GB2329654A - A hold down for the suspension of instrumentation in a well - Google Patents

Abstract

A hold down 28 for use in a drill collar in a well (11, fig 16), the hold down 28 comprising an annularly extending part, from which instrumentation (20, fig 1) can be suspended at the drill collar. The instrumentation (20, fig 1) is subject to travel in the well to and from the drill collar.

Description

APPARATUS FOR THE PROTECTION OF INSTRUMENTATION PLACED WITHIN A DRILL STRING This invention relates to apparatus for the protection of instrumentation placed within a drill string and, more particularly, to cushioning located in a well to absorb or cushion loads exerted radially of a well axis, and/or loads exerted about that axis, i. e., torsional loads.

There is need to protect instrument packages traveled in well drill pipe or tubing strings; and in particular, there is need for such protection against loads exerted radially, and/or torsionally on such packages, or other devices traveled in a well.

Accordingly, the apparatus of the present invention provides, in combination: (a) support structure, including a carrier sized for reception in the string, or a support structure sized for reception in the string to be carried by the string; and b) elastomeric structure carried by the support structure, and including multiple e1uetoic pads spaced about a longitiidinal axis defined in the well, the jades extending generally longitudinally, and protruding in directions radially of the axis to absorb radial loading and torsional loading exerted in directions about the axis, and to deflect ia said directions of radial and torsional loading.

As will be seen, a carrier movable relative to the string may carry the elastomeric structure, and the elastomeric structure typically defines hollows to receive cashioning fluid, such as well fluid, and orifices are typically provided to pass well fluid between the interior and the exsrior of the hollows in response to loading. The hollows are preferably formed in the pads, as are the orifices.

There may be provided at least three of the pads spaced about the axis; and there may be multiple sets of such pads, the sets spaced apart axially, and they may be staggered, as will be seen.

There may be a pad support structure that includes cores to which the pads are attached, the carrier having an inner side and an outer sidle, the cores attached to the carrier at the inner side thereof. Such cores may be attached to the carrier as by fasteners. The cores may have longitudinally spaced opposite ends; and blocking structure is typically attached to the carrier to interfit the core ends to block core and pad endwise displacement. The blocking structure also deflects movement of instrumentation in the carrier to endwise engage the pads, and not the cores. Thus, a shielding and centralizing function is provided.

One may locate the cushioning pads outside the carrier, as will be seen.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: Fig. 1 is a vertical elevation showing one form of apparatus incorporating the invention, installed in a well; Fig. 2 is a perspective view of a carrier, with pads therein; Fig. 3 is a view showing the Fig. 2 carrier broken away in part to show interior construction; Fig. 4 is a side elevation showing a carrier partly broken away to show interior construction; Fig. 5 is an enlarged section taken on lines 55 of Fig. 4; Fig. 6 is an exploded perspective view showing multiple carriers as related to drill pipe; Fig. 7 is an exploded view showing a cushioning pad, as related to end blocks; Fig. 8 is an enlarged section taken on lines 8- 8 of Fig. 7; Pig. 9 is a perspective view showing an end block holding a pad structure in position; Fig. 10 is a side elevation showing a carrier; Fig. 11 is an enlarged side elevation showing a J-slot connector on the carrier; Fig. 12 is an enlarged section taken on lines 12-12 of Fig. 10; Fig. 13 is an end view taken on lines 13-13 of Fig. 11; Fig. 14 is a section taken through a nonmagnetic drill collar; Fig. 15 is a side elevation taken on lines 1515 of Fig. 14; and Fig. 16 shows use of the centralizing and cushioning means LXI a well.

Referring first to Figs. 1 and 16, a drill string pipe 10 is shown in a well 11, with drilling mad circulating downwardly at 12. Such mud travels to a mud motor 13, effecting its operation to rotate and drill bit 14, which drills the well downwardly. Elements 13 and 14 are schematically shown.

Drill cuttings are carried upwardly by the circulating mud flowing upwardly in an annulus 15 between the well bore and the string, as is well known.

The mud and cuttings flow to the surface for separation of cuttings and return of mud to the string.

As the motor and drill bit cuts against the underground formation, there is axial and sideward shock loading and rotary shock loading, all transmitted to the lower end of the string, as to pipe or collar 10 causing the pipe or collar to move axially up and down, and sidewardly back and forth, and to more rotatably back and forth about the pipe axis, such movements constituting vibration in multiple modes.

A well survey instrument 20 is shown lowered in the hole, by line 20a, to the location, as shown, within the drill pipe. One example is a magnetic survey tool, such tool being well known. Fig. 16 shows the hole II deviated to near horizontal, the well head indicated at 100. In order that such instrument may operate to best advantage, its substantial isolation from the multi-mDde vibrating motion of the drill pipe 10 is sought, in accordance with the invention, as by cushioning the instrument. This is particularly desirable when the instrument 20 is very narrow (say 2.5 on (one inch) to 3.8 3n (one and one-half inch) in diameter), since it is subjected to bending and flutter, disturbing its operation.

As contemplated, such cushioning is effected by hydraulically cushioning the instrument, both radially and rotatably, as by means acting to isolate the tool, as by dampening radial and torsional vibration. One way b accomplish thins is by means of pads 30, which may include pads 30a-30c, as in Fig. 2. The pads are elongated,as shown, and held in place as via fasteners 36 extending through side openings in a wall 41 of a carrier, as at 24 in Fig. 2, and into metallic cores 37 associated with the pads. A second set of circularly spaced pads 30d- 30f is also shown in and attached to the carrier 41, bnt circularly staggered relative to pads 3Oa-30c.

See for example Figs. 4 and 8 showing fasteners 36, each having a head 36a received in counterbore 40 in the carrier wall 41; and a fastener shank 36h extending through bore 42 in wall 41, through pad elastomeric outer wall 43, and into a threaded opening 44 in a core plate 45. The pad has an inner wall 46 spaced from 43, and free standing side walls 47 and 48 protruding, as shown in Fig. 8. A pad hollow 49 receives well fluid 50 via orifices 51 in a pad side wall or walls at upper and lower ends of the pad. Arrows at 52 show hydraulic well fluid flow into and out of the pad in response to wall 46 movement radially and/or wall 47 and 48 movements circumferentially (see arrows 53). Such movements occur in response to engagement of the pipe-vibrated pad with the instrument 20.

The pad structures provide both radial and rotary cushioning, with hydraulic dampening, due to restricted flow through the. orifices. The multiple pads spaced about the pipe axis all contribute to such multimode vibration isolation and protect an instnnnent 70.

To repeat, support structure is provided which in this embodiment includes a carrier, or stackable carriers, provided for reception in the drill string; and elaetmeric structure is carried by the support structure, examples being multiple elastomeric pads spaced about the carrier longitudinal axis. The pads typically extend generally longitudinally and protrude in directions radially of the axis to absorb radial loading as well as torsional loading exerted in directions about the axis, and to deflect in directions of radial and torsional loading.

Further, the elastomeric structure, such as the pads, typically define hollows to receive cushioning fluid, such as well fluid, which moves into and out of the pads via orifices to provide dampening of pad relative movement, radially and torsionally, in response to vibrating movement of the drill string or non-magnetic collar, relative to the survey instrument centered by the pads.

In Fig. 1, four tubular carriers 2124 are shown, stacked end-to-end, the lowermost seated at step shoulder 26a provided in the drill pipe or non-magnetic collar between bore 26 and the enlarged bore or counterbore 27 in the collar. A hold down 28 engages the top uppermost carrier 21 at 29. The hold down 28 may comprise an annular part via which the instrument 20 is suspended. Hollow elastomeric pads 30 are supported by the carriers to protrade imRardly into close proximity to the casing or wall 20a of the elongated survey instrument 20, for cushioning relative motion, with dampening, between the drill string and pads on the one hand, and the instrument 30, on the other hand.

Figs. 2 and 3 show a single cylindrical carrier 24 defining a bore 24a against which two sets of cushioning pads are supported. Upper set includes pads 30a--30c spaced equidistantly about the carrier axis 34; and lower set includes pads 30d--30f also spaced equidistantly about axis 34, but staggered relative to pads 30a- 30c1 with the cushioned instrument 20 also indicated in Fig. 8. his affords additional support of the instrument package in directions normal to the bore axis. Spiral of angular positioning of the pads may alternatively be employed. Staggering may be omitted.

Multiple fasteners 36 are shown to retain the pads, as described in Fig. 8, while allowing their radial and torsional resilient cushioning and dampening, as described above.

Further features are as follows: 1) The carriers 21--24, cores 45 and fasteners 36 may consist of non-magnetic material, such as stainless steel or brass, so as not to interfere with the magnetic survey performed by tool 20.

2) Room temperature vulcanizing (R.T.V.) material 50, or other like material, is applied at locations 71 and 72 between the pad and carrier, as seen in Fig. 8, and also at 73, to further attach the pad to the carrier, and to block endwise creep of the pad, under axial loading imposed by the instrument 20. In addition, the material 50 blocks out possible intrusion of contaminants and magnetic scale particles, which could otherwise become lodged and affect the magnetic calibration.

3) Blocks 55 are installed at opposite ends of the cores (see Figs. 4, 7 and 9) to resist endwise creep of the pads. The blocks are connected by fasteners 56 to the carrier; and they overlap end extents 57 crf the pads.

4) Spaces 59, formed between circularly successive pads, allow mud flow downwardly within the carrier. The spaces 59 also extend radially between the instrument 20 and the bore of the carrier. See Fig. 5.

5) Merely as illustrative, the wall thickness of an elastomeric pad 30 may typically be between 1/16 inch and 3/16 inch; and the diameter or cross dimension of an orifice 51 may be about 1/4 inch. The length of the pad 30 may be between, 12 and 36 inches.

6) Typical instruments 20 include commercial magnetic survey tools knawn U =-=, made by Applied Navigation Devices, Paso Robles, California, and PINDER and SEEKER bore orientation tools produced by that company. Other instrumts are also usable.

7) Fig. 11 shows the provision of a J-slot 65 in the end of a carrier wall 41, and opening at 65a through the carrier end 4u2 That slot allows retrieval of the carrier endwise upwardly via a retrieval tool, indicated schematically at 66 in Fig. 11.

8) The survey tool 20 is shown in Fig. 1 as having a fishing neck at 70, by which it may be retrieved upwardly in the well, as by a retrieval tool.

9) The carriers may have elongated and enlarged through openings 68 in their side walls 45 to enable finger insertions, for installing or assembling the pads 30 and cores 45 in positions relative to fastener openings 42 in the carrier walls, at the wall head.

10) Fig. 5 also shows an alternate position of a pads 30', and its mounting structure at the outer side of a carrier 21 or 22.

Referring to Fig. 1, the carrier or carriers, as at 21-24, may be amitted, and the pads 30 may be fixedly or removably attached to the drill string, or a sub in the string, at the bore thereof.

A further advantage of the invention is the achieved relaxation of stresses on the instrument package 20, normal to directional drilling a bore hole. The instrument package is not "ctlrved" as severely as the drill string itself, due to cushioning afforded by the pads 30; yet, the Lnstrnment package maintains an average centered position within the cushioning system, permitting string "dog-legs" more severe than normally would be tolerated.

Embodiments of the invention, which is as claimed in the claims, may include the features recited in the following enumerated paragraphs ("paras").

1. Apparatus for the protection of instrumentation placed within a drill string in a well, as during drilling, the combination comprising.

(a) support structure, including a carrier sized for reception in the string, or a support structure sized for reception in the string to be carried by the string; and b) elastomeric structure carried by said support structure and including multiple elastomeric pads spaced about a longitudinal axis defined in the well, said pads extending generally longitudinally, and protruding in directions radially of said axis to absorb radial loading and torsional loading exerted in directions about said axis, and to deflect in said directions of radial and torsional loading.

2. The apparatus of para 1 wherein said elastomeric structure defines hollows to receive cushioning fluid.

3. The apparatus of para 2 wherein there are orifices to pass well fluid between the interior and the exterior of said hollows in response to said loading.

4. The apparatus of any preceding para wherein there are at least tee of said pads spaced about said axis.

5. The apparatus of any preceding para wherein there are at least three of said pads in a first set, spaced about said axis and from one another, and at least three of said pads in a second set, spaced about said axis and from one another.

6. The apparatus of para 5 wherein said two sets of pads are spaced apart, axially, in the well.

7. The apparatus of para 6 wherein the pads in the first and second sets are relatively staggered about said axis.

8. The apparatus of para 2 wherein said hollows extend in said pads.

9. The apparatus of any preceding para incliiding - said carrier wherein said support structure includes cores to which said pads are attached, said carrier having an inner side and an outer side, said cores attached to the carrier at said inner side thereof.

10. The apparatus of para 2 or any one of paras 3; to 9 as dependent on claim 2 wherein said carrier is generally tubular, the pads defining said hollows.

11. The apparatus of para 9 wherein said carrier is generally tubular, there being longitudinally spaced fasteners attaching the cores to the tubular carrier.

12. The apparatus of para 11 wherein said cores extend longitudinally and are spaced about said axis, said cores having longitudinally spaced opposite ends, and there being blocking structure attached to the carrier and interfitting said core ends to block endwise displacement of the cores and to shield the cores from enciwise engagement with instrumentation traveling in the well.

13. The apparatus of any preceding para wherein said carrier is generally tubular and has an inner side and an outer side, said pads being at the inner side of the carrier.

14. The apparatus of any one of paras 1 to 12 wherein said carrier is generally tubular and has an inner side and an outer side, said pads located at the outer sides of the carrier.

15. The apparatus of para 13 including instrumentation extending endwise in the carrier for sideward engagement with the pads.

Claims (2)

CLAIMS 1. Apparatus for use in a drill collar in a well, including instrumentation being subject to travel in the well to and from the drill collar, comprising a) said instrumentation having upper and lower end portions and being elongated between said end portions, b) there being tongue and groove interfit elements to suspend the instrumentation at the drill collar, c) one of said elements configured to be carried by the drill collar, and the other of said elements carried by the upper portion of the instrumentation, whereby said elements interfit as, in use, said instrumentation is travelled downwardly in the drill collar with said instrumentation lower portion hanging freely below the level of said elements. Amendments to the claims have been filed as follows CLAIMS:

1. A hold down for use in a drill collar in a well, including instrumentation being subject to travel in the well to and from the drill collar, said instrumentation having upper and lower end portions and being elongated between said end portions, the hold down comprising an annularly extending part and from which the instrumentation can be suspended at the drill collar.

2. A hold down for use in a drill collar in a well, substantially as hereinbefore described with reference to Figures 1 and 6 of the accompanying drawings.