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Publication numberUS3865199 A
Publication typeGrant
Publication dateFeb 11, 1975
Filing dateMar 25, 1974
Priority dateMar 25, 1974
Publication numberUS 3865199 A, US 3865199A, US-A-3865199, US3865199 A, US3865199A
InventorsDermott Raymond W
Original AssigneeSchlumberger Technology Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for perforating sub-sea well bores
US 3865199 A
Abstract
In the representative embodiment of the present invention disclosed herein, a new and improved perforating gun includes a plurality of relatively-short metal strips respectively carrying one or more encapsulated shaped explosive charges and which are tandemly intercoupled by unique couplings cooperatively arranged so that the strips can pivot freely about two perpendicular transverse axes but with little or no rotation or twisting of the strips about the longitudinal axis of the gun assembly. In this manner, the gun assembly can be readily dispatched through multicurved flow lines to selected remotely-situated sub-sea well bores and halted in a predetermined position with assurance that the several shaped charges will be oriented in a predetermined angular direction. The gun assembly may also include one or more tandemly-coupled tubular members which are connected between the gun positioner and the uppermost strip as required for locating the shaped charges at a predetermined distance below the positioner. These tubular members are cooperatively arranged for temporarily bending as the gun assembly is dispatched to a sub-sea well bore while still retaining the strips in a selected angular orientation relative to the gun positioner.
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Description  (OCR text may contain errors)

United States Patent 91 Dermott [451 Feb. 11, 1975 APPARATUS FOR PERFORATING SUB-SEA [73] Assignee: Schlumberger Technology Corporation, New York. N.Y.

221 Filed: Mar. 25, 1974 211 Appl. No.: 454,495

[52] U.S. Cl 175/451, 175/453, 403/162 [51] Int. Cl. E211) 43/117 [58] Field of Search l75/4.5l, 4.53, 4.6; 166/551; 403/161, 162, 111; 102/20; 89/] [56] References Cited UNITED STATES PATENTS 2,540,319 2/1951 Bitzer 403/161 2,799,224 7/1957 Long 175/46 X 2,960,930 ll/l960 Bell 175/453 3,100,443 8/1963 Pohoriles i 175/453 X 3,177,808 4/1965 Owen 102/20 3,282,213 ll/l966 Bell et al l75/4.6 X 3,465,836 9/1969 Fields 175/4.5l

FOREIGN PATENTS OR APPLICATIONS 143,322 4/1961 U.S.S.R 175/453 Primary Examiner-David H. Brown Attorney, Agent, or Firm-Ernest R. Archambeau, Jr.;

William R. Sherman; Stewart F. Moore [57] ABSTRACT In the representative embodiment of the present invention disclosed herein, a new and improved perforating gun includes a plurality of relatively-short metal strips respectively carrying one or more encapsulated shaped explosive charges and which are tandemly intercoupled by unique couplings cooperatively arranged so that the strips can pivot freely about two perpendicular transverse axes but with little or no rotation or twisting of the strips about the longitudinal axis of the gun assembly. In this manner, the gun assembly can be readily dispatched through multicurved flow lines to selected remotely-situated sub-sea well bores and halted in a predetermined position with assurance that the several shaped charges will be oriented in a predetermined angular direction. The gun assembly may also include one or more tandemlycoupled tubular members which are connected between the gun positioner and the uppermost strip as required for locating the shaped charges at a predetermined distance below the positioner. These tubular members are cooperatively arranged for temporarily bending as the gun assembly is dispatched to a sub-sea well bore while still retaining the strips in a selected angular orientation relative to the gun positioner.

19 Claims, 5 Drawing Figures APPARATUS FOR PERFORATING SUB-SEA WELL BORES Many proposals have, of course, been advanced heretofore for producing oil and gas from sub-sea wells. Typically, a number of these sub-sea wells are drilled at spaced intervals about a central surface platform to minimize drilling costs as well as to later simplify the collection of oil or gas from the wells. To facilitate the performance of various completion operations, generally-horizontal production lines are usually laid along the ocean floor from this central platform and respectively terminated in a large-radius reverse bend or nearly circular upright loop of tubing arranged on each wellhead for providing access to the usually-vertical production string in the well bore. As described more completely in U.S. Pat. No. 3,419,694, U.S. Pat. No. 3,465,836 and U.S. Pat. No. 3,490,280, so-called through-the-flowline or TFL pump-down equipment is preferably employed for conducting the various servicing and completion operations which are ordinarily done with cable-suspended tools where the wellheads are directly accessible from above.

Production systems such as discussed above have geen generally satisfactory where the sub-sea wells are grouped reasonably close to their associated production platform. It will be appreciated, however, that a production system for a large number of widelydispersed sub-sea wells requires either many small surface platforms at scattered locations around the subsea field or only one or two large platforms with a large number of very long production lines. In either case, there are obviously many economical and ecological disadvantages.

Accordingly, as described in detail in the December, 1970, issue of World Oil, it has recently been proposed to instead conveniently locate a self-contained underwater production unit near each of several groups of closely-spaced wellheads in a given sub-sea field and use a minimum number of common gathering lines for connecting each of these self-contained units either to a single surface platform or to a suitable nearby gathering station on land. It will, therefore, be recognized that this arrangement will eliminate the necessity of running large numbers of individual production lines between each well and their central gathering points. The many advantages of production systems such as this are, of course, readily apparent to those skilled in the art.

As best illustrated on pages 47 and 48 of the aforementioned World Oil article, these self-contained production units include complex piping and valve manifolds with many closely-spaced bends or elbows which are so compactly distributed that any given production line makes many changes in both direction and elevation over a relatively-short distance. Thus, it will be recognized that when a particular TFL tool is dispatched from the central gathering location into a given sub-sea well, the tool will experience many changes in direction; and most of these directional changes will be made in relatively limited spans of travel which may well be substantially less than the overall length of that tool. This, therefore, makes it essential for any TFL completion or servicing tool that is used with these new sub-sea production systems to be fully flexible or highly articulated throughout its entire length so as to readily negotiate these many turns.

Those skilled in the art will appreciate, of course, that most completion and servicing tools can be generally arranged for providing sufficient flexibility or articulation to enable that tool to be successfully used in a underwater production system with the aforementioned self-contained production units. Techniques such as those shown in U.S. Pat. No. 3,490,280 will, therefore, be suitable in most situations. It will be realized, however, that most servicing and completion tools are capable of operating independently of their angular orientation in a production string.

Several particular difficult problems are presented, however, in providing reliable TFL tools for perforating sub-sea wells which are served by these selfcontained production units. First of all, it will be recognized that any perforating tool which is to be used in these production systems will necessarily employ a number of tandemly-disposed shaped explosive charges which are respectively enclosed in individual pressuretight capsules. As previously discussed, these shaped charges must be movably or loosely intercoupled in such a manner that even an exceptionally-long assembly of these encapsulated charges can safely negotiate the many turns and restrictions in the production unit and the flowlines extending between the production unit to a given sub-sea wellhead and the central gathering point. It is, of course, essential that these charge capsules be firmly secured in such a manner that they will not be dislodged from the perforating assembly as the tool is moved through the various turns and obstructions it will encounter.

A simple, completely-flexible interconnection between the several charge capsules in a given perforating tool will, however, not always be wholly satisfactory. In particular, there are many sub-sea wells with two or more formation intervals that are individually completed and separately connected to different production strings. Since such sub-sea wells commonly employ a so-called multiple completion technique, this results in a first shorter production string being terminated in the highest productive interval and at least a second longer production string being extended through this first interval to a second lower productive interval. As a result, it is, of course, essential that perforation of this highest productive interval is safely accomplished without damaging or piercing the longer production string. U.S. Pat. No. 3,338,317 shows how such multiple-completion wells are typically arranged; and, from that patent, it can be recognized how critical it is to accurately orient a perforating gun in these wells. A similar problem will also exist even where only one production string is employed in a sub-sea well since the usual practice is to have a parallel string of tubing which is used to reverse tools out of the production string. This, of course, means that perforation of the production string must also be done without hitting the parallel string.

Accordingly, it will be recognized that one ofthe most reliable techniques for perforating such multiplecompletion wells is to arrange the perforating tool and the lower end of each production string as generally shown in U.S. Pat. No. 3,465,836. As fully described in that patent, a landing nipple coupled into the lower portion of the pipe string is provided with a prepositioned indexing groove which is adapted to receive a complementary locating lug arranged on the perforating tool for positively orienting its several shaped charges away from any adjacent tubing strings. The same or a similar arrangement would, of course, be used where there is only a single production string and a parallel return-flow string.

TFL perforating tools such as these have heretofore used various types of carriers or connectors for intercoupling the shaped charges. For example, spaced-wire carriers such as shown in U.S. Pat. No. 3,282,21 3 have been successfully used in the older sub-sea production systems. Similarly, various arrangements of interlinked capsules as shown in U.S. Pat. No. 2,799,224 or U.S. Pat. No. 3,100,443 are also entirely suitable for TFL perforating operations in these earlier types of sub-sea production systems.

It must be recognized, however, that all of these previous arrangements for intercoupling shaped charges so as to allow limited bending of the overall carrier were designed specifically for those earlier sub-sea completion systems which had production lines with only a single large-diameter loop at the wellhead and perhaps a few widely-dispersed gradual bends lying flat along the sea floor. In particular, since these previous sub-sea completion systems were deliberately installed so as to avoid any sharp turns, it was sufficient, and even preferred, that a TFL perforating carrier was capable of flexing in only one bending plane or plane of movement at any one time. Arrangements such as this were, moreover, specifically designed so as to greatly minimize, if not totally eliminate, the capability of these prior-art carriers to either bend in another plane of movement of twist about their longitudinal axis so as to be certain that the charges would always remain in their predetermined orientations.

It will be recognized, however, that since these recently-proposed self-contained production units have so many closely-spaced sharp bends and changes of both direction and elevation in short distances, none of the perforating tools described in the aforementioned patents are at all capable of safely negotiating these turns. In fact, as far as is now known, only the somewhat-elaborate carrier shown in U.S. Pat. No. 3,! 77,808 could possibly be capable of safe operation in production systems using these new self-contained sub-sea production units.

Accordingly, it is an object of the present invention toprovide TFL perforating apparatus of a straightforward and inexpensive design which is capable of safely negotiating many closely-spaced changes in direction and elevation in a sub-sea production piping system such as that shown in the aforementioned World Oil article.

This and other objects of the present invention are accomplished by arranging new and improved TFL perforating apparatus to include a plurality of relatively-short charge-supporting members which are tandemly intercoupled respectively by upright linking pins loosely disposed in a socket for joining the ends of adjacent charge-supporting members to enable these members to pivot freely about the pins in a first plane of movement as well as to turn freely in a second plane of movement which is generally perpendicular to the first movement plane. Significant twisting of the chargesupporting members about the overall longitudinal axis of the entire assembly is, however, prevented by uniquely arranging the adjacent interengaged surfaces of the adjoining ends to accommodate turning in the first and second planes of movement but to resist twisting about this axis as well by providing biasing means to maintain these adjacent surfaces coengaged.

The novel features of the present invention are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may be best understood by way of the following description of exemplary apparatus employing the principles of the invention as illustrated in the accompanying drawings, in which:

FIG. 1 shows a preferred embodiment of new and improved perforating apparatus arranged in accordance with the principles of the present invention positioned in a schematically-represented sub-sea well bore of a typical design;

FIGS. 2 and 3 are enlarged views of a portion of the perforating apparatus shown in FIG. 1 for illustrating the details of a new and improved strip-intercoupling arrangement which facilitates the passage of the perforating apparatus through the production conduits extending between the depicted sub-sea well bore and a distant location at the surface;

FIG. 4 is a cross-sectional view taken along the lines 4-4 in FIG. 2; and

FIG. 5 depicts a preferred embodiment of another portion of the new and improved perforating apparatus of the present invention.

Turning now to FIG. 1, a preferred embodiment of new and improved perforating apparatus 10 arranged in accordance with the principles of the present invention is illustrated as it will appear within a production system 11 which is coupled to a typical sub-sea well bore 12 penetrating one or more productive earth for mations, as at 13. As is common, a typical casing string 14 which is cemented, as at 15, in place and extended to a considerable depth in the well bore 12 is supported by a suitable wellhead 16 mounted on the floor 17 of the sea or whatever body of water is situated thereabove. The production system 17 includes a number of flowlines, as at 18 and 19, which are coupled to valves 20 and 21 on the wellhead 16 and laid along the sea floor 17 to a distant underwater production unit (not shown) such as described in the aforementioned World Oil article. In the example illustrated, two or more strings of piping, as at 22 and 23, have been suspended side-by-side in the well bore 12 and extended to a short distance below the lower limit of the formation 13. Depending upon the particular operating requirements for that particular well, it will, of course, be appreciated that packers (not shown) may also be coupled into the pipe or tubing strings 22 and 23 for isolating the formation 13 from other intervals in the well bore 12 above the formation. Similarly, other pipe strings (not shown) may also be arranged in the well bore 12 as required for obtaining production fluids from other formations penetrated by the well bore.

In any event, in the representative arrangement of the production system 11 illustrated in FIG. 1, the tubing string 22 was installed in the well bore 12 to serve as the production string and the tubing string 23 was installed to provide a reverse-flow string. As described in the aforementioned World Oil article, when the well bore 12 was being completed for production, a suitable locating or landing nipple 24 of a suitable design was coupled in the production string 22 and positioned at a predetermined distance above the formation 13 to provide a stop for subsequently halting well completion or servicing tools, such as the new and improved perforating apparatus 10, at a known position and in a selected angular orientation in the production string. An interconnecting line, as at 25, was also arranged between the closed lower ends of the pipe strings 22 and 23 so that these tools, such as the perforating apparatus 10, can be selectively returned to the surface by simply flowing fluids into the reverse-flow string, through the interconnecting line, and back to the surface by way of the production string.

it will, of course, be recognized by those skilled in the art that FIG. 1 simply illustrates one of several possible commonly-used production string arrangements being used or currently under consideration by the industry for such sub-sea wells. Thus, the well bore 12 could just as well have been arranged as a multiple-completion well as shown generally in U.S. Pat. No. 3,338,317 so that one production string and its reverse-flow line are terminated at a packer set somewhat above the upper limit of a given formation (as is shown in U.S. Pat. No. 3,419,694) and another production string and its reverse-flow line are extended on beyond that formation to a second packer set above a deeper formation interval. in that situation, standard landing nipples, such as the one at 24, would be appropriately arranged in each production string to allow the lower portions of completion tools, such as the new and improved perforating apparatus 10, to hang below the open end of that string. In either well bore arrangement, it would, of course, be equally essential that the perforating apparatus comes to rest in a specified angular orientation so as to clearly avoid damaging either the adjacent reverse-flow line or the adjacent longer string of production tubing. Since the design of the new and improved perforating apparatus 10 is, however, equally suited for any arrangement of pipe strings in the well bore 12, the specific details of these various arrangements are of no consequence for understanding the principles of the present invention.

As illustrated in FIG. 1, the preferred embodiment of the new and improved perforating apparatus 10 is comprised of a number of tandemly-intercoupled tool units including flow or pressure-responsive tool-transporting or tool-propelling means 26, selectively-operable gunactuating means 27, tool or gun-positioning means 28 and a dependently-suspended perforating gun 29. in the depicted embodiment of the perforating apparatus 10, the tool-propelling means 26 preferably include a short body 30 around which is mounted one or two sealing members or opposed swab cups, as at 31. These sealing members 31 are, of course, suitably sized for providing a bidirectionally-sealing, but slidable, fit with the internal walls of the various pipes, as at 18 and 22, in the production system 11 and on the sub-sea production unit (not shown) that the perforating apparatus 10 must pass through as it is controllably moved into and out of the well bore 12 in response to the selective application of an increased pressure or fluid flow to the surface ends of those conduits connected by way of the production unit to the pipe strings 22 and 23. Suitable locomotion units. as at 26, are of course, well known by those skilled in the art and, therefore, need no further description.

The new and improved perforating apparatus 10 further includes the gun-actuating means 27 which are basically comprised of one or two short pressure-tight housings, as at 32 and 33, tandemly coupled to one another by suitable articulated or flexible joints 34, such as that shown in U.S. Pat. No. 3,216,751, positioned between the locomotion unit 26 and the housing 35 of the gun-positioning means 28. The housings 32 and 33 are arranged for carrying a self-contained power supply, such as a group of batteries (not shown), and one or more control devices (not shown) for selectively actuating detonating means, such as an electricallyresponsive detonator 36 on the lower end of a detonating cord 37 carried on the perforating gun 29, whenever the perforating apparatus 10 has been landed and is safely positioned in the landing nipple 24.

Although it will be recognized that the gun-actuating means 27 can employ any number of various control devices such as those described in U.S. Pat. No. 3,465,836, for example, a preferred arrangement of the control system for the perforating apparatus 10 includes a position-responsive switch (as at 21 in that patent) which is best arranged on the housing 35 of the gun-positioning means 28 for establishing an electrical circuit only when the gun-positioning housing is correctly seated in the landing nipple 24. As an added safety precaution, it is also preferred that the electrical control system for the perforating apparatus 10 further include a pressure-responsive switch (as at 22 in U.S. Pat. No. 3,465,836) which can be arranged on any one of the housings 32, 33 or 35 for completing an electrical detonating circuit only when the pressure in the production string 22 is selectively increased to at least,

a predetermined pressure level.

Accordingly, as fully explained in U.S. Pat. No. 3,465,836, by electrically connecting the positionresponsive switch and the pressure-responsive switch (as respectively shown at 21 and 22" in that patent) in series relationship with the detonator 36 and the power supply in the control housings 32 and 33, it can be reliably assumed that this detonating circuit for the perforating apparatus 10 will be actuated only when the tool is correctly seated in the landing nipple 24 and the pressure in the production string 22 has been deliberately raised to a predetermined level such as by selectively operating a pump (not shown) at the surface which is in communication with the production string. Alternatively, the pressure-responsive switch could be arranged to close when the perforating apparatus 10 is at a safe depth in the well bore 12 (i.e., by the known hydrostatic pressure at that depth) so that the perforating gun 29 will be actuated when the positionresponsive switch later closes. Other common techniques, such as a time-actuated switch, can, of course, just as well be used for the detonating circuit so long as some fool-proof arrangement is provided to positively avoid premature actuation of the perforating apparatus 10 before it is unquestionably seated and correctly oriented in the landing nipple 24.

The principal function of the gun-positioning means 28 is, of course, accomplished by cooperatively arranging the housing 35 (and the landing nipple 24) so that this housing will always come to rest in a predetermined angular position in the landing nipple upon movement of the gun-positioning means into the landing nipple. Arrangements such as shown in U.S. Pat. No. 3,465,836, for example, will, of course, be appropriate for achieving the objects of the present invention. Since the particular details of the gun-positioning means 28 are not important for fully understanding the present invention, it is, of course, necessary only to emphasize the necessity of the housing 35 always being seated in a predetermined angular position or orientation with respect to the landing nipple 24 whenever the perforating apparatus has come to rest on the landing nipple. Once this is accomplished, the housing 35 will assuredly be oriented in a predetermined relationship with the reverse flow line 23.

It will, of course, be appreciated from the preceding discussion that the perforating gun 29 must be capable of simultaneously passing through two or more shortradius bends which are relatively close to one another and lie in perpendicularly-intersecting planes. Accordingly, in the preferred manner of attaining the objects of the present invention, the new and improved perforating gun 29 is cooperatively arranged as best seen in FIGS. 1 and 2 to include a number of short chargesupporting members, as at 38 and 39, of a rigid explosion-resistant material and which are tandemly intercoupled to one another by biaxially-pivotal coupling means, as at 40, for respectively interconnecting the adjoining ends of the several charge-supporting members. For reasons which will subsequently be explained,

' it is preferred to form the charge-supporting members,

as 38 and 39, of flat strips of steel having sufficient thickness to reasonably resist significant twisting or torsion about their longitudinal axes. It will, of course, be recognized that the lengths of the charge-supporting strips, as at 38 and 39, will be dependent upon the smallest radius of curvature that the perforating apparatus 10 will be expected to encounter. Similarly, it will also be recognized that the total number of perforations which are to be produced during a given perforating operation will determine the overall number of charge-supporting strips, as at 38 and 39, that the perforating gun 29 must include.

Each of the charge-supporting strips, as at 38 and 39, is cooperatively arranged for carrying one or more encapsulated shaped explosive charges, as at 41 and 42, which are securely mounted on the strips to be certain that they do not become loosened or detached as the perforating apparatus 10 is moved from the surface through the sub-sea production system 1 1 and into the proper position in the production string 22 as illustrated in FIG. 1. Since there are, of course, many types of shaped charges (such as those shown in US. Pat. No. 3,094,930 and U.S. Pat. No. 3,268,016) which can be used here, it is unnecessary to elaborate further on the details of the charges 41 and 42 except to say that most, if not all, encapsulated shaped charges which are typically employed with prior-art strip carriers will be suitable for the perforating gun 29. Similarly, although the detonating cord 37 can be arranged in several different ways on the perforating gun 29, it has been found particularly advantageous to secure the cord to the gun, as by clips 43 and 44, located conveniently between each of the charges, as at 41 and 42, and as well as on each of the coupling means 40 assuring that the cord will positively remain in detonating proximity of each of the several shaped charges.

Turning now to FIGS. 2-4, different views are shown of the adjoining end portions of the charge-supporting strips 38 and 39 and a preferred embodiment of the hiaxially-pivotal coupling means 40. As illustrated there, the new and improved coupling means 40 include the tongue-like terminal end portions 45 and 46 of the strips 38 and 39, which are respectively offset, as at 47 and 48, in relation to the major portions of the strips. In this manner, the mating end surfaces of the end portions 45 and 46 will each lie in a common transverse plane located at least substantially midway between the forward and rearward surfaces of the strips 38 and 39. It will be appreciated, moreover, that this unique arrangement will be effective for respectively longitudinally aligning the forward and rearward surfaces of each of the several strips, as at 38 and 39, as well as the shaped charges, as at 41 and 42, employed in the perforating gun 29. This will, therefore, allow the largest-possible size of shaped charges, as at 41 and 42, to be used for perforating a given production string, as at 22, without having to needlessly make a clearance allowance just for the added dimension (i.e., the thickness of one strip) which otherwise would be required where the end portions 45 and 46 of the strips 38 and 39 instead simply overlapped without the offsets, as at 47 and 48.

The new and improved coupling means 40 further include a single pivot, such as a typical machine bolt 49 and nut 50, that is passed through enlarged circular holes 51 and 52 respectively formed in the center and near the end of each of the strip end portions, as at 45 and 46. Particular attention should be given, first of all, to the substantial diametrical enlargement of the holes 51 and 52 in relation to the diameter of the bolt 49. Moreover, it should also be particularly noted that instead of snugly clamping the opposed inner surfaces of the end portions 45 and 46 between the head of the bolt 49 and the nut 50, these coengaged surfaces are instead yieldably held together by biasing means such as a spring or an enlarged and fairlythick elastomeric grommet 53 which is cooperatively interposed between a washer 54 under one end of the bolt and the adjacent outer surface of one of the end portions.

As represented by the arrows 55 in FIG. 2, the coupling means 40 will, of course, allow the strips 38 and 39 to. pivot relative to one another about the central axis of the pivot bolt 49 in a first plane of movement. By rounding or cutting off the corners of the end portions 45 and 46, as at 56 and 57, it will be appreciated that the strips 38 and 39 can turn freely through a substantial arc of rotation. The plane of this first pivotal movement is, of course, perpendicular to the axis of the bolt 49 and parallel to the transverse planes defined by the opposed co-engaged surfaces of the end portions 45 and 46.

The coupling means 40 are, however, cooperatively arranged for also allowing the strips 38 and 39 to turn freely in a second plane of rotational movement which is substantially perpendicular to the above-described first plane of rotational movement. To achieve this further object of the present invention, it will be noted in FIG. 3 that the extreme ends or tips of the end portions 45 and 46 are preferably curved slightly outwardly, as at 58 and 59, away from the opposed mating surfaces of the end portions. Thus, in view of the relative en largement of the bolt holes 51 and 52 with respect to the diameter of the bolt 49 as well as the resilience of the grommet 43, it will be recognized that, as shown by the arrows 60, the strips 38 and 39 are capable of rolling or turning in a second plane of rotational movement which is substantially perpendicular to the first plane. It will, of course, be appreciated that the detonating cord 37 is sufficiently flexible that it will not unduly interfer with these biaxial turning movements of the strips 38 and 39.

As previously mentioned, it is essential that the several shaped charges, as at 41 and 42, be positively retained in a position where they are all facing in the same lateral direction once the perforating apparatus 10 has been seated in the landing nipple 24. In other words, the several strips, as at 38 and 39, making up the gun 29 must be respectively prevented from twisting or turning about their longitudinal axes. Since they are relatively short, the strips 38 and 39 themselves will be of sufficient stiffness that they will twist little if any. Thus, for any serious twisting of the gun 29 to take place, it would have to occur at the junctions of the several charge-supporting strips, as at 38 and 39, making up the gun 29.

The new and improved coupling means 40 are, however, cooperatively arranged to at least limit, if not prevent, any undue twisting of the several strips 38 and 39 about the overall longitudinal axis of the gun 29. To achieve this, it will be appreciated from FIG. 4 that torsional turning of the end portion 45 in relation to the other end portion 46 would, for example, require one longitudinal edge, as at 61, to serve as the fulcrum as the opposite longitudinal edge, as at 62, is lifted up from its normal co-engaged position against the other end portion. This unwanted twisting movement, however, prevented by the biasing action of the grommet 53. It must also be realized that the biasing action provided by the grommet 53 is particularly effective for preventing this unwanted turning by virtue of the major transverse distance (as at 63 in FIG. 4) between the edge 61 and the bolt 49. Conversely, however, due to the closeness of the bolt 49 to the rounded ends 58 and 59 of the end portions 45 and 46 (as shown by the minor dimension 64 in FIG. 2), the biasing action of the grommet 53, at best, imposes only a minimum restraint against turning of the strips 38 and 39 in their second plane of rotational movement.

Referring again to FIG. 1, it will be recognized that in most situations, the formation to be perforated, as at 13, will be at a substantial distance below the landing nipple 24. Thus, some suitable arrangement must be made to couple the several strips, as at 38 and 39, to the gun-positioning housing 35 so as to correctly position the several shaped charges 41 and 42 in relation to the pipe string 23. For apparent reasons, therefore, it will be realized that the perforating gun 29 must be cooperatively arranged so that the strips 38 and 39 are reliably held in a predetermined angular alignment with the gun-positioning means 28.

Accordingly, in the preferred embodiment of the new and improved perforating apparatus 10, the uppermost one of the charge-supporting strips, as at 38, is coupled to the gun-positioning housing 35 by means of an appropriate number of elongated extension members, such as small-diameter tubular mandrels 65 and 66, which are tandemly intercoupled by suitable couplings, as at 67. As best seen in FIG. 5, each of the tubular mandrels, as at 65 and 66, is comprised of a selected length of small-diameter thin-wall tubing. In one arrangement of the new and improved perforating apparatus 10, it was found particularly advantageous to employ commercially-available stainless steel tubing of a sufficiently-high yield strength to prevent permanent deformation in service and having an outside diameter of 7/l6-inch and a wall thickness of 0.120-inch. Although these dimensions obviously represent only a typical situation and are not to be considered as limiting the scope of the present invention, it will, of course, be appreciated that lengths of tubing of this nature will be readily capable of momentarily flexing easily as the perforating apparatus 10 is dispatched through the production system 11.

Of particular importance to the success of the present invention, it should also be noted that the use of a number of relatively-short mandrels, as at 65 and 66, will allow the perforating apparatus 10 to be progressively assembled (or disassembled) at the surface and successively moved into (or out of) the surface end of a production line that is under pressure. Techniques for progressively introducing and removing extralong well tools into and out of pressured well bores are, of course, well known in the art and need not, therefore, be discussed further.

As illustrated in FIG. 5, each of the couplings 67 is comprised of a set of complementally-matched male and female tubular connector bodies 68 and 69 which are respectively mounted on the adjacent ends of the mandrels 65 and 66 and adapted to be telescopically fitted together. It will, of course, be appreciated that each mandrel, as at 66, will have a female connector body, as at 69, on one end and a male connector body, as at 68, on the other end of the mandrel to facilitate the interchangeable intercoupling of any number of the mandrels into an assembly of a selected overall length. Since it is essential that the several mandrels, as at 65 and 66, remain in a predetermined angular alignment with one another, the connector bodies 68 and 69 are respectively secured on the ends of the mandrels as by threads 70 and 71 and set screws 72 and 73 and cooperatively aligned as by a lateral key 74 on one body complementally fitted into a longitudinal slot 75 on the other body.

Since the key 74 and the slot 75 prevent relative rotation between the bodies 68 and 69, it is preferred to counterbore and internally thread the mouth of the female connector body ahead of the key for threadedly receiving an externally-threaded coupling sleeve 76 which is loosely mounted coaxially around the male connector body and positioned by a stop ring 77 to the rear of the key slot. Thus, once the nose of the male body 68 is inserted into the rear of the counterbore 78 in the female body 69, rotation of the threaded coupling sleeve 76 will serve to draw the connector bodies longitudinally together until an externally-enlarged shoulder 79 on the threaded sleeve is firmly clamped between an enlarged shoulder 80 on the male connector body and the end of the female connector body.

Since there must be an electrical connection between the gun-actuating means 27 and the detonator 36, it is preferred to also employ the tubular mandrels, as at 65 and 66, as conduits for carrying serial sections of a single wire, as at 81 and 82, leading to the perforating gun 29. The body of the gun 29 will, of course, serve as an electrical return. Accordingly, the adjacent ends of the wire sections 81 and 82 are connected to a set of typical male and female electrical connectors, as at 83 and 84, which are respectively arranged in the mandrel connector bodies 68 and 69. Since it is preferred to at least minimize shifting of the electrical connectors 83 and 84, tubular sockets, as at 85 and 86, are coaxially arranged within each end of the mandrel connector bodies 68 and 69 and complementally shaped for respectively supporting at least the rear portions of the electrical connectors. As a further precaution, the electrical wires 81 and 82 may also be retained in place by providing insulating sleeves, as at 87 and 88, which are positioned so as to be respectively clamped by the set screws 72 and 73. It will, of course, be recognized that by virtue of the sockets 85 and 86, the electrical connectors 83 and 84 will be retained in an aligned position so as to be simultaneously coupled as the mandrel connector bodies 68 and 69 are drawn together by rotation of the coupling sleeve 76.

It will be recognized, therefore, that the asssembly of the perforating apparatus can be readily accomplished on a sequential basis. Thus, for example, a selected number of the charge-supporting strips, as at 38 and 39, with shaped charges, as at 41 and 42, arranged thereon can be inserted into the surface end of a selected conduit in the production system 11 and progressively moved into the conduit as a selected number of the extension mandrels,, as at 65 and 66, are added to continue the progressive assembly of the perforating apparatus 10. Once the uppermost one of the extension mandrels, as at 65, is coupled to the next-highest mandrel, as at 66, the upper end of the uppermost mandrel is secured to the lower end of the housing 35 so as to position the mandrels in a selected angular orientation in relation to that housing. Since it is, of course, known that the charge-supporting strips, as at 38 and 39, are secured in a known orientation relative to each of the mandrels 65 and 66, it will be similarly assured that the shaped charges, as at 41 and 42, will be in a known angular relationship to the gunpositioning housing 35. The remainder of the perforating apparatus 10 is assembled and then moved into the production system 11 for being selectively dispatched into the sub-sea well bore 12.

As the assembled perforating apparatus 10 traverses a first bend (not shown) in the production system 11 which requires articulation of any two adjacent chargesupporting strips, as at 38 and 39, in the aforementioned first plane of rotational movement (shown in FIG. 2), there will, of course, be little, if any, restraint of the relative movements of the strips in the directions shown by the arrows 55. lt will be recognized that the bolt 49 will simply serve as a pivot in this situation. On the other hand, assume that the perforating apparatus 10 is navigating a second bend (not shown) in the production system 11 which lies at right angles to the aforementioned first bend. As adjacent chargesupporting strips, as at 38 and 39, are moved through this second bend, they will have to move relative to one another in the aforementioned second plane of rotational movement (as represented by the arrows 60 in FIG. 3). This relative movement is, of course, accomplished by virtue of the large annular clearance space between the bolt 49 and the sides of the holes 51 and 52 in the strip end portions 45 and 46, respectively, and the relatively-short longitudinal spacing between the rounded noses 58 and 59 of the end portions and the edges of the holes.

As mentioned previously, turning in this second plane of movement is facilitated since the grommet 53 will yield as necessary to allow the extreme end or transverse edge of the rounded nose, as at 58, of one strip end portion 45 to roll in relation to the other end portion 46 as the strips 38 and 39 turn out of coincidental alignment with one another as necessary to navigate a bend in the production system 11. It will, however, be recognized that the relatively-wide widths of the strips,

as at 38 and 39, will preclude twisting or turning of one strip in relation to the other about their longitudinal axes. As previously discussed, therefore, it will be well assured that one strip, as at 38, cannot twist relative to the other strip 39.

Moreover, the grommet 53 will cooperate to resiliently bias the opposed surfaces of the end portions 45 and 46 together. Thus, it will be known as a certainty that once the perforating apparatus 10 is seated in the landing nipple 24 and has been properly oriented by the cooperation of the gun-positioning means 28 therewith, all of the several charge-supporting strips, as at 35 and 36, will be longitudinally aligned in a predetermined common elongated plane as detined by the faces of the strips. This will, of course, mean that the several shaped charges, as at 41 and 42, will be selectively directed so as to avoid damaging the adjacent piping string 23 upon actuation of the detonator 36.

As the perforating apparatus 10 moves through the production system 11, it will, of course, be recognized that the several extension members, as at 65 and 66, of the perforating gun 29 will also have to bend as necessary to navigate the several bends in the system. However, as previously mentioned, the several smalldiameter extension mandrels 65 and 66 are all of sufficient resilience that they can momentarily flex as necessary and then return to their original straight configuration after passing a bend in the production system 11. Since the extension members 65 and 66 are all keyed together, it will, of course, be assured that the perforating gun 29 will have remained in its initial predetermined angular orientation in relation to the gunpositioning housing 35 once the housing is seated in the landing nipple 24.

Accordingly, it will be appreciated that the present invention has provided new and improved perforating apparatus 10 which is specially arranged for operation in remote sub-sea wells that are communicated to the surface by means of many short-radius bends which are closely spaced from one another. By virtue of the unique coupling means employed with the perforating apparatus of the present invention, it will be known that the several shaped charges carried by the peforating apparatus will always be safely directed to avoid damaging an adjacent string of well piping once the perforating apparatus is seated in a correctlypositioned landing nipple in the pipe string carrying the perforating apparatus.

While only a particular embodiment of the present invention has 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. Perforating apparatus adapted for movement through multi-curved conduits between the surface and a selected position in a well bore and comprising:

a plurality of elongated members including at least two members thereof respectivelyarranged for carrying at least one shaped explosive charges and including similar tongue-like coengageable terminal portions on said two members with generallyplanar opposed surfaces bounded by the longitudinal edges thereof extending to their respective outermost ends and each having a hole located about midway between its said edges and longitudinally spaced from its said end by a predetermined distance which is less than the spacing between said hole and either of said edges;

a pivot member mounted in said holes for intercoupling said terminal portions of said two members and defining a first pivotal axis generally perpen dicular to said opposed surfaces, said pivot member being sized sufficiently smaller than said holes for allowing said end of either of said terminal portions to roll on the said opposed surface of the other of said terminal portions about a second pivotal axis extending generally at right angles to said first pivotal axis; and

biasing means mounted between said pivot member and one of said terminal portions for normally urging said opposed surfaces into slidable coengagement as said two members pivot about said first pivotal axis and cooperatively arranged for yielding to allow said opposed surfaces to diverge as said two members pivot about said second pivotal axis.

2. The perforating apparatus of claim 1 wherein said two members are generally-rectangular, substantiallyrigid strips respectively coupled to said terminal portions and having at least one opening therein adapted for receiving a shaped explosive charge.

3. The perforating apparatus of claim 1 wherein said two members are generally-rectangular, substantiallyrigid strips respectively having at least one opening therein adapted for receiving a shaped explosive charge, said terminal portions being the integral end portions of said strips.

4. The perforating apparatus of claim 1 wherein said two members are generally-rectangular metal strips respectively having at least one opening therein adapted for receiving a shaped explosive charge, others of said elongated members are substantially-flexible metal tubes, and further comprising:

coupling means cooperatively arranged for tandemly intercoupling said tubes to one of said strips as well as to one another and including first and second coengageable coupling members on the adjoining ends of each of said tubes, and means including a longitudinal slot on one of said coupling members and a lateral key on the other of said coupling members adapted for complementary reception in said slot for co-rotatively intercoupling said tubes into a predetermined angular alignment relative to one another and to said strips.

5. Perforating apparatus adapted for movement through multi-curved conduits between the surface and a selected position in a well bore and comprising:

a plurality of elongated metal strips, each of said strips respectively having at least one enlarged opening in an intermediate portion thereof for cooperatively supporting a shaped explosive charge and a reduced opening centrally located in at least one terminal portion thereof and longitudinally spaced away from its transverse end by a predetermined distance which is less than half of its lateral width; and

a plurality of biaxially-pivotal coupling means cooperatively arranged for tandemly intercoupling the overlapped terminal portions of each intercoupled set of said strips, each of said coupling means including a pivot member in said reduced openings for defining a first pivotal axis, said pivot member being sized sufficiently smaller than said reduced openings for allowing said transverse end of either of said overlapped terminal portions to roll on the opposing surface of the other of said overlapped terminal portions about a second pivotal axis extending generally at right angles to said first pivotal axis, and biasing means mounted between said pivot member and one of said overlapped terminal portions normally urging said opposing surfaces into slidable coengagement as said intercoupled strips pivot about said first pivotal axis and cooperatively arranged for yielding to allow said opposing surfaces to diverge as said intercoupled strips pivot about said second pivotal axis.

6. The perforating apparatus of claim 5 wherein said terminal portions are respectively offset in relation to said intermediate portions of said strips for locating said opposing surfaces in a plane substantially parallel to and between the planes respectively defined by the forward and rearward faces of said intermediate strip portions.

7. The perforating apparatus of claim 5 further including:

a plurality of substantially-flexible metal tubes; and

tube-coupling means cooperatively arranged for tandemly intercoupling said tubes to one of said strips and to one another and including first and second coengageable tube-coupling members on the adjoining ends of each of said tubes, and means including a longitudinal slot on one of said tubecoupling members and a lateral key on the other of said tube-coupling members adapted for reception in said slot for co-rotatively intercupling said tubes into a predetermined angular alignment relative to one another and to said strips.

8. The perforating apparatus of claim 5 wherein the outermost part of each of said terminal portions is curved outwardly from the plane respectively defined by said opposing surface of said terminal portion for providing a rolling surface adjacent to its said transverse end.

9. The perforating apparatus of claim 8 wherein each of said terminal portions is offset in relation to its adjacent intermediate portion so as to position its said opposing surface in a plane generally parallel to and between the planes respectively defined by the forward and rearward surfaces of said adjacent intermediate portion.

10. The perforating apparatus of claim 9 wherein said outermost part of each of said terminal portions also has its corners removed so as to reduce said transverse end to a dimension less than said lateral width.

11. Perforating apparatus adapted for movement through multi-curved conduits between the surface and a selected position in a well bore and comprising:

perforating means including a plurality of shaped explosive charges and detonating means cooperatively arranged for selectively detonating said shaped charges;

means for supporting said shaped charges for movement to a selected position in a well bore and including a plurality of elongated metal strips, each strip respectively having at least one enlarged opening in an intermediate portion thereof for cooperatively supporting one of said shaped charges and a reduced opening centrally located in at least one terminal portion of each of said strips and longitudinally spaced away from the transverse end thereof by a predetermined distance which is less than half of the lateral width of said terminal portion;

a plurality of biaxially-pivotal coupling means cooperatively arranged for tandemly intercoupling successive ones of said strips, each of said coupling means including a pivot member mounted through the reduced openings in the coengaged terminal portions of at least a first and second one of said strips for defining a first pivotal axis, said pivot member being sized sufficiently smaller than said reduced openings for allowing said transverse end of either of said coengaged terminal portions to roll on the opposing surface of the other of said coengaged terminal portions about a second pivotal axis extending generally at right angles to said first pivotal axis, and biasing means mounted between said pivot member and one of said coengaged terminal portions normally urging said opposing surfaces into slidable coengagement as said first and second strips pivot about said first pivotal axis and cooperatively arranged for yielding to allow said opposing surfaces to diverge as said first and second strips pivot about said second pivotal axis;

tool-propelling means adapted for movement through such conduits in response to selected pressure changes in such conduits; and

means tandemly intercoupling said tool-propelling means to said first and second strips.

12. The perforating apparatus of claim 11 wherein said coengaged terminal portions are respectively offset in relation to said intermediate portions of said first and second strips for locating said opposing surfaces in a plane parallel to and between the planes respectively defined by the forward and rearward faces of said intermediate portions of said first and second strips.

13. The perforating apparatus of claim 11 wherein said means tandemly intercoupling said tool-propelling means to said strips include:

a plurality of substantially-flexible metal tubes;

tube-coupling means cooperatively arranged for tandemly intercoupling said tubes to one of said strips and to one another and including first and second conengageable tube-coupling members on the adjoining ends of each of said tubes, and means including a longitudinal slot on one of said tubecoupling members and a lateral key on the other of said tube-coupling members adapted for reception in said slot for co-rotatively intercoupling said tubes into a predetermined angular alignment relative to one another and to said strips.

14. The perforating apparatus of claim 11 wherein the outermost part of each of said coengaged terminal portions is turned outwardly from the plane respectively defined by its said opposing surface for providing a rolling surface adjacent to its said transverse end.

15. The perforating apparatus of claim 14 wherein each of said coengaged terminal portions is offset in relation to its adjacent intermediate portion so as to position its said opposing surface in a plane lying parallel to and between the planes respectively defined by the forward and rearward surfaces of its adjacent intermediate portion.

16. The perforating apparatus of claim 15 wherein said outermost part of each of said terminal portions also has its corners removed so as to reduce said transverse end to a dimension less than said lateral width.

17. The perforating apparatus of claim 11 further including:

tooLpositioning means cooperatively arranged between said tool-propelling means and said strips for selectively orienting said strips into a predetermined angular position upon movement of said perforating apparatus to said selected well bore position.

18. The perforating apparatus of claim 17 further including:

means cooperatively coupled to said detonating means for selectively disarming said detonating means at least until said strips are in their said predetermined angular position.

19. The perforating apparatus of claim 18 wherein said means tandemly intercoupling said tool-propelling means to said strips include:

a plurality of substantially-flexible metal tubes;

tube-coupling means cooperatively arranged for tandemly intercoupling said tubes to one of said strips and to one another and including first and second coengageable tube-coupling members on the adjoining ends of each of said tubes, and means including a longitudinal slot on one of said tubecoupling members and a lateral key on the other of said tube-coupling members adapted for reception in said slot for co-rotatively securing said tubes in a predetermined angular alignment relative to one another and to said strips.

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4624308 *Apr 15, 1985Nov 25, 1986Halliburton CompanySour gas cable head
US4648444 *Apr 17, 1985Mar 10, 1987Halliburton CompanyTensile ring cable head assembly
US6095258 *Aug 28, 1998Aug 1, 2000Western Atlas International, Inc.Pressure actuated safety switch for oil well perforating
Classifications
U.S. Classification175/4.51, 403/162, 175/4.53
International ClassificationE21B43/119, E21B43/11, E21B43/117
Cooperative ClassificationE21B43/117, E21B43/119
European ClassificationE21B43/117, E21B43/119