Title:
Well bore perforating apparatus
United States Patent 3923106
Abstract:
In the representative embodiment of the present invention disclosed herein, new and improved selectively operated perforating apparatus is arranged to include two or more enclosed thin-walled tubular carriers carrying a corresponding number of sets of shaped explosive charges which are to be independently actuated for successively perforating a cased well bore at selected depth intervals. To effectively protect the charges in the yet-unfired carriers during the sequential operation of the perforating apparatus, the carriers are tandemly joined by a unique shock-isolating inter-carrier coupler cooperatively arranged for carrying interconnecting wires between the carriers as well as for at least substantially absorbing the longitudinally directed and laterally directed explosive shocks or impacts which are inherently developed by such sequential firing operations.


Inventors:
BOSSE-PLATIERE MICHEL J
Application Number:
05/529418
Publication Date:
12/02/1975
Filing Date:
12/04/1974
Assignee:
Schlumberger Technology Corporation (New York, NY)
Primary Class:
Other Classes:
166/55.1
International Classes:
E21B43/1185; E21B43/119; (IPC1-7): E21B43/11
Field of Search:
166/55,55.1 175
View Patent Images:
US Patent References:
3566510N/A1971-03-02Wendt
3441093JET PERFORATING GUN ARMING SWITCH AND CIRCUITRY1969-04-29Boop
3216751Flexible well tool coupling1965-11-09Der Mott
3190680Flexible coupling1965-06-22Maly
2620165Well drilling transmission power means1952-12-02Crickmer
2267085Knock eliminator1941-12-23Dezendorf
2146764Coupling1939-02-14Ricefield
1786720Current-collector support1930-12-30Moore et al.
Primary Examiner:
Brown, David H.
Attorney, Agent or Firm:
Archambeau Jr., Ernest Sherman William Moore Stewart R. R. F.
Claims:
What is claimed is

1. Perforating apparatus comprising:

2. The perforating apparatus of claim 1 wherein said coupler members are annularly shaped and further including:

3. The perforating apparatus of claim 1 wherein said rigid and yieldable coupler members are alternately disposed in a unitary stack along the longitudinal axis of said perforating guns.

4. The perforating apparatus of claim 3 wherein said first perforating gun is above said second perforating gun and said first rigid coupler member is positioned below said second rigid coupler member and said intercoupling means further include:

5. The perforating apparatus of claim 1 wherein there are at least four of said rigid coupler members and at least three of said yieldable coupler members alternately disposed in a unitary stack along the longitudinal axis of said perforating guns.

6. The perforating apparatus of claim 5 wherein said first perforating gun is above said second perforating gun and said intercoupling means further include:

7. The perforating apparatus of claim 6 wherein said coupler members are annularly shaped and further including:

8. The perforating apparatus of claim 6 further including:

9. Well bore apparatus adapted for tandemly intercoupling the adjacent tubular end portions of upper and lower perforating carriers and comprising:

10. The well bore apparatus of claim 9 wherein said coupler members are annular and further including:

11. The perforating apparatus of claim 10 further including:

Description:
Present-day completion techniques often require the perforation of a well at two or more different depth intervals. Very often this must be carried out without removing the small-diameter production tubing from the well. To accomplish this, it is customary to tandemly arrange a corresponding number of small-diameter perforating guns into a selectively controlled unitary assembly and, by means of a typical electrical cable, lower the assembled tool through the production string to the depth interval where the first gun is to be operated. Thereafter, the perforator tool is repositioned and the second gun is operated for perforating the formations at the second depth interval. This procedure is repeated until all of the several guns in the perforator tool have been fired.

Those skilled in the art will, of course, appreciate that where each of these guns include a number of shaped explosive charges, the simultaneous detonation of these charges will impose severe shocks and sudden impacts on the entire perforator tool. This problem has been accentuated by the recent development of more-powerful charges. In particular, where the charges are carried in thin-Wall tubular carriers such as those shown in U.S. Pat. No. 3,048,102 and U.S. Pat. No. 3,429,384, these carriers are typically so light that the entire perforator tool will often be driven laterally with considerable force each time the charges in one of the carriers in the tool are detonated.

Accordingly, it has been not at all uncommon to find that the operation of the first set of charges in a tandem assembly of such light-weight carriers has damaged one or more of the unexpended shaped charges in the adjacent carriers in the perforator tool. For example, as shown in FIG. 2 of the aforementioned U.S. Pat. No. 3,429,384, there is ordinarily a minimal clearance space between the internal carrier wall and the forward and rearward portions of the shaped charges. Thus, the sudden impact or shock developed upon firing of one set of charges will rapidly drive or shift an adjacent carrier of this type laterally in relation to the several shaped charges enclosed therein since the charges are typically supported by only a thin, generally flexible metal strip. Forceful inertial movements of this nature are known to be particularly responsible for damage to the exposed forward ends or skirt portions of the fragile liners typically used in such shaped charges. Similarly, it has been found that vertical movements or jumping of the perforator tool caused by detonation of one set of charges can also damage the metal strips carrying the unexpended shaped charges in adjacent carriers. In either case, it has been found that often one or more of the shaped charges in these adjacent carriers are sufficiently damaged that they will not operate properly when these charges are subsequently detonated.

Accordingly, it is an object of the present invention to provide new and improved repetitively operated shaped charge perforating apparatus which is cooperatively arranged for protecting unfired shaped charges in the apparatus from explosive impacts or violent shocks which might otherwise damage or disrupt these unexpended charges upon the detonation of other shaped charges in the apparatus.

This and other objects of the present invention are attained by tandemly intercoupling upper and lower perforating guns by means of alternately disposed rigid and yieldable coupling members, with one of the guns being secured or coupled to one of the rigid members located below an intermediately located yieldable member and the other gun being secured or coupled to another one of the rigid members located above that yieldable member. In this manner, the yieldable member disposed between the two rigid members will effectively isolate the two guns from explosive impacts and shocks developed upon actuation of the other gun. The assembly of coupler members are further arranged to define a protective wire passage for carrying interconnecting electrical wires between the two guns.

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 new and improved perforating apparatus arranged in accordance with the present invention as that apparatus is being positioned in a typical well bore;

FIG. 2 is an enlarged longitudinal cross-sectional view of a preferred embodiment of a new and improved shock-resistant inter-carrier coupler incorporating the principles of the present invention;

FIGS. 3 and 4 are transverse cross-sectional views of the unique inter-carrier coupler respectively taken along the lines 3--3 and 4--4 in FIG. 2; and

FIG. 5 is an isometric view of the embodiment of the new and improved inter-carrier coupler depicted in FIG. 2.

Turning now to FIG. 1, new and improved through-tubing perforating apparatus 10 is shown as it is being positioned in a typical cased well bore 11 adjacent to one of two producible earth formations 12 and 13. As is customary, a string of small-diameter tubing 14 is suspended in the well bore 11 and extended through a typical packer 15 set therein above the earth formations 12 and 13 for isolating the two producing zones from that portion of the well bore above the packer. The perforating apparatus 10 is suspended in the usual manner from a suitable electrical cable 16 that is spooled from a winch (not shown) at the surface and connected to the upper end of the perforating apparatus. As is customary, a typical casing collar locator 17 is employed for providing indications at the surface representative of the depth of the perforating apparatus 10.

Inasmuch as it is intended that the perforating apparatus 10 will be successively positioned opposite each of the formations 12 and 13, the perforating apparatus includes separate upper and lower guns 18 and 19 which are cooperatively arranged to be individually operated upon command from the surface. In the preferred embodiment depicted in FIG. 1, the two guns 18 and 19 are respectively arranged in accordance with the through-tubing perforators shown in either U.S. Pat. No. 3,048,102 or U.S. Pat. No. 3,429,384, each of which is hereby incorporated by reference. Thus, as fully described in either of the aforementioned patents, each of the guns 18 and 19 respectively includes an enclosed carrier 20 and 21 formed of a suitable length of thin-walled steel tubing which has a number of typical shaped explosive charges, as at 22 and 23, mounted at longitudinally spaced intervals along an elongated metal strip (not shown) arranged therein for positioning each of the charges for firing in a selected lateral direction. It will, of course, be appreciated that each of the guns 18 and 19 is respectively provided with an electrically responsive detonator (not shown) which is coupled to a length of typical detonating cord (not shown) operatively disposed along the rear portion of each of the charges, as at 22 or 23, for simultaneously detonating them when the detonator in that gun is energized.

Since the guns 18 and 19 are to be independently fired, suitable provisions must be made for their selective operation. Those skilled in the art will recognize, of course, that any one of several typical switching arrangements may be utilized for achieving such selective control. For example, selectively operated switching systems such as those shown in either U.S. Pat. No. 3,327,791 or U.S. Pat. No. 3,517,758 could be successfully employed with the new and improved perforating apparatus 10 of the present invention where the switching is to be directly controlled from the surface. Alternatively, if it is preferred that the switching be accomplished upon firing of the lower gun 19, for example, a detonation-responsive control system, as at 24, would be included with the new and improved perforating apparatus 10. Typical detonation-responsive control systems, as at 24, are fully described in U.S. Pat. No. 3,246,707 and U.S. Pat. No. 3,246,708, each of which is incorporated herein by reference. It will, of course, be appreciated that since it is ordinarily preferred to shoot the lowermost gun first and then subsequently shoot the next-higher gun, the detonation-responsive control system 24 is operatively positioned adjacent to the upper end of the lower gun 19 so that successful detonation of the charges, as at 23, will electrically connect the cable 16 to the detonator for the yet-unexpended charges, as at 22, in the upper gun 18. Since the two last-mentioned patents fully explain the operation of the detonation-responsive control system 24, no further explanation is believed necessary. It should be realized, however, that regardless of the control system used, electrical wires must be connected between the upper and lower guns 18 and 19 and it is essential to their successful operation that these wires remain undamaged at least until the upper gun is fired.

The upper and lower guns 18 and 19 in the new and improved perforating apparatus 10 are tandemly intercoupled by means of a uniquely arranged shock or impact-resistant inter-carrier coupler 25 which, as will be subsequently explained, is cooperatively arranged for substantially absorbing the severe impact or shock forces developed upon detonation of the shaped charges, as at 23, in the lower gun 19 to thereby protect the yet-unfired charges, as at 22, in the upper gun 18 from unwanted damage. Thus, as best seen in FIG. 2, in its preferred embodiment the unique shock or impact-resistant inter-carrier coupler 25 includes an alternately-disposed stack of two or more annular members 26-29 of a rigid material such as steel and two or more annular members 30-32 of a yieldable or resilient shock-absorbing material such as a suitable elastomer. These stacked coupler members 26-32 are preferably disposed within a protective sleeve 33 of an elastomeric material.

The unique shock-resistant inter-carrier coupler 25 further includes a cylindrical body or upper head 34 which is adapted to be complementally fitted and secured in a known angular position within the lower tubular end of the upper carrier 20 and is further provided with a pair of bifurcated bars or depending support arms 35 and 36 extending downwardly along the opposite sides of the stacked coupler members 26-32. Similarly, a cylindrical body or lower head 37 on the other end of the impact-resistant coupler 25 is secured in a known angular position in the lower carrier 21 and provided with a pair of bifurcated bars or upright support arms 38 and 39 which extend upwardly along the opposite sides of the stacked coupler members 26-32 and are angularly oriented so as to be respectively positioned about midway between the depending support arms 35 and 36 when the coupler is assembled. As best seen in FIG. 5, it is preferred that the rigid arms 35 and 36 as well as 38 and 39 be integral extensions of their respective heads 34 and 37, with each arm being progressively tapered to a lesser width at its outer end so as to allow the bases of the adjacent oppositely directed arms to be of a greater width and, therefore, maximum strength.

It will, of course, be appreciated that where the switching system 24 is arranged in accordance with the aforementioned U.S. Pat. No. 3,246,707 or U.S. Pat. No. 3,246,708, for example, the lower head 37 can also be conveniently arranged as necessary for readily supporting the components of such a detonation-responsive system as well as for being complementally fitted and fluidly sealed within the upper end of the lower carrier 21.

In any event, as collectively illustrated in FIGS. 2-5, it will be recognized that the two pairs of bifurcated arms 35 and 36 as well as 38 and 39 are respectively disposed at uniform, circumferentially spaced intervals around the stacked members 26-32. Accordingly, to yieldably intercouple the several support arms, the depending arms 35 and 36 are coupled or secured, as by laterally oriented bolts 40 and 41, to the next-to-the-highest rigid coupler member 27 as well as to the lowermost rigid coupler member 29 in the stack. Conversely, the upstanding support arms 38 and 39 are coupled or secured, as by laterally-oriented bolts 42 and 43, to the highest rigid member 26 as well as to the next-to-the-lowest rigid member 28 in the stack of annular coupler members. The cooperative function of this arrangement will be subsequently explained.

To facilitate the necessary electrical interconnection between the guns 18 and 19, a wire passage is provided through the inter-carrier coupler 25 by way of an elongated and somewhat-flexible tubular conduit 44 which is coaxially disposed within the stacked coupler members 26-32 and has its enlarged upper and lower ends 45 and 46 fluidly sealed within complemental counterbores 47 and 48 respectively formed in longitudinal passages 49 and 50 respectively arranged through the upper and lower coupling heads 34 and 37. It will be noted from FIG. 2 that although the upper end 45 of the wire conduit 44 may be secured, as by a snap ring 51, within the counterbore 47, the lower counterbore 48 is of sufficient length to accommodate the longitudinal movements of the conduit during the use of the new and improved inter-carrier coupler 25. As a matter of operating convenience, a lateral port 52 with a threaded plug 53 are provided in the lower head 37 to facilitate the splicing of the interconnecting detonator wires (not shown) running between the two guns 18 and 19.

It should be noted that the depicted interlocking arrangement of the arms 35 and 36 as well as 38 and 39 will assure that the charges 22 and 23 will remain in a selected angular orientation with respect to one another. However, should it be desired to position the charges 22 to be facing in an opposite lateral direction from the charges 23, it is, of course, easy to accomplish this by simply removing the bolts, as at 40 and 41, temporarily and reassembling the coupler 25 with the positions of the arms, as at 35 and 36, reversed from their depicted positions.

It will be recognized, therefore, that with the upper and lower guns 18 and 19 being intercoupled to one another solely by the unique coupler 25, the lower gun is directly connected to the upper gun only by way of the resilient members 30-32. Thus, an upwardly directed shock on the upper gun 18 as will be occasioned by the detonation of the charges, as at 23, in the lower gun 19 will be substantially cushioned by the respective expansion and compression of the resilient coupler members 30-32. Similarly, since the resilient members are sufficiently yieldable under impact for allowing the rigid coupler members 26 and 28 to tilt in relation to the rigid members 27 and 29, the resilience of the several resilient coupler members 30-32 will effectively absorb or dampen a considerable amount of the laterally directed shocks or impacts which would otherwise be transmitted to the upper gun 18 when the lower gun 19 is fired. It should be noted at this point that although firing of the lower gun 19 will impart a substantial accelerational force to the lower gun, the operation of the inter-carrier coupler 25 will be effective for at least minimizing or reducing the acceleration of the upper gun 18.

In using the perforating apparatus 10 it has been found that the lateral flexibility of the unique inter-carrier couplers 25 may present some problems. For example, in handling of the apparatus 10, it has been noted that where the upper and lower guns 18 and 19 are particularly long or there are several of these guns joined by two or more of the inter-carrier couplers 25, the support arms 35 and 36 (or 38 and 39) may possibly bend as the tool is being picked up by its upper end and raised from a horizontal position should the full weight of the tool be imposed on the couplers. However, one technique which has been found to be particularly useful in avoiding such unwanted bending is to temporarily slip a stout, close-fitting metal tube (not shown) over each of the inter-carrier couplers 25, with this tube being of such length that its ends will be supported on the adjacent guns, as at 18 and 19, as the tool 10 is being raised. It has also been noted that under particularly severe explosive impacts, the brief but substantial accelerational forces may, in some instances, tend to spread the bifurcated support arms 35 and 36 (or 38 and 39) and sometimes even pull the ends of these arms over the heads of their respective fastening bolts, as at 41. This, however, can be avoided by installing close-fitting metal bands (not shown) over each pair of fastening bolts, as at 41.

Accordingly, it will be appreciated that the new and improved repetitively-operated perforating apparatus of the present invention is well suited for guarding yet-unfired shaped charges from damage as other shaped charges on the apparatus are fired. By intercoupling two or more typical shaped charge guns with the new and improved inter-carrier coupler disclosed herein, the severe explosive shocks and excessive accelerational forces developed upon actuation of one of the guns in the assembled tool will be sufficiently dampened or absorbed that there will be little or no risk of damage to the shaped charges in the other guns.

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.