CA2183505A1 - Method of and apparatus for assembling a tool string - Google Patents

Abstract

A method of and apparatus for assembling a tool string includes a body member (12) and a coupling mechanism (6, 7, 8, 9) on the body member (12). The coupling mechanism (6, 7, 8, 9) releasably secures the body member (12) to an internal profile (3) in the borehole (1). The apparatus also includes a support mechanism (15, 19, 20, 21, 22, 23) on the body member (12). The support mechanism (15, 19, 20, 21, 22, 23) is movable between a support position (50) in which the tool string or a portion (24) of the tool string is supported on the body member (12), and a release position (52) in which the tool string or portion (24) is released from the body member (12).

Description

2 1 8~5a5 l "A ~ethod of and ~pparatus for A~ '1 In~ a Tool 2 String"

4 The in~en~ion relates to a ~ethod of and apparatu~ for asse~bling a tool ~tring.
7 Coil tubing i~ frequently used in borehole9, especially 8 highly deviated bvreh~les ~o perform operations within 9 the borehole. It i~ pos~ible to attach ~pecialised equlpment to the end of the coil tubing to per~orm 11 specific operation~ in the borehole, fiuch as sur~ey 12 equipment. In general, a num~er of different too~ may 13 be attached to the en~ ~i the coil tu~ing and the 14 att~ched tools are norm~lly re~erred to as the ~tool ~tring" An advantage of using coil tubin~ is that 16 because the coil tubing itxelf is relatively rigid and 17 non-flexiblo co~pared with wireline, the coil tubing 18 and attached tool 6tring can be pushed along highly 19 deviated wells, such as horizontal ~ell~. Such operations would gene~ally not ~e po~sible with 2l wireline.

23 However, ~ disadvantage of coi1 ~ubing is th~t, due to 24 the inflexible n~ture of the coil tubiny and the type of e~uipment required to ins~rt tho coil tubing into a z 2 1 83~0~
1 bo~ehole, proble~s are encountered when trying to 2 inse~t relatively long ~ool s~rings in~o the borehole '3 ~u~ to ~pace limit~tions. Hence, it may only be 4 po~ible to u~e ~ relativel~ ~hort tool ~tring wi~h coil tubing.

7 In ac~ord~nce with the pre~ent invention, a method of 8 as~embling a tool string co~p~ises in~rodu~ing a body 9 me~he~ into a borehole an~ relea~ably ~ecu~ing the body me~ber to an internal px~file in the borehol~, 11 supporting a first portion of th~ tool ~triny ~o be 12 as~embled on the ~ody memb~r to support the 8aid 13 portion in the borehole, intrcducing a second portion 1~ of the tool string into the ~orehole, coupling the 15 second portion to the fir~t po~tion to as~emble the 16 tool ~tring, and su~sequently rele~sing the as~embled 17 tool string from the body member.
1~
19 In accor~Ance with a ~econd a6pect of th~ pres~nt inv~ntion, apparatu~ for ds~embling a tool string in a 21 ~orehole comprises a body member, a coupling mechanism 22 on the body member to releasably secure the l~ody me~nber 23 to an internal profile in the horehole, and a support 24 mechanism on the body ~nember, the ~u~o~L mechanism being movable between a ~upport position, in which the 26 tool st~ing or a portion thereof is supported on the 27 body member, and a firs~ release position, in which the 28 tool string or the por~ion ib rolea~ed from the body 29 member.
31 The invention ha6 the ad~antage of permitting a tool 32 string to ~e assem~led within a borehole ~nd is 33 especially, but not ~olely, u~eful for a6~embling tool 34 string~ for coil tubing.

3~ ~referably, the internal profile to which the apparatus 1 is releasably secured may take the form of a landi~g 2 nipple in a tu~ing string.

4 Preferably, the body member is tubular with a through 5 bore having a longitudinal axi~, whi~h is subs~antially 6 parallel to the longitu~l n~ 1 axis of ~he portion of the 7 borehole in which the body member i~ reieasably 8 secured, in use. Typic~lly, the first po~tion o~ the 9 tool string is ~upported within the through ~ore of the body member and ~he second portion may enter the 11 through bore to eouplo to the fiLst portion.

13 Typically, the support mechanism may in~lude an 14 indexing mechani~m to guide the ~uppoxt me~hanism between the ~uppo~t position an~ the first release 1~ po~ition. Prefera~ly, the sup~ort mechani~;m i~
17 provid~d with a second release position and typically, 18 the support positi~n is lo~ated ~etween the two release 19 po~itions .
2'1 Prefer~bly, the support mechanism m~y include a fi~st 22 mo~able member which enyages a first xhoulder on a tool 23 forming part of the first portion of the tool string 24 when in the support po~ition, an~ move~ out of eng~gement with the fir~t sho~ld~r when in the first 2~ relea~e position. Preferably, the fir~t movable me~ber 27 is bias ed to the ~upport po~ition from the first 2R ~l~a~Q po~ition.

Preferablyr tho fir~t movablo m~mber i~ ~ dog which i5 31 typically located in a ~ovable ~leeve mountQd on the 32 body m~mbeL.

34 Typi~ally, a second mov~ble member i~ pro~ided whi~h eng~ges with a se~ond shoulder on ~he first portion of 3~ the tool string when the support mechanism in the 1 support posi~ion, and which move~ out of engagement 2 with the se~ond shoulder when the 5upport mechani~m is 3 in the f ir6~ relea~e po~ition or the ~econd relea~e 4 position.

~ Preferably, the su~port position and the first release 7 position, and ~he second release position if pre~ent, 8 are aligned in a direction which is s~bstantially 9 parallel to the longitudinal AXi~ 0~ the body ~mber.
11 Preferably, the secon~ r~l~a~e po~ition is used to ai~
12 disassembly of the ~ool 8t~ing in order to recove~ ~he 13 tool string from the borehole.

Examples of a method of and apparatus ~or assembling a 16 tool string in acco~dance with the invention will now 17 be described with referen~e to ~he accompanyin~
18 d~awings, in which:-lg Fig. 1 i~ a partial c~OS~-~eC~iQn through a first 21 example of apparatu6 for assembling a tool ~tring 22 in a first positi~n in ~ landing nipple in a 23 borehole;
24 Fig. 2 is a partial cros~-section through the appar~tus o~ Fig. 1 in a second position;
26 Fig. 3 is a partial cros~-bection through ~he 27 appara~us of Fig. 1 in a third po~ition;
28 ~ig. 4 is a partial ~osQ-~ection through the 29 apparatus of Fig. 1 in a fourth position;
Fig. 5 is a side view of an in~exing slot for use 31 with the apparatus ~hown in Figs. 1 to 4;
32 Fig. 6 i~ partial cro~ ectional view through a 33 second example of apparatus for a~sembling a tool 34 string in a borehole, shown in a running in config~ration; and, 36 Fig. 7 iS a ~ide view of an indexing ~lot for use ~ 1 835~5 1 with ~pparatus ~hown in Fig. 6.

3 Fig. l sh~ws a tubing ctring 1 located within a 4 borehole and a lan~ing nipple 2 lo~ated on the tubing ~t~ing l. The landin~ nipple 2 has an internal profile 6 3.

8 Apparatu~ 4 is located in the landing nipple 2. The 9 appara~u~ 4 comprises a connection ~ub 5 which is ~hreadedly coupled to a locking slide 6. The locking 11 ~lide ~ i~ located within an upper body member 7 which 12 include~ a numbe~ of ~prung finger6 B (only one shown).
13 Each of the sprung fingers 8 has a head portion ~ which 14 en~a~e~ with the inte~nal p~ofile 3 of the landing nieple 2. The upper ~ody member 7 also includes a 16 shear pin lO and a ~p~ing loaded shear pin ll. The 17 upper body memhe~ 7 i~ threadedly coupled at its lower lR end to a lower body mem~er 12 which has a downwardly 19 facing shoulder 13 on its outex surface ~hich engage~
with a ~houlder 14 on the landing nipple 2. The lower 21 body mcm~er 12 ha~ a ~leeve slide 15 located within it.

23 Two helical springs 16, 17 are positioned at either end 24 of the slide 15. A bottom sub 18 i~ attached to the lower end of the lower body mem~er 12 and moun~ed on 26 the sub 18 i8 an indexing pin 19 which engage~ with an 217 indexing slot 20 formed in the ~lide 1~. The indexing 2~ slot 20 is continuous ~round the ~lide 15. ~o~ated 2g within the 61ee~e 15 i6 a dog 21. Th~ lower ~ody 3~ me~ber 12 also has two rece~eh 22, 23 into which the 31 dog 21 may move when the ~leeve 15 has moved again~t 32 the bia~siny action of either of the sprinys 17, 16 so 33 th~t the dog 21 coincide~ with either of the recessea 34 2~, 23. Al~o shown in Flg. 1 is ~he top en~ of a tool 3S 2~ which is to form part of a coil tubing tool ~tring, 36 as will be explaine~ ~elow. ~he upper end of the tool 2 1 8~05 24 includes a downw~r~ly facing shoul~er 25 whi~h 2 eng~es wi~h the d~g 21 when in ~he position ~hown in 3 Fig. 1 and a connector profile 26 which takes the fonm 4 of an enlarged head on th~ upper end of the tool Z4.

6 In u~e, the to~1 24 iY in~erted into the apparat~s 4 on 7 the surface and the app~xatu~ 4 with ~he ~ool 24 8 ex~ending from it may be inse~ted into the tubin~
~ ~tring 1 Vid conven~ional wiroline or coil tu~ing operations. After being ~nserted into the tubing 11 6tring 1, the apparatu~ 4 is lowered until the 6hou1der 12 13 on the lower ~ody mem~er 12 hits shoulder 14 on the 13 landing nipple 2. In this position the heads 9 of the 1~ ~pru~g fin~ers 8 will engage the intexnal profile 3 on the landing nipple 2. The locking ~lide 6 is ret~in~
16 in the position shown in Fig. 1 during loweriny of the 17 as~embly into the tubing 6tring 1 by means of the shear 18 pin 10 which lacks the locking slide 6 to the upper 19 body member 1.
21 After the position shown in Fig. i is obtained, a 22 downwar~ fo~ce, fo~ exa~ple by use of a jar mechiln;~mt ~3 is applied to the connection sub 5 and locking slide 6 24 to shear the shear pin 10. This then permit~ the locking ~lide 6 to move to the position shown in Fig.
26 2~ in which the connection su~ 5 abuts against ~he top 27 end of the upper mem~er 7 and locking heads 27 of the 28 locking sli~e 6 abut ~gainst the head~ ~ of the sprung 2 9 f in~ers ~ to pre~ent the heads 9 becoming dis~ngaged from the internal profile 3. In this position, the 31 ~prun~ shear pin 11 can extend into recess 28 in the 32 locking slide 6 to retain the locking ~ e 6 in the 33 position shown in Fig. 2.

During this operation ~h~ tool 24 is suppor~ed in the 36 apparatu~ 4 by me~ns of ~he locking dog 21 which ~buts 2 ~ '~35~S
1 against shoulder 25 on the tool 24.

3 After the appax~us 4 has been locked into the l~nding 4 nippl~ 2, the wireline or ~oil tubing used to run the apparatu~ 4 into the lAn~i ny nipple is disconnected 6 ~rom the connection sub 5 and retrieved to the ~urf~ce.

~ The coil tu~ing to which the tool çtring i8 to be 9 attached is prepared and the desired upper portion of the tool ~tring ic ~ttached to the lower end of the 11 coLl tubing and inserted into the tubing string 1 in a 12 conventional manne~. The upper portion of the tool 13 string is then lowe~e~ on the end of the coil tu~ing 14 until a connection sub 29 on the l~wer end of the upper portion of the tool ~tring contacts the top end of the 16 tool 24. The conne~ion s~ 29 includes a lower 17 mandrel 30 which engages with the central bore of the 18 tool 24. The outer ~hape of the m~ndrel 30 i8 19 pxefe~a~ly non-circul~ and the central bore o~ tool 24 ~ al~o non-circular t~ prevent the ~an~rsl 30 rotating 21 with respect to the tool 24. Threadedly attached to 22 the lower mandrel 30 i8 a central body member 31 and 23 threadedly coupled ~o the other end of the central body 24 ~ember ~1 is ~n upper sub 32. Slidably locate~ on the outsi~e of the central body mem~er 31 is a sleeve 33 to 26 which i8 attached a number of ~prung finger6 34 with 27 engagement hea~s 35. The coil tubing and the 2~ connection ~ub 29 i~ lowered until it reaches the 29 position shown in Fig. 3. In this po~ition, the heads 26 and 35 abut again6t each other and fur~her downwa~d 31 mo~ement of the connection sub ~g causes the finger~ 34 32 and sleeve 33 t~ in station~ry with re6pect to the 33 landing nipple 2, as the head 26 pu~hes the sprung 34 fingers 34 and slee~e 33 against the action o~ the spring 36 M~ the lower mandrel 30 mo~e~ furth~r into 36 the tool 24 and the connection ~ub 32 and centr~l body 1 membeL 31 move downwards. This downward mo~ement of 2 the central body member 31 while the fingers 34 remain 3 stationary with respect to the landing nipple 2 permits 4 the heads 35 on the fingers 34 to enter recess 37 in the centxal ~ody me~ber 31. The heads 35 when in this 6 position then ride underneath the hea~ 26 and move t~
7 the position ~ho~n in Fig. 4 in whi~h the connection B ~ub 29, and therefore the uppe~ portion of the tool 9 string att~ched to the lower end of the coil tu~ing, i6 coupled to the tool 24 by means of the head~ 26, 35.

12 The configu~tion of the indexing slot ~0 i~ shown 13 schem~tically in ~i~. 5. In the positions shown in 14 Figs. 1 to 4, the i n~eYi n~ pin lg i~ at position 50.
Prior to inserting tho tool ~4 into the apparatu~ 4 and 16 the wei~ht of tool 24 being fiupp~rted by dog 21, the 17 pin is in an unloaded equili~rium position 49. When ~8 the weight of the tool 24 i~ applied to dog 21, pin 19 1~ mo~es along th~ slot 20 in tho ~lid~ 15 to po~ition 50.
After th~ po~ition ~hown in Fig. 4 i~ rea~hed an upward 21 forc~ i~ applied ~o ~he ~oil ~ubing s~ that the head 35 22 pu118 Bgainst the head 26. Thi~ v~ wei~ht from 23 the dog 21 and permit~ the ~lide 15 to return to its 24 equilibrium po~iti~n which mo~es the indexing pin 19 along 510t 20 to the position 51 shown in Fig. S.

27 ~etting down weight on the coil ~u~ing then forces the 28 tool 24 ~ownw~rd~ against the dog 21 whi~h moves the 29 indexing pin 19 along slot 20 to po~ition 52. In this position the dog 21 is adjacent recess 23, and force 31 exerted downwardly by the shoulder 25 on the dog 21 32 causes the dog 21 to enter the re~e~ 23 there~y 33 permitting the tool strin~ ~o pa~s down through the 34 apparatus 4 into the ~u~ing ~t~ing below the nipple 2.
After the tool string h~6 cle~re~ the body member 4, 36 the Ypring 16 pushes th~ slido 15 back toward~ it~
I

1 equili~rium position ~nd pin 19 moves to po~ition 53.

3 The opeLator may then carry out the de6ire~ operation~
g in the borehole using the assembled tool st~ing.
s 6 In order to retrieve the tool string ~om the bo~ehole 7 the coil tubing is reeled in until the head 25 c~ntact~
8 the lower si~e of the dog 21. Further upward movement 9 of the tool xtring then cau~e8 the head 26 to push the ~og 21 and slide 15 upwards and pin lg moves further up 11 slot 20 to posi~ion 54. In this position the dog ~1 12 moves into rec~ss 22 ~hereby permitting the head ~6 to 13 p~S6 the dog 21. The ~og 21 ~ove~ out of the recess 22 14 and the slide 15 returns to its equilibrium position when the shoulde~ 2~ has cleared the dog 21 in ~n 16 upward~ direction. This corre~ponds to pin 19 moving 17 along slot 20 to re~urn to po~ition 4~. Setting weight 18 down on the coil tu~ing ~tring then c~uses the shoulder 19 25 to en~age with the 6houlder 21 and move to the 2~ po~ition shown in ~ig~. 1 to 4 in which the ~houlder ~1 21 ~upport~ the weight of the tool strin~. In thi~
22 position, the pin 19 h~s moYed to position 50.

24 At this point in ~he operation, fluid is pumped into 2S the coil tubing at a high enou~h pre~ure to open port6 26 38 in the cen~ral body member 31 whi~h pe~mi~ fluid ~o 27 enter the fluid oavity 39. The pre~u~e of the fluid 28 entering the fluid cav~ty 3~ ca~ses the ~inger~ 34 ~nd 29 slide 33 to move again~t the action of ~p~ing 36 so that the head 35 of fingers 34 enter rece~ 37 in the 31 central body ~ember 31 at which point the uppe~ portion 32 of the tool string an~ connector 29 may be removed from 33 the upper end of the lower portion of tool 24. After 34 the upper portion of the tool string h~ been removed from th~ upper en~ of ~ool 24, the to~l 24 i~ ~upported 36 by locking dog 21 on th~ apparatu~ 4.

lo ~1 83~5 1 After the coil tubing and upper portion of the tool 2 string i~ remo~ed from the tubing string coil tubing 3 may then ~e rerun into the hale or wireline run into the h~le to engage the ~onnector sub 5. Upward ~arring 5 on the connector sub 5 then shears pin 1~ and fu~the~
6 upward l,lo~ent exerted on the connection sub ~ move~
7 the locking slide 6 and heads Z7 to the position 6hown 8 in ~ig. 1. Thi~ permits the ~prung fin~rs 8 to g deflect inwards, on ~urther upward force, ~o that the apparatu6 ~ and tool 24 may be l'F ved from the nipple 11 and retrie~ed up the tubing string and out o~ the 12 borehole. When the tool 24 i5 .~,o~ed from the 13 ~pp~r~tu~ 4, the ~lide 15 reverts to it~ eq~ rium 14 position and pin 19 move~ to po~ition 51.
Fig. 6 is a partial cr~ss-LQctional view throu~h a 17 ~econd example of apparatus 60 for assembling a tool 18 string in a landing nipple in a ~ore hole. The 19 apparatus 60 comprises a deployment tool 61 which is ~0 conn~cted to a running tool 62 for xunning the 21 deployment tool and setting the deplo~ment tool in a 22 nippl~ in a borehol~. Al~o ~hown in Fig. 6 i~ th0 top Z3 en~ o~ a t~ol 71 which is to form par~ of ~ ~oil ~ubing 24 too~ string, as explained bslow. The deployment to~l 61 is su~Rtantially the same a~ the apparatu~ 4 26 described above in Figs. 1 to S. The main difference 27 between the deployment tool 61 and the apparatus 4 i8 23 tha~ ~he deployment tool 61 lncludes a pair of dogs 63, 2~ ~ on a ~lide ~5 which slide~ within a lower bod~
~nember 66 which ha~ three locking dog re~e~se~ 67, 6~, 31 59. In addition, an 1n~ing slot 70 (see Fig. 7) in 32 slide 65 ha~ a different configuration to the indexing 33 sl~t 20. The parts of the deploymen~ tool 61 which are 3~ the ~ame ~s the apparatus ~, have been given the ~ame reference numerals.

~ 1 8350~

The upper end of the tool 71 has two ~hou~ ders 72, 73 2 which are ~upported by dogs 63, 64, respectively.

4 AII advantage of ~he deployment tool 61 i~ th~t 3~y S providing two support dogs 63, 64 and a modified 6 indexing slot 70, additional s~curlty is provided to 7 he~ p preven~ tool 71 falling into the bore hole in the R event that the upper end of the tool 71 i~ not properly 9 engaged with an upper tool prior to tool 71 being released from engagelnent with the dogs 63, ~4.

12 In use, the appara~s 60 and the deFloyment tool 61 a~e 13 used in a similar manne~ to the apparatu~ 4. Th~ tool 14 71 is inserted into the deployment tool 6 L on the surf ace and the deployment too~ ~1 with the tool 71 i5 16 inserte~ into the tubing string via the runnlng tool fi~
17 using con~entional wireline or coil tubing. The 18 deployI[~ent tool ~l is set in a lAnd;ng nipple in the 19 same ~nn~r a~ for the apparat-ls 4 de6cribed above.
21 However, with the deployment tool 61, the pin l~ is 22 initially in po~ition 75 in ~lot 70 ~6ee Fig. 7) and 23 move~ to po~ition 76 when the weight of the tool 71 i~
24 support~d by the dogs 63r 6~. Afte~ the second tool haE; ~een run into the hol~ and ongaged with the upper 26 end of tool 71, an ovorpull is ~pplied to the coil 27 tubing to ensuxe that tool6 71 and the second tool are 28 properly connected. During th~ overpull, t~e pin 19 2~ moves to the position 77. Aftor the overpull has been applied and there is confirmation that the toOlfi ~re 31 connected together~ weight i6 set down on the tool 71 32 to move the pin 19 ~o the position 78 in slot 70. A
33 further pull upwards on the ooil tubing r~ the 34 weight of tool 71 from the dogl; 63, 64 and permLt~ the pin lg to move to po~ition 79 in the slot 70. Setting 36 w~ight down on tool 71 then mo~es pin 1~ to po~ition 80 12 2 1 83~35 1 in which the locking dogs 63, 64 may enter the rece~Qs 2 69, 68, respectively. This relea~e6 the tool 71 from 3 enghge~ent with the deployme~t tool 61 and permits the 4 tool string to be run into the hole below the nipple to which the deployment tool 61 is ~ecu~ed. During 6 retrieval o~ the tool ~tring, the operation is the same 1 as that descri~ed abo~e for the ~pparatu~ 4 and 8 position ~1 in the slot 70 corre~pond~ to position 54 9 in the indexing ~lot 20 fox the apparatus 4.
11 In addition, both the ~pparatu~ 4 an~ the deployment 12 tool 61 may be used for multiple connection~ of coil ~3 tubing tool~. In the caso of the apparatu~
14 shoulder 25 is pxovided on the upper end of ea~h tool to be connected. Hence, a~er the lower tool ~ ha~
16 passed through the dog 21, the dog ~1 is free to return 17 to the e~lilih~ium po~ition. The wei~ht of the tool 1~ above applied to the dog 21 through the shoulder 25 on 19 the tool above will then c~u~e the pin 19 to mo~e ~o 2D posi~ion 50 and furth~r tool or tools may be connected 21 to the tool now supported by the dogs 21. In the case 22 Or the apparatus 60, 6upport shoulders 72, 73 are 23 provided on the upper end of each connecti~g tool.
24 Hence, after the lower tool 71 ha6 passed through the dogs 63, 64, the dog~ 63, 64 will be free to return to 26 the equilibrium position and the next ~upport shoulders 27 on the tool abov~ the tool 71 engage with the dogs 63, 28 64. Thi~ cau~ the pin 19 to move to po~ition 7G via 29 equili~ri~ po~ition 75. In thi~ manner tho doploym~nt ~ool 61 can ~e used to connect a numb~r of coil tubing 31 tools together.

33 The invention has the advantage of permitting 34 relati~ely long tool strings which could not normally be used with coil tubing, to ~e u6ed with coil tubing 36 by assemblin~ the tool ~tring ~ithin the borehole.

218~505 ~odifications and i~p~ov~ ~nts may be made without 2 departing from ~he ~cope of ~he in~ention.

Claims (11)

1. Apparatus for assembling a tool string in a borehole comprising a body member, a coupling mechanism on the body member to releasably secure the body member to an internal profile in the borehole, and a support mechanism on the body member, the support mechanism being movable between a support position, in which the tool string or a portion thereof is supported on the body member, and a first release position, in which the tool string or portion is released from the body member.

2. Apparatus according to claim 1, wherein the support mechanism includes an indexing mechanism to guide the support mechanism between the support position and the first release position.

3. Apparatus according claim 1 or claim 2, wherein the support mechanism includes a first movable member which engages a first shoulder on a tool forming part of the tool string when the support mechanism is in the support position, and which moves out of engagement with the shoulder when the support mechanism is in the first release position.

4. Apparatus according to claim 3, the apparatus further comprising a biassing device to bias the support mechanism to the support position from the first release position.

5. Apparatus according to claim 3 or claim 4, wherein a second movable member is provided which engages a second shoulder on the tool forming part of the tool string when the support mechanism is in the support position, and which moves out of engagement with the second shoulder when the support mechanism is in the release position.

6. Apparatus according to any of the preceding claims, wherein the support mechanism is movable between the support position and a second release position.

7. Apparatus according to claim 6, wherein the second release position permits the tool string to pass through the support mechanism prior to supporting the tool string for disassembly of the tool string.

8. Apparatus according to claim 6 or claim 7, wherein the support position is located between the first and the second release positions.

9. Apparatus according to any of the preceding claims, wherein the tool string is a coiled tubing tool string.

10. A method of assembling a tool string comprising introducing a body member into a borehole and releasably securing the body member to an internal profile in the borehole, supporting a first portion of the tool string to be assembled on the body member to support the said portion in the borehole, introducing a second portion of the tool string into the borehole, coupling the second portion to the first portion to assemble the tool string, and subsequently releasing the assembled tool string from the body member.

11. A method according to claim 10, the method further comprising pulling upwardly on the tool string after the second portion has been coupled to the first portion and releasing the upward pull before subsequently releasing the assembled tool string from the body member.