GB2399583A - Eccentrically weighted articulated spacer for perforating guns - Google Patents

Abstract

A perforating gun in a deviated wellbore is oriented by an articulated and eccentrically weighted spacer body 40 attached to the charge carrier and gun string by alignment plates 48. Preferably, the spacer body comprises multiple parts joined together by interlocking jigsaw-style connections 44 that allow some relative movement in any direction so that the body can bend to match the curvature of the borehole. The spacer body may be a hollow half-cylinder 46 of semi-circular section in which is placed a similarly shaped bias weight 50. The flat upper surface of the spacer body may have tabs (58, figure 17) cut into it that can be bent normal to the surface to support a detonating cable.

Description

METHOD OF ORIENTING PERFORATING DEVICES

BACKGROUND OF THE INVENTION

Field of invention.

The present invention relates to the field of perforating. More specifically, the invention relates to devices and methods for both orienting perforating devices and confirming their orientation.

Background of the Invention.

Formations penetrated by a downhole well, particularly horizontal or highly deviated wells, are studied to determine the most advantageous orientation of perforations. The desired orientation may be selected based on the possibility of sand production, based on the heavy overburden pressure and/or shear stress existing, or based on the location of control lines and/or other downhole equipment and tools.

There exists, therefore, a need for an apparatus and method for orienting perforating guns and for confirming that the correct orientation has been achieved.

SUMMARY

According to the present invention, there is provided a method of orienting a perforating gun in a deviated wellbore, the method comprising providing an articulated weight spacer within the perforating gun, the spacer comprising a plurality of eccentrically weighted segments engaged such that the individual segments are adapted to bend without becoming disengaged from the surrounding segments.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional view of a prior art conventional perforating gun.

Figure 2 is a cross-sectional view of a perforating gun having a modified shaped charge geometry.

Figure 3 is a cross sectional view of another perforating gun having a modified shaped charge geometry.

Figure 4 is a cross-sectional view of another perforating gun having a modified loading tube.

Figure 5 is a cross-sectional view of another perforating gun having a modified loading tube.

Figure 6 is a cross-sectional view of another perforating gun having a modified gun carrier.

Figure 7 is a cross-sectional view of another perforating gun having a modified gun carrier and loading tube.

Figure 8 is a cross-sectional view of another perforating gun having a modified shaped charge and loading tube.

Figure 9 illustrates a perforating gun having a weighted swiveling loading tube.

Figure 10 illustrates a perforating gun having a swiveling loading tube and lower weights.

Figure 11 illustrates a perforating gun wherein the loading tube is weighted around the shaped charges.

Figure 12 is a cross-sectional view of the perforating gun illustrated in Figure 11.

Figure 13 is a perspective view of the orienting weight of Figures 11 and 12.

Figure 14 is a perspective view of an articulated weight spacer.

Figure 15 is a top view of the articulated weight spacer of Figure 14.

Figure 16 is a side view of the articulated weight spacer of Figure 14.

Figure 17 is a perspective view of the cover of the articulated weight spacer of Figure 14.

Figure 18A - 18C provides top, side, and end views of the shaped weight of the articulated weight spacer of Figure 14.

Figure 19 is a top view of an articulated loading tube of a perforating gun.

Figure 20 is a top view of the articulated loading tube of Figure 19.

Figure 21 is a perspective view of the articulated loading tube of Figure 19.

Figure 22 is a perspective view of a "bent torque response" assembly.

Figure 23 is a plot representing torque versus angle of rotation.

Figure 24 is a perspective view of a positive alignment carrier of a perforating gun Figure 25 is a perspective view of an adapter of the positive alignment carrier of Figure 24.

Figure 26 is a perspective view of a shoulder ring of the positive alignment carrier of Figure 24.

Figure 27 is a side view of the shoulder ring of Figure 26.

Figure 28 is a perspective view of a spring ring of the positive alignment carrier of Figure 24.

Figure 29 provides a side view of an alternative form of the spring ring of Figure 28.

Figure 30 provides a top view of the spring ring of Figure 29.

Figure 31 provides a cut perspective view of spring ring of Figure 29.

Figure 32 is a perspective view of a locking ring of the positive alignment carrier.

Figure 33 is a top view schematic of a typical casing/control line configuration indicating the relative bearing and the direction of perforation.

Figure 34 is a side view of a confirmation device for use in a perforating gun.

Figure 35 is an enlarged side view of the confirmation device illustrated in Figure 34.

Figure 36 is a cross-sectional view of the confirmation device illustrated in Figure 34.

Figure 37 illustrates another kind of confirmation device for use in a perforating gun.

Figure 38 illustrates yet another kind of confirmation device for use in a perforating gun.

Figure 39 illustrates another kind of confirmation device for use in a perforating gun.

Figure 40 illustrates another kind of confirmation device for use in a perforating gun.

Figure 41 illustrates another kind of confirmation device for use in a perforating gun.

Figure 42 illustrates another kind of confirmation device for use in a perforating gun.

Figure 43 illustrates another kind of confirmation device for use in a perforating gun.

DETAILED DESCRIPTION

Figure 1 shows a conventional perforating gun. The conventional perforating gun, indicated generally as 1, comprises a shaped charge 10, a loading tube 12, a gun carrier 14, and a detonating cord 16. The illustrated gun I also includes a scallop 18 machined out of the gun carrier 14 and aligned with the shaped charge 10. Although the illustrated conventional perforating gun I is a scalloped gun 1, it could equally well be a slick-walled gun.

Figure 2 illustrates another perforating gun, wherein the geometry of the case of the shaped charge 10 is modified so that the weight distribution provides enough torque to orient the gun 1. As shown in Figure 2, the case of the shaped charge 10 has additional material 1 Oa provided thereon at the back, or bottom of the case of the charge 10, to provide an eccentric weight moving the center of gravity from the axis of the gun. Such a design causes the charge l O to orient for firing in an upward direction. Note that the additional material/weight 1 Oa may be integral with the shaped charge 10 or added thereto as a separate component such as by screwing a weight to the shaped charge 10.

Figure 3 illustrates another perforating gun, wherein the geometry of the case of the shaped charge 10 is modified. In the example of Figure 3, additional material I Oa is provided at the front, or mouth, of the case of the charge 10. Such a design causes the charge 10 to orient in a downward direction. As discussed with reference to Figure 2, the additional material/weight lOa may be integral with the shaped charge 10 or added thereto as a separate component.

Note that in alternate arrangements, the charge case 10 may be additionally mounted in such a way that the center of gravity is further removed from the axis of rotation Providing a plurality of charges 10 modified in the manner described with reference to Figures 2 or 3 multiplies the effect of the eccentricity that can provide a significant orienting torque. For example, by modifying the geometry of the back of the PJ2906 charge case manufactured by SCHLUMBERGER TECHNOLOGY CORPORATION, 48 grams of extra material can be added per charge. For a 200 ft (6 lm) gun, an extra torque of 68 inch-lb (79cm-kg) is generated. This illustrative amount of torque represents a 40% increase over a 7 ft (2.1m) weighted spacer in a similar gun if steel is used as the weight material. Additionally, the gun using the modified shaped charge 10 provides a better utilization of the space and provides a space savings.

Figure 4 illustrates another perforating gun wherein the loading tube 12 is modified to provide the needed torque. For example, the loading tube 12 may have more material on one side of the tube 12 than the other. As shown in Figure 4, the loading tube 12 has more material 12a on the bottom side (i.e., the side that is intended to be on bottom during firing).

Accordingly, the loading tube 12 has an eccentric weight balance that has a center of gravity that is offset from the axis of rotation. In this way, gravity will cause the loading tube 12 to rotate and orient in a preferential manner.

The perforating gun of Figure 5 provides a loading tube 12 with material 12b removed from one side of the shaped charge 10 to provide for a different orientation than that provided in the perforating gun of Figure 4. In the perforating gun of Figure 5, the loading tube 12 has a center of gravity offset from the axis of rotation that tends to orient the shaped charges 10 in a horizontal direction.

Figure 6 illustrates perforating gun where the gun carrier 14 is modified similarly. For the gun carrier 14, scallops or thinned portions 18 may be provided on one side of the gun carrier 14 so that the carrier 14 itself will provide a degree of preferential orientation. In Figure 6, the gun carrier 14 has multiple scallops 18 provided on its top portion. Thus, the housing has a center of gravity that is offset from the axis of rotation and gravity will cause the gun carrier 14 to rotate and orient in a preferential manner.

The features described with reference to Figures 2 through 6 may be combined to enhance orientation or used individually. For example, as shown in Figure 7, the gun I may use a modified gun carrier 14 and a modified loading tube 12 with conventional charges 10.

Another example, shown in Figure 8, combines modified charges 10 with a modified loading tube 12 and a conventional gun carrier 14. The above are intended to be illustrative and not limiting with respect to the possible combinations.

The guns 1 may include some charges 10 that are modified and some that are not modified, or conventional. As one example, of many possible, the charges 10 of a gun 1 oriented in a first direction are eccentric and of the modified type (i.e., having a center of gravity that is offset from the axis of rotation), whereas those oriented in another direction are of the conventional type. In another arrangement, the charges 10 are used in a gun I to provide an oriented 0-180 phasing arrangement.

Another perforating gun 1, illustrated in Figure 9, has the shaped charges 10 mounted in a loading tube 12 that swivels within the gun carrier 14. In addition to the shaped charges 10, the loading tube 12 carries a weight 20 that causes the swiveling loading tube 12 to rotate to the orientation desired (downward in Figure 9).

In the provided example, the weight 20 provided is a semi-circular weight. However, other configurations are possible. Further, the weight 20 can be any number of types or configurations such as hollow flask type weights filled with a high density material, or half solid metal bars, for example.

In the case of slick-walled perforating guns, no further alignment is necessary as the gun carrier 14 has a uniform thickness around its circumference. Similarly, in the case of a perforating gun 1 having machined grooves extending circumferentially around the gun carrier 14 at each shaped charge interval, no further gun 1 alignment is necessary.

In the case of scalloped perforating guns 1, shown in Figure 9, the gun carrier 14 must be oriented to align with the shaped charges 10 such that the shaped charges 10 shoot through the scallops 18. The perforating gun illustrated in Figure 10, provides for orientation of the gun carrier 14. As shown, the gun carrier 14 is lowered into the well 22 by the work string 24.

A swivel 26 is affixed between the gun carrier 14 and the work string 24 to enable the carrier 14 to rotate as necessary. One or more weights are affixed to the lower end of the carrier 14 to cause the carrier 14 to rotate such that the scallops 18 are facing downward.

The perforating gun illustrated in Figure 10 provides a middle weight 28 and a bottom weight 30. The middle weight 28 has a gun thread on the top end and a gun thread on the bottom for receipt of additional weights. The lower weight 30 has a rounded bottom end 30a to help guide the string 24 into liner tops and around the corner in highly deviated or horizontal wells. Because the middle weights 28 and bottom weights 30 are subject to well conditions, they can be made of heat treated steel to survive the trip in and out of the well.

It should be understood that the perforating gun illustrated in Figure 10 is provided as one example the numerous combinations of weights that can be used. For example, a plurality of middle weights 28 can be used depending upon the orienting weight needed. Further, depending upon the application, it may not be necessary to provide any middle weights 28.

Figure 11 illustrates another perforating gun wherein the loading tube 12 is weighted around the shaped charges 10. The perforating gun I is a slick-walled gun 1 having a swiveling loading tube 12 therein. However, this perforating gun can also be used with a stationary loading tube 12 where the entire perforating gun I swivels. By surrounding a portion of the shaped charge 12 with an orienting weight 32, the necessity of additional length added to the string is avoided.

Figures 12 and 13 illustrate a version of the perforating gun 1 having the loading tube 12 weighted around the shaped charges 10. Figure 12 provides a cross- sectional view of the perforating gun 1, while Figure 13 provides a perspective view of the orienting weight 32. As shown, the orienting weight 32 is configured and located such that the loading tube 12 and shaped charge 10 is oriented in a horizontal plane. The cutouts 32a in the orienting weight 32 match the pattern of the shaped charges 10 so that the orienting weight 32 does not interfere with either the charges 10 or the detonating cord 16.

While the above example illustrates use of the orienting weight 32 to perforate in a horizontal plane, it should be understood that the orienting weight 32 can be configured to provide orientation in any desired plane.

Figures 14- 18 show an articulated weight spacer 40 to provide correct orientation of the perforating gun throughout a tortured wellbore trajectory. As illustrated, the articulated weight spacer 40 comprises a semi-circular spacer tube 42 that is deployed within a hollow gun carrier 14 (shown in phantom lines in Figure 1). However, in alternate arrangements, the articulated weight spacer 40 may take on any number of shapes.

The spacer tube 42 contains a plurality of jigsaw puzzle-like cuts 44 spaced along its length. The cuts 18 traverse the circumference of the tube 42 in such a way as to cut the spacer tube 42 into separate segments 46 without enabling the segments 46 to be disengaged from each other. The cuts 44 allow the spacer tube 42 to bend a little at each cut 44 without causing the spacer tube 42 to lose its structural properties and primary function (i.e., orienting the gun string in the right direction). The segments 46 at each end of the spacer tube 42 are attached to alignment plates 48 that are used to lock the articulated weight spacer 40 to the gun carrier 14 or gun string.

Within each segment 46 is an appropriately shaped weight 50 (best illustrated in Figures 18A - 18C). The weights 50 orient the spacer 40 and thus the gun string in the desired orientation. In the arrangement shown in which the spacer tube 42 has a semi-circular shape, the weight 50 may also have a semi-circular shape enabling it to fit nicely within each segment 46. However, other shapes and types of weights are possible. Each segment 46 may also include an end plate 56 at each of its ends to prevent the axial movement of the weight within the spacer tube 42.

As shown in Figure 14, 15, and 17, a cover 52 is attached to each segment 46 enclosing and securing the weight 50 therein. The cover can be connected to its corresponding segment 46 by the use of tabs 54 snapping into engaged to the segment 46, for example. Each cover 52 also has partially cut out tabs 58 that may be bent from the cover 52.

Each tab 58 has an opening 60 therethrough sized for receipt of a detonating cord (not shown). When the gun string is assembled, the tabs 58 can be bent to extend away from the cover 52, and the detonating cord can be passed through each opening 60 to secure the detonating cord within the spacer 40.

The articulated weight spacer 40 does not contain a directionally preferred stiffness in bending. It has the same stiffness, or resistance to bending, or bending moment of inertia, in all directions. Although it will still provide a gravitational correcting torque to the gun string when the gun string is not oriented in the desired direction, the articulated weight spacer 40 will not rotate the guns out of the intended gravitationally preferred direction when the spacer assembly is bent in a non-straight wellbore (i.e., when the bend is not in the 6 or 12 o'clock plane).

Thus, by fabricating the spacer tube 42 in this manner, the segments 46 remain stiff while the spacer tube 42 as a whole is able to bend with no resistance in any direction. The quantity and length of segments 46 and the width of the cuts 44 can be chosen to allow a suitable bending radius. In this manner, the gun can be passed through a bent wellbore without concern that the spacer tube 42 will try to incorrectly orient the gun string.

Figure 19-21 illustrates an articulated loading tube 70 that incorporates the principles of the articulated weight spacer 40 described above. The articulated loading tube 70, which is deployed within a hollow gun carrier 14 (shown in phantom lines in Figure 19), contains a plurality of jigsaw puzzle-like cuts 72 spaced along its length. The cuts 72 traverse the circumference of the loading tube 70 in such a way as to cut the loading tube 70 into separate segments 74 without enabling the segments 74 to be disengaged from each other. The cuts 72 allow the loading tube 70 to bend a little at each cut 72 without causing the loading tube 70 to lose its structural properties and primary function (i.e., holding the shaped charges in their correct position inside the gun carrier 14). The segments 74 at each end of the loading tube 70 are attached to end plates 76 that are used to lock the articulated loading tube 70 to the gun string.

Each segment 74 may include a plurality of openings 78 for receipt of shaped charges (not shown). Tabs 80 may also be included in order to help secure the shaped charges in place. An opposing opening 82 may also be defined opposite each opening 78 for receipt of the back end of the corresponding shaped charge.

By fabricating the loading tube 70 in this manner, the individual segments 74 remain stiffwhile the loading tube 70 as a whole is able to bend with no resistance in any direction.

The quantity and length of segments 74 and the width of the cuts 72 can be chosen to allow a suitable bending radius. In this manner, the gun can be passed through a bent wellbore without concern that the loading tube 70 will try to incorrectly orient the gun string.

As a method of compensating for non-uniformity of the bending moment in gun string components (i.e., gun carriers, gun spacers,and weighted housings), a length of gun component raw material is bent in a curvature resembling that which may be experienced in a bent wellbore. While the material is bent, it is rotated about its longitudinal axis. The amount of torque required to accomplish the rotations is measured versus the angle of rotation between a reference "zero" and 360 degrees. Such measurement can be accomplished using a "bent torque response" assembly as illustrated in Figure 22.

Figure 23 provides a graphical representation of the required torque plotted against the angle of rotation. The plot illustrates the effect that a non-uniform bending moment of inertia will have on the gun string components. The "static" or resting position is described as the location where the torque/rotation plot crosses zero torque. Using the data, the "optimal angular position" is identified. This optimal angular position, referred to as the "bent torque zero angle," is the angle at which the component would actively orient itself along the inside curvature surface of the casing of the bent wellbore.

By knowing in advance the wellbore trajectory, and knowing the "angle of bend," gun carriers, gun spacers, and weighted spacer housings can be provided that will actively orient the gun string in the desired direction. The gun carriers, gun spacers, and weighted spacer housings that are known or planned to be located in a bent section can be manufactured to have the bent torque zero angle coincident with the angle of the bend of the bent wellbore.

The magnitude of the torque provided, or available, in the active orientation can be determined as well from the characterization of the raw material in the bent material torque response tests. The magnitude will vary depending on the individual piece of raw material, the degree of bend, and the length of the bent portion of the wellbore. The longer the bent portion of the wellbore, the greater the active orienting torque available. The higher the bend angle in the wellbore, the greater the active orienting torque available. Finally, the greater the amount of torque required to rotate a piece of raw material through one revolution, as identified in the bent material torque response tests, the greater the active orienting torque available.

Figures 24-32 show a positive alignment carrier that removes alignment error in subsequent gun strings that exists due to machining tolerances and clearances. In other words, the positive alignment carrier 90 illustrated in Figures 24-32 ensures that additional gun strings affixed to a first oriented gun string maintain the orientation of the first string.

Referring first to Figure 24 the positive alignment carrier 90 comprises an adapter 92, a shoulder ring 94, a spring ring 96, and a lock ring 98. As shown, the positive alignment carrier 90 is engaging both a second positive alignment carrier 100, and a downhole tool 102 such as an additional perforating gun carrier. The positive alignment carrier 90 can be used to advantage to engage any number of downhole string components, tools and pieces of downhole equipment.

Figure 25 provides a perspective view of the adapter 92 of the positive alignment carrier 90. In the version shown, both ends 104, 106 of the adapter 92 can be used to positively align adjoining components. In alternate versions, one end of the adapter 92 can be integral with one of the adjoined components, or can be fixed to an adjoining component in a standard manner such as threading.

The adapter 92 has a shoulder 108 having threads 110. Proximate the threads 110 are a plurality of set screw receptacles 112. The set screw receptacles 112 are located around the circumference of the adapter 92. The adapter surface 114 is further defined by a plurality of tapered keys 116 that protrude from the adapter surface 114. The tapered keys 116 have tapered sides 118. In the version shown, the tapered keys 116 are rectangular in shape.

However, in alternate versions, the tapered keys 116 can take on any number of regular or irregular shapes.

Referring to Figures 26 and 27, the shoulder ring 94 is shown in perspective and side views. The internal diameter of the shoulder ring 94 is defined by a plurality of keyways 122 that correspond and align with the tapered keys 116 of the adapter 92. The keyways 122 enable the shoulder ring 94 to pass by the tapered keys 116 in either direction without interference. The interior of the shoulder ring 94 is further defined by threads 120 that can matingly engage the threads 110 of the adapter shoulder 108. A plurality of notches 124 are located around the circumference of the shoulder ring 94.

Referring to Figure 28, the spring ring 96 is shown in perspective view. The spring ring 96 is a conventional spring, such as a wave spring, that has a series of keyways 126 defined along its internal diameter that enable the spring 96 to pass over the tapered keys 116 of the adapter without interference. An alternate version of the spring 96 is shown in Figures 29-31.

Figure 32 provides a perspective view of the locking ring 98. The locking ring 98 has a plurality of locking tabs 128 that protrude axially from the locking ring 98. The locking tabs 128 are defined by tapered surfaces 130. The locking tabs 128 are sized and shaped to engage corresponding tapered notches in the ends of gun carriers, spacers, other adapters, and other downhole components. The inner surface of the locking tabs 128 are key receptacles 132 having tapered sides 134. The key receptacles 132 are sized and shaped such that an interference exists between the tapered keys 116 and the key receptacles 132 at all times as the locking ring 98 is maneuvered across the tapered keys 116. Thus, the locking ring 98 must deform to fit over the adapter 92 removing all clearance between the two.

In operation, the shoulder ring 94 is first maneuvered along the adapter 92 toward the threaded shoulder 108. The shoulder ring 94 is able to pass by the tapered keys 116 by aligning the keyways 122 with the tapered keys 116. After passing the tapered keys 116, the shoulder ring is threaded onto the threads 116 of the shoulder 108. The spring ring 96 is then maneuvered onto the adapter and located in proximity of the shoulder ring 94.

After the spring ring 96 is placed on the adapter 92, the locking ring 98 is maneuvered onto the adapter 92 such that the key receptacles 132 engage the tapered keys 116. As stated above, there exists an interference between the tapered keys 116 and the key receptacles 132 such that the locking ring 98 must deform to fit over the adapter 92. Such deformation removes any clearance between the two.

Once the locking ring 98 is positioned over the tapered keys 116, the locking ring 98 is held in place by the shoulder ring 94 and spring ring 96. The shoulder ring 94 is backed off of the threads 116 of the adapter shoulder 108 until the spring ring 96 is acting on the locking ring 98 with the desired force. Once the desired force is attained, set screws are inserted through the notches 124 of shoulder ring 94 into the set screw receptacles 112 in the adapter.

The set screws maintain the position of the shoulder ring 94, which in turn maintains the force supplied by the spring ring 96 on the locking ring 98. The spring ring 96 acts to hold the locking ring 98 in place, but also acts to absorb the forces generated by any axial displacement of the locking ring 98 toward the shoulder ring 94. Such axial displacement can occur during downhole operations.

In an alternative arrangment, the shoulder ring 94 is backed off of the threads 116 of the adapter shoulder 108 until the shoulder ring 94 is in abutment with the locking ring 98.

Thus, the spring ring 96 is not needed. However, any axial displacement or axial forces acting on the locking ring 98 must be carried by the set screws and/or threads 110 of the shoulder ring 94.

Once the locking ring 98 is secured in place over the tapered keys 116, the mating component (gun carrier, spacer, adapter, etc.) can be attached. As shown in Figure 24, the mating component (100 or 102) has tapered notches 136, 138 that are engaged by the locking tabs 128 on the locking ring 98. The tapered notches 136, 138, have tapered surfaces that facilitate a secure engagement with the tapered surfaces 130 of the locking tabs 128.

The locking ring 98 is positively aligned and secured by both the interaction between the keyways 132 and the tapered keys 116 and the action of the shoulder ring 94. The mating component (gun carrier, spacer, adapter, etc.) is positively aligned and secured by engagement with the locking tabs 128 on the locking ring 98. Consequently, manufacturing tolerances are eliminated and the connection is positively aligned.Duplicating this type of connection throughout an entire string assembly results in a string assembly that does not have a gradual "drift" of alignment.

To avoid interfering with control lines and other downhole components during perforating, methods (acoustic, electrical, nuclear, thermal, magnetic, etc.) of detecting them are provided, based on the detection of various materials contained therein or of various characteristics thereof. As illustrated in Figure 33, by detecting the control line 140 with one sensor and at the same time mapping its position with respect to a fixed position in the casing 142 (e.g. Relative Bearing (RB) to the high side or low side of the hole), the information needed to position the perforating guns 1 in the desired direction is provided. As shown in the illustration, the control line 140 is mapped with respect to the high side RB, and the perforating gun I is oriented and fired in a direction (indicated by the arrow) that avoids any interference with the control line 140.

It is important to note, that the method is equally applicable to detecting downhole sensors, controls, downhole equipment and downhole tools that can be damaged or affected if in or near the path of a shaped charge jet. For ease of discussion, however, the method will be discussed with reference to control lines.

In the method for detecting control lines 140 (and other components), the control line is mapped and the gun I is indexed during the same trip in the hole. In the method, focused (ie directional) detector(s) are used to determine the position of the control line 140, and a gyro is used in conjunction with the detector(s) to map the position of the control line with respect to the low or high side of the casing 142. Once this is determined a gun string with an inclinometer/relative bearing tool (Wireline Perforating Inclinometer Tool) and gyro is run in the hole. This is used to verify that the inclinometer/relative bearing tool is in agreement with the gyro (required for wells with small inclinations). During the shooting pass the guns I and inclinometer/relative bearing tool are run (the gyro tool is removed) with the gun 1 positioned in the desired shooting direction. The inclinometer/relative bearing tool is used to confirm that the gun 1 is positioned in the desired direction and the guns I are fired.

The guns 1 can be oriented by any of the above mentioned methods, Further, the guns can be positioned by conventional passive means (Wireline Oriented Perforating Tool, Weighted Spring Positioning Device) or active means (downhole motor - Wireline Perforating Platform).

The focused detector(s) are selected based upon what the control lines 140 (or other components) are made of or contain. In one arrangement, the method uses radioactive detection. In this arrangement, a gamma ray imaging tool is used to detect the control line or any component in the control line 140 that is doped with radioactive tracer elements (cobalt 60, cesium, etc.). Likewise, the gamma ray imaging tool can be used to detect a radioactive pip tag placed in the brackets that fasten the control line 140 to the casing/tubing.

The gamma ray imaging tool can also be used to detect radioactive fluid injected into the control line 140.

In another arrangement, the method of detecting control lines 140 involves detector(s) that are used for acoustic detection. Ultrasonic imaging tools can be used if the control line has a significant difference in acoustic impedance from the surrounding media (cement, mud cake, formation, gravel pack, etc.).

In yet another arrangement, the method of detecting control lines 140 involves focused detector(s) that are used for thermal detection. In this arrangement, thermal detection tools (Production Services Platform, Manometer Temperature Sonde) can be used to detect cooling fluid that is pumped down the control line 140.

In still another arrangement, the method of detecting control lines 140 utilizes electrical detection. In this arrangement, the control line 140 is detected where the coupling of an induced EMF signal on the control line side of the casing 142 differs from the opposite side. Alternatively smart card type transducers, or other electronic tags, can be oriented in the casing 142 or control line 140 and detected.

In another arrangement, the method of detecting control lines 140 uses magnetic detection. A Magnetometer can be used when a magnetic tag is placed in the control line 140, control line brackets or the casing 142.

An apparatus for confirming that a correct orientation of the perforating gun 1 has been achieved is illustrated in Figures 34-36, which shows a confirmation device 200 housed within the gun carrier 14 and affixed to the loading tube 12. It should be noted that in alternative arrangements, it is not necessary that the confirmation device 200 be affixed to the loading tube 12, as long as the confirmation device 200 is attached to the gun string at a fixed angle with respect to the orientation of the shaped charges 10.

The confirmation device 200 provides a trigger charge (small shaped charge) 202 that is initiated by the same detonating cord 16 that initiates the main shaped charges 10. Upon detonation, the trigger charge 202 shoots into a proof plate 204 to provide evidence of the gun I orientation at the time of firing. The evidence is provided without piercing the gun carrier 14 and risking damage to the wellbore or wellbore components.

In the illustrated arrangement, the proof plate 204 is a semi-circular plate housed within a highly polished track 206. The proof plate 204 has one or more wheels 204a that enable the plate 204 to rotate, within the track 206, around the center axis of the gun 1. Due to its own weight, the proof plate 204 will always be on the bottom side of the well. The trigger charge 202 is positioned to shoot straight down relative to the correct orientation of the loading tube 12 and main charges 10 (whether at 0, 90, 180, or any other deviated angle) when properly oriented. Thus, if the orientation of the loading tube 12 is correct, the trigger charge 202 will always shoot straight through the center of the proof plate 204. If the charges are not correctly oriented, the degree of misalignment can be measured by the shot fired into the proof plate 204.

It should be noted that in alternate arrangements, the proof plate 204 can be manufactured to extend completely around the trigger charge 202 and still be ordinated by gravity to record slight and large deviations.

In another version of the confirmation device 200, illustrated in Figure 37, the trigger charge 202 is positioned in a rotating support 208 housed within the loading tube 12. The support 208 has a counter weight 210 thereon that biases the support 208 such that the weight 210 is oriented toward a lower position. In the version shown, the trigger charge 202 faces opposite the counter weight 210 such that the trigger charge 202 is always oriented in an upward direction (although in other versions it could point in other directions).

The detonating cord 16 is provided in operable attachment to the trigger charge 202 such that detonation of the detonating cord causes the trigger charge 202 to fire. Upon detonation, the trigger charge 202 fires creating an indication on the loading tube 12 that can be inspected to determine the orientation of the perforations. Once again, the orientation is confirmed without the necessity of penetrating the gun carrier 14 with the trigger charge 202.

Another way of confirming that a correct orientation of the perforating gun 1 has been achieved is illustrated in Figure 38. In this arrangement, the confirmation device 200 is affixed to the loading tube 12 (as shown), housed within the loading tube 12, or attached to the gun string in fixed relation to the shaped charges (not shown). The confirmation device can be located inside a space protected from damage from the firing of the shaped charges (not shown) such as spacer subs, trapped pressure regulators, swivels, etc. The confirmation device 200 has an upper alignment plate 212 and a lower alignment plate 214 rigidly affixed within an external housing 216. The upper alignment plate 212 and the lower alignment plate 214 each provide a centralized guide 212a, 214a, for receipt of a central shaft 218. The guides 212a, 214a allow the central shaft 218 to rotate freely at both ends. Fixedly attached to the central shaft 218 is a counter weight 210 that is always positioned in the lower portion of the confirmation device 200 due to the force of gravity.

The detonating cord 16 passes through the central shaft 218. Upon detonation of the detonating cord 16 to fire the shaped charges (not shown), the pressure inside the central shaft 218 rises quickly causing the central shaft 218 to expand and lock itself inside the upper and lower guides 212a, 214a. Thus, the central shaft 218 is locked in the position it was in upon firing of the shaped charges. Upon retrieval of the gun string, the position of the central shaft 218 within the confirming device 200 can be examined to determine the orientation of the gun string at the time of detonation.

It should be noted that it is only necessary that the central shaft 218 expand to lock with one of the guides 212a, 214a. For example, the lower guide 212a may be made of plastic and only used for guiding purposes rather than locking purposes. It should further be noted that the guides 212a, 214a can include uneven surfaces that mechanically lock the central shaft 218 so as to not rely on friction alone to maintain the locked position.

Yet another version of the confirmation device 200 is illustrated in Figure 39. In this version, the confirmation device 200 is once again attached within the gun string in fixed relation to the orientation of the shaped charges. The external housing 216 of the confirmation device 200 is again affixed to an upper alignment plate (not shown). Within the external housing 216 is a confirming weight 220 held in position by two roller bearings 222.

The confirming weight 220 provides a hardened spear 221 and is shaped such that it will preferentially, by means of gravity, orient itself on the lower side of the confirmation device 220 and point the spear 221 in the upward direction. The detonating cord (not shown) passes through the center drill hole 224 of the confirming weight 220.

Upon detonation of the detonating cord, the pressure rises rapidly within the drill hole 224 causing the spear 221 to be driven upward. The hardened spear 221 strikes and indents the inside surface of the external housing 216 at the time of detonation. After the perforating job is completed, the external housing 216 is removed and examined to determine the actual orientation of the perforations in the wellbore.

Another version of the confirmation device 200 is illustrated in Figure 40. Once again, the confirmation device 200 is attached within the gun string in fixed relation to the orientation of the shaped charges. In this version, the confirmation device 200 includes two disks 226 with a gap 228 defined therebetween. A sleeve 230 is disposed circumferentially between the disks 226. The disks 226 and sleeve 230 are fixed in relation to the external housing 216 such as by screws 231, or pins 232, for example.

A spear mechanism 234 provides a tube 236, two bearings 238, a hub 240, a barrel 242, and a spear 244. The tube 236 is positioned within the central openings 246 defined through the disks 226. The bearings 238 are mounted on the tube 236 on either side of the hub 240, with the tube 236 also passing through the central opening 248 in the hub 240. The bearings 238 enable rotation of the hub 240. The barrel 242 extends from the hub 240 and is in communication with the central opening 248. The spear 244 is located within the barrel 242 and may be initially held in place by a shear pin 250. The spear mechanism 234 is weighted, such as by the inclusion of the barrel 242 and spear 244, such that the barrel 242 and spear 244 are oriented, by gravity, on the lower side of the gun string.

The detonating cord 16 (shown in dashed lines) passes through the central openings 246 in the disks 226 and through the interior of the tube 236. Upon detonation of the detonating cord 16, the tube 236 is disintegrated and the pin 250 is sheared, causing the spear 244 to be driven downward and indent the inside surface of the sleeve 230. After the perforating job, the location of the indentation can be used to determine the actual orientation of the perforations.

Still another version of the confirmation device 200 is illustrated in Figure 41. In this version, a ball bearing (or counter weight) 252 is housed within a bearing housing 254 and allowed to rotate therein so that the ball bearing 252 remains on the low side of the bearing housing 254. The detonating cord 16 extends through the bearing housing 254 such that the ball bearing 252 is positioned between the detonating cord 16 and the inner wall 256 of the housing 254.

Upon detonation of the detonating cord 16, the pressure increase within the housing 254 causes the ball bearing 252 to create an indentation in the inner wall 256 of the housing 254. The bearing housing 254 is fixed in relation to the shaped charges such that the indentation is used to verify orientation of the perforations at the time of detonation.

In alternative arrangements, the housing 254 contains multiple ball bearings 252. Further, it should be noted that by using a housing 254 having a rounded shape in the axial direction, the orientation of the gun string may be determined in multiple axes. In other words, the ball(s) 252 rotate to the low side of the housing 254 enabling determination of the longitudinal angle of the guns as well as the rotational orientation.

Yet another version of the confirmation device 200 is illustrated in Figure 42. In this version, an eccentric weight 260 is mounted on a bearing support 262 having a bearing surface 264. The eccentric weight 260 rotates so that the weighted side remains in the lowermost position. The bearing support 262 has at least one radial passageway 266 extending therethrough. The detonating cord 16 extends through the central axis of the bearing support 262. An alignment tube 268 surrounds the detonating cord 16.

Upon detonation of the detonating cord 16, the alignment tube 268 creates shrapnel that passes through the one or more radial passageways 266 in the bearing support 262 and impinges the inner bearing surface of the eccentric weight 260. By knowing the orientation of the one or more radial passageways 266 with respect to the orientation of the shaped charges, the orientation of the perforations may be determined by inspection of the eccentric weight 260.

In an alternative arrangement of that illustrated in Figure 42, the detonation cause the bearing support 262 to swell lock the relative position of the eccentric weight 260 and the bearing support 262. One example arrangement using the swell lock method is shown in Figure 43. In this arrangement, the eccentric weight 260 has one or more radial passageways 270 that are aligned with the one or more radial passageways 266 of the bearing support 262.

When the guns are fired in the correct orientation and the weight 260 is locked to the bearing support 262, the one or more radial passageways 266, 270 are aligned. The orientation may be verified by simply inserting a pin into the aligned passageways 266, 270 or by other inspection of the passageways 266, 270.

It should be noted that the confirmation devices 200 can be used at both ends of a fixed string of guns. In this manner, the orientation at both ends of the gun string can be confirmed. It should be further noted that the above versions of the confirming device 200 are illustrative only, and can be varied. As one example, the hardened spear 221 of Figure 39 can be used to pierce through a cylindrical sleeve thereby locking the sleeve to the external housing 216 and fixing their respective positions.

Claims (5)

1. A method of orienting a perforating gun in a deviated wellbore, the method comprising: providing an articulated weight spacer within the perforating gun, the spacer comprising: a plurality of eccentrically weighted segments engaged such that the individual segments are adapted to bend without becoming disengaged from the surrounding segments.

2. A method as claimed in claim l, wherein the spacer comprises an elongate generally semi-circular-section member having a plurality of jigsaw-puzzle-like cuts which are spaced along its length to create said segments and which permit adjacent segments to bend with respect to each other.

3. A method as claimed in claim 2, wherein each segment contains a respective generally semi-circular-section weight.

4. A method as claimed in claim2 or claim 3, wherein each segment of the semi-circular section member is provided with a respective cover.

5. A method as claimed in claim 4, wherein each cover includes one or more bendable tabs each having a respective opening for receiving a detonating cord.