GB2179079A - Well casing tools - Google Patents

Abstract

A kit of parts comprises one or more collars adapted to be fitted around a conduit. Each collar is typically made up of a number of collar segments 4,6. The kit includes a variety of functional units for attachment to the collar or collar segments by means of a latching mechanism 12,14 which enables the functional units to be securely fitted to a collar. This can be accomplished either before or after the collar is fitted to a conduit. The kit enables any of a variety of installation devices to be assembled and fitted to a conduit by selection on site of the requisite components. Thus, installation devices suited to a particular purpose can be assembled and secured to a length of conduit as a conduit string is disposed in a substrate such as a well bore in the oil and gas industries. The functional unit may include centralizer blades, scratchers or cement basket segments. <IMAGE>

Description

SPECIFICATION Installation devices for drill casings and like underground conduits This invention relates to installation devices for casings and similar conduit strings in well bores such as are made in the oil and gas industries. Particularly, it is concerned with the accomplishment of a number of ends which are normally pre-requisite in successful drilling of an oil or gas well.

When an oil well is drilled, either inland or offshore, a casing must be laid in the main bore through which the drill string passes. It is important that the casing is properly located in the bore, and additionally that it is secured with respect to the wall of the bore. Centering devices have been designed to locate a casing with respect to its associated bore, and to ensure that the surfaces defining the space between the casing and the bore wall provide a good key for a cement which is cast in the space to secure the casing once located.Typical of such devices are centralizers in which elements extend from collars mounted on the casing to space the casing from the bore wall; scratchers in which abrasive elements are adapted to extend lateraliy form the casing to the bore wall to remove any coating formed thereon which might adversely affect the key formed by cement cast in the space; and cement baskets for giving support to the cement slurry when it is poured. Scratchers are often needed particularly where a bore is made under drill mud which can separate during drilling and leave a deposit on the bore wall which must be broken up or removed before cement is cast thereagainst. All these devices are manufactured separately, and while they may be adapted to a particular task on site, their respectively central functions are determined at the point of manufacture.

The devices are normally used fixed on one or more lengths of casing, performing their function as the lengths are installed. In some instances however, they can be moveably mounted and shifted to their final position during or after installation. They can also extend over couplers or joints which link successive lengths.

The present invention is directed at the provision of a family of units which may be selectively combined at the working site to form a variety of location devices of the kind that is exemplified above. The family is based on a collar for disposal around a casing, and to which selected other units can be attached to form the particular device required. The collar and each of the units include complementary latching mechanisms enabling each unit to be securely attached to the collar without risk of unintentional collapse or disassembly.

The basic collar will normally comprise two halves which are hingedly inner-connected. In this form, the collar must itself be adapted to a particular casing size. However, it will be understood that collars may be designed within the scope of the invention which are themselves adaptable to a variety of casing diameters, and where a collar comprises two or more segments which extend round the periphery of the casing, a degree of adjustability needs to be provided only to allow for adjustment between the circumference defined by a given number of segments and that definde by the provision of an additional segment. Each segment will have one or more discrete latching mechanisms to which the other units can be attached. Thus, the other units do not need to have any facility for adjustment specifically in respect of a given casing diameter.

In use, devices assembled in accordance with the invention will be mounted on a length of casing, and may if desired be locked thereonto, for example either by tightening the collar itself or fixing a wedge between the collar and the casing. In another alternative, an additional collar may be used with one or more wedges to act as a stop collar which holds a collar supporting other units in place either against a shoulder or coupling in the casing or against an adjacent stop collar.

The primary advantage of the present invention is the suitability of devices assembled in accordance therewith for assembly at the point of use which considerably simplifies the manufacture and freight of the component units thereto. As will be readily appreciated from the following description, the actual construction of the devices is such that their packaging and carriage, assembled, to an actual site will involve considerably more labour and expense than would that of the component units as proposed herein. Further, their assembly on site reduces the storage requirements at the point or use as the packaging of the components occupies less space.

Further features and advantages of the invention will be apparent from the following description of embodiments thereof by way of example. Reference will be made to the accompanying drawings wherein like references are used to identify like parts. In the drawings: Figure 1 is a perspective view of a collar forming the primary component of the invention; Figure 2 is a section taken on line 2-2 of Fig. 1, showing the casing wall with a wedge locking the collar thereagainst, and one form of unit latched thereon; Figure 3 shows a view similar to that of Fig.

2 but with another form of unit latched on the collar; Figure 4 to 9 show various views of typical units that can be combined with the collar of Fig. 1 for use in accordance with the invention; and Figure 10 to 13 are perspective views of devices that can be assembled in accordance with the invention.

The collar shown in Fig. 1 comprises two matching halves 4, 6, each formed from a steel sheet pressed and stamped into a semicylindrical shape bounded at either axial edge by fingers 8, 10 which are curled and interdigitated with their counterparts on the other half. The halves are held together by pintles (not shown) which may be fitted and locked in place to fit the collar on a casing (also not shown). Two halves 4, 6 are shown by way of example only; it will be understood that three on more cylinder segments may be coupled together to complete the collar.

The dimensions of the collar are not required to exactly match those of the casing upon which the collar is to be mounted. One or more of the pintle connections may be foregone in favour of adjustable connections such as jubilee clips or the like enabling the required degree of tightness of the collar on the casing to be obtained.

The collar halves 4, 6 shown are formed with openings 12 and latching tabs 14. Their purpose is better shown in Figs. 2 and 3.

Also shown better in Figs. 2 and 3 is the inner lip 16 at the lower edge of each half.

The collar half or segment 4 in Fig. 2 is shown in place on a section of casing wall indicated at 18. It is held by a wedge 20 (see Figs. 9) which locks the upper edge of the collar, while the lip 16 at the lower edge maintains the spacing from the casing wall 18.

The unit shown fitted in Fig. 2 could be a plain spacer element (Figs. 4 or 6); a scratcher element (Figs. 7) or a petal element (Figs. 5). The latching end of the element has a bend at 22 and an opening at 24. It is forced through the opening 12, past the tab 14, and against the lip 16, whereby it is irremovably secured in place between the collar and the casing wall 18, the tab 14 occupying the opening 24.

The unit shown latched of the collar and casing in Fig. 2 is a scratcher 26 such as shown in Fig. 8, formed from a length of wire or moulded cable 28. Although different in construction, the nature of its latching is the same as that of the unit in Fig. 2 in that the lower arcuate end of the unit 26 is bound in the space defined by the lip 16, the casing wall 18 and the tab 14. The operative arms 30 of the unit extent from a bend 32 at the end of the area outward both circumferentially and radically with respect to the casing wall 18.

Figs. 4A and 4B show in elevation and section a plain spring steel spacer unit. At either end it has an opening 24 and a bend 22, additional bends 34 providing a substantially planar length 36 therebetween defining the major portion of the unit. With other similar units, that of Fig. 4 is shown in Fig. 10 mounted between collars 38 axially spaced a fixed distance on a casing (not shown), which distance is less than that of the length 36, thus forcing the length 36 to bow outwards to engage the wall of a well bore 40, thus locating the casing therein.

Figs. 5A and 5B show in elevation and section a petal unit which, when latched with others to a collar on a casing as shown in Fig.

12 forms a cement basket for use to confine cement between the casing and the well bore.

It does though, also serve a locating function, in that the resilience of the combined petal units is effective to limit movement of the casing laterally in the bore. Each petal unit comprises a latching end as described above for fitment as in Fig. 2, and a leaf 42. As shown in Fig. 12 the leaves 42 overlap to define the basket.

Figs. 6A and 6B show in elevation and section rigid steel spacer unit. This is essentially similar to the spring unit of Figs. 4 with the exception that the central length 44 is twisted through substantially 90" such that it is relatively inflexible in the plane containing the line between the ends. Units of Fig. 6 are shown in Fig. 13 mounted between collars 38 to form an essentially rigid spacer device.

Figs. 7A and 7B show in elevation and in section scratcher units similar to the spring elements of Figs. 4 but with scratcher members 46 extending thereform at spaced intervals. Similar to the scratcher 26 of Fig. 8, each scratcher member 46 is formed from moulded cable 28 with the threads loosened at its distal end 48. Each inner end passes through an hole 50 in the length 52 of the unit, and welded thereto on the inner surface thereof. Units of Figs. 7 are shown latched to collars 38 to form a rotary scratcher in Fig.

11. The Units can also be mounted bowed as those of Fig. 10.

The unit shown in Fig. 8 can be mounted with others on one collar 38 to form a single scratcher for scraping the inner surface of a well bore as the casing on which the collar is mounted is installed. The rotary scratcher of Fig. 11 can be similarly employed. The devices may also be used when only loosely mounted on the casing, and of course may be mounted contiguously on a length of casing so that a plurality of purposes may be simultaneously carried out.

Figs. 9A and 9B show orthogonal perspective views of the wedge 20 shown in Fig. 2.

As can be seen, it may be shaped from sheet steel as each collar half 4, 6.

It will be appreciated from the above that the units described are only examples of the components that might be combined with one or more collars to form devices for use as described in the drilling industry. For example, units may be latched to collars to form guides for auxiliary conduits, electrical wiring etc.

along the external surface of a casing. As noted above, devices performing different functions may be mounted contiguously on a length of casing, and in some circumstances units having different functions can be latched to the same collar or pair of collars. By providing devices in modular form, the invention enables a wide variety of devices to be available from the minimum of storage requirements. Most of the devices currently in use can be readily assembled at the work site from those described herein.

Claims (15)

1. A kit of parts for selectively assembling devices for use in the installation of a conduit in a substrate, which parts comprise collar segments for the formation of collars; securement means for mounting a so-formed collar around a conduit; and a selection of functional units for attachment to the collar segments, the collar segments and units having complementary latching means for securing units to a said so-formed collar on the conduit, whereby a chosen installation device is assemblable from selected ones of the parts in accordance with a desired function.

2. A kit of parts according to Claim 1 including pairs of collar segments, each pair being adapted to the formation of a collar for a conduit of specific diameter.

3. A kit of parts according to Claim 1 including a plurality of similar collar segments; and means capable of coupling a selected number of segments to form a collar for a conduit of a selected diameter.

4. A kit of parts according to Claim 1 including pintles for coupling contiguous edges of circumferentially adjacent collar segments in the formation of a collar.

5. A kit of parts according to Claim 1 wherein the securement means comprises wedge means for fixing a so-formed collar on a conduit.

6. A kit of parts according to Claim 1 wherein the latching means comprises resilient lips on the collar segments, each functional unit having a latch member adapted to be held behind a said lip to secure same to a said segment.

7. A kit of parts according to Claim 6 wherein said latch member is formed at the end of an arm formed on each unit, the respective collar segment defining an opening through the wall thereof for receiving the arm from the outer side, the resilient lip being disposed on the inner side of the wall.

8. A kit of parts according to Claim 7 wherein each collar segment has a flange at one axial and thereof for preventing passage of a latch member.

9. A device for use in the installation of a conduit in a substrate comprising a plurality of collar segments coupled together to form a collar; means for mounting a so-formed collar on a said conduit, and a plurality of functional units, which units are attached to said collar by complementary latching means on the units and collar.

10. A device according to Claim 9 mounted on a conduit wherein the attachment of the units to the collar is secured by the cooperation of the conduit wall with the latching means.

11. A device according to Claim 9 or Claim 10 wherein the functional units are selected from the group comprising centralizer elements, abrasive elements, and cement basket elements.

12. A device according to Claim 11 wherein the units attached to the collar comprise two of said element types.

13. A device for use in the installation of a conduit in a substrate comprising a pair of collars each being formed from a plurality of coupled collar segments; means for mounting the collars on a said conduit; and a plurality of functional units each having an arm at two ends thereof, each unit extending between the two collars and being attached thereto by complementary latching means on the respective arms and collars.

14. A device according to Claim 13 wherein the units are flexible, and wherein the spacing between the collars when mounted on the conduit is adjustable to distort the units with respect to the conduit to perform a chosen function.

15. A device according to Claim 13 wherein the units are substantially rigid, and determine the spacing of the collars on the conduit.