AU617586B2

AU617586B2 - Wellhead repair unit

Info

Publication number: AU617586B2
Application number: AU49280/90A
Authority: AU
Inventors: Thomas F. Bailey; Charles E. Lancaster; Richard Lee Palmer; James N. Strickland
Original assignee: Drilex Systems Inc
Current assignee: Drilex Systems Inc
Priority date: 1989-02-21
Filing date: 1990-02-08
Publication date: 1991-11-28
Anticipated expiration: 2010-02-08
Also published as: AU634093B2; CA2010326A1; AU4928090A; CA2010326C; JPH02292492A; IT1240767B; IT9047656A0; AU8389391A; NZ232571A; IT9047656A1

Description

AUSTRALIA

PATENTS ACT 1952 Form COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: 17586 Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: SPriority: Related Art: R e e o S e t I TO BE COMPLETED BY APPLICANT It I 9tto Name of Applicant: DRILEX SYSTEMS, INC.

Address of Applicant: 3317 WEST 11TH STREET HOUSTON, TEXAS 77008

U.S.A.

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: 0 WELLHEAD REPAIR UNIT.

The following statement is a full description of this invention including the best method of performing it known to me:-

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WELLHEAD REPAIR UNIT Backqround Of The Invention I. Field of the Invention This invention relates to a unit for isolating a wellhead for removal and repair of the wellhead and, in 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.

oOo II. Description of the Prior Art 0000 0o 0Various devices have been developed to isolate a well 0o 0 for removal and repair of the wellhead in a geothermal well.

s0 0 o o The extreme temperatures and pressures found in geothermal 000 wells makes it important to safely seal off the well prior "00: 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 o0 surface. Some tools include means for increasing the o0.: 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 K 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 tool. 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 reach, re-engagement may not be I r 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 0Q#0 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 o repair of the wellhead.

0. According to one aspect of the present invention there is provided a well packer mechanically settable and retrievable 0. within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: S9 oan inner mandrel; a sleeve assembly movably mounted to said inner S mandrel, said sleeve assembly selectively releasable from said Smandrel for longitudinal movement of said mandrel in a first direction relative to said sleeve assembly to set said packer; and, locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly to unset said packer, said ratchet means being selectively disengageable to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer for retrieval thereof; said sleeve assembly including at least one packing element selectively compressible into sealing engagement with the

~V.

well bore and at least one slip selectively engageable with the well bore to set said packer within the well bore.

According to another aspect of the present invention there is provided 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 release/tie back sleeve detachably connected to an upper end of said mandrel, the running tool secured to said sleeve for running and retrieving said packer from the well bore; a sleeve assembly movably mounted to said inner mandrel, 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 releasable 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 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 packer element and said at least one slip for retrieval of said packer; said release/tie back sleeve detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer.

According to another aspect of the present invention there is provided a well packer mechanically settable and Sretrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; an outer sleeve assembly mounted to said inner mandrel, said outer sleeve assembly including slip means and packing means selectively engageable with the well bore upon movement of said B4 mandrel in a first direction relative to said sleeve assembly to set said packer; locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said outer sleeve assembly to unset said packer, said ratchet means being selectively disengageable to allow longitudinal movement of said mandrel in said second direction relative to said outer sleeve assembly to unset said packer for retrieval, said ratchet means including at least one ratchet nut connected to said outer sleeve assembly and a ratchet surface formed on said mandrel; and, a release/tie back sleeve detachably connected to an upper end of said mandrel, the running tool secured to said release/tie back sleeve for running and retrieving said packer from the well bore, said release/tie back sleeve detachably connected to said mandrel by a J-slot assembly.

According to another aspect of the present invention there is provided a well packer settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: 0400*t an inner mandrel; .nde a sleeve assembly releasably attached to said inner 1 mandrel by first latching means, said sleeve assembly selectively detachable from said mandrel for longitudinal movement of said mandrel in a first direction relative to said sleeve assembly to S set said packer; and, locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly to unset 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; 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 to set said packer within the well bore.

According to another aspect of the present invention

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i" P' there is provided 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 a selectively detachable from said mandrel for longitudinal 5. movement of said mandrel in a first direction relative to said o o sleeve assembly to set said at least one packer element and said S 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 unsetting said packer, said o ratchet means being selectively releasable to allow longitudinal S movement of said mandrel in said second direction relative to said sleeve assembly to unset said at least one packer element S and said at least one slip for retrieval of said packer; said connector sub detachable from said mandrel to S leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer.

Brief Description of the Drawinq 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 4A i~-ili-- liY3 Ilin__ .4 v. 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 wall; FIGURE 4 is a perspective view of the present invention with the well packer being retrieved from the well bore; ,o FIGURE 5 is an enlarged perspective partially in 4444 ,0 cross-section of a first embodiment of the packer prior to being run into the well bore; 8 4 FIGURE 6 is an enlarged perspective partially in 8444 S 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 o 8: released packer unset by a first method; FIGURE 9 is a partial cross=sectional view of the O 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 oY present invention; and FIGURE 11 is an enlarged perspective of a second embodiment of the well packer set within the well bore.

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Detailed Description Of A Preferred Embodiment 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 16,116 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 o detachably secured to the packer 16,116. The hydraulic 0 0 0 0o extension assembly 18 controls the raising and lowering of o° the running string 20 in order to run and retrieve the 0000 oo packer 16,116 within the well bore 14. As will be oo oo oo subsequently described in greater detail, the packer 16,116 0 oo is rut into the well bore 14 using the hydraulic extension assembly 18, mechanically set in the well 14, and detached from the running string 20 to allow removal and repair of 0004 0 the wellhead 12. Once repairs are completed, the unit 10 is 0° again attached to the wellhead 12 and the running string is lowered to retrieve the packer 16,116 for continued o 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.

°oO i o. As shown in Figure 1 through 4, the repair unit includes a lubricator assembly 4 and hydraulic cylinders 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 T 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 20 which extends into the lubricator 4. The running string 9 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 tha 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 oOo first embodiment of the packer 16 hanging freely prior to 1 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 04 S packer 16 set within the well bore 14. A first embodiment 0 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 tic( 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 26 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

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ii i 7 I 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 48 which extends beneath the packing elements 44 and spacer rings 46 to essentially carry the assembly and a lower packer collar 50. The packing elements 44 and spacer rings 46 are slidably 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 receiven a slide screw 54.

i i i i i i i if i i s1 ii i iii 6%

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0D n O 0 00 0 0 0) o, 0490 0 04i ta( 4 4 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 to i 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 22 is a ratchet sleeve 58 having a ratchet surface 60 formed at the lower end thereof. Similarly, the mandrel 22 includes a ratchet surface 62 formed proximate I- the downhole end of the mandrel 22. Both ratchet surfaces and 62 are helical in the form of threads to allow rotating disengagement and permit longitudinal movement in only one direction. A lower ra nut 64 is engageable with the ratchet surface 62 of the mandrel 33 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.

a The housing sleeve 76 is connected at its upper end to the t S lower packer collar 50 and secured by set screw 78 and at S its lower end to an end sub 80 through threads 82. The Shousing sleeve 76 is also detachably connected to the S mounting sleeve 68 by second shear screw 84.

The end sub 80 includes a throughbore 86 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 commun'.cates with a port 90 in the o connector assembly 28. The ports and bores form a O selectively closable fluid bypass passageway which facilitates pressure equalization as the packer 16 is run 0 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 Y~ I the slide valve 92 to a release/tie back sleeve 98 and are 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 96 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 a00°0 amount of tension is applied to shear the bolt 106 ensuring eoo ooo that the packer 16 is set. The release/tie back sleeve 98 o S is connected to the running string 20 by threaded DU engagement.

oooo 00 Operation of the first embodiment of the present 0o0 o os 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.

Prior to running into the well bore 14 (Fig. the ratchet u0a0 0000 assembly 56 is disengaged and allowed to hang freely so long as the drag blocks 30 do not engage the casing wall 14. As so the tool is run into the hole using the running tool 20 and S controlled by the hydraulic extension system 18, the drag blocks 30 will engage the wall 14 placing a tension on the outer sleeve assembly 26. The frictional engagement of the drag blocks 20 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 mandrel 22 will cause the packer 16 to set in the well bore 14 (Fig. 3) although the packer 16 can be run downhole any necessary depth.

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 o0O. elements 44 against the packing sleeve 48. Continued .O o tension will cause lower slip cone 38 to move towards upper o o slip cone 36 forcing the slip elements 34 outwardly into o engagement with the casing will 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, With the packer 16 set within the well bore 14, additional upward tension will cause the tensile bolt 106 to *000 o, break allowing the release/tie back sleeve 98 to separate 000°" from the mandrel 22. As this occurs, the upward movement of b 0 the sleeve 98 will draw the slide valve 92 upwardly until o: fingers 96 seat within the recess 102 of the mandrel 22. 0 00 The upward movement of the slide valve 92 will have closed the lateral port 88 of the mandrel 22 by positioning the 0 o seals 94 an opposite side 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 98 removed from the well bore 14 to permit work on the wellhead 12.

Once repairs have been completed, the release/tie back sleeve 98 is run into the hole on the string 20 into engagement with the packer 16. As the release/tie back

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sleeve 98 re-engages, the slide valve 92 will be forced downwardly tco aign the ports 99 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 20 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 ooo 42 and the slip assembly 32 from engagement with the well 0.000 bore 14. Since the ratchet surfaces have not been preset 0 ao o0 0 through downward movement, the pacler 16 can be retrieved 00 0 without resetting.

0000 Since release of the packer 16 occurs when the mandrel 22 is released from the outer sleeve assembly 26, the packer ooo 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 oos oo assembly 26, from the ratchet mechanism 56 and the mandrel 00.0 22 as shown in Figure 9. A still further alternative combines shear force with threaded disengagement.

0* 0 0. Sufficient force is applied to shear screw 74 of the upper ratchet nut 66 and thereafter the upper ratchet nut is threadably disconnected form 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 20 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 embodying the present invention, the packer 116 is connected to the running string 20 by a pin 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 144 and against longitudinal movement by a pin and slot arrangement 146. A series of flexible fingers 148 facilitate reconnection of the sub 140 to the mandrel 142 as will be subsequently 0"0 described.

o o 0o Mounted coaxially to the inner mandrel 142 is an outer S sleeve assembly 150 which carries the setting components of the packer 116. The sleeve assembly 150 is releasably 9990 o secured to the inner mandrel 142 by a J-latch 12 which o 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 .o 142 includes a partial axial bore 154 to open to the bottom S of the packer 116 and extending upwardly to a point above the sleeve assembly 150. A lateral selectively closable o 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 o 116 run into the hole 14 and prior to 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 -T I I i.f .t 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.

S Positioned above the slip means 168 are a plurality of drag 0 blocks 176 which aid in setting the packer 116 by creating a frictional drag against the casing 14 to inhibit movement of 0 o o 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 o" ~against movement relative to the mandrel 142 which would 9009 S release the packer 116. In a preferred embodiment, the o locking ratchet means 180 is positioned beneath the drag blocks 176 and includes a ratchet sleeve 182 secured to the 0 94 mandrel 142 and a ratchet nut 184 mounted to the sleeve assembly 150. The ratchet nut 184 is mounted to the sleeve S44 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 i 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 L relative longitudinal movement in a second direction to release the packer 116. A :catchet 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 having the packer 116 positioned within the lubricator 4, is attached to the top flange 3 of the wellhead 12 (Fig. 1) o After opening the valve 2, the hydraulic cylinders 8 are o retracted to push the running string 20 and packer 116 through the wellhead 12 into the well bore 14 (Fig. 3) *0 0 Additional sections of running string 20 can be added until S the desired setting depth for the packer 116 has been o reached. In a preferred embodiment, once the desired depth is reached, the packer 116 is set by extending the cylinders to pull up on the running string 20 approximately one inch while 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. 5, 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 175 until the 1 j

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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 142 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 1 relative to the sleeve assembly 150 to set the packer but o will not allow the mandrel 142 to move downwardly to release the packer 116.

o With the packer 116 set in the well 14, the running *oV, string 20 can be disconnected from the packer 116 to allow the wellhead 12 to be removed (Fig. The hydraulic cylinders 5 are retracted to push the running string 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 lIst the arms of the cylinders 8 the running string 20 and connector sub 140 are removed from the hole 14 into the S lubricator 4. The wellhead valve 12 can now be replaced or repaired. Once the repairs are completed the repair unit 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

-U,

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0000 0 0 0000 an a a 0 0 000 0 00a o a oooo 0 0 0 000 9 O 0 0 0 oQa a 0 o o a a a 0 0 0 0 0 040 o o a 00 0+ 0 04* threadably/rotatably disconnected from the ratchet sleeve 182 by applying rotation to the string until the ratchets release. This allows the mandrel 142 to be moved longitudinally downwardly relative to the sleeve assembly 150 releasing the packing elements 162 and the slips 170.

Retraction of the cylinders 5 is continued until the lower J-latch 152 is relatched to allow removal of the packer 116.

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.

Claims

3. The packer as defined in 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 in said first direction while preventing longitudinal movement in said second direction.
4. The packer as defined in claim 3 wherein said ratchet sleeve 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 o *packer for retrieval. 'o 5. The 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. "'tI 6. The packer as defined in claim 1 wherein said Oat sleeve assembly includes at least one drag block to facilitate setting of said at least one packing element and l said at least one slip.
7. The packer as defined in claim 2 wherein said mandrel includes a partial axial passageway in fluid Os communication with an equalizing port.
8. The packer as defined in claim 7 wherein said release/tie back sleeve includes a lateral port selectively alignable with said equalizing port of said mandrel to provide fluid pressure equalization above and below said packer. P- I
9. The packer as defined in claim 8 wherein said release/tie back sleeve is selectively connected to said mandrel by a J-slot assembly. 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 release/tie back sleeve detachably connected to an upper end of said mandre:., the running tool secured to said sleeve for running and retrieving said packer from the well bore; a sleeve assembly movably mounted to said inner S mandrel, said sleeve assembly including at least one packing element selectively compressible into sealing engagement 4 s. with the well bore and at least one slip selectively engageable with the well bore, said sleeve assembly selectively releasable from s3aid 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 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 packer element and said at least one slip for retrieval of said packer; said release/tie back sleeve detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer.
11. The packer as defined in claim 10 wherein said sleeve assembly incl des at least one drag block engageable with the well bore to facilitate setting of said at least one packer element and said at least one slip.
12. The packer as defined in claim 10 wherein said locking ratchet means includes a ratchet surface formed on said inner mandrel and a ratchet nut connected to said sleeve assembly, said ratchet surface and said ratchet nut having cooperating ratchet surfaces which permit relative longitudinal movement in said first direction to set said packer while preventing relative longitudinal movement in said second direction to release said packer.
13. The packer as defined in claim 12 wherein said Sratchet nut includes shear means for releasing said ratchet S. nut from said 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.
14. The packer as defined in claim 12 wherein said :0 ratchet nut threadably engages said ratchet surface such that said locking ratchet means may be rotatably released to a allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to unset said packer. The packer as defined in claim 10 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 21 oo0 I1 partial axial bore forming a selectively openable equalizing fluid passageway.
16. A well packer mechanically settable and retrievable within a well bore using a running tool to selectively isolate the wellhead, said packer comprising: an inner mandrel; an outer sleeve assembly mounted to said inner mandrel, said outer sleeve assembly including slip means and packing means selectively engageable with the well bore upon movement of said mandrel in a first direction relative to said sleeve assembly to set said packer; o. locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said outer sleeve assembly to unset said packer, °°said ratchet means being selectively disengageable to allow o longitudinal movement of said mandrel in said second direction relative to said outer sleeve assembly to unset said packer for retrieval, said ratchet means including at least ore ratchet nut connected to said outer sleeve S assembly and a ratchet surface formed on said mandrel; and I a release/tie back sleeve detachably connected to an S upper end of said mandrel, the running tool secured to said S release/tie back sleeve for running and retrieving said packer from the well bore, s release/tie back sleeve detachably connected to said mandrel by a J-slot assembly. 16
17. The packer as defined in claim -5 wherein said mandrel includes a partial axial bore open to the bottom of J said packer and a selectively closable lateral port formed i in said mandrel to provide selective fluid communication between said partial axial bore and the well bore above said packer, said lateral port closable and openable upon -4 detachment and attachment of said release/tie back sleeve respectively.
18. The packer as defined in claim 16 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.
19. The packer as defined, in claim 16 wherein said ratchet nut threadably disengages said ratchet surface such that said ratchet locking means may be rotatably released by rotating said mandrel and ratchet surface relative to said :o ratchet nut and outer sleeve assembly to allow longitudinal movement of said mandrel in said second direction relative to said sleeve assembly to release said packer for retrieval from the well bore.
20. The packer as defined in claim 16 wherein said I, outer sleeve assembly includes at least one drag block A 'engageable with the well bore to facilitate setting of said slip means and packing means.
21. The packer as defined in claim 16 and 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.
22. 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; 23 0 a sleeve assembly releasably attached to said inner mandrel by first latching means, 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 packer; and locking ratchet means to selectively prevent longitudinal movement of said mandrel in a second direction relative to said sleeve assembly to unset said packer, said ratchet means being selectively unlockable to allow longitudinal nmveent of said mandrel in said second direction relative to said sleeve assembly to unset said 0 0 "o packer for retrieval. thejreof; So said sleeve assembly incl-'ding at least one packing o"o S element selectively compressible into sealing engagement with the well bore and at least one slip selectively engageable with the well bore to set said packer within the 0O. well bore.
23. The packer as -fined in claim 22 and further comprising a connector sub detachal annected to an upper end of said mandrel by second latching means, said connector o sub attached to the running tool and selectively detachable I from said mandrel whereby tension on the running tool will be transmitted to said mandrel to set said packer and said connector sub is reconnectably detachable from said mandrel Sto leave said set packer within the well bore. 0 0
24. The packer as defined in claim 23 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 movement in said first direction and preventing longitudinal movement in said second direction. 24 The packer as defined in claim 24 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.
26. The packer as defined in claim 24 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 Oo9 said packer. 0 oo o o S4 27. The packer as defined in claim 22 wherein said sleeve assembly includes at least one drag block to 0 O 0 o facilitate setting of said at least one packing element and said at least one slip.
28. The packer as defined in claim 22 wherein said first latching means comprises a J-latch assembly.
29. The packer as defined in claim 24 and further comprising an equalizing fluid passageway selectively openable to provide fluid communication above and below said sleeve assembly. '30. 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; L 4 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 packer element and said at least one slip; and locking rat iet means to selectively prevent longitudinal movement of said mandrel in a second direction 0 e o o 00 0 00o relative to said sleeve assembly unsetting said packer, said o GO ratchet means being selectively releasable to allow S longitudinal movement of said mandrel in said second oo direction relative to said sleeve assembly to unset said at o o0 least one packer element and said at least one slip for ~retrieval of said packer; said connector sub detachable from said mandrel to leave said set packer within the well bore and reconnectable to said mandrel to unset and retrieve said packer. ooo $OGG o00 31. The packer as defined in claim 30 wherein said Ssleeve assembly includes at least one drag block engageable o with the well bore to facilitate setting of said at least one packer element and said at least one slip. 9 aP
32. The packer as defined in claim 30 wherein said first latching means comprises a J-latch selectively connecting said inner mandrel to said sleeve assembly.
33. The packer as defined in claim 30 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 relative longitudinal movement in said first direction to set said packer and preventing relative longitudinal movement in said second direction to release said packer.
34. The packer as defined in claim 33 wherein said ratchet sleeve includes shear me.ans 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. The packer as defined in claim 33 wherein said ratchet nut threadably engages said ratchet sleeve such that *o 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.
36. The packer as defined in claim 30 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.
37. A well packer substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 28th day of August, 1991. DRILEX SYSTEMS, INC. By it's Patent Attorneys: GRIFFITH HACK.& CO. Fellows Institute of Patent Attorneys of Australia. 27