Seal assembly releasing tool

A seal assembly releasing tool is shown having an outer support case and an inner unlocking element rotatably mounted on a shaft and coupled by a planetary gear train. The seal assembly is provided with cam surfaces into which cam followers latch for securely connecting the tool to the seal assembly and enabling the outer case to turn the assembly in one direction while the inner element turns the locking sleeve of the seal assembly in the other direction to release the seal assembly.

BACKGROUND OF THE INVENTION 
The present invention relates to a seal assembly releasing tool and, more 
particularly, to a releasing tool which may be landed on a casing hanger 
seal assembly of a well, such as an oil well, and rotated in one direction 
to lock with the casing hanger seal assembly thus permitting the tool to 
rotate in the opposite direction for releasing the seal assembly from the 
outer well head casing. 
In conventional wells including oil wells used for subsea drilling, it is 
common to use an outer well head casing through which is run an inner well 
head casing. As the subsea wells often extend some 6,000 feet to the sea 
floor, it is necessary to assemble the riser runs in sections. In order to 
do this, it is clear that means must be provided for connecting and 
sealing the inner and outer well head casings. 
After the outer well head casing has been assembled by bolting or otherwise 
fastening the casings together, the inner well head casing is lowered one 
section at a time to the sea floor. As each inner well head casing is put 
into its desired position, a casing hanger member, attached to the top of 
the inner well head casing is landed on a shoulder formed on the inner 
surface of the outer well head casing and latched thereto by resilient 
means, for example. 
The casing hanger may then be cemented into its desired position by use of 
a so called land and cement casing hanger tool. One example of a tool for 
landing an assembly which incorporates the casing hanger with a seal is 
shown in U.S. Pat. No. 3,273,646, which issued Sept. 20, 1966, by R. W. 
Walker, entitled Circulating Casing Hanger Assembly. 
Another approach to casing sealing is to use two separate running tools, 
one to land a casing hanger, and the second to land a separate casing 
hanger seal assembly upon the top of the casing hanger member. By rotation 
of the running tool attached to the seal assembly, the casing hanger seal 
assembly is locked into place against the inner surface of the outer well 
head casing and the outer surface of the inner well head casing. Provision 
is then made to pressure test the assembled seal. 
If a faulting seal is found, it will be necessary to remove the casing 
hanger seal assembly. Before this invention, when this necessity arose, 
the running tool which was used to assemble the casing hanger steel 
assembly was used by rotation in an opposite direction from its 
installation rotation to disassemble the seal. In this situation, it was 
hoped that the seal assembly would break loose and free itself before the 
drill pipe connection between the casing hanger member and the inner well 
head casing, for example, would break loose. When the seal assembly was 
not the first to break loose from its connection with the inner surface of 
the outer well head casing, substantial problems were created retrieving 
the seal. 
One of the earliest solutions to the problem of retrieving a loose tool 
within a well is discussed in U.S. Pat. No. 1,737,305, which issued Nov. 
26, 1929, by C. T. Flemming, entitled Fishing Tool Attachment. This patent 
discloses a fishing tool which includes a planetary gear arranged for 
providing a reversible direction of rotation to allow unscrewing of tools 
or pipes, other than oil well tools or pipes. This tool relies on wedges 
to engage the inner surface of a well casing. Once engaged, the wedges 
cause a reverse rotational motion to be transmitted through planetary 
gears to a center piece which threadably engages the tool to be retrieved. 
This tool does not lend itself to the retrieval of seal assemblies, 
however. 
Other planetary gear devices have been proposed for use in disconnecting 
well pipes which employ a planetary gear, including: U.S. Pat. No. 
1,627,842, issued May 10, 1927 by C. R. Edwards; U.S. Pat. No. 3,322,006, 
issued May 30, 1967 by C. C. Brown; and U.S. Pat. No. 3,434,543, issued 
Mar. 25, 1969 by D. D. Webb. None of these devices are designed to engage 
and retrieve a seal assembly. The releasing tool of the present invention 
was developed to assure proper engagement with a seal assembly and a 
timely release and retrieval thereof. Accordingly, an object of the 
present invention is to provide a seal assembly releasing tool which may 
be used to release the casing hanger seal assembly from engagement with 
the inner and outer surfaces of outer and inner well head casings. 
BRIEF DESCRIPTION OF THE INVENTION 
In accomplishing the foregoing object, there is provided a specially 
adapted tool which is attached to a running string that may be lowered 
into an outer well head casing to remove a faulting casing hanger seal 
assembly. The lower termination of the running string includes a support 
casing which has attached at its lower terminus a plurality of spring 
loaded cam followers which engage recessed cam surfaces located in the 
inner upper periphery of the casing hanger seal assembly. The cam recesses 
and cam followers act as detents which positively engage the seal assembly 
and prevent further rotation of the support case. 
Further rotation of the running string is then translated through a 
planetary gear arrangement to an inner unlocking element which is 
rotatably mounted within the support case. With the support case 
restraint, the clockwise, for example, rotation of the running string 
causes a counterclockwise rotation of the unlocking element. Located at 
lower portions of the locking element is a second set of detents whose cam 
followers engage cam recesses located in a locking sleeve of the seal 
assembly. Continued rotation of the running string causes the second set 
of detents to rotate the locking sleeve thus lowering the toroidally 
shaped locking cam within the seal assembly and releasing locking wedges 
for freeing the seal assembly from the inner surface of the outer well 
head casing. The seal assembly may then be removed from the outer well 
head casing. 
After the faulty seal assembly has been removed, the last installed inner 
well head casing and casing hanger member which remains may then be 
rewound or a new seal may be inserted for testing.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, FIG. 1 illustrates the seal assembly 10 for 
a casing hanger being installed within the inner diameter of an outer 
wellhead casing 12 by a running string 14. The running string 14 lowers 
the seal assembly until it lands upon a casing hanger 16. The casing 
hanger 16 was previously landed upon an upperly directed sloping support 
shoulder 18 formed within the inner diameter of the outer casing 12. The 
casing hanger 16 is retained against shoulder 18 by a resilient snaps 20 
which are spring loaded by springs 22, FIG. 2. The casing hanger may then 
be cemented in place as described in Patent 3,273,646 by R. W. Walker. 
As the casing hanger 16 is landed and retained in its desired position, it 
carries with it an inner well head casing 24 which is also landed on a 
seal assembly 10 previously assembled in the next lowered section of the 
riser run. With the casing hanger 16 and inner wellhead casing 24 in 
place, it is then desired to insert the seal assembly 10 prior to lowering 
the next casing hanger. This is accomplished through the use of the 
running string 14 to which is attached a seal assembly running tool 26 
which comprises a tubular continuation of the running string 14 having a 
toroidally shaped lower section 28. The lower section 28 is provided with 
opposite cam follower receiving chambers 30 the inner surfaces of which 
have been drilled and taped to receive mounting bolts 32. A cam follower 
34 is inserted into the cam chamber 30 and retain therein by bolts 32 
which also retain springs 38 that urge the cam follower 34 away from the 
inner surface of cam chamber 30. Cam followers 34 extends beyond the outer 
surface of the toroidally shaped section 28 to form a locking detent that 
will be described below. The upper surface of the lower section 28 is 
relieved to form a shoulder 39 that receives a locking collar 40 which is 
retained on the running tool 26 by a retaining collar 42 that fits into an 
annular groove 44 formed on the upper surface of collar 40. An annular 
sleeve bearing 46 is configured to fit within the annular groove 44 to 
rotatably support the tool 26 upon collar 40 when the tool is landed on 
seal 10. 
The seal assembly 10 comprises a tubular member 48 whose upper edge 50 it 
tapers inwardly to receive and align the locking collar 40. The inner 
surface of member 48 is outwardly relieved to form an annular chamber 52 
which receives a reduced male section 54 formed on the lower portion of 
collar 40. Just below the upper edge 50 of the tubular member 48 are bored 
a plurality of apertures 56 into which are inserted shear bolts 58. The 
shear bolts 58 engage apertures 60 within the outer surface of section 54. 
The shear bolts retain the seal assembly 10 upon the running tool 26 until 
such time as it is desired to remove the running tool. 
The remaining portion of the seal assembly 10 consist generally of the 
tubular member 48 whose is relieved by a plurality of ports 62 which 
receive wedge members 64. The wedge members 64 are actuated by a 
toroidally shaped tapered collar 66 which is raised and lowered by a 
locking sleeve 68 that engages the tapered collar 66 through screw 
threads, such as acme threads. 
The locking sleeve 68 is retained within the lower inner diameter of the 
tubular member 48 by a detent collar 70 which is attached to member 48 by 
screw threads. Extending from the lower surface of detent collars 70 are a 
plurality of spring loaded detents 72 mounted upon a thread stud 74. 
Attached to the outer surface of the detent collars 70 is a seal mounting 
sleeve 76 whose upper surface is counterboard at 77 to receive a plurality 
of bolts 78 urged in a downward direction by springs 79. The lower surface 
of the sleeve 76 is relieved to allow its inner and outer diameter to form 
an annular sleeve which receives a seal 80. A similarly configured lower 
seal sleeve 82 is provided with a similar set of counterboards and bolts 
78 urged in an upward direction by springs 79. 
It will be seen that the seal 80 has an H-shaped cross section with 
threaded inserts 84 which receive the spring loaded bolts 78. In this 
manner, the seal is retained to the upper seal sleeve 76 and retains the 
lower seal sleeve 82. A cap 86 is attached to the lower surface of the 
lower seal sleeve 82 which lands upon a shoulder 87 formed in hanger 16 to 
complete this portion of the assembly. The inner surface of the lower seal 
sleeve 82 is thread free and abuts against external threads on the casing 
hanger 16 which act as a labyrinth seal. 
The details of the wedge members 64 may be more fully explained with 
reference to FIG. 3 where it will be seen that port 62 is provided with a 
pair of shoulders 88 along its inner upper surfaces. The upper edges of 
the wedge 64 are also slotted at 89 to receive a pair of rolling pins 90. 
The lower surface of the wedge 64 is provided with a pair of apertures 
into which are inserted springs 92, FIG. 1. As seen best in FIG. 3, the 
inner surface of the locking sleeve 68 is provided with a plurality of cam 
surfaces or detents 94 which receive the cam followers 34. 
As the running tool 26 is lowered through the inner diameter of the outer 
well head casing 12, the seal assembly 10 is landed on and brought into 
engagement with the casing hanger 16. The running tool 26 is then rotated 
to cause the rotation of the seal assembly 10 and the engagement of 
detents 72 into apertures in the upper surface of casing hanger 16. As the 
detents 72 engage, continued turning causes the cam followers 34, engaged 
within cam surfaces 94, to exert enough torque upon the locking sleeve 68 
to cause its rotation, thus raising the tapered collar 66. As the tapered 
collar 66 raises, it causes the wedges 64 to extend outwardly upon rollers 
formed by pins 90. It will be seen that the outer surface of the wedges is 
threaded with a fine pitch thread which matches a similar thread on the 
inner surface of casing 12. Continued rotation of tool 26 causes the 
tapered collar 62 to rise further and fully extend the wedge member 64 
which threadably engage the inner threads on well head casing 12 causing 
the tubular member 48 to move in a downward direction for urging the upper 
seal sleeve 76 against the seal 80 thus expanding it and sealing the seal 
assembly 10 between the inner diameter of the outer casing 12 and the 
outer diameter of casing hanger 16. 
The lower section of the running tool 26 which fits within the inner 
diameter of the inner well head casing 24 previously lowered with the 
casing hanger 16 is provided with a seal, not shown. It is now possible to 
pressurize the outer casing 12. That pressure passes through ports 96 and 
down into the inner diameter of casing 24. In this manner, the seal 
assembly 10 can be pressure tested before it is finally locked into place. 
If the test is not satisfactory, the seal assembly may be immediately 
retrieve by reversing the rotational motion of the running tool. 
If the seal is satisfactory, the tool 26 is removed by pulling the tool in 
a vertical direction which shears the shear bolts 58, FIG. 2, for freeing 
the locking collar 40 from the tubular seal assembly member 48. In the 
prior art, if the seal was not satisfactory or if it became necessary to 
remove the seal assembly 10 after the running tool 26 had been removed, 
the running tool was reinserted. By rotating the tool to the left it was 
hoped that the seal assembly would break loose before the drill pipe 
connection. As this method was not satisfactory in many situations, the 
seal assembly releasing tool of the present invention was developed. 
As seen in FIG. 4, a running string 98 is extended through the inner 
diameter of the outer well head casing 12 with a seal assembly releasing 
tool 100 attached to its lowermost end. The inner diameter of the 
lowermost end of running string 98 is outwardly relieved and threaded to 
receive a sleeve 102 whose outer surface mounts a gear 104. The outer 
surface of the lower most end of running string 98 includes an outwardly 
extending annular shoulder 106 which mounts a seal assembly retaining 
collar 108. The retaining collar 108 forms part of a support case 110 
whose lower surface is inwardly relieved to fit within the tapered edge 50 
of tubular member 48. 
The relieved surface of the support case 110 which extends below the member 
48 includes cam follower chambers 112 which receive cam followers 114 
similar to cam followers 34 which are retained within the recess 112 by 
bolts 116 and spring 118. Mounted within the support case 110 is an 
unlocking element 120 which extends beyond the lower portion of the 
support case 110 and includes a lower tubular member 121 having cam 
follower chambers 122 which mount cam followers 124. Unlike the cam 
followers 114, the cam followers 124 are mounted on bolts 126 which 
provide a sliding surface for the follower that is urged in an outward 
direction by springs 128 which fit into recesses 129 between the bolts 126 
rather than about the bolts as do springs 118. 
The remaining portion of the support 110 includes an annular collar 130 
attached to the lower surface of collar 108 by bolts 132. Extending from 
the lower surface of the collar 130 is an annular sleeve 134 which has 
been centrally bored to receive a shaft 136. The side walls of the sleeve 
134 are milled to receive a gear 138 having a center bore through which 
the shaft 136 may pass which is retained within the bore by a clipring 
140. 
The support case 110 fits within a relief 141 on the lower surface of 
collar 130 and is retained therein by bolts 142. The inner surface of the 
support case 110 receives the unlocking element 120 which has a pair of 
sleeve bearings 144 mounted in grooves 145 in the outer surface for 
sliding engagement with the inner surface of support case 110. The inner 
surface of the unlocking element 120 mounts a gear 146 which interacts 
with gears 138 and 104. The lower portion of the unlocking element 120 
includes a horizontal shoulder 148 and sleeve 150 which fits within the 
inner diameter of the lower section of support case 110. An annular 
bearing 152 mounts between the shoulder 148 of unlocking element 120 and 
the support case 110 to provide rotational support for the unlocking 
element 120. Similarly, a second annular bearing 154 mounts between the 
lower surface of shoulder 106 and the upper surface of collar 130 to 
permit the support case 110 to rotate on the shoulder 106 of running 
string 98. 
It will be seen that the completed seal assembly releasing tool 100 shown 
in FIG. 4 may be lowered into an outer well head casing 12 and landed upon 
the seal assembly 10. As the seal assembly releasing tool 100 is inserted 
into the seal assembly 10, tapered surfaces 156 on both cam followers 114 
and 124 engage similar tapered surfaces 50 and 158 on the tubular member 
48 and yield inwardly against the urging of springs 118 and 128, 
respectively. The lower most outer edge of the support case 110 is tapered 
at 160 to engage the tapered innner surface of the member 48. As these two 
surfaces meet, the tool 100 is firmly landed upon the seal assembly 10. 
Rotation in a clockwise direction, for example, when viewed from above, of 
riser string 98 will cause the support case 110 and, perhaps, the 
unlocking element 120 to rotate in the clockwise direction. As each cam 
follower 114 engages a key way 152 in the outer diameter of member 48, it 
extends into that recess under the urging of springs 118 and is latched 
therein. With the cam 114 latched, the rotational motion of support case 
110 ceases. Further clockwise rotation, counterclockwise in the bottom 
view of FIG. 5, of the string 98 causes continuing rotation of the sleeves 
102 and gear 104. With the outer surface of support case 110 now locked 
firmly in place, the string 98 and sleeve 102 will now begin to rotate 
free of support case 110 including collars 108 and 130. Gear 104 will thus 
cause the rotation of gear 138 about shaft 136, which, in turn, will 
rotatably drive gear 146 for rotating the unlocking element 120 in a 
counterclockwise direction, clockwise in FIG. 5. As the unlocking element 
turns, the cam follower 124 will engage the recess 94 located within the 
locking sleeve 68. 
Once the cam follower 124 has engaged the cam surface 94 formed by this 
recess, the cam will transmit counterclockwise rotation to the locking 
sleeve 68 for unscrewing and lowering the tapered collar 66 and freeing 
wedge members 64. Further rotation will free the seal assembly 10 from the 
well head casing 12 and permit the removal of the seal assembly 10 and its 
releasing tool 100. It will be seen that this operation permits the 
removal of the seal assembly 10 without breaking the threaded drill pipe 
connections. Once the seal assembly is free, it can be raised by 
retrieving the string 98. 
The seal assembly releasing tool has been described as having cam followers 
mounted upon inner and outer concentric members which may be rotated in 
opposite directions by a planetary gear system. Clearly, the specific 
arrangement of the cam followers may be varied provided the cams are 
arranged on two oppositely rotating sleeves, one having a larger outer 
diameter than the other for engagement with two apertures one having a 
larger inner diameter than the other. While the cam surfaces may be 
varied, it will be understood that other modifications and variations are 
possible within the framework of the invention as claimed. Accordingly, 
the invention should be limited only the by the following claims.