 80, 84 at the time of detonation of the charges 32 becomes fixed. Since the relative azimuthal orientation between the portion 80 and the charges 32 at the time of detonation is also known, it follows that the relative azimuthal orientation between the portion 84 and the charges can be readily determined, which will indicate the azimuthal orientation of the charges relative to vertical .

If the portion 80 is instead rigidly attached to the gun carrier 36, then the azimuthal orientation of the charges 32 relative to vertical at the time of detonation can still be readily determined. The charges 32 will form openings 90 (see FIG. 1) in the gun carrier 36 at the time of detonation and, upon retrieval of the gun 30, the relative azimuthal orientation of the openings in the carrier will be known. Since the relative orientation between the portion 80 and the carrier 36 will also be known, it follows that the relative azimuthal orientation between the portion 84 and the charges can be readily determined, which will indicate the azimuthal orientation of the charges relative to vertical.

It may now be fully appreciated that the above disclosure provides significant benefits to the art of oriented well perforating. The system 10 and associated method described above enable convenient determination of the azimuthal orientation of perforating charges at the time of detonation.

In particular, a well perforating system 10 is described above which includes a perforating gun 30 with a rotating perforating assembly 48, and an orientation marker 70 operative to indicate an azimuthal orientation of at least one perforating charge 32 of the perforating assembly at a time of detonation of the perforating charge. The orientation marker 70 includes a portion 84 thereof which is biased by gravitational force to remain in a vertically downward position as the perforating assembly 48 rotates.

The orientation marker 70 may include another portion 80 which rotates with the perforating assembly 48 prior to detonation of the perforating charge 32. A relative orientation between the two portions 80, 84 may become fixed at the time of detonation of the perforating charge 32. The relative orientation between the portions 80, 84 may directly correspond to the azimuthal orientation of the perforating charge 32 at the time of detonation.

The portion 84 may comprise a ball which rotates about a rotational axis 52 of the perforating assembly 48. The ball may rotate relative to an enclosure which compresses against the ball, thereby fixing a relative orientation between the ball and the enclosure, at the time of detonation of the perforating charge 32.

The enclosure may be formed in a substantially circular shape having an axis 82 which is aligned with the rotational axis 52 of the perforating assembly 48. The enclosure may rotate with the perforating assembly 48 prior to detonation of the perforating charge 32.

The portion 84 may remain in the vertically downward position prior to detonation of the perforating charge 32, and after detonation of the perforating charge a relative orientation between the portion and the perforating assembly 48 may remain fixed. The orientation marker 70 may be exposed to increased pressure generated by detonation of the perforating charge 32, and a relative orientation between the portion 84 and the perforating assembly 48 may remain fixed in response to the increased pressure.

Also described above is a method of indicating an azimuthal orientation of at least one perforating charge 32 at a time of detonation of the perforating charge. The method may include the steps of: assembling the perforating charge 32 into a rotating perforating assembly 48 of a perforating gun 30; attaching an orientation marker 70 to the perforating gun 30; permitting a portion 84 of the orientation marker 70 to remain in a vertically downward position as a result of gravitational force acting on the portion, until the perforating charge 32 is detonated; and in response to detonation of the perforating charge 32, fixing an orientation of the portion 84.

The orientation fixing step may include fixing the orientation of the portion 84 relative to the perforating gun 30. The orientation fixing step may include fixing the orientation of the portion relative 84 to a tubular gun carrier 36 of the perforating gun 30. The orientation fixing step may include fixing the orientation of the portion 84 relative to the perforating assembly 48.

The orientation fixing step may include compressing a another portion 80 of the orientation marker 70 against the first portion 84. The compressing step may be performed in response to generation of increased pressure due to detonation of the perforating charge 32.

The method may include the step of enclosing the first portion 84 within the second portion 80. The method may include the step of rigidly attaching the second portion 80 to the perforating assembly 48.

The method may include the step of rigidly attaching the second portion 80 to the perforating gun 30.

The method may include the steps of retrieving the perforating gun 30 from a well, and then determining the azimuthal orientation of the perforating charge 32 at the time of detonation by viewing a fixed relative position of the portion 84.

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present disclosure. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A well perforating system, comprising: a perforating gun including a rotating perforating assembly, and an orientation marker operative to indicate an azimuthal orientation of at least one perforating charge of the perforating assembly at a time of detonation of the perforating charge; and the orientation marker including a first portion thereof which is biased by gravitational force to remain in a vertically downward position as the perforating assembly rotates .

2. The system of claim 1, wherein the orientation marker includes a second portion thereof which rotates with the perforating assembly prior to detonation of the perforating charge.

3. The system of claim 2, wherein a relative orientation between the first and second portions becomes fixed at the time of detonation of the perforating charge.

4. The system of claim 3, wherein the relative orientation between the first and second portions directly corresponds to the azimuthal orientation of the perforating charge at the time of detonation.

5. The system of claim 1, wherein the first portion comprises a ball which rotates about a rotational axis of the perforating assembly.

6. The system of claim 5, wherein the ball rotates relative to an enclosure which compresses against the ball, thereby fixing a relative orientation between the ball and the enclosure, at the time of detonation of the perforating charge.

7. The system of claim 6, wherein the enclosure is formed in a substantially circular shape having an axis which is aligned with a rotational axis of the perforating assembly.

8. The system of claim 6, wherein the enclosure rotates with the perforating assembly prior to detonation of the perforating charge.

9. The system of claim 1, wherein the first portion remains in the vertically downward position prior to detonation of the perforating charge, and after detonation of the perforating charge a relative orientation between the first portion and the perforating assembly remains fixed.

10. The system of claim 1, wherein the orientation marker is exposed to increased pressure generated by detonation of the perforating charge, and wherein a relative orientation between the first portion and the perforating assembly remains fixed in response to the increased pressure.

11. A method of indicating an azimuthal orientation of at least one perforating charge at a time of detonation of the perforating charge, the method comprising the steps of: assembling the perforating charge into a rotating perforating assembly of a perforating gun; attaching an orientation marker to the perforating gun; permitting a first portion of the orientation marker to remain in a vertically downward position as a result of gravitational force acting on the first portion, until the perforating charge is detonated; and in response to detonation of the perforating charge, fixing an orientation of the first portion.

12. The method of claim 11, wherein the orientation fixing step further comprises fixing the orientation of the first portion relative to the perforating gun.

13. The method of claim 12, wherein the orientation fixing step further comprises fixing the orientation of the first portion relative to a tubular gun carrier of the perforating gun.

14. The method of claim 11, wherein the orientation fixing step further comprises fixing the orientation of the first portion relative to the perforating assembly.

15. The method of claim 11, wherein the orientation fixing step further comprises compressing a second portion of the orientation marker against the first portion.

16. The method of claim 15, wherein the compressing step is performed in response to generation of increased pressure due to detonation of the perforating charge.

17. The method of claim 15, further comprising the step of enclosing the first portion within the second portion.

18. The method of claim 15, further comprising the step of rigidly attaching the second portion to the perforating assembly.

19. The method of claim 15, further comprising the step of rigidly attaching the second portion to the perforating gun.

20. The method of claim 11, further comprising the steps of retrieving the perforating gun from a well, and then determining the azimuthal orientation of the perforating charge at the time of detonation by viewing a fixed relative position of the first portion.