NZ232571A - Method and apparatus for isolating a geothermal wellhead using a retrievable packer which is ratchet settable - Google Patents

Description

2 3 2 5 7 ti Priority Duic(^): Complete f lb. 7^1.9.

Class: :,\c<o; c ft Publication D; 2 5 FEB 1993 ....

P.O. Journal, No: Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION > WELLHEAD REPAIR UNIT WE, DRILEX SYSTEMS, INC. of 3317 West 11th Street, Houston, Texas 7 7008, United States of America, <>\ op^-kjL hereby declare the invention, for which We pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: (followed by Page la) fJ .'3,} T " 1 — o <_ \) i jL WELLHEAD REPAIR UNIT Background Of The Invention I. Field of the Invention This invention relates to a unit for isolating a particular, to a packer for a wellhead repair unit which securely packs off the well to permit safe removal of the wellhead and which subsequently can be retrieved mechanically to allow continued production.

II. Description of the Prior Art Various devices have been developed to isolate a well for removal and repair of the wellhead in a geothermal well. The extreme temperatures and pressures found in geothermal wells makes it important to safely seal off the well prior to removal of the wellhead. The prior known repair systems utilize a hydraulically set packer which is dependent upon the pressure balance between the downhole pressure and the hydraulic pressure applied through the running tool from the surface. Some tools include means for increasing the gripping action within the casing in the event downhole pressure increases. To release the packer once the repairs are completed and the wellhead is replaced, the hydraulic pressure is increased to overcome the downhole pressure.

Because the past known repair units are dependent upon a critical pressure balance, variations in the downhole pressure can cause release and travel of the packer or in the extreme case a blowout of the tocl. Pressure variations may also cause the hydraulically set packer to slip down into the casing. As a result, because the retrieval tool has limited downhole ^-c^gagement may not be well for removal and repair of the wellhead and, in (followed by Page 2) possible requiring other fishing techniques or lost production. Alternatively, an increase in downhole pressure can cause the packer to form a harder grip with the casing wall requiring an increased hydraulic pressure to release the packer.

Other packers are well known for a variety of applications. However, not all packers are suitable for the environment of a geothermal well. Moreover, many packers are not retrievable and are merely drilled out when further work is needed on the well. These are not suitable alternatives for a completed and operated geothermal well.

Summary Of The Present Invention This invention overcomes the disadvantages of the prior known geothermal wellhead repair units by providing a mechanically set and released packer for the repair unit which securely packs-off the geothermal well to facilitate removal and repair of the wellhead.

The geothermal wellhead repair unit of the present invention generally comprises a hydraulic extension assembly attachable to the top flange of the wellhead valve, a running tool extending through an upper seal assembly and connected to a well packer. The hydraulic extension assembly includes hydraulic cylinders for the controlled insertion and retraction of the running tool and packer to the desired position within the casing.

A first embodiment of the invention relates to a well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead of a well for removal of the wellhead valve, said packer comprising: an inner mandrel; a connector sub detachably connected to an upper end of said mandrel, the running tool secured to said connector sub for running and retrieving said packer from the well bore; a sleeve assembly releasably connected to said inner mandrel by first latching means, said sleeve assembly including at least one packing element selectively compressible into sealing engagement with the well bore and at least one slip selectively engageable with the well bore, said sleeve assembly selectively detachable from said mandrel for longitudinal movement of said' mandrel (followed by page FC 2*2 <T7/ in a first direction relative to said sleeve assembly to set said at least one packing element and said at least one slip; and locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly, thereby preventing unsetting of said packer, said ratchet means being selectively releasable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said at least one packing element and said at least one slip for retrieval of said packer; said connector sub being detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer.

Another embodiment of the invention relates to a method of isolating a wellhead valve comprising the steps of: attaching a lubricator assembly to the wellhead valve, said lubricator having a packer positioned within said lubricator, the packer being as defined in any one of the preceding claims, a running tool releasably connected to said packer, and means for extending said running tool through said lubricator to move said packer into the well below the wellhead valve; extending said running tool to position said packer into the well below the wellhead valve; unlatching an inner mandrel of said packer from a sleeve assembly of said packer to permit longitudinal movement of said inner mandrel relative to said sleeve assembly; applying an upward tension to said running tool to move said inner mandrel longitudinally relative to said sleeve assembly to set said packer within the well below the wellhead; and disconnecting said running tool from said packer and retracting said running tool from the well and wellhead valve to leave said packer within the well.

Another embodiment of the packer includes a plurality of packing elements separated by packing spacers, a slip assembly for selective engagement with the casing wall, and a set of drag blocks to facilitate setting of the tool. The setting assemblies are disposed within an outer sleeve concentrically mounted to an inner mandrel having a pressure equalizing passageway formed therein. A J-slot connector is used at the upper end to facilitate disconnection and ; , V 2a (followed 752571 connection of the running string from the packer. The lower end of the packing tool includes a ratchet thread assembly which controls the selective setting and release of the packer and connects the outer sleeve assembly to the inner mandrel. The packer is provided with at least two means for release to ensure retrieval of the tool for further production.

The packer of the second embodiment is set through mechanical longitudinal movement of the mandrel relative to the outer sleeve assembly. As the tool is run into the hole, the frictional engagement of the drag blocks with the casing will cause the tool to be pre-loaded as a bottom ratchet nut engages a ratchet sleeve. Once the packer is positioned, the mandrel is drawn upwardly against the friction of the drag blocks causing the slip assembly and packing elements to be set against the casing. With the packer set in the casing, the running tool can be disconnected through disconnection of the release/tie back sleeve from the upper end of the packer which will also cause the pressure equalizing passageway to be closed. With the required repairs completed, the release/tie back sleeve is reconnected to the packer thereby opening the equalizing passageway. The primary and preferred method of releasing the second packer is by rotating the mandrel relative to the outer sleeve assembly to threadably disconnect the ratchet nut from the ratchet sleeve resulting in release of the packer. Other methods of release involve shear pins and added longitudinal force to release the connection between the outer sleeve assembly and the mandrel. With the packer unset, the tool can be removed from the hole for further production.

A third embodiment of the packer includes a plurality of packing elements disposed near the lower end of the tool and separated by packing spacers, a slip assembly 232 5 71] for selective engagement with the casing wall, a drag block to facilitate setting, a J-slot assembly for independent retraction of the mandrel relative to the outer sleeve assembly, and a means for equalizing the pressure above and below the packer prior to retrieving the packer from the hole. The packer is set by applying an upward force to the mandrel following disconnection of the J-assernbly to set the slips and packing elements and close the equalizer port. In order to subsequently release the packer additional upward force is applied to shear the release screw and ratchet ring. Alternatively, the ratchet ring and ratchet sleeve may be threadably disconnected to release the packer.

The method of the present invention allows mechanical isolation of a wellhead for repair or replacement of the wellhead of a geothermal well. The repair unit is attached to the top flange of the wellhead valve. The hydraulic cylinders are then retracted to push the packer into the well bore until the packer reaches the desired depth. Following setting of the packer, the running tool is released from the packer and pulled from the well. The wellhead can now be repaired or replaced. Once repaired/replaced, the repair unit is again attached to the top flange and the running tool is run through the wellhead into the hole for re-engagement with and release of the packer. Once the packer is released, the entire unit can be retrieved and removed from the wellhead.

Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.

Brief Description Of The Drawing The present invention will be more fully understood by reference to the following detailed description of a preferred embodiment of the present invention when read in 4 conjunction with the accompanying drawing in which like reference characters refer to like parts throughout the views and in which: FIGURE 1 is a perspective view of the Wellhead Repair Unit embodying the present invention mounted to a wellhead of a well bore; FIGURE 2 is a perspective view of the present invention with the well packer being run into the well bore; FIGURE 3 is a perspective view of the present invention with the well packer set within the well bore and the wellhead shown in phantom disconnected from the well; FIGURE 4 is a perspective view of the present invention with the well packer being retrieved from the well bore; FIGURE 5 is an enlarged perspective partially in cross-section of a first embodiment of the packer prior to being run into the well bore; FIGURE 6 is an enlarged perspective partially in cross-section of a first embodiment of the packer being run into the well bore; FIGURE 7 is an enlarged perspective partially in cross-section of a first embodiment of the packer set in the well bore; FIGURE 8 is a partial cross-sectional view of the released packer unset by a first method; FIGURE 9 is a partial cross-sectional view of the packer unset by a second method; FIGURE 10 is a partial cross-sectional perspective of a second embodiment of the well packer forming a part of the present invention; and FIGURE 11 is an enlarged perspective of a second embodiment of the well packer set within the well bore.

Detailed Description Of Preferred Embodiments Of The Present Invention Referring first to Figures 1 through 4, there is shown an apparatus 10 for isolating a wellhead 12 of a well bore ^ 14 for removal and repair of the wellhead 12. The repair unit 10 includes a packer 16 (corresponding to reference 116 in Figures 10 and 11) embodying the present invention for packing off the well bore 14 to permit safe removal of the well head 12. Either embodiment of the packer 16,116 may be utilized as part of the repair unit 10 since both embody a mechanically set and released packer 16,116 which provides more reliable operation. The unit 10 is mountable to the wellhead 12 and includes a hydraulic extension assembly 18 which connects to a running string 20 detachably secured to the packer 16,116. The hydraulic extension assembly 18 controls the raising and lowering of the running string 2 0 in order to run and retrieve the packer 16,116 within the well bore 14. As will be subsequently described in greater detail, the packer 16,116 is run into the well bore 14 using the hydraulic extension assembly 18, mechanically set in the well 14, and detached from the running string 2 0 to allow removal and repair of the wellhead 12. Once repairs are completed, the unit 10 is again attached to the wellhead 12 and the running string 20 is lowered to retrieve the packer 16,116 for continued production. The packer 16,116 of the present invention allows mechanical setting and retrieval of the packer 16,116 while ensuring a secure pack-off of the well bore 14. -j As shown in Figure 1 through 4, the repair unit 10 includes a lubricator assembly 4 and hydraulic cylinders 5 positioned parallel to the lubricator 4. The lubricator 4 and cylinders 5 include a mounting flange 6 to mount the repair unit to a top flange 3 of the wellhead 12 to facilitate removal or repair of the wellhead valve 2. The lubricator 4 may include a blooie line 7 to bleed the pressure from within the lubricator chamber. The hydraulic cylinders 5 include telescoping extension arms 8 which operate to move a connecting yoke 9 upwardly or downwardly. Connected to the yoke 9 is at least one section of running string 2C which extends into the lubricator 4. The running string 20 extends through a packing gland 11 at the upper end of the lubricator 4 to prevent fluid leakage out of the lubricator 4 past the running string 20. Thus, as the arms 8 of the hydraulic cylinders 5 are retracted the running string 20 will extend through the lubricator 4 and the wellhead 12 into the well bore 14.

Referring now to Figures 5 through 7, Fig. 5 shows a first embodiment of the packer 16 hanging freely prior to being run into the well bore 14, Fig. 6 shows the packer 16 as it is run into the well bore 14, and Fig. 7 shows the packer 16 set within the well bore 14. A first embodiment of the packer 16 generally comprises an inner mandrel 22 having a partial axial bore 24, outer sleeve assembly 26 which carries the setting components of the packer 16 and is longitudinally movable relative to the mandrel 22, and a connector assembly 28 which detachably connects the packer 16 to the running string 20. The packer 16 is mechanically set by applying tension to the mandrel 22 relative to the sleeve assembly 26 to set the components thereof and thereafter released by rotating the mandrel 22 relative to the sleeve assembly 26 as will be subsequently described. A secondary method of release can be accomplished by applying added tension to the mandrel 22 in the event rotation does not release the tool.

The outer sleeve assembly 2 6 includes a set of drag blocks 30 which are spring-biased outwardly to engage the casing wall 14 and provide an initial tension to the packer 16. Positioned within the sleeve assembly 26 just downhole of 7 . V o\\ *3r "■ 1 O O / 1 the drag blocks 30 are slip assemblies 32 selectively engageable with the wall 14 as the packer 16 is set to securely position the packer 16. The slip assemblies 32 preferably include slip elements 34 which have wall engaging teeth and upper slip cone 36 and lower slip cone 38 to drive the slip elements 34 outwardly into engagement with the wall 14. The slip elements 34 are retained by slip body 40. The slip elements 34 are driven outwardly into engagement with the casing 14 as upper slip cone 36 and lower slip cone 38 are drawn together beneath the slip elements 34.

Spaced downhole of the slip assembly 32 is the sealing packer 42 comprising at least one packing element 44 selectively compressible into sealing engagement with the well bore 14. The packing elements 44 are spaced apart by spacer rings 46 and are seated between an upper packer sleeve 4 8 which extends beneath the packing elements 44 and spacer rings 4 6 to essentially carry the assembly and a lower packer collar 50. The packing elements 44 and spacer rings 4 6 are slidable and sealingly engage the packer sleeve 48 to facilitate packing compression. The elements 44 are compressed into sealing engagement as the collar 50 shifts relative to the packer sleeve 48. In order to limit relative movement between the collar 50 and sleeve 48, the sleeve 48 includes a groove 52 which receives a slide screw Referring still to Figs. 5-7, disposed primarily longitudinally downhole of the packer assembly 42 is locking ratchet means 56 which selectively prevents movement of the outer sleeve assembly 26 relative to the mandrel 22 thereby locking the packer 16 in its set position. Extending beneath the packer and slip assemblies in sliding engagement with the mandrel 2 2 is a ratchet sleeve 58 having a ratchet surface 60 formed at the lower end thereof. Similarly, the mandrel 22 includes a ratchet surface roximate 54 8 the downhole end of the mandrel 22. Both ratchet surfaces 60 and 62 are helical in the form of threads to allow rotating disengagement and permit longitudinal movement in only one direction. A lower ratchet nut 64 is engageable with the ratchet surface 62 of the mandrel 22 while an upper ratchet nut 66 is engageable with the ratchet surface 60 of the ratchet sleeve 58. The ratchet nuts 64 and 66 are connected to each other by a mounting sleeve 68. The lower ratchet nut 64 is slidably secured to the mounting sleeve 68 by a torque screw 70 received within a longitudinal slot 72 of the sleeve 68. The upper ratchet nut 66 is releasably secured to the mounting sleeve 68 by a first shear screw 74. The ratchet means 56 is housed within a housing sleeve 76. The housing sleeve 7 6 is connected at its upper end to the lower packer collar 50 and secured by set screw 7 8 and at its lower end to an end sub 80 through threads 82. The housing sleeve 7 6 is also detachably connected to the mounting sleeve 68 by second shear screw 84.

The end sub 80 includes a throughbore 8 6 which communicates with the axial bore 24 of the mandrel 22. Formed at the upper end of the axial bore 24 is a lateral port 88 which selectively communicates with a port 9 0 in the connector assembly 28. The ports and bores form a selectively closable fluid bypass passageway which facilitates pressure equalization as the packer 16 is run into the hole and prior to release and retrieval of the packer 16.

The connector assembly 28 includes a slide valve 92 mounted to the mandrel 22 and having spaced apart seals 94. The port 90 is preferably formed in the slide valve 92 and the seals 94 are spaced so as to seal off the lateral port 88 of the mandrel 22 as will be subsequently described. Extending upwardly from the slide valve 92 are a plurality of connecting fingers 96. The fingers 96 detachably connect 9 the slide valve 92 to a release/tie back sleeve 98 and'Ar^'' received within a recess 100 formed in the release/tie back sleeve 98. The mandrel 22 includes a similar recess 102 to receive the fingers 95 when the slide valve 92 is drawn upwardly a predetermined distance to allow disconnection of the release/tie back sleeve 98 from the mandrel 22 and slide valve 92. The release/tie back sleeve 98 is connected to the mandrel 22 by a J-latch assembly 104. Additionally, the release/tie back sleeve 98 is detachably connected to the mandrel 22 by a tensile bolt 106 such that the sleeve 98 will release from the mandrel 22 only when a predetermined amount of tension is applied to break the bolt 106 ensuring that the packer 16 is set. The release/tie back sleeve 98 is connected to the running string 2 0 by threaded engagement.

Operation of the first embodiment of the present invention provides mechanical setting and release of the packer 16 including up to three alternative methods of unsetting the packer 16 as will be subsequently described.

The upper ratchet assembly is engaged when the tool is assembled. However, this ratchet can be subsequently release to unset the packer. Prior to running into the well bore 14 (Fig.l), the lower ratchet of the ratchet assembly 56 is disengaged from the ratchet surface 6 2 and allowed to hang freely so long as the drag blocks 30 do not engage the casing wall 14. However the ratchet assembly 5 6 (which includes both ratchets 64 and 66) is considered disengaged. As the tool is run into the hole using the running tool 2 0 and controlled by the hydraulic extension system 18, the drag blocks 30 will engage the wall 14 placing a tension on the out sleeve assembly 26. This tension is additional to that resulting from friction,between the drag blocks and the casing acting, against the weight of the outer sleeve. The frictional engagement of the — drag blocks 30 against the wall 14 will cause the mandrel 22 to move downwardly faster than the outer sleeve assembly 26 forcing the ratchet surface 62 of the mandrel 22 into engagement with the lower ratchet nut 64 pre-setting the packer 16. At this point, any upward movement of the jjandrel 22 will cause the packer 15 to set in the well bore fe. M J" 3) although the packer 15 can be run downhole any ■;V nece&sary depth. •^15 MAY 1992* »? c e i >r Once the packer 16 is positioned a sufficient depth within the well bore 14, the packer 16 can be set by applying upward tension on the mandrel 22 through the running string 20. Since the mandrel 22 is now connected to the outer sleeve assembly 26 through the lower ratchet nut 64 upward tension on the mandrel 22 will draw the outer sleeve assembly 26 against the frictional engagement of the drag blocks 30. As upward tension is applied, the force will be conducted through the lower ratchet nut 64, the mounting sleeve 68, and housing sleeve 76 against the lower collar 50 causing initial compression of the packing elements 4 4 against the packing sleeve 48. Continued tension will cause lower slip cone 38 to move towards upper slip cone 36 forcing the slip elements 34 outwardly into engagement with the casing wall 14. With the slip assembly 32 set, continued tension will cause full compression of the packing elements 44 into sealing engagement with the wall 14 as shown in Fig. 7. The ratchet sleeve 58 functions as a tension member to connect the ratchet assembly 56 to the top of the outer sleeve assembly 26 as this outer sleeve is placed in compression and after disconnection of the running line.

With the packer 16 set within the well bore 14, additional upward tension will cause the tensile bolt 106 to break allowing the release/tie back sleeve 9 8 to separate 2T(3 from the mandrel 22. / tnis occurs, the upward movement of the sleeve 98 will draw the slide valve 92 upwardly until fingers 96 seat within the recess 102 of the mandrel 22. The upward movement of the slide valve 9 2 will have closed the lateral port 88 of the mandrel 22 by positioning the seals 94 on opposite sides thereof closing the bypass passageway. The release/tie back sleeve 98 can now be disconnected from the packer 16 by disconnecting the J-latch 104 and the running string 20 and sleeve 9 8 removed from the well bore 14 to permit work on the wellhead 12.

Once repairs have been completed, the release/tie back sleeve 9 8 is run into the hole on the string 20 into engagement with the packer 16. As the release/tie back m ,J IX '■> ~ 1 •- O«.) / J. sleeve 98 re-engages, the slide valve 92 will be forced downwardly to align the ports 88 and 90 equalizing the pressure above and below the packer 16. With the running string 20 reattached the packer 16 can now be mechanically unset and retrieved. The preferred method of unsetting is to rotate the running string 2 0 and mandrel 22 relative to the outer sleeve assembly 26. This will cause the thread-like ratchets 62 of the mandrel 22 and the lower ratchet nut 64 to threadably disconnect releasing the sleeve assembly 26. Upon release the packer 16 will return to its unset position shown in Fig. 4 releasing the packer assembly 42 and the slip assembly 32 from engagement with the well bore 14. Since the ratchet surfaces have not been preset through downward movement, the packer 16 can be retrieved without resetting.

Since release of the packer 16 occurs when the mandrel 22 is released from the outer sleeve assembly 26, the packer 16 can be unset by applying additional upward tension on the mandrel 22 until the second screw 84 shears freeing the housing sleeve 76, which is secured to the outer sleeve ^ assembly 26, from the ratchet mechanism 56 and the mandrel 22 as shown in Figure 9. A still further alternative combines shear force with threaded disengagement. Sufficient force is applied to shear screw 74 of the upper ratchet nut 66 and thereafter the upper ratchet nut is threadably disconnected from the ratchet surface 60 of the sleeve 58 releasing the packer 16.

A second embodiment of the packer 116 is adapted to be run into the well 14 using the running string 2 0 and mechanically set below the wellhead 12 to isolate the wellhead 12 for removal of the wellhead 12 as will be subsequently described. Referring now to Figs. 10 and 11 which shows the mechanically set and unset packer 116 & n r Qfibodying the present invention, the packer 116 is connected A\ 0\\ 14 FEB 1992 ^ 12 coupling. to the running string 20 by a / 138 which forms a portion of a connector sub 140 utilized to selectively connect and disconnect the running string 20 to the packer 116 during operation of the repair unit 10. The connector sub 140 is releasably attached to the upper end of an inner mandrel 142 of the packer 116 which extends substantially the length of the packer 116. The sub 140 is connected to the mandrel 142 against rotation by a shear screw 14 4 and against longitudinal movement by a pin and slot arrangement 146. A series of flexible fingers 148 facilitate reconnection of the sub 14 0 to the mandrel 14 2 as will be subsequently described.

Mounted coaxially to the inner mandrel 142 is an outer sleeve assembly 150 which carries the setting components of the packer 116. The sleeve assembly 150 is releasably secured to the inner mandrel 142 by a J-latch 152 which allows the inner mandrel 142 and sleeve assembly 150 to be simultaneously run into the bore 14 and upon unlatching, allows longitudinal movement of the mandrel 142 relative to the sleeve assembly 150 to set the packer 116. The mandrel 142 includes a partial axial bore 154 open to the bottom of the packer 116 and extending upwardly to a point above the sleeve assembly 150. A lateral selectively closable port 156 provides fluid communication between the bore 154 and the exterior of the packer 116. The partial bore 154 and port 156 act as an equalizing passageway as the packer 116 is run into the hole 14 and while retrieving the packer 116. The equalizing passageway is closed after the packer 116 is set and opened prior to release of the packer 116.

Secured to the lower end of the mandrel 142 is a nose end 158. The nose 158 abuts and engages packing means 160 coaxially mounted to the mandrel 142. The packing means 160 preferably includes at least one compressible packing 13 v \ ^4 m ') ') ') r- •- «■•» •- \j element 162 separated by packing spacers 164. The packing \ elements 162 and spacers 164 are positioned between retainer ? rings 166. Positioned longitudinally above the packing means 160 is slip means 168 which includes at least one slip 170 selectively engageable with the well casing 14 to secure the packer 116 against longitudinal movement within the —^ hole. The slip means 168 includes upper and lower slip cones 172 which travel beneath the slips 170 to move the slips 170 into engagement with the casing 14 as will be subsequently described. The slips 170 are biased inwardly by slip spring 174 to facilitate release of the slips once the slip cones 172 are retracted from beneath the slips 170. Positioned above the slip means 168 are a plurality of drag blocks 176 which aid in setting the packer 116 by creating a frictional drag against the casing 14 to inhibit movement of the sleeve assembly 150 as tension is placed on the mandrel 142. The drag blocks 176 are biased outwardly into engagement with the well bore 14 by a drag block spring 178.

Referring to Fig.10 and 11, the packer 116 includes locking ratchet means 180 to lock the sleeve assembly 150 ^ against movement relative to the mandrel 142 which would release the packer 116. In a preferred embodiment, the locking ratchet means 180 is positioned radially inwardly of the drag blocks 17 6 and includes a ratchet sleeve 182 secured to the mandrel 142 and a ratchet nut 184 mounted to the sleeve assembly 150. The ratchet nut 184 is mounted to the sleeve ^ assembly 150 by a set screw 186 and biased radially inwardly into engagement with the ratchet sleeve 182 by at least one ratchet spring 188. The ratchet sleeve 182 is coaxially mounted to the mandrel 142 and selectively secured against movement relative to the mandrel 142 by at least one shear screw 190. The ratchet sleeve 182 and ratchet nut 184 have cooperating ratchet surfaces which allow relative movement ^-^^in a first direction to set the packer 116 but prevents *«• G v K" 14 1 5 MAY 1992 yjf relative longitudinal movement in a second direction to release the packer 116. A ratchet sleeve key 192 positions the ratchet sleeve 182 while aiding movement to set and lock the packer 116.

Operation of the second embodiment of the present invention allows the isolation of the wellhead 12 by setting the packer 116 below the wellhead 12 and subsequent retrieval of the packer 116 for continued operation of the well 14. Referring to the drawings, the repair unit 10, having the packer 116 positioned within the lubricator 4, is attached to the top flange 3 of the wellhead 12 (Fig. 1) . After opening the valve 2, telescopic extension arms'8 are retracted to push the running string 20 and packer 116 through the wellhead 12 into the well bore 14 (Fig. 2) Additional sections of running string 2 0 can be added until the desired setting depth for the packer 116 has been reached. In a preferred embodiment, once the desired depth is reached, the packer 116 is set by extending the cylinders 5 to pull up on the running string 20 approximately one inch after rotating the string 20 counterclockwise to unlatch the lower J-latch 152. Continued extension of the hydraulic cylinders 5 will set the packer 116. Approximately 40,000 lbs. of tension must be applied to fully set the packer 116.

As best shown in Fig. 10., the packer 116 is set following unlatching the J-latch 152 by pulling upwardly on the inner mandrel 142. With the mandrel 142 unlatched from the sleeve assembly 150, the drag blocks 176 will create a frictional resistance with the casing 14 to inhibit longitudinal movement of the sleeve assembly 150 as the mandrel 142 moves upwardly. Upward tension on the mandrel 142 will cause the nose 158 to initially compress the packing elements 162 into engagement with the casing 14. Continued tension will move lower slip cone 172 and the slip body 173 upwardly toward the upper slip cone 1.75 until the slip body 173 engages the drag blocks 176 allowing the lower slip cone 172 to pass beneath the slips 170. As the slip cones 172 and 175 move beneath the slips 170, the sloped surfaces of the cones will force the slips 170 outwardly into engagement with the casing. Continued tension will fully compress the packing elements 162 into sealing engagement with the casing. As the mandrel 14 2 is drawn upwardly relative to the sleeve assembly 150, the ratchet sleeve 182 will move beneath the ratchet nut 184 engaging the cooperating ratchet teeth. The orientation of the ratchet teeth allows upward movement of the mandrel 142 relative to the sleeve assembly 150 to set the packer but will not allow the mandrel 142 to move downwardly to release the packer 116.

With the packer 116 set in the well 14, the running string 20 can be disconnected from the packer 116 to allow the wellhead 12 to be removed (Fig. 3) . The hydraulic cylinders 5 are retracted to push the running string 20 towards the packer 116 approximately one inch and rotated clockwise to unlatch the upper latch 146 and allow removal of the connector sub 140 from the packer 116. By extending the arms of the cylinders 8 the running string 2 0 and connector sub 140 are removed from the hole 14 into the lubricator 4. The wellhead valve 12 can now be replaced or repaired. Once the repairs are completed the repair unit 10 is again attached to the flange 3 of the wellhead 12.

To retrieve the packer 116 once repairs are completed, the hydraulic cylinders 5 are retracted to move the connector sub 140 and running string 20 into the well 14. The connector sub 140 will automatically engage the top of the packer 116. Continued retraction until a force of approximately 60,000 lbs. is applied will cause screw 190 to shear releasing the ratchet assembly 180 from the mandrel 142. Alternatively, the ratchet nut 184 may be E"/V 16 •V 2325 threadably/rotatably disconnected from the ratchet sleeve 182 by applying rotation to the string until the ratchets \ 7 release. This allows the mandrel 14 2 to be moved longitudinally downwardly relative to the sleeve assembly 150 releasing the packing elements 162 and the slips 17 0. Retraction of the cylinders 5 is continued until the lower J-latch 152 is relatched to allow removal of the packer 116.

N Once released, the packer 116 can be removed by extending the cylinder arms to bring the packer 116 up into the lubricator 4. Thereafter, the valve is closed, the blooie line 7 is opened to bleed the lubricator 4, and the repair unit 10 removed from the wellhead 12 to continue production operations.

Thus, the present invention provides a mechanically set and unset packer 16,116 for use in a wellhead repair unit which ensures sealing pack-off of the well while also allowing for simple retrieval of the packer 16,116.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art without departing from the scope and spirit of the appended /' claims.

—I- el aim i 17

Claims (2)

1. WHAT WE CLAIM IS: 1. A well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; a connector sub detachably connected to an upper end of said mandrel, the running tool secured to said connector sub for running and retrieving said packer from the well bore; a sleeve assembly releasably connected to said inner mandrel by first latching means, said sleeve assembly including at least one packing element selectively compressible into sealing engagement with the well bore and at least one slip selectively engageable with the well bore, said sleeve assembly selectively detachable from said mandrel for longitudinal movement of said mandrel in a first direction relative to said sleeve assembly to set said at least one packing element and said at least one slip; and locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly, thereby preventing unsetting of said packer, said ratchet means being selectively releasable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said at least one packing element and said at least one slip for retrieval of said packer; said connector sub being detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer. - 19 - 232571 2. a packer as defined in claim 1 , further comprising a release/tie back sleeve detachably connected to second an upper end of said mandrel by/latching means, said release/tie back sleeve attached to the running tool and selectively detachable from said mandrel whereby tension on the running tool will be transmitted to said mandrel to set said packer and said release/tie back sleeve is reconnectably detachable from said mandrel to leave said set ***} packer within the well bore. 3. A packer as defined in claim i or claim 2, wherein said locking ratchet means includes a ratchet surface formed on said inner mandrel and a ratchet nut mounted to said sleeve assembly, said ratchet surface and' said ratchet nut having cooperating threaded ratchet surfaces which permit longitudinal movement of said sleeve assembly in said first direction relative to said mandrel while preventing corresponding longitudinal movement in said second direction. 4. A packer as defined in claim 3 wherein said ratchet surface and ratchet nut are threadably disengageable whereby said locking ratchet means may be rotatably released to allow longitudinal movement of said sleeve assembly in said second direction relative to said mandrel to unset said ^ packer for retrieval. 5. a packer as defined in claim 3 wherein said ratchet nut is detachably connected to said sleeve assembly whereby said sleeve assembly may be disconnected from said ratchet means to unset said packer for retrieval. 6 . A packer as defined in claim 2 wherein said mandrel includes a partial axial passageway in fluid communication with an equalizing port. 7 , a packer as defined in claim 6 wherein said release/tie back sleeve includes a lateral port selectively alignable with said equalizing port of said, ■."mariclrel to provide fluid pressure equalization above and below said packer' '22 DECmM ^ -• - . - <- ■/'' £32571 -20- 8. A packer as defined in claim 1, wherein said release/tie back sleeve is selectively connected to said mandrel by a J-slot assembly. 9. A packer as defined in any one of claims 1, 2, 3 or 8, wherein said sleeve assembly includes at least one drag block engageable with the well bore to facilitate setting of said at least one packing element and said at least one slip. 10. A packer as defined in claim 8 or claim 9, wherein said inner mandrel includes a partial axial bore open to the bottom of said packer and a selectively closable lateral port formed through said mandrel to provide selective fluid communication between said partial axial bore and the well bore above said sleeve assembly, said lateral port and partial axial bore forming a selectively openable equalizing fluid passageway. 11. A packer as defined in claim 10 when appended to claim 2, wherein the selectively closable lateral port formed in said mandrel provides selective fluid communication between said partial axial bore and the well bore above said packer, said lateral port closable and openable upon detachment and attachment of said release/tie back sleeve respectively. 12. A packer as defined in claim 9 or claim 11 when appended to claim 3, wherein said ratchet nut includes shear means for releasably connecting said ratchet nut to said outer sleeve assembly such that said mandrel and ratchet nut may move longitudinally in said second direction relative to said sleeve assembly to release said packer for retrieval from the well bore. : '' O \ 2.
2. 2 DECJ992 A ZUZ-II -21- 13. A packer as defined in claim 9 when appended to claim 3, wherein said ratchet nut threadably engages said ratchet surface such that said locking ratchet means may be rotatably released to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. 14. A packer as defined in claim 13 wherein said ratchet locking means may be rotatably released by rotating said mandrel and ratchet surface relative to said ratchet nut and outer sleeve assembly. 15. A packer as defined in claim 10 when appended to claim 8, further comprising a shear bolt connecting said release/tie back sleeve to said upper end of said mandrel, said bolt shearing prior to disconnection of said J-slot assembly. 16. A well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; a connector sub detachably connected to an upper end of said mandrel, the running tool secured to said connector sub for running and retrieving said packer from the well bore; a sleeve assembly releasably connected to said inner mandrel by first latching means, said sleeve assembly including at least one packing element selectively compressible into sealing engagement with the well bore, at least one slip selectively engageable with the well bore and drag means engaging said well bore to retard longitudinal movement of said sleeve \z 10 DEC 1992 -22- assembly, said sleeve assembly selectively detachable from said mandrel for longitudinal movement of said mandrel in a first direction relative to said sleeve assembly to set said at least one packer element and said at least one slip; and locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly, thereby preventing unsetting of said packer, said ratchet means disposed between said sleeve assembly and said inner mandrel, said locking ratchet means being selectively releasable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said at least one packer element and said at least one slip for retrieval of said packer; said connector sub being detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer. //<•> 1 L " -\ ••••v *-\\ \ *OOECJ9921 1 7-tt 5"7l - 23 - 17. A packer as defined in claim 16, wherein the connector sub is detachably connected to the upper end of said mandrel by second latching means, said connector sub being selectively detachable from said mandrel whereby tension on the running tool will be transmitted to said mandrel to set said packer,. 18.. A packer as defined in claim 17, wherein said locking ^.a^ohet. means includes a ratcnet sleeve rsleasably connected to said inner mandrel and a ratchet nut mounted to said sleeve assembly, said ratchet sleeve and said ratchet nut having cooperating ratchet surfaces which Dermit i longitudinal movement of said ratchet nut in said first direction relative to said ratchet sleeve and prevent longitudinal movement of said ratchet nut in said second direction relative to said ratchet sleeve. 19, a packer as defined in claim 18,wherein said ratchet sleeve includes means for releasing said ratchet sleeve from said inner mandrel to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. 20. K packer as defined in claim 18, wherein said ratchet sleeve and ratchet nut are threadably engageable whereby said locking ratchet means may be rotatably released to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. • \\ i ' * 0£>£Ci9i£ J 232 C7/ " 24 ~ 21. - A packer as defined in claim 16,wherein said drag means includes at least one drag block to facilitate setting of said at least one packing element and said at least one slip. 22. A packer as defined in claim 16, wherein said first latching means comprises a J-latch assembly. 23. A packer as defined in claim 18, further comprising an equalizing fluid passageway selectively openable to provide fluid communication above and below said sleeve assembly. 24. A packer as defined in claim 18, wherein said ratchet sleeve includes shear means for releasing said ratchet sleeve from said inner mandrel such that said mandrel moves longitudinally in said second direction relative to said ratchet means and sleeve assembly to release said packer for retrieval from the well bore. 25. a packer as defined in claim 18, wherein said inner mandrel includes a partial axial bore open to the bottom of said packer and a selectively closable lateral port formed through said mandrel to provide selective fluid communication between said partial axial bore and the well bore above said sleeve assembly, said lateral port and partial axial bore forming a selectively openable equalizing fluid passageway. 26. A well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; a sleeve assembly releasably attached to said inner mandrel by first latching means, said sleeve assembly selectively releasable from said mandrel for -25- 2?2C7/ longitudinal movement of said mandrel in a first direction relative to said sleeve assembly to set said packer; a connector sub detachably connected to an upper end of said mandrel by second latching means, said connector sub attached to the running tool; locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly, thereby preventing unsetting of said packer, said ratchet means being selectively unlockable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer for retrieval thereof; and an equalizing fluid passageway selectively operable to provide fluid communication above and below said sleeve assembly; said sleeve assembly including at least one packing element selectively compressible into sealing engagement with the well bore, at least one slip selectively engageable with the well bore, and drag block means engaging said well bore to facilitate setting of said at least one packing element and at least one slip to set said packer within the well bore; said connector sub selectively detachable from said mandrel to leave said packer in the well bore, tension applied by the running tool to said sub being transmitted to said mandrel for closing said equalizing fluid passageway and setting said packer, said sub reconnectable to said mandrel for opening said passageway, release of said locking ratchet means and retrieval of said packer. 27. The packer as defined in claim 26 wherein said locking ratchet means includes a ratchet sleeve detachably connected to said inner mandrel and a ratchet nut mounted to said sleeve assembly, said ratchet sleeve and said ratchet nut having cooperating ratchet surfaces which permit longitudinal m -26- 2?2T7/ movement of said ratchet sleeve relative to said ratchet nut in said first direction and prevent corresponding longitudinal movement in said second direction. 28. The packer as defined in claim 27 wherein said ratchet sleeve includes means for releasing said ratchet sleeve from said inner mandrel to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. 29. The packer as defined in claim 27 wherein said ratchet sleeve and ratchet nut are threadably engageable whereby said locking ratchet means may be rotatably released to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. 30. The packer as defined in claim 26 wherein said sleeve assembly includes at least one drag block to facilitate setting of said at least one packing element and said at least one slip. 31. A well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; a connector sub detachably connected to an upper end of said mandrel for applying tension to said mandrel in a first direction, said sub connected to said mandrel through lost motion latching means, the running tool secured to said connector sub for running and retrieving said packer from the well bore; a sleeve assembly releasably connected to said inner mandrel by first latching means, said sleeve assembly mounted on said mandrel and including at least one packing element selectively compressible into sealing engagement with the well bore, at least one slip selectively engageable with the well bore, and at least one drag block engaging the well bore to retard 2*2 T7/ -27- longitudinal movement of said sleeve assembly, said sleeve assembly selectively releasable from said mandrel for longitudinal movement of said mandrel in a first direction relative to said sleeve assembly and resistant to longitudinal movement by said drag blocks thereby setting said at least one packing element and said at least one slip into engagement with the well bore; locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly thereby unsetting said packer, said ratchet means being selectively releasable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said at least one packing element and said at least one slip for retrieval of said packer; and an equalizing fluid passageway formed through said packer to provide selective fluid communication between said well bore above and below said sleeve assembly, said equalizing passageway closed upon extension of said connector sub relative to said mandrel and opened upon contraction of said sub relative to said mandrel; said connector sub being selectively detachable from said mandrel to leave said set packer with the well bore and reconnectable to said mandrel for releasing said sleeve assembly to unset and retrieve' said packer. ,/v ';'<2 I I0DEC,9Y<.: - 28 - 2S2 5*7/ 22 • An apparatus for removal of the wellhead valve of a geothermal well, said apparatus comprising: a lubricator having means for connecting said lubricator to the wellhead valve; a mechanical packer as claimed in any one of the preceding claims, positioned within said lubricator and movable through the wellhead valve into the well, said — packer mechanically settable within the well to isolate the wellhead valve from the well for removal of the valve; a running tool releasably connected to said packer, said running tool extending into said lubricator; means for extending said running tool through said lubricator to move said packer into the well below the wellhead valve, said packer being set within the well upon the application of an upward tension through said running tool. 33 . An apparatus as defined in claim 32, wherein said packer includes a connector sub detachably connected to an upper end of said mandrel, said running tool connected to said connector sub. 34 . An apparatus as defined in claim 33, wherein said sleeve assembly is releasably attached to said inner mandrel by latching means whereby said sleeve assembly is released from said inner mandrel and an upward tension on said mandrel through said running tool and connector sub sets said packing element and said slip in the well. 35 . A method of isolating the wellhead of a well for the removal of the wellhead valve comprising the steps of: attaching a lubricator assembly to the wellhead valve, said lubricator having a packer positioned within said lubricator, the packer being as defined in any one of the preceding claims, a running tool releasably connected to said packer, and means for extending said running tool through said lubricator to move said packer into the well below the wellhead valve; * 29 2.32 5*7/ extending said running tool to position said packer into the well below the wellhead valve; unlatching an inner mandrel of said packer from a sleeve assembly of said packer to permit longitudinal movement of said inner mandrel relative to said sleeve assembly; applying an upward tension to said running tool to move said inner mandrel longitudinally relative to said sleeve assembly to set said packer within the well below the wellhead valve; and disconnecting said running tool from said packer and retracting said running tool from the well and wellhead valve to leave said packer within the well. 36- A method as defined in claim 35, wherein said packer is retrieved from the well to continue production by extending the running tool through the wellhead valve into the well, reconnecting said running tool to said packer, applying release tension through said running tool to said inner mandrel to release said packer from within the well, and retracting said running tool to move said packer into said lubricator. 3 7, A well packer mechanically settable and retrievable within a well bore using a running tool to selectively isolate the wellhead substantially as herein described with reference to any one of the Drawings. 38. An apparatus for removal of the wellhead valve of a geothermal well substantially as herein described with reference to any one of the Drawings. 30 - 232f7/ 39. a method of isolating Che wellhead of a well for the removal of the wellhead valve subscantially as herein described with reference co any one of the Drawings. DRILEX SXSTyEMS, INC. By