BAKER HUGHES INCORPORATED
`AND
`BAKER HUGHES OILFIELD
`OPERATIONS, INC.
`BAKER HUGHES INCORPORATED
`Exhibit 1026
`Exhibit 1026
`Page 1 of 9
`
`

`
`I|||||||||||l|||||||||||||||||||||||||||||||||l||||||||||||||||||||||||||||
`
`USUl]623(}811B1
`
`(12) Ulllted States Patent
`Ringgenhcrg et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,230,311 B1
`May 15, 2001
`
`411937 Ringgenbcrg ...................... .. 1661323
`4_.657_.os3 '—
`2119811 Pringlc
`.
`ttsraflt?
`4324,9118 *
`T,’199lJ Von gonten, Jr.
`16of3£I4
`*
`?‘;‘1U‘)2 Dickson ct al.
`Ififa.-"323
`:_1_.l;'t'_.4':’6 *
`llJ,’19i)4 Wallet et al.
`166,821
`:."'§:3“=97’9 :
`‘J!199f) Manke ct al.
`16f),."3l9
`:a_..'3:‘)8_.l(>2
`* cited by exztminer
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`
`ll’?-‘imiiffit’ E'Xfl!!Iffl€f—Eil¢Cfl D‘ Lillis
`Assf.s1‘rrm E.mtt1iner—.lo|1n I-{reek
`(74) Attorrtey, Agent, or1"z'rm—l’aul 1. Hannah; Lawrence
`R. Yousl
`
`"B5TR"C"‘
`(57)
`A downhole tool (100) for selectively providing fluid corn-
`munication between the interior and the exterior of the tool
`(100). The tool (100) comprises :1 housing (102), a safety
`mandrel (130) slidahly received within the housing (102)
`and an vpcrating mandrc1(Il4)slidal1Iy rcc<>ivc<| within the
`h0USin2.(102)-The Safely mandr¢l(130}0P¢ralcS'3C1W1=¢n «'1
`first position and a second position relative to the housing
`(102) 1“ ’F5P““5° "1’ P’°'53"'° "°}“3 “PPW3 “’ ‘lm °"‘°"“' "f
`the hous1ng'(ll]2).‘ l'he operating nnindrel (I14) o-p-crates
`trom El nonetrculattng ]JOSll10|'I to a ctrculattng pGSilJ(‘:I] In
`response to pressure being applied to the interior of the
`housing (102) once the safety mandrel (130) has operated to
`its second position.
`
`20 Claims, 3 Drawing Sheets
`
`BAKER HUGHES INCORPORATED
`Exhibit 1026
`Page 1 of 9
`Page 1 of 9
`
`(54)
`
`(75)
`
`IN'1‘1«:RNAI. I’Rl«:SSURl~: ()I>ER/\’I‘t-ll)
`C1R(_‘U1_A'[‘[NG VALVE w[T1.[ ANNULU5
`PRESSURE 0pERATED sAFE'[Y MANDREL
`
`Inventors: Paul I). Ringgenherg. Carrolllon, TX
`(US); Michael Narnia“, Melbourne! FL
`(US)
`
`(73) Assignee: Hallihurlon Energy Services, Ine.,
`r)a|1,-is, Tx (Us)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`u.s.c. 154(b) by 0 days.
`
`(2l) Appl. No.: IJ9[238,266
`
`53"‘ 37’ 1999
`(32) Mid:
`(51)
`Int. C1.’ ........................... .. E2113 34106; E21 B 34111:
`(52) U.S. C1.
`........................ .. 166374; 166.386; 166,-'32{l;
`165,-3311
`(53) Field of Search ..................................... 1661386, 374.
`166’,-320, 321, 3321], 334'‘ 3344; [3-H{_Q8
`
`(56)
`
`References Cited
`
`US. PATENT DOCUMENTS
`4_.429,?'4? *
`2_1'1934 W'i|liarnson_. Jr.
`.................... 166132]
`4.4?4.242 * W191-14
`tlpchurch ........................... .. 1t:6,*323
`
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`Page 2 of 9
`Page 2 of 9
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`

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`U.S. Patent
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`Page 4 of 9
`Page 4 of 9
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`

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`US 6,230,811 B1
`
`1
`INTERNAL PRESSURE OPERATED
`CIRCUIATING VALVE WITH ANNULUS
`PRESSURE OPER/\'l'ED SAl*‘l'1'l'Y MANl)RlilI.
`
`TECI-INICAL FIELD OF THE INVENTION
`
`to an apparatus and
`This invention relates, in general,
`method used during formation testing and, in particular to,
`an internal pressure operated circulating valve that is placed
`in the operating position only if sutficient annular hydro-
`static pressure unlocks a safety mandrel.
`
`BACKGROUND OF THE INVENTION
`
`Without limiting the scope of the present invention, its
`background is described in connection with perfonning tests
`to determine the production capabilities of a fonnation
`traversed by a wellbore, as an example.
`the
`During the course of drilling an oil or gas well,
`wellhore is typically filled with a fluid known as drilling
`fluid or drilling mud. One of the purposes of this drilling
`fluid is to contain formation fluids within the formation
`intersected by the wellhore. To contain these formation
`fluids, the drilling mud is weighted with various additives so
`that
`the hydrostatic pressure of the drilling mud at
`the
`formation depth is sufficient to maintain the formation fluid
`within the formation without allowing it to escape into the
`wellbore.
`
`When it is desired to test the production capabilities of the
`formation, a test string is lowered into the wellbore to the
`formation depth and the formation fluid is allowed to flow
`into the test string in a controlled testing program. Lower
`pressure is maintained in the interior of the test string as it
`is lowered into the wellbore. This is usually done by keeping
`a valve in the closed position near the lower end of the test
`string. When the testing depth is reached, a packer is set to
`seal
`the wellbore thus closing in the formation from the
`hydrostatic pressure of the drilling fluid in the well annulus.
`The valve at the lower end of the test string is then opened
`and the formation fluid, free from the restraining pressure of
`the drilling fluid, can flow into the interior of the test string.
`The testing program typically includes periods of forma-
`tion How and periods when the formation is closed in.
`Pressure recordings are taken throughout the program for
`later analysis to determine the production capability of the
`formation. Ifdesired, a sample ofthe formation fluid may be
`caught in a suitable sample chamber.
`/\t the end of the testing program, a circulation valve in
`the test string is typically opened so that formation lluid in
`the test string may be circulated out. Since the hydrostatic
`pressure of the drilling lluid near the formation is generally
`much higher than the formation fluids in the test string, it is
`usually only necessary that the annulus be placed in fluid
`communication with the interior of the test string to start to
`reverse out the formation fluids from the test string.
`I'-‘ol-
`lowing this circulation step, the packer may he released so
`that the test string may be withdrawn from the wellbore.
`Typically, the circulating valves used in a test string may
`include a sliding sleeve that
`is opened in response to
`pressure in the annulus. It has been found, however, that
`when it is desirable to have more than one circulating valves
`in a test string to be operated at different times, each tool
`must be set to operate at a different pressure. Since 500 psi
`typically separates the pressures at which respective circu-
`lating valves will operate, extremely high pressures would
`be required to operate the later circulating valves in such a
`configuration. which may damage the well casing.
`
`it)
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`_
`
`60
`
`65
`
`2
`To overcome this problem, attempts have been made to
`utilize internal pressure operated circulating valves that
`operated in response to pressure in the test string. It has been
`found, however, that internal pressure operated circulation
`valves may be inadvertently opened as the result of an
`increase in the pressure within the test string. For example,
`when the test string is made up and lowered into the
`wellbore, it is desirable to periodically pressure test the test
`string to assure that the pipe joints have been adequately
`made up. Such testing requires closing of a valve in the
`lower part of the test string and applying pump pressure to
`the interior or the test string at the surface of the well. If the
`test string includes an interior pressure operated circulation
`valve,
`it may be inadvertently opened during such a test
`string pressure test.
`intemal pressure operated
`It has also been found that
`circulation valves may be inadvertently opened as the result
`of an unexpected increase in pressure from a formation that
`is not properly under control. If an inlcmal pressure operated
`circulation valve is not operated during a testing program
`and is pulled out of the hole in the unopcrated position, such
`a pressure upset from the formation could open an internal
`pressure operated circulation valve and allow formation
`lluids to be release at the surface.
`
`Therefore, a need has arisen for an internal pressure
`operated circulation valve that will not inadvertently opened
`as the result of an increase in the pressure within the test
`string du ring a pressure test of the test string. A need has also
`arisen for such an internal pressure operated circulation
`valve that will not
`inadvertently open as a result of an
`unexpected pressure surge from the formation particularly
`when the internal pressure operated circulating valve is at or
`near the surface.
`
`SUMMARY OF THE INVENTION
`
`invention disclosed herein comprises an
`The present
`internal pressure operated circu.lation valve that will not
`inadvertently open as the resultof an increase in the pressure
`within the test string during a surface pressure test of the test
`string. Likewise, the integral pressure operated circulation
`valve of the present inception will not inadvertently opened
`as a
`result of an uninspected pressure stu'ge from the
`formation.
`
`The internal pressure operated circulation valve of the
`present invention comprises a housing, a safety mandrel and
`an operating mandrel. The safety mandrel
`is slidably
`received within the housing. The safety mandrel operates
`from a lirst position to a send position relative to the housing
`in response to pressure being applied to the exterior of the
`housing. The operating mandrel
`is also slidably received
`within the housing. Tl1c operating mandrel operates from a
`noncirculating position to the circulation position in
`response to pressure being applied to the interior of the
`housing. The operating mandrel, however, will only operate
`to the circulating position when the safety mandrel has
`operated to the second position. When the operating mandrel
`is in the circulating position, lluid flow through a circulating
`port formed through a wall of the housing is permitted.
`A portion of the safety mandrel is slidably received within
`the operating mandrel to selectively prevent the operation of
`the operating mandrel. In one embodiment, the safety man-
`drel physically preventing the movement of the operating
`mandrel in the second direction. In another embodiment, the
`safety mandrel prevents the operation of the operating
`mandrel by preventing the pressure applied to the interior of
`the housing from acting on the operating mandrel.
`
`Page 5 of 9
`Page 5 of 9
`
`

`
`US 6,230,811 B1
`
`3
`The internal pressure operated circulation valve of the
`present invention may include a biasing device, such as a
`coil spring, to urge the safety mandrel to its first position
`such that a predetermined pressure applied to the exterior of
`the housing is required to operate the safety mandrel to its
`second position. The internal pressure operated circulation
`valve of the present invention may also include a frangible
`restraining device, such as one or more sheer pins,
`to
`selectively prevent the movement of the operating mandrel
`such that a predetermined pressure applied to the interior of
`the housing is required to operate the operating mandrel to
`the circulating position.
`invention, an operating
`In the method of the present
`mandrel disposed within a housing is operated by, disposing
`a safety mandrel in the housing for initially preventing the
`operation of the operating mandrel, applying pressure to the
`exterior of the housing to operate the safety mandrel
`between a lirst position and a second position relative to the
`housing and applying pressure to the interior of the housing
`to operate the operating mandrel from a nocirculating posi-
`tion to a circulating position, thereby permitting fluid flow
`through a circulating port formed through a wall in the
`housing.
`In the method, the safety mandrel initially prevents the
`operation of the operating mandrel by disposing a portion of
`the safety mandrel within the operating mandrel.
`In one
`embodiment, this is achieved by physically preventing the
`movement ofthe operating mandrel in the second direction.
`In another embodiment. this is achieved by preventing the
`pressure applied to the interior of the housing from acting on
`the operating mandrel.
`The method of the present inventon may require that a
`predetermined pressure he applied to the exterior of the
`housing to operate the safety mandrel to the second position
`by biasing the safety mandrel
`to the first position with a
`biasing device. Likewise, the method of the present inven-
`tion may require that a predetermined pressure be applied to
`the interior of the housing to operate the safety mandrel to
`circulating position by frangibly restraining the operating
`mandrel.
`
`BRIEF DESCRIPTION OF THE. DRAWINGS
`
`For a more complete understanding of the features and
`advantages of the present invention, references now made to
`the detailed description of the invention along with the
`accompanying figures in which corresponding numerals in
`the different figures refer to corresponding parts and in
`which:
`
`FIG. 1 is a schematic illustration of an offshore oil or gas
`drilling platform operating a test string including an internal
`pressure operate circulating valve of the present invention;
`FIGS. 2A—2C are quarter sectional views of an internal
`pressure operated circulating valve of the present invention
`in its various operating positions; and
`FIGS. 3A—3C are quarter sectional views of an internal
`pressure operated circulating valve of the present invention
`in its various operating positions.
`
`DETAILIED DESCRIPTION OF THE
`INVENTION
`
`While the making and using of various embodiments of
`the present invention is discussed in detail below, it should
`be appreciated that
`the present
`invention provides many
`applicable inventive concepts which can be embodied in a
`wide variety of specific contexts. The specific embodiment
`
`ll)
`
`15
`
`'
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`60
`
`65
`
`4
`discussed herein are merely illustrative of the specific ways
`to make and use the invention. and do not limit the scope of
`the invention.
`
`Referring to FIG. 1, an offshore drilling and testing
`operation is schematically illustrated and generally desig-
`nated 10. A semi-submersible platform 12 is centered over
`a submerged oil or gas formation 14 located below the sea
`floor 16. A well comprising a wellbore 18 is lined with a
`casingstring 20 extending from the platform 12 to formation
`14. Casing string 20 includes a plurality of perforations 22
`at
`its lower end which provide communication between
`formation 14 and the interior of the wellbore 18.
`
`A wellhead installation 24 which includes blowout pre-
`ventors 26 is located on sea floor lti.Aconductor 28 extends
`from wellhead installation 24 to platform 12. Platform 12
`includes a work deck 30 that supports a derrick 32. Derrick
`32 supports a hoisting apparatus 34 for raising and lowering
`pipe strings such as fonnation testing string 36. A supply
`conduit 38 is provided that extends from a hydraulic pump
`40 on deck 3|] of platform 12 and extends to the wellhead
`installation 24 at a point below blowout preventors 26 to
`allow the pressurizing of the well annulus 42 surrounding
`test string 36.
`During testing, a seal assembly 44 is used to isolate
`formation 14 from fluids in well annulus 42. Aperforated tail
`piece 46 is provided at the lower end of test string 36 to
`allow fluid communication between formation 14 and the
`interior of test string 36. The lower portion of test string 36
`also includes intermediate conduit portion 48 and torque
`transmitting pressure and volume balanced slip joint 50. An
`intermediate conduit portion 52 is provided for imparting
`setting weight to seal assembly 44. Near the lower end of test
`string 36 is located a tester valve 54 which may typically be
`an annulus pressure operated tester valve. Apressure record-
`ing device 56 is located below tester valve 54. immediately
`above tester valve 54 is an internal pressure operated cir-
`culating valve 58 of the present invention.
`liven though FIG. 1 depicts an offshore environment. it
`should be understood by one skilled in the art
`that
`the
`downhole component described herein is equally well-suited
`for operation in an onshore environment.
`Referring now to FIGS. 2A—2C therein is depicted quarter
`sectional views of one embodiment of an internal pressure
`operated circulating valve of the present invention that is
`generally designated 100. Valve 100 includes a cylindrical
`outer housing 102 having an upper housing adapter 104
`which includes threads 106 for attaching valve 100 to the
`portion of test string 36 located above valve 100. At the
`lower end of housing 102 is a lower housing adapter 108
`which includes an external threaded portion 110 for con-
`nection of valve 100 to that portion of test string 36 located
`below valve 100.
`
`Slidahly and sealably received within inner bore 112 of
`housing 102 is operating mandrel 114. Operating mandrel
`114 is initially frangibly retained in its noncirculating posi-
`tion by one or more shearable members such as a shear pin
`116 which is disposed through a radial bore 118 of housing
`102 and received within a radially extending bore 120 of
`operating mandrel 114. The exact number and size of the
`shearahle members will be determined based upon the
`desired operating pressure for operating mandrel 114.
`In the noncirculating position as depicted in FIG. 2A,
`operating mandrel 114 prevents the [low of fluids between
`the exterior of valve 100 and the interior of valve 100
`through circulating port 122. Operating mandrel 114
`ineludes a plurality of spring fingers. one of which is finger
`
`Page 6 of 9
`Page 6 of 9
`
`

`
`US 6,230,811 B1
`
`5
`124. Spring linger 124 is terminated by head 126. In the
`rtoncirculating position, head 126 rests against the upper
`shoulder of annular ledge 128 of housing 102.
`Slidably and sealably received within inner bore 112 of
`housing 102 below operating mandrel 114 is safety mandrel
`134. Safety mandrel 130 includes an upper end 132 that is
`closely received within head 126 of operating mandrel 114
`to physically prevent the movement of operating mandrel
`114.
`
`5
`
`ill
`
`6
`acid-treating formation 14. After testing and treatment, but
`prior to raising test string 36 out of wellbore 18,
`it
`is
`desirable to reverse circulate fluids from test string 36. Such
`is accomplished by moving the operating mandrel down-
`wardly so that circulation port 122 is in communication with
`the interior of housing 102.
`'ll1ereafter,
`fluid is pumped
`downwardly in the annulus through port 122 and upwardly
`through test string 36 thereby reverse circulating fluids from
`test string 36.
`Valve 100 is opened by shifting safety mandrel 130 then
`shifting operating mandrel 114 as follows. With valve [00 in
`the configuration of FIG. 2A and suspended on test string 36
`as shown in FIG. 1, the hydrostatic pressure of the annulus
`fluids upwardly bias safety mandrel 130 via communication
`port 142. Seal 138 defines an outer diameter and seal 140 an
`inner diameter of safety mandrel 130. When the hydrostatic
`force reaches the predetermined level necessary to overcome
`the bias force of spring 134, safety mandrel 130 moves
`upwardly with upper end 132 ofsafety mandrel 130 no loner
`contacting head 126 of spring finger 124 of operating
`mandrel 114. Alternatively. rupture disk 143 may be placed
`within communication port 142 which maybe set to burst at
`a predetermined pressure.
`After safety mandrel 130 has moved to its upper position
`as best seen in FIG. 213, test string 36 is pressurized thus
`permitting pressurired lluid to act on operating mandrel 114.
`Seal 144 defines an outer diameter and seal 146 defines the
`inner diameter of operating mandrel 114. When the pressure
`reaches the predetermined level necemary to shear the shear
`pins 116, operating mandrel 114 moves quickly down-
`wardly. In the lower position of operating mandrel 114, as
`best seen in FIG. 2C, seal 144 is below port 122 and thus
`llnid communication is permitted between the annulus and
`the interior of housing 102 thereby allowing reverse circu-
`lation.
`
`Once operating mandrel 114 has opened circulating port
`122, it remains open. When the formation fluids are circu-
`lated out of test string 36 and fully replaced by the lluids
`from the annulus, test string 36 may be pulled from the
`wellbore.
`
`Thus, it can be seen that prior to the operation of safety
`mandrel 130, for example during a surface test string pres-
`sure test, there is no risk of inadvertently opening circulation
`port 122 since interior pressure will not operate operating
`mandrel 114. Before pressure in test string 36 can be so
`communicated, safety mandrel 130 must be urged upwardly
`until upper end 132 no longer interferes with the movement
`of operating mandrel 114. It should be noted that if interior
`pressure is not applied to operating mandrel 114 while safety
`mandrel 130 is in the uppermost position, spring 134 will
`return safety mandrel 130 to the position seen in FIG. 2A
`when the bias force of spring 134 becomes greater than the
`hydrostatic force acting upwardly on safety mandrel 130.
`Referring now to FIGS. 3/\—3C therein is depicted quarter
`sectional views of another embodiment of an internal pres-
`sure operated circulating valve of the present invention that
`is generally designated 200. Valve 200 includes a cylindrical
`outer housing 202 having an upper housing adapter 204
`which includes threads 296 for attaching valve 200 to the
`portion of test string 36 located above valve 200. At
`the
`lower end of housing 202 is a lower housing adapter 208
`which includes an external threaded portion 210 for con-
`nection of valve 200 to that portion of test string 36 located
`below valve 200.
`
`Slidably and sealably received within inner bore 212 of
`housing 202 is operating mandrel 214. Operating mandrel
`
`Page 7 of 9
`Page 7 of 9
`
`Acoil compression spring 134 has its upper end engaging
`the lower shoulder of annular ledge I28 and has its lower
`end engaging annular upper end surface 136 of safety
`mandrel 131]. Spring 1314 biases safety mandrel 130 down-
`wardly to maintain upper end 132 against head 126 and
`prevent movcmentofoperating mandrel 114. In this position
`of valve 100, internal pressure testing of testing string 36
`may periodically occur without moving operating mandrel
`114 or loading shearable members 116.
`Spring 134 is initially retained in a substantially uncom-
`pressed state until extemal pressure applied to safety man-
`drel 130 through communication port 142 of housing 102
`acts between seals 138 and 140. When the external hydrow
`static pressure reaches a sulficient level, safety mandrel 130
`travels upwardly relative to housing 102 compressing spring
`134, as best seen in FIG. 2B. A rupture disk 143 may be
`placed within communication part 142 to selectively prevent
`the external hydrostatic pressure from communicating with
`safety mandrel 130 until the external hydrostatic pressure
`reaches a sufficient level to burst rupture disk 143. Once
`safety mandrel 130 has traveled upwardly, safety mandrel
`130 no longer physically restrains the movement of operat~
`ing mandrel 114.
`If the external hydrostatic pressure is
`reduced below the predetermined level, valve 100 is reset
`into the position depicted in FIG. 2A due to the bias force of
`spring 134. The procedure may be repeated without moving
`operating mandrel 114.
`When valve 100 is in the position depicted in FIG. 21},
`application of internal pressure then acts on operating man-
`drel 1l4 between seals 144 and 146 thus urging operating
`mandrel 114 downwardly. When sufficient pressure is
`applied, pin 116 shears thus permitting operating mandrel
`114 to move downwardly. As operating mandrel 114 moves
`downwardly. the spring fingers, such as spring finger 124,
`are no longer restrained by upper end 132 of safety mandrel
`130 and spring inwardly around annular ledge 128 of
`housing 102, as best seen in FIG. 2C.
`It should be apparent to those skilled in the art that the use
`of directional terms such as above, below, upper,
`lower,
`upward, downward, etc. are used in relation to the illustra-
`tive embodiments as they are depicted in the figures, the
`upward direction being towards the top of the corresponding
`figure and the downward direction being toward the bottom
`of the corresponding figure.
`It is to be understood that the
`downhole component described herein may be operated in _
`vertical, horizontal, inverted or inclined orientation without
`deviating from the principles of the present invention.
`the
`In operation, valve 100 is initially assembled at
`surface as shown in FIG. 2A. Thereafter, valve 100 is
`incorporated into a test string such as that shown in FIG. I
`and lowered into the wellhore as shown in FIG. 1. When in
`this configuration, tester valve 54 of FIG. 1 may be repeatw
`edly opened and closed by application of annulus pressure in
`order to conduct pressure tests of test string 36 which may
`shift safety mandrel 130 but will not shift operating mandrel
`I14 ofvalve 100. Thereafter, lluids may be pumped through
`test string 36 and into formation 14, for example,
`for
`
`15
`
`25
`
`30
`
`35
`
`4-0
`
`45
`
`50
`
`60
`
`65
`
`

`
`US 6,230,811 B1
`
`ill
`
`15
`
`25
`
`30
`
`7
`214 is initially frangibly retained in its noncirculating posi-
`tion by one or more shearable members such as shear pin
`216 which is disposed through a radial bore 218 of housing
`202 and received within a radially extending bore 220 of
`operating mandrel 214.
`In the noncirculating position as
`depicted in l~‘I(j. 3A, operating mandrel 214 prevents the
`flow of fluids between the exterior of valve 200 and the
`interior ofvalve 200 through circulating port 222. Operating
`mandrel 214 includes a communication port 225.
`Slidably and sealably received within inner bore 212 of
`housing 202 above operating mandrel 214 is safety mandrel
`230. Safety mandrel 230 includes a lower end 232 that is
`closely received within operating mandrel 214 to prevent
`internal pressure from entering communication port 225
`thereby preventing the movement of operating mandrel 214.
`Acoil compression spring 234 has its upper end engaging
`the lower shoulder 23'? of housing 202 and has its lower end
`engaging annular upper end surface 236 of safety mandrel
`230. Spring 2.34 biases safely mandrel 230 downwardly to
`maintain lower end 232 within operating mandrel 214 and
`prevent movement ofoperating mandrel 214. In this position
`of valve 200, internal pressure testing of testing string 36
`may periodically occur without moving operating mandrel
`214 or loading shearable member 216.
`Spring 234 is initially retained in a substantially uncom~
`pressed state until external hydrostatic pressure acting
`between seals 238 and 240 through communication port 242
`of housing 202 reaches a predetermined level. When the
`external hydrostatic pressure reaches a sufiicicnt
`level,
`safety mandrel 230 travels upwardly relative to housing 202
`compressing spring 234-, as best seen in FIG. 3B. A rupture
`disk 243 may be placed within communication port 242 to
`selectively prevent
`the external hydrostatic pressure from
`communicating to safety mandrel 230 until
`the external
`hydrostatic pressure reaches a sulficient level to burst rup-
`ture disk 243. Once safety mandrel 230 has traveled
`upwardly, seal 24] no loner prevents internal pressure from
`entering communication port 225. If the external hydrostatic
`pressure is reduced below the predetermined level, however,
`valve 200 will reset into the position depicted in 1'-'IG.3Adue
`to the bias force of spring 234. This procedure may be
`repeated without moving operating mandrel 214.
`When valve 200 is in the position depicted in FIG. 3B,
`application of internal pressure acts on operating mandrel
`214 between seals 244 and 246 thus urging operating
`mandrel 214 downwardly. When sullicient pressure is
`applied, pins 216 shear thus pemtitting operating mandrel
`214 to move downwardly, as best seen in FIG. 3C.
`the
`In operation, valve 200 is initially assembled at
`surface as shown in FIG. 3A. Thereafter, valve 200 is
`incorporated into test string 36 as shown in FIG. 1 and
`lowered into wellbore 18. After testing and treatment, but
`prior to raising test string 36 out of wellbore 18,
`it
`is
`desirable to reverse circulate lluids from test string 36 which _
`may shift safety mandrel 230 but will not shift operating
`mandrel 114 at valve 200. Such is accomplished by moving
`operating mandrel 214 downwardly so that circulation port
`222 is in communication with the interior of housing 202.
`Thereafter,
`fluid is pumped downwardly in the annulus
`through port 222 and upwardly through test string 36
`thereby circulating well fluids from test string 36.
`Valve 200 is opened by shifting safety mandrel 230 then
`shifting operating mandrel 214 as follows. With valve 200 in
`the configuration of FIG. 3A and suspended on test string 36
`as shown in FIG. 1, the hydrostatic pressure of the annulus
`fluids upwardly bias safety mandrel 230 via communication
`
`35
`
`40
`
`45
`
`50
`
`60
`
`65
`
`8
`port 242. Seal 238 defines an outer diameter and seal 240 an
`inner diameter of safety mandrel 230. When the hydrostatic
`force reaches the predetermined level necessary to overcome
`the bias force of spring 234, safety mandrel 230 moves
`upwardly with lower end 232 and seal 241 ofsafety mandrel
`230 no longer contacting operating mandrel 2.14. A rupture
`disk 243 may additionally be placed within communication
`port 242 that is set to burst at a predetermined pressure.
`After safety mandrel 230 has moved to its upper position
`as best seen in FIG. 313, test string 36 is pressurized thus
`permitting pressurized lluid to travel through communica-
`tion port 225 and act on operating mandrel 214. Seal 244
`defines an outer diameter and seat 246 defines the inner
`diameter of operating mandrel 214. When the pressure
`reaches the predetermined level necessary to shear the shear
`pins 216. operating mandrel 214 moves quickly down-
`wardly.
`In the lower position of operating mandrel 214 as best
`seen in FIG. 3C, seal 244 is below port 222 and thus lluid
`communication is permitted between the annulus and the
`interior of housing 202 thereby allowing reverse circulation.
`Thus,
`it can be seen that prior to operating of safety
`mandrel 230 there is no risk of inadvertently opening
`circulation port 222 since interior pressure will not operate
`operating mandrel 214. Before pressure in test string 36 can
`be so communicated, safety mandrel 230 must be urged
`upwardly until seal 241 is above communication port 225 of
`operating mandrel 214.
`Once operating mandrel 214 has opened circulating port
`222, it remains open. When the formation fluids arc circu-
`lated out of test string 36 and fully replaced by the fluids
`from the annulus, test string 36 may be pulled from wellbore
`18.
`While this invention has been described with a reference
`
`to illustrative embodiments, this description is not intended
`to be construed in a limiting sense. Various modifications
`and combinations of the illustrative embodiments as well as
`other embodiments of the invention, will be apparent
`to
`persons skilled in the art upon reference to the description.
`It is therefore, intended that the appended claims encompass
`any such modifications or embodiments.
`What is claimed is:
`1. A downhole tool comprising:
`a housing;
`a safety mandrel slidably received within the housing, the
`safety mandrel operating in a Iirst direction between a
`first position and a second position relative to the
`housing in response to pressure being applied to the
`exterior of the housing; and
`an operating mandrel slidably received within the
`housing, the operating mandrel operating in .1 second
`direction from a first position to a second position
`relative to the housing in response to pressure being
`applied to the interior of the housing when the safety
`mandrel is in the second position of the safety mandrel
`rela