Well tool locking system for staggered bore

A well tool locking system adapted for releasably locking a lock mandrel and surface-controlled subsurface safety valve in a staggered well bore is disclosed. The subject locking system comprises a collapsible, slidably engaged no-go ring and locating dogs that are operatively coupled to a locking sleeve to pre-prop locking keys in the annular recesses of a landing nipple prior to applying control line pressure to the safety valve. The subject locking system is designed to lock in the direction of flow, does not require the use of shear pins, and will not release from the running tool until the safety valve is activated and the lock mandrel locking keys are fully engaged with the landing nipple.

TECHNICAL FIELD OF THE INVENTION 
This invention relates to well tools, and more particularly, to a locking 
system suitable for use with a wireline tool string. The locking system of 
the invention is particularly useful for releasably locking a well tool 
such as a surface-controlled subsurface safety valve (SCSSV) in a 
staggered well-bore. 
BACKGROUND ART 
Lock mandrels useful for releasably locking other well tools such as a 
wireline-retrievable SCSSV inside a flow conductor are well known. Such 
lock mandrels have previously been disclosed, for example, in U.S. Pat. 
Nos. 4,545,434 and 4,745,974. These patents teach the use of a running 
tool in a wireline tool string for driving a lock mandrel having a SCSSV 
connected to it into a landing nipple disposed in the flow conductor of a 
well. The safety valve and lock mandrel are driven downwardly into the 
landing nipple until a fixed no-go ring on the outer surface of the lock 
mandrel contacts an opposing no-go shoulder in the landing nipple. The 
running tool is not releasable from the lock mandrel until the SCSSV has 
been pressured open, permitting the running tool core to drop, and until 
the locking keys have engaged in the locking annulus of the landing 
nipple. The locking keys in the lock mandrel are engaged by jarring 
upwardly on the running tool. 
Although the locking systems disclosed in U.S. Pat. Nos. 4,545,434 and 
4,745,974 possess significant advantages when compared to the conventional 
locking systems previously known, problems have been encountered in using 
those locking systems when the wellbore is staggered or graduated between 
the landing nipple and that section of the bore in which the SCSSV is set. 
In such situations, the control line pressure exerted to pump the safety 
valve open during the locking process instead forces the lock mandrel and 
valve assembly upward before the lock mandrel locking keys can be set due 
to the area differential in the two sections of the staggered bore. 
To avoid the foregoing problem, specially modified running tools, safety 
valves and landing nipples have been required to utilize the locking 
systems disclosed in U.S. Pat. Nos. 4,545,434 and 4,745,974 in staggered 
well-bores. These modifications permit the running tool to temporarily 
lock the lock mandrel in the landing nipple while the safety valve is 
being pressured open prior to completion of the locking procedure and 
removal of the running tool. 
A releasable well tool locking system is therefore needed that can be used 
in a flow conductor having a staggered internal bore without the need for 
a specially modified running tool, safety valve or landing nipple. Such a 
locking system will preferably comprise a lock mandrel adapted to pre-prop 
the lock mandrel locking keys in the annular receptacle of the landing 
nipple to prevent the lock mandrel from being forced upward and out of 
alignment with the annular receptacle of the landing nipple while the 
safety valve is being pressured open. A preferred well tool locking system 
for use in staggered bores will desirably achieve the foregoing objectives 
in a structure that is adapted to be locked by a sleeve moving in the flow 
direction; that will not release the running tool unless the safety valve 
is functional and securely locked by the lock mandrel in the landing 
nipple; and that does not require the use of shear pins to release and 
remove the lock mandrel and safety valve from the well-bore. 
SUMMARY OF THE INVENTION 
The well tool locking system disclosed herein comprises a collapsible, 
moving no-go that facilitates setting and releasably locking a lock 
mandrel in a well having a staggered internal bore. 
According to a preferred embodiment of the invention, the subject locking 
system comprises a lock mandrel further comprising a collapsible, slidable 
no-go that cooperates with the locking sleeve to pre-prop the lock mandrel 
keys when the lock mandrel and a well tool such as a SCSSV are driven into 
engagement with a conventional landing nipple. The collapsible, slidably 
engaged no-go of the invention preferably comprises a snap ring adapted to 
selectively engage and conform to adjacent graduated-diameter sections of 
the lock mandrel locking sleeve. The subject no-go preferably further 
comprises diametrically opposed locating dogs adapted to project outwardly 
through windows in the locking key retainer sleeve prior to locking for 
contacting a cooperating no-go shoulder in the landing nipple. After 
locking, the subject no-go ring is collapsed, drawing the locating dogs 
radially inward and out of contact with the landing nipple. 
According to another embodiment of the invention, a well tool locking 
system is provided that comprises a lock mandrel adapted to releasably 
lock a well tool such as a SCSSV in a staggered bore through the use of a 
locking sleeve that actuates the lock mandrel locking keys while moving in 
the flow direction. 
According to another embodiment of the invention, a well tool locking 
system is provided that comprises a lock mandrel adapted to be released 
from the running tool used to install the lock mandrel and a well tool 
such as a SCSSV in a staggered well bore only after the SCSSV has been 
operatively coupled to the control line hydraulic system and after the 
lock mandrel locking keys have fully engaged the locking annulus of the 
landing nipple.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, running tool 10, lock mandrel 12 and safety valve 14 
are shown as they are operatively coupled when being run into well bore 16 
as part of a wireline tool string. Running tool 10 used for installing 
lock mandrel 12 has a fishing neck 20 provided with standard wireline 
features for connection in a wireline tool string, not shown. Neck 20 
includes a reduced diameter threaded upper end portion 21 and an external 
annular flange 23. Running tool 10 further comprises running tool top sub 
22, threadedly engaged upper setting sleeve 24, retainer sleeve 26, core 
28 and coil spring 30. Retainer sleeve 26 and core 28 are maintained in 
fixed longitudinal alignment by pin 32 extending through window 34 in 
upper setting sleeve 24. Running tool 10 further comprises lower setting 
sleeve 36 and insertion sleeve 38. Insertion sleeve 38 is held on core 28 
by pin 40 extending through slot 42. Spring 44 cooperates with pin 40 to 
bias insertion sleeve 38 upwardly against shoulder 46 of core 28. The 
downwardly extending end portion of running tool 10 comprises core adapter 
nut 52 and adjustable core extension assembly 48 further comprising 
annular stop plate 50. Radially expandable retainer dogs 54 releasably 
couple running tool 10 to fishneck 108 on head 56 of lock mandrel 12 
during installation of lock mandrel 12 and safety valve 14 in well bore 
16. 
Referring to FIGS. 1 and 8, lock mandrel 12 preferably further comprises 
locking key retainer sleeve 58, locking keys 60, locking sleeve 62, 
locking sleeve retainer ring 64 and collapsible no-go ring 66 further 
comprising no-go locating dogs 68. Referring to FIGS. 1 and 7, locking 
keys 60 are fully retracted within windows 70 of locking key retainer 
sleeve 58 to avoid impeding the insertion of lock mandrel 12 into well 
bore 16. Windows 72 in locking key retainer sleeve 58, shown in greater 
detail in FIG. 9, are provided to permit no-go locating dogs 68 to extend 
therethrough during landing and locking of lock mandrel 12 in landing 
nipple 18. During insertion of running tool 10, lock mandrel 12 and safety 
valve 14 into well bore 16, locking sleeve 62 is maintained in the 
position shown in FIG. 1 by an interference fit with locking sleeve 
retainer ring 64, which is a snap ring, and by locking lugs 74 which 
extend into annular recess 76 on the inwardly facing surface of locking 
sleeve 62. 
Safety valve 14 preferably further comprises piston 78 slidably disposed in 
bore 80 and adapted to be actuated by hydraulic pressure applied through 
port 82 and annulus 84 against annular lug 86. 
Referring to FIG. 2, lock mandrel 12 and safety valve 14 are driven into 
landing nipple 18 to the point where no-go locating dogs 68 contact 
inwardly facing annular no-go shoulder 88. When no-go locating dogs 68 
contact annular shoulder 88, no-go locating dogs 68 and no-go ring 66 are 
caused to slide upwardly until external no-go shoulder 69 on locking key 
retainer sleeve 58 stops against annular no-go shoulder 88 in landing 
nipple 18. As no-go locating dogs 68 slide upward, top edge 92 of no-go 
ring 66, which abuts outwardly facing annular notch 94 of locking sleeve 
62, causes locking sleeve 62 to travel upwardly the same distance. As 
locking sleeve 62 moves upward, beveled shoulder 96 of locking sleeve 62 
contacts and slides past cooperating bevelled shoulder 98 of locking keys 
60, causing locking keys 60 to be forced radially outward through windows 
70 to partially engage cooperating recesses 90 in landing nipple 18. 
The use of no-go locating dogs 68 that can slide upwardly in windows 72 
upon contact with annular shoulder 88 of landing nipple 18 to cause 
bevelled shoulder 96 of locking sleeve 62 to pre-prop or partially engage 
locking keys 60 in annular recesses 90 of landing nipple 18 is a 
significant feature of the present invention that is not disclosed by the 
prior art. This pre-prop locking feature prevents lock mandrel 12 and 
locking keys 60 from being pressured upward out of alignment with annular 
recesses 90 of locking nipple 18 whenever hydraulic force is applied 
through control line 104, port 82 and annulus 84 to lug 86 of piston 78 of 
safety valve 14 in a flow conductor having a staggered internal bore. 
FIG. 11 discloses a portion of safety valve 14 disposed below locking key 
retainer sleeve 58 of lock mandrel 12 in which piston 78 is shown in the 
same position as in FIG. 2, after lock mandrel 12 is landed in landing 
nipple 18. Shoulder 138 of landing nipple 18 defines the beginning of a 
downwardly extending, inwardly staggered bore section, as shown adjacent 
to packing 140, that has a diameter smaller than that of the upwardly 
extending bore section adjacent packing 118. 
As lock mandrel 12 is landed in landing nipple 18, bottom edge 106 of 
running tool top sub 22 as shown in FIG. 1 slides downward over retainer 
sleeve 26 into contacting and abutting relation with fishneck 108 of lock 
mandrel 12. As running tool top sub 22 slides downward over retainer 
sleeve 26, upper setting sleeve 24 moves downward to a point where 
internal annular recess 110 of upper setting sleeve 24 is aligned with 
transfer lug 112 in lower setting sleeve 36 aligned with recess 114 of 
core 28. Simultaneously, top edge 116 of window 34 moves downward relative 
to pin 32, thereby compressing coil spring 30. 
After lock mandrel 12 is landed in landing nipple 18, locking keys 60 are 
pre-propped in annular recesses 90 of landing nipple 18 and running tool 
top sub 22 is forced downward over retainer sleeve 26 into contacting and 
abutting relationship to fishneck 108 of lock mandrel 12. Hydraulic 
pressure is applied to annular lug 86 of safety valve piston 78 from a 
surface valve (not shown) through control line 104. Referring to FIGS. 3 
and 11, packing 118, 140 between locking key retainer sleeve 58 and the 
interiorly facing surface of landing nipple 18 confine hydraulic fluid in 
annulus 120 and directs the fluid through port 82 into annulus 84. As 
safety valve 14 is pressured open, valve piston 78 is forced downward, 
permitting core 28 of running tool 10 to drop under gravitational force, 
partially relaxing coil spring 30. As core 28 drops, recess 114 moves 
downward past transfer lug 112 camming transfer lug 112 into internal 
annular recess 110 of upper setting sleeve 24. Because lower setting 
sleeve 26 is at this point connected to upper setting sleeve 24 by 
transfer lug 112 and to locking sleeve 62 by locking lug 74, lock mandrel 
12 is in a position to be fully locked by jarring upwardly on top sub 22 
of running tool 10. Unless locking keys 60 are pre-propped into annular 
recesses 90 as safety valve 14 is pumped open, the differential pressure 
caused by the staggered internal bore will force lock mandrel 12 and 
safety valve 14 upwardly relative to landing nipple 18, simultaneously 
forcing locking, keys 60 out of alignment with annular recesses 90. 
Referring to FIG. 3, because locking keys 60 are pre-propped into annular 
recesses 90 as described above, annular recesses 90 limit locking keys 60 
and lock mandrel 12 from further upward motion relative to landing nipple 
18 until locking keys 60 are fully locked as described below. 
Referring to FIG. 4, running tool 10 is jarred upwardly by the wireline 
equipment (not shown) causing upper setting sleeve 24, co-acting with 
lower setting sleeve 36 through transfer lug 112 and locking lugs 74, to 
force locking sleeve 62 upward to a position where locking keys 60 are 
fully engaged in annular recesses 90 of landing nipple 18. As bevelled 
shoulder 96 moves upward under locking keys 60, locking sleeve retainer 
ring 64 is cammed radially outward by annular boss 100. Annular boss 100 
is more clearly depicted in FIG. 6, although the relative positions of 
locking sleeve 62, boss 100, locking key retainer sleeve 58 and locking 
key 60 as shown in FIG. 6 correspond to the relative positions of those 
elements as shown in FIG. 1, before bevelled shoulder 96 of locking sleeve 
62 moves upward past bevelled shoulder 98 and behind the most inwardly 
extending surface 102 of locking key 60. As locking sleeve 62 fully props 
keys 60 into annular recesses 90 of landing nipple 18, annular notch 94 in 
locking sleeve 62 moves upward beyond the range of travel of no-go 
locating dogs 68 in window 72, causing no-go ring 66 to snap radially 
inward. This in turn causes no-go locating dogs 68 to be withdrawn from 
contact with annular no-go shoulder 88 within landing nipple 18. The 
diameter of no-go ring 66 is desirably sized to conform to the outer 
diameter of section 119 of locking sleeve 62. Sawcut 121 in no-go ring 66, 
as shown in FIG. 8, enables the ring to be expanded slightly for 
installing the ring around annular notch 94 during makeup of lock mandrel 
12. 
Referring to FIG. 5, once safety valve 14 is activated by pressure exerted 
through control line 104 and locking sleeve 62 has propped locking keys 60 
into their fully engaged positions relative to annular recesses 90 of 
landing nipple 18, running tool 10 can be released from lock mandrel 12 
and removed from the well bore. As lower setting sleeve 36 raises locking 
sleeve 62 to its uppermost position, locking lug 74 is cammed out of 
annular recess 76 in locking sleeve 62 and into recess 122 in insertion 
sleeve 38, thereby releasing lower setting sleeve 36 from direct 
attachment to lock mandrel 12. As locking sleeve 62 moves to its uppermost 
position relative to locking sleeve retainer ring 64, boss 100 slips 
upward past locking sleeve retainer ring 64, permitting it to snap into 
detent 124 which is more clearly shown in FIG. 6. Once locking sleeve 
retainer ring 64 has snapped into detent 124, locking sleeve 62 is 
maintained in its uppermost position so as to keep locking keys 60 propped 
outwardly into annular recesses 90 of landing nipple 18. Retainer dogs 54 
release fishneck 108 in head 56 of lock mandrel 12, and running tool 10 is 
thereafter withdrawn from lock mandrel 12. 
Once it is desired to remove lock mandrel 12 and safety valve 14 from the 
well bore, a wireline tool string having a conventional pulling tool 
assembly such as a Type "GR" pulling tool assembly manufactured by Otis 
Engineering Corporation and having an unlocking tool 126 as shown in FIG. 
10 operatively coupled to its distilled end is driven downward through the 
well bore into engagement with lock mandrel 12. Referring to FIG. 10, dogs 
128 on the unlocking tool engage annular recess 76 in locking sleeve 62 
before the collet dogs of the pulling tool (not shown) engage fishneck 108 
of head 56 of lock mandrel 12. Dogs 128 of unlocking tool 126 are forced 
radially outward by springs 130 and the spring force exerted on dogs 128 
is desirably greater than the force required to move boss 100 of locking 
sleeve 62 downward past locking sleeve retainer ring 64 so that locking 
keys 60 can be retracted out of annular recesses 90 in landing nipple 118 
into flush alignment with the outside surface of windows 70 in locking key 
retainer sleeve 58. As locking sleeve 62 is forced downward, collapsed 
no-go ring 66 is moved sufficiently downward that by advancing shoulder 
132 (as shown in FIG. 5), that locking key 60 can be fully disengaged from 
landing nipple 18 by upward jarring. 
Although the locking system of the invention is described herein in 
relation to its preferred embodiment comprising a lock mandrel and a 
surface-controlled subsurface safety valve, it will be apparent to those 
of ordinary skill in the art upon reading this disclosure that the 
collapsible, slidably engaged no-go ring and locating dogs disclosed 
herein can be similarly useful when selectively applied to other well 
tools. Once lock mandrel 12 is disengaged from landing nipple 18, it can 
be lifted out of the well by the wireline equipment. Other alterations and 
modifications of the invention will also become apparent to those of 
ordinary skill in the art upon reading the present disclosure, and it is 
intended by the inventor that the scope of the invention be limited only 
by the broadest interpretation of the appended claims to which h is 
legally entitled.