United States Patent £19J
`Dallas
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`US005372202A
`5,372,202
`[11] Patent Number:
`[45] Date of Patent: Dec. 13, 1994
`
`[54] WELLHEAD ISOLATION TOOL AND
`METHOD OF USE
`Inventor: Murray Dallas, 801 New England
`Ct., Allen, Tex. 75002
`
`[76]
`
`[21] Appl. No.: 160,477
`[22] Filed:
`Dec. 1, 1993
`
`Related U.S. Application Data
`[63] Continuation-in-part of Ser. No. 958,502, Oct. 8, 1992,
`Pat. No. 5,332,044.
`Int. Cl.5 .............................................. E21B 33/00
`[51]
`[52] U.S. Cl ........................................ 166/386; 166/86
`[58] Field of Search ............. 166/386, 387, 381, 86-88
`
`[56]
`
`References Cited
`U.S. PA TENT DOCUMENTS
`
`2,009,888 7/1935 Hild ······································· 166/86
`3,731,742 5/1973 Sizer et al ....................... 166/386 X
`4,427,060 1/1984 Villers, Sr ....................... 166/386 X
`4,646,844 3/1987 Roche et al. ..................... 166/86 X
`
`Primary Examiner-Michael Powell Buiz
`Attorney, Agent, or Firm-Varnum, Riddering, Schmidt
`& Howlett
`[57]
`ABSTRACT
`A wellhead isolation tool is disclosed that is unique
`because the tool has no direct connection between the
`high pressure valve and the mandrel. Well stimulation
`fluids are pumped through one or more high pressure
`bores which communicate with a mandrel injection
`head that directs the fluids into the mandrel. The injec(cid:173)
`tion head and the mandrel are enclosed in a sealed bore
`and reciprocatably movable with a piston which is used
`to stroke the mandrel into and out of a wellhead and to
`lock the mandrel in an operating position wherein ports
`in the injection head are aligned with the high pressure
`bores. The piston may be reciprocated using a mechani(cid:173)
`cal screw. A concentric mandrel embodiment providing
`a pack-off nipple expander is also disclosed. The tool
`provides superior safety features and ease of operation.
`
`15 Claims, 8 Drawing Sheets
`
`0
`
`44
`
`00001
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 1of8
`
`5,372,202
`
`0
`
`38
`
`22
`
`40
`42
`36
`
`30 ey-20
`
`38
`
`62
`
`70
`
`70....--
`
`FIG. lA
`
`58
`FIG. 1
`
`00002
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 2 of 8
`
`5,372,202
`
`0
`
`40
`42
`~~-36
`30
`"~--J62
`
`FIG. 2
`
`44
`
`~78
`
`00003
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 3 of 8
`
`5,372,202
`
`40
`42
`:::iu---- 3 6
`30
`____,,62
`
`_
`
`68
`
`-FI G. 3
`
`44
`
`_...,-78
`
`00004
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 4 of 8
`
`5,372,202
`
`72
`
`44
`
`FIG. 4
`
`...,-78
`
`vi----82
`
`00005
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 5 of 8
`
`5,372,202
`
`72
`
`40
`42
`.... ~-36 88
`
`~~ 30 6/20
`
`FIG. 5
`
`44
`
`....,--78
`
`---84
`
`00006
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 6 of 8
`
`5,372,202
`
`6~20
`
`FIG. 6
`
`44
`
`00007
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 7 of 8
`
`5,372,202
`
`30 /20
`
`44
`
`FIG. 7
`
`00008
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`U.S. Patent
`
`Dec. 13, 1994
`
`Sheet 8 of 8
`
`5,372,202
`
`114
`--120
`~~ 118
`116
`~~,....,__122
`
`90
`102
`
`30 /20
`
`44
`
`FIG. 8
`
`..,--78
`
`00009
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`1
`
`5,372,202
`
`WELLHEAD ISOLATION TOOL AND METHOD
`OF USE
`
`RELATED APPLICATIONS
`This application is a continuation in part of U.S. pa(cid:173)
`tent application Ser. No. 07 /958,502 which was filed on
`Oct. 8, 1992, U.S. Pat. No. 5,332,044.
`
`FIELD OF THE INVENTION
`The present invention relates to wellhead equipment,
`and in particular to a wellhead isolation tool useful in
`isolating wellhead equipment from the extreme pres(cid:173)
`sures, abrasive and/or caustic substances used in well
`stimulation treatments.
`
`15
`
`2
`capacity for accepting abrasive proppants is exceeded
`and the entire apparatus, including the wellhead isola(cid:173)
`tion tool, is packed with abrasives injected under ex(cid:173)
`treme pressure. In addition, it is preferable to provide a
`5 wellhead isolation tool having a mandrel that is com(cid:173)
`pletely enclosed in a sealed bore. This feature is desir(cid:173)
`able for two reasons. First, an exposed stuffing box can
`leak or fail and discharge hydrocarbons to the atmo(cid:173)
`sphere when a mandrel is being stroked in or out of a
`10 wellhead. Second, if large quantities of coarse abrasive
`are pumped in one session, the abrasives can wear a hole
`through the sidewall of a mandrel. If this occurs, an
`exposed mandrel cannot be safely stroked out of the
`well.
`In a first generation of prior art wellhead isolation
`tools the high pressure valves used to control well stim(cid:173)
`BACKGROUND OF THE INVENTION
`ulation fluid pressures are located too high above the
`wellhead and are therefore difficult to access. These
`Oil and gas wells frequently require stimulation in
`first generation tools were also arranged so the appara-
`order to recommence or improve a flow of hydrocar-
`bo~ from the hydrocar~n bearing f~rmati~n with 20 tus used to stroke a mandrel through a wellhead was left
`which .a well bore comm~mcates. ~ell ~tunulat~on gen-
`on the wellhead during well stimulation treatments.
`erally mvolves the J?Umpmg of flwd mIXtures mto t~e
`This places strain on the wellhead and subjects the
`h~drocarbon formation at e~treme. pressur~s. The fluid
`wellhead to excessive racking forces if "line jack" oc-
`mixt~es frequently compnse a~id solutions and/or
`curs during a stimulation treatment. "Line jack" is a
`abrasive proppants such as. bauxite granules or sand. 25 high speed vibration or whipping of stimulation lines
`We.llheads gene~ally compns~ one or more valves, a
`which occurs if a blockage develops while pumping
`casmg spool, tubmg spool, tubm~ h~ger, ?lowout pre-
`slurries high in sand content or when a h draulic valve
`venter, and related apparatus which is designed to con-
`malfunctio s
`Y
`tain and control well fluids at well pressures. Wellheads
`.
`.
`n ·
`.
`In at secon~ ~enerat~ont~f well;e~d ~solatihon tool
`are not usually designed to withstand the abrasive ef- 30
`,
`0 s ro e
`fects of well stimulation proppants or the extreme pres-
`appara us use.
`e man re t roug a we 1-
`hea? was ?esign~d to be removed from t~e wellhead
`sures of well stimulation treatments. It is therefore nee-
`essary to provide a tool for isolating the wellhead from
`durmg a stimulatioi: treatment so. th_at the high pressure
`the caustic and/or abrasive fluids as well as the extreme
`valve was located m closer proxirmty to the wellhead,
`fluid pressures used in well stimulation treatments. 35 th~r.eb?' .making the. valve more readily a~ces.sible and
`Many wellhead isolation tools have been invented for ~mg the racking forces exe~ed by lm~ Jack. The
`disa~vantage of th~ second generation .tools is that they
`satisfying this requirement. The prior art considered
`most relevant to the present invention includes:
`require that ~ portion of the tool be disassembled after
`Canadian Patent 1,137,869-Surjaamadja
`the mandrel is stroked through the wellhead and reas-
`Canadian Patent Application 1,277,230-McLeod
`40 sembled before the mandrel can be stroked out of the
`Canadian Patent Application 1,281,280-McLeod
`w~llhea?. In the event .of a blow-out or a fire during a
`Canadian Patent Application 1,292,675-McLeod
`stunulation treatment, .1t may be difficult or impossible
`Canadian Patent Application 2,055,656-McLeod
`to reassemble t?e tool m order to stroke out the mandrel
`Wellhead isolation tools are alike in that each tool
`so that the mam control valve or a blow out preventer
`inserts a length of high pressure tubing, hereinafter 45 in the wellhead can be closed to bring the situation
`under control.
`referred to as a mandrel, through a vertical passage
`defmed by the wellhead, the lower end of the tubing
`The known wellhead isolation tools fall to provide all
`being sealed or packed off in the production robing or
`of the desirable features required to minimize the ha-
`casing of the well. Each tool also requires a mechanism
`zards of well stimulation and maximize the ease and
`to prevent well bore gases from escaping to atmosphere 50 speed of preparing a well for stimulation treatment.
`while stroking t?e man?rel into our out of the '"'.e~lhead.
`SUMMARY OF THE INVENTION
`Each also requires a high pressure valve, trad1t10nally
`connected to a top of the mandrel, to control pressure
`while the mandrel is seated and packed off in the well
`tubing or casing.
`Well stimulation treatment is a potentially dangerous
`operation because of the extreme pressures used to in(cid:173)
`ject fluid mixtures into a well bore. It is therefore desir(cid:173)
`able to provide a wellhead isolation tool which permits
`ready and easy access to the injection lines used for well 60
`stimulation. It is also desirable to provide a tool which
`locates the hook-up point for the injection lines as close
`to the wellhead as possible in order to minimize the
`stress of the racking forces sometimes exerted by fluid
`pressures in the injection lines. It also desirable to pro- 65
`vide a wellhead isolation tool which can be extracted
`from the wellhead trader any condition, including
`"screen out" in which a blockage occurs or the well's
`
`It is a primary object of the invention to provide a
`wellhead isolation tool which is more convenient to use
`and safer to operate than wellhead isolation tools
`known in the prior art.
`The present invention also achieves a plurality of
`further objects which include:
`a wellhead isolation tool having a mandrel that can be
`stroked in and stroked out of the wellhead without
`closing the high pressure valve of the tool;
`a wellhead isolation tool that is hydraulically locked
`in place without mechanical contrivances of any
`kind, thus enabling the mandrel to be stroked in or
`out of the wellhead by using a hydraulic valve
`which is located a safe distance from the wellhead;
`a wellhead isolation tool which permits the mandrel
`to be stroked out of the wellhead with a well stimu-
`
`1s
`
`55
`
`000010
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`5,372,202
`
`4
`3
`In accordance with a further aspect of the invention,
`lation line connected to a high pressure valve in an
`there is advantageously provided a pull rod which ex-
`instance of a high pressure valve failure or an in-
`stance of severe screen out when abrasives block
`tends through a top end the hollow cylinder used to
`stroke the mandrel into and out of the wellhead. The
`the gate of the high pressure valve so that the valve
`5 pull rod serves the function of a positive indicator to
`cannot be properly closed;
`graphically illustrate the position of the mandrel in the
`a wellhead isolation tool which permits the well stim-
`wellhead at any given time. In addition, the pull rod
`ulation line(s) to be left connected to the high pres-
`sure valve while the mandrel is stroked out of the
`provides a means for extracting the mandrel if the well
`is "killed" during a stimulation treatment and all natural
`wellhead in an instance of a fire, blow-out or simi-
`IO well pressure is lost, or a well having no natural pres-
`lar emergency;
`sure must be stimulated. In the event that a well has no
`a wellhead isolation tool which has no exposed pack-
`natural pressure, a cable hooked to an eye in a top end
`ing that could permit blow-by or blow-out while
`stroking the mandrel into or out of the wellhead;
`of the pull rod may be used to stroke the mandrel out of
`the well. Under normal conditions, natural well pres-
`a wellhead isolation tool having a mandrel which can
`be stroked out of the wellhead under any condition 15 sure is used to stroke the mandrel out of the well.
`regardless of whether the well exerts high natural
`In accordance with another preferred embodiment of
`pressure or no pressure at all;
`the invention, there is provided a well head isolation
`a wellhead isolation tool which may be operated
`tool equipped with a mechanical screw for stroking the
`using wellhead pressure to stroke in or stroke out
`mandrel into or out of a well. The mechanical screw is
`the mandrel, thus eliminating a requirement for a 20 preferably a worm gear ball screw which provides
`hydraulic system in remote or inaccessible areas;
`excellent mechanical advantage. The mechanical screw
`is conveniently driven by a hydraulic motor, although
`and,
`a wellhead isolation tool having a mandrel which can
`other drive mechanisms are acceptable. The mechanical
`be stroked out of the wellhead as soon as the injec-
`screw has the advantage of minimizing the hydraulic
`tion pumps are stopped, permitting a blow-out 25 power requirements for the equipment used to stroke
`the mandrel into or out of the well. To isolate a well-
`preventer valve to be closed almost immediately in
`the event of a fire at the wellhead, thereby contain-
`head of a well with a very high natural pressure, say
`10,000 psi or more, high performance hydraulic equip-
`ing the well without serious consequences and
`without endangering personnel.
`ment is required to set the tool in accordance with the
`In accordance with the present invention there is 30 first embodiment of the invention. It is not necessarily
`practical to provide an entire fleet of tools with high
`provided a wellhead isolation tool to permit the
`injection of fluids, solid particles and mixtures
`performance hydraulics. It is therefore more practical
`thereof into a wellhead having a sealed bore there-
`to provide a tool equipped with a mechanical screw for
`through and including at least one valve and into a
`use in isolating wellheads on wells with extreme natural
`well having a production robing or a well casing 35 pressure. It is also practical to use this tool for wells
`with normal natural pressure or with no natural pres-
`aligned with the sealed bore, the tool comprising:
`means for attaching the tool to the wellhead;
`sure at all.
`In accordance with yet another preferred embodi-
`a pressure relief valve located adjacent the means for
`attaching the tool to the wellhead;
`ment of the invention, there is provided a well head
`a high pressure valve located above the pressure 40 isolation tool equipped with a mechanical screw and a
`relief valve;
`pack-off nipple expander for ensuring that the pack-off
`a hollow cylinder located above the high pressure
`nipple is in sealing contact with the production tubing
`valve, the cylinder having a piston forcibly recip-
`or well casing. This permits the use of a pack-off nipple
`rocatable therein;
`that is more readily inserted through the well tree and
`a mandrel reciprocatable with the piston in a sealed 45 into the production casing or the well tubing, while
`bore defined by the tool, the mandrel including an
`providing a reliable sealing engagement with the pro-
`axial bore and an injection port which communi-
`duction tubing or the well casing after the mandrel is
`cate8 with the axial bore so that the injection port
`stroked into the well. The pack-off nipple expander is
`aligns with a bore selectively closed by the high
`carried on an inner mandrel attached to a rod that ex-
`pressure valve when the mandrel is extended 50 tends through an axial bore in the mechanical screw.
`The inner mandrel is slidingly received in an outer
`through the wellhead and a pack-off nipple at-
`tached to a bottom end of the mandrel sealingly
`mandrel that carries an elastomeric pack-off nipple. The
`engages the production tubing or the casing; and
`pack-off nipple expander attached to the bottom end of
`packing means for engaging a periphery of the man-
`the inner mandrel is typically frusto conical in shape.
`drel in a fluid-tight seal which permits reciprocal 55
`movement of the mandrel, the packing means being
`located in the sealed bore between the pressure
`relief valve and the high pressure valve.
`The invention therefore provides a wellhead isolation
`tool which is compact, requires no disassembly after a 60
`mandrel is inserted into the wellhead and permits the
`mandrel to be extracted from the wellhead at any time
`without disconnecting the well stimulation lines, clos(cid:173)
`ing the high pressure valves, or otherwise changing the
`disposition of the tool. This provides a great deal of 65
`flexibility in operating the tool and minimizes the effort
`required to prepare a wellhead for a well stimulation
`treatment.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The invention will now be further explained by way
`of example only and with reference to the following
`drawings, wherein:
`FIG. 1 is a longitudinal cross-sectional view of a
`wellhead isolation tool in accordance with the inven-
`ti on;
`FIG. lA is a side elevational view of a mandrel injec(cid:173)
`tion head in accordance with the invention;
`FIG. 2 is an elevational cross-section of the wellhead
`isolation tool shown in FIG. 1 mounted on a wellhead;
`FIG. 3 is an elevational cross-section of the wellhead
`isolation tool shown in FIG. 2 with the mandrel ex-
`
`000011
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`5,372,202
`
`6
`5
`high pressure valves 44 may be provided. Each high
`tended through the wellhead and the pack-off nipple
`pressure valve 44 is connected by a hammer union 46 to
`assembly sealingly engaged in the production tubing of
`a high pressure bore 48 that communicates with a sealed
`the well.
`bore 50 defined by the tool.
`FIG. 4 is an elevational cross-section of the wellhead
`The pressure relief valve assembly 26 includes a pres-
`isolation tool shown in FIG. 1 with the mandrel ex- S
`sure relief valve 52 which is connected by a hammer
`tracted from the wellhead after a stimulation treatment;
`union 54 to a pressure relief bore 56 that communicates
`and
`with the sealed bore 50. The pressure relief assembly 26
`FIG. 5 is a elevational cross-section of the wellhead
`also includes a plurality of packing rings 58 that sur-
`isolation tool on the wellhead shown in FIG. 2 with the
`master valve of the wellhead closed so that the well- 10 rounds a periphery of a lower end of the mandrel assem-
`head isolation tool can be removed after a well stimula-
`bly 28 to provide a fluid seal between the pressure relief
`valve 52 and the high pressure valves 44. The packing
`tion operation.
`FIG. 6 is a longitudinal cross-sectional view of a
`rings 58 are retained in position by a packing nut 60.
`second preferred embodiment of a wellhead isolation
`The mandrel assembly 28 includes an injection head
`tool in accordance with the invention;
`lS 62, the construction of which will be described in more
`FIG. 7 is a longitudinal cross-sectional view of the
`detail with reference to FIG. lA, and a mandrel 64
`wellhead isolation tool shown in FIG. 6, adapted to
`which preferably threadedly engages a lower end of the
`injection head 62. Attached to a bottom end of mandrel
`accommodate a pack-off nipple expander using concen-
`tric mandrels, the tool being shown in an installed con-
`64 is a pack-off nipple assembly 66, well known in the
`dition on the wellhead wherein the pack-off nipple has 20 art. A variety of pack-off nipple assemblies in a range of
`been lowered into the well tubing but not yet expanded
`sizes are commonly available. The pack-off nipple as-
`to effect a secure seal with the well tubing;
`sembly 66 is used to form a fluid-tight connection of the
`FIG. 8 is an elevational cross-section of the embodi-
`mandrel 64 with a well casing or tubing (not illustrated
`ment of the invention shown in FIG. 7, with the pack-
`in this figure) in a well to be treated. The mandrel as-
`off nipple in an operative position, the wellhead isola- 25 sembly 28 is affixed to piston 36. The connection of the
`mandrel assembly 28 and the piston 36 is preferably
`tion tool being ready for a well stimulation procedure.
`made with screw or bolt fasteners (not illustrated) in a
`DETAILED DESCRIPTION OF THE
`manner well known in the art. The mandrel assembly 28
`PREFERRED EMBODIMENT
`is therefore forcibly reciprocatable in the sealed bore.
`FIG. 1 shows a wellhead isolation tool in accordance 30 50 with the piston 36. The movement and control of the
`with the invention, generally referred to by reference
`piston 36 will be explained in detail with reference to
`20. The wellhead isolation tool 20 includes a mandrel
`FIGS. 2 through 5.
`positioning assembly 22, a high pressure valve assembly
`FIG. lA shows a detailed elevational view of a pre-
`24, a pressure relief valve assembly 26 and a mandrel
`ferred construction for the injection head assembly 62.
`assembly generally referred to by reference 28. The 35 The injection head 62 includes an axial bore 68 (see
`FIG. 1) and at least one injection port 70 for each high
`mandrel positioning assembly 22 includes a hollow cyl-
`inder 30 having a closed top end 32 and an open bottom
`pressure bore 48 (see FIG. 1 ). The injection head 62
`end which may be connected by means of a hammer
`also has a tapered shoulder 72 which abuts a comple-
`union 34 to the high pressure valve assembly 24. The
`mentary region 74 (see FIG. 1 ) in the sealed bore 50
`cylinder further includes a piston 36 constructed in a 40 when the mandrel assembly 28 is extended through a
`wellhead and the pack-off nipple assembly 66 is seal-
`manner well known in the art. The piston 36 is forcibly
`reciprocatable within the cylinder 30. Attached to a top
`ingly engaged with the well tubing or casing. This en-
`side of the cylinder 36 is a pull rod 38 which is prefera-
`sures that the injection ports 70 align with the high
`bly provided but not a mandatory component of the
`pressure bores 48 to permit stimulation fluid to be
`tool. The function of the pull rod 38 will be explained 4S pumped through the high pressure bores 48 and the
`mandrel 64 into the well bore. The high pressure bores
`hereinafter in detail. Pull rod 38 passes through the
`closed top end 32 of the cylinder 30. A fluid seal 40,
`48 are preferably inclined at an angle of about 40° -50°
`commonly known in the art, prevents the egression of
`with respect to the sealed bore 50. The angle of inclina-
`hydraulic fluid from the cylinder while permitting re-
`tion is not critical. The inclination of the high pressure
`ciprocal movement of the pull rod 38. A pair of hook 50 bores 48 reduces backwash of abrasive laden fluids and
`thereby extends the service life of the injection head 62.
`eyes 42 are also preferably provided in the closed top
`end 32 of the cylinder. The hook eyes provide a hook
`An injection head 62 will eventually erode to a point
`up for a cable harness used to hoist the wellhead isola-
`that it must be replaced if large volumes of abrasive
`tion tool 20 to and from a derrick truck and onto a
`fluids are pumped for extended periods of time. The
`wellhead. The cable harness (not illustrated) preferably SS injection head is therefore preferably affixed to piston
`36 with screw or bolt fasteners, as noted above, and the
`includes a spreader to prevent contact of the cable with
`the pull rod 38 while the wellhead isolation tool 20 is
`lower end of the injection head 62 preferably includes a
`being moved. Cable harnesses of this type are well
`threaded joint 76 to which the mandrel 64 is attached,
`known in the art. Chain, rope or other attachments may
`permitting the injection head 62 and/or mandrel 64 to
`also be used to move the tool to a working location. The 60 be replaced as required.
`FIG. 2 shows a wellhead isolation tool 20 in accor-
`closed top end 32 of the cylinder is preferably closed by
`a cap which threadedly engages the side walls of the
`dance with the invention installed on a wellhead gener-
`cylinder 30 in a manner well known in the art. This
`ally indicated by reference 78. The wellhead 78 includes
`permits access to an interior of the cylinder so that
`at least a master valve 80, a tubing spool 82 and a pro-
`repairs or maintenance of the piston and/or the push 6S duction tubing 84. Other well components which make
`rod may be effected.
`up the wellhead such as ball valves, blow-out preven-
`The high pressure valve assembly 24 preferably in-
`tion stacks, drilling spools, tubing bonnets, casing
`eludes at least one high pressure valve 44. Two or more
`spools, casing bowls and related flanges in various com-
`
`000012
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`5,372,202
`
`8
`7
`due to an equipment failure is minimized and the risk of
`binations are not illustrated. When a well is to be stimu-
`personal injury for personnel servicing the wellhead is
`lated, the master valve 80 is closed and a wellhead cap
`reduced.
`(not illustrated) is removed from a top of the wellhead
`After the mandrel assembly 28 is seated in a position
`and the wellhead isolation tool 20 is bolted to the well-
`head. An 0-ring 86 or similar sealing device ensures a 5 ready to begin a well stimulation treatment as shown in
`FIG. 3, the pressure relief valve 52 is opened to ensure
`pressure tight seal of the tool to the wellhead. After the
`wellhead isolation tool 20 is bolted to the wellhead, the
`that the pack-off nipple assembly 66 is effectively sealed
`in the well robing or casing 84. If any pressure escapes
`master valve 80 is opened to permit the mandrel assem-
`bly 28 to be stroked through the wellhead. The mandrel
`from pressure relief valve 52, the pack-off nipple assem-
`assembly 28 is stroked downwards by introducing pres- 10 bly 66 is damaged and the tool must be removed from
`the wellhead for repairs. If no pressure escapes from
`surized fluid through a hydraulic valve 88 located at a
`top of the cylinder 30 just beneath the closed top end 32
`pressure relief valve 52, the well treatment pumps are
`of the cylinder. The pressurized fluid may be a hydrau-
`tested against the closed high pressure valves 44 to
`lie fluid supplied by a hydraulic line (not illustrated).
`ensure that the well treatment lines are intact and in a
`Alternatively, well gases may be used to set the mandrel 15 condition to begin the well treatment. High pressure
`assembly 28 if the wellhead has a high natural pressure.
`valves 44 are then opened and well stimulation treat-
`This can be accomplished by connecting a high pressure
`ment begun. The packing 58 located between the high
`hose between the pressure relief valve 52 and the hy-
`pressure valves 44 and the pressure relief valve 52 en-
`draulic valve 88. The introduction of pressurized fluid
`sures that no well stimulation fluids migrate into the
`through the hydraulic valve 88 forces the piston 32 and 20 wellhead during the stimulation treatment. The pres-
`the mandrel assembly 38 downwards through the well-
`sure relief valve 52 is preferably left in a partially
`head 78. The pull rod 38 provides a position gage which
`opened condition during a stimulation treatment so that
`indicates the travel of the mandrel assembly 28. This
`pressure in the wellhead can be monitored to ensure
`that a failure of the mandrel 64 or the pack off nipple
`can be very helpful in setting a mandrel assembly since
`an operator of the wellhead isolation tool 20 is always 25 assembly 66 is detected. An 0-ring 86 located at a top of
`certain of the exact position of the mandrel within the
`the high pressure valve assembly 24 ensures that no well
`wellhead. Pressurized fluid is injected through the hy-
`stimulation fluids migrate into cylinder 30 where they
`draulic valve 88 until the mandrel assembly 28 is com-
`could foul the cylinder and interfere with the reciprocal
`pletely seated and the pack-off nipple assembly 66 seal-
`movement of the piston 36.
`ingly engages the well robe 84, as shown in FIG. 3.
`30 After a well stimulation treatment is complete, hy-
`Once the mandrel is fully seated the fluid pressure
`draulic pressure is relieved through valve 88 to permit
`above the piston 36 is preferably increased to a pressure
`the well pressure exerted on the injection head 62 to
`which exceeds the maximum pump pressure of the well
`force the piston 36 and the mandrel assembly 28 up-
`wards until the mandrel 64 is stroked out of the well-
`stimulation treatment. This locks the cylinder 36 and
`the mandrel assembly 28 in the service position shown 35 head, as shown in FIG. 4. Under normal operating
`conditions, it is preferable to equalize the pressure on
`in FIG. 3. When the mandrel assembly 28 is properly
`seated, the pack-off nipple assembly 66 sealingly en-
`the wellhead with the pressure in the well before the
`gages the well robe or well casing 84 and only the hook
`pack-off nipple assembly 66 is extracted from the pro-
`eye 92 at the top end of the pull rod 38 is visible above
`duction tubing 84 so that the wellhead 78 is not sub-
`the closed top end 32 of cylinder 30. In this position, the 40 jected to a sudden pressure surge when the mandrel 64
`is stroked out of the wellhead. This is accomplished by
`injection ports 70 (see FIG. lA) in injection head 62
`align with the high pressure bores 48 which connect the
`connecting opposite ends of a high pressure hose (not
`high pressure valves 44 with the sealed bore 50, Well
`illustrated) to one of the high pressure valves 34 and the
`stimulation lines can then be connected to the free ends
`pressure relief valve 52, respectively. The two valves
`of the high pressure valves 44 to begin a well stimula- 45 are opened to permit an equalization of the pressure and
`closed to maintain the equalized pressure before the
`tion treatment. Fluid pumped through one or more of
`mandrel 64 is stroked out of the wellhead 78. In an
`the high pressure valves 44 passes through the high
`pressure bores 48 and the injection head 62. The fluid
`emergency situation this procedure can be bypassed.
`then passes through an axial bore 68 in the mandrel 64
`In the event that a well has no natural pressure or the
`50 well is killed during a stimulation treatment, a cable
`and subsequently into the well bore.
`As is apparent from FIG. 3, the mandrel assembly is
`harness or the like (not illustrated) may be attached to
`maintained in the well by the overburden of fluid pres-
`the hook eye 92 at the top end of the pull rod 38, and the
`sure introduced through valve 88. The mandrel assem-
`mandrel maybe extracted using a derrick or a crane.
`bly can therefore be extracted from the wellhead by When the mandrel is extracted using a derrick or a
`releasing fluid pressure from valve 88. Normally, the 55 crane, valve 88 must be in the full open position in order
`fluid pressure to valve 88 is supplied by a hydraulic line
`to permit the escape of pressurized fluid from the space
`which is connected to a hydraulic pump that is located
`above the piston 36. The pull rod 38 also ensures that
`a safe distance from the wellhead. In a case of emer-
`the mandrel 64 can be extracted from the wellhead even
`in the event of severe screen out when the entire well
`gency this arrangement permits the mandrel assembly
`28 to be stroked out of the wellhead by operating a 60 stimulation apparatus is plugged with abrasives packed
`under extreme pressure. This provides a distinct advan-
`relief valve at the pump, thus obviating any requirement
`tage over the prior art since it permits the extraction of
`to approach the wellhead. When fluid is relieved
`through valve 88, the well pressure exerted on the injec-
`the mandrel 64 from the wellhead under any anticipated
`circumstance, even if the high pressure valves 44 cannot
`tion head 62 strokes the mandrel from the well. A blow-
`out preventer (not illustrated) can then be forced closed 65 be closed and the well stimulation lines (not illustrated)
`by a remote hydraulic control, or similar safety equip-
`cannot be disconnected from the high pressure vales 44.
`ment can be operated without approaching the well-
`In case of an emergency, it is not necessary to discon-
`head. Thus, the danger of loss of control of a wellhead
`nect the stimulation lines, close the high pressure valves
`
`000013
`
`GREENE'S ENERGY 1021
`Greene's Energy v. Oil States IPR2014-216
`
`

`

`5,372,202
`
`10
`9
`ensure a positive seal of an elastomeric pack-off nipple
`or make any other preparations prior to stroking the
`106 with the production tubing 84 of the well. The
`mandrel 64 out of the wellhead. The only requirement is
`wellhead isolation tool 20 shown in FIG. 7 has been
`to stop the stimulation pump(s) prior to evacuating
`mounted to the wellhead 78 and stroked do