Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3356140 A
Publication typeGrant
Publication dateDec 5, 1967
Filing dateJul 13, 1965
Priority dateJul 13, 1965
Publication numberUS 3356140 A, US 3356140A, US-A-3356140, US3356140 A, US3356140A
InventorsDouglas Young James
Original AssigneeGearhart Owen Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Subsurface well bore fluid flow control apparatus
US 3356140 A
Abstract  available in
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Dec. 5, 1967 J. D.'YOUNG 3,356,140

SUBSURFACE WELL BORE FLUID FLOW CONTROL APPARATUS Filed July l5, 1965- 5l PW? /05 l /09- j V K 55 *g3 6/ 8 n .90 8l 99 /0/ /6 /02 /07 67 65 77 F f 22 /5 /3 99 /87 95 d] 89 G 25 i? 95\ -79 .29 f, 7/ x 75 l N VENTOR.

United States Patent O 3,356,140 SUBSURFACE WELL BORE FLUID FLOW CONTROL APPARATUS .lames Douglas Young, Fort Forth, Tex., assignor to Gearhart-wen, Inc., Fort Worth, Tex. Filed .luly 13, 1965, Ser. No. 471,539 2 Claims. (Cl. 166-128) ABSTRACT OF THE DISCLOSURE Improved valve means controls fluid flow from and to first and second zones in a well bore, with the zones being isolated except via the valve means. The improved valve means includes a floating valve member reciprocable within a valve retainer which has three cylindrical portions of different diameters each of which is engageable by a respective seal means on the floating valve member. The arrangement is such that, when the floating valve member is closed, fluid impinging on respective seals from either or both of the zones creates unbalance forces that act to maintain the floating valve member in the closed position. Also provided are improved means for moving the floating valve member from the closed to the opened position.

My invention relates in general to subsurface well bore equipment and in particular to well packers adapted to be set in well casings or similar conduit strings.

Previously, well packers were developed that included valve elements that can be selectively closed or opened to control the flow of fluid between axial passages extending through the packers to the exterior thereof below the expansible gripping and packing means. Such previously developed valve elements are generally mechanically operated and have a number of disadvantages. For example, prior art valve elements sometimes fail to function properly when subjected to the adverse conditions encountered in well bores, and occasionally become lodged in an opened or elo-sed position.

It is the general object of my invention to provide improved well packers of the type having valve members movable between opened and closed positions to control the flow of fluid through the axial passages that extended through the packers.

Another object of my invention is to provide in well packers improved valve means for opening or closing fiuid passages that extend through the packers to region-s below the gripping and sealing means.

These and other objects are effected by my invention as will be apparent from the following description, taken in accordance with the accompanying drawing, in which:

FIG. 1 is a view of subsurface well apparatus asl seen in longitudinal cross section, said apparatus embodying the principles of my invention;

FIG. 2 is an enlarged fragmentary view, as seen in longitudinal section, showing the lower portion of the apparatus of FIG. 1;

FIG. 3 is a cross sectional view of the apparatus as seen looking alon-g the lines III-III of FIG. 1;

FIG. 4 is a cross sectional view of the apparatus as seen looking along the lines IV-IV of FIG. 1.

The packer apparatus A of FIG. 1 is adapted to be lowered into a well casing B by a wire line (not shown). This apparatus has gripping means C and packing means D that are radially expansible to engage the well casing B. Such packing and gripping means are mounted on a body E. A valve member F is disposed to engage the lower portion of body E and is 'restrained from unlimited axial movement by valve retainer means G. The valve member controls the fiow of fluid between an axial passage in the packer to the exterior of the packer below the gripping l means C and the packing means D and is urged toward a closed position by fluid pressure, as will be explained in detail later. A valve member actuator means H is engageable with the valve member F to move valve member F to its opened position.

The packing means D, the gripping means C, and the portions of the apparatus A used to operate these means are illustrated by way of example in the drawing b-ut can be of any desired type. The one illustrated has a release ring 11 with a threaded interior cylindrical surface that is secured to an adaptor 13. A seal ring 14 is provided between the release ring and the adaptor to prevent fluid flow in this region. The release ring 11 has a weakened region 15 that fails when subjected to a predetermined amount of axial force. A conventional setting tool (not shown) is secured to the upper, threaded portion 16 of the release ring. The setting tool and the apparatus A are lowered into the well casing on a wire line until the desired depth or location in ca-sing B is reached.

The adaptor 13 is secured to an upper threaded region 17 of the body E of the apparatus. Seal rings 21, 23 are provided in the threaded region between body A and adaptor 13 to prevent fluid flow therebetween. Adaptor 13 engages a cup 25 that is slidably supported on cylindrical body E and retained thereon by means of a shear pin 27. The shear pin 27 prevents accidental axial movement ofthe cup 25 with respect to body E.

Cup 25 has a lower, radially extending shoulder 29 that engages a mating shoulder on gripping means C` The gripping means C includes upper segmental, annular slips 31 havin-g upwardly facing teeth 33 that are adapted to engage the casing B to prevent upward movement of the apparatus A when the gripping means are expanded. The slips 31 are held around body E by a plurality of resilient slip rings 35 that are disposed in external annular recesses 37. The upper segmental slips 31 surround the upper end portion of a conical expander or wedge 39, which surrounds the body E and is adapted for axial movement thereon. Accidental movements of expander 39 are prevented by a shear pin 40.

A lower radially extending shoulder 41 of expander 39 engages a mating shoulder on a preferably hard rubber upper shoe 43. This shoe has a downwardly extending annular lip 45 that mates with a beveled region of a soft rubber, resilient packing ring 47 that also surrounds the body E. A lower shoe 48 (also of -hard rubber) that is similar to the upper shoe 43, but in an inverted position, engages a Ilower beveled end of the packing ring 47. A lower expander or wedge 49 engages lower shoe 48 and in turn is engaged by lower segmental slips 51 that are held around body E by a resilient split ring 53 disposed in an annular groove 55. Expander 49 is held in position iby a shear pin 54. The body E has a lower shoulder 57 which Y supports lower slips 51.

To set the gripping means C and packing means D at a selected position in casing B, the setting tool (not shown) is actuated so that a downward force is exerted against cup 25. This downward force is large enough to shear the shear pins 27, 46 and 54, and the upper and lower slips 31, 51; the -upper and lower expanders 39, 49; and the upper and lower shoes 43, 48 are moved axially together. The packing ring 47 expands radially into sealing engagement with the casing B, and the upper and lower slips 31, 51 are urged radially'outwardly on the conical expanders 39, 49 into gripping engagement with the casing B. Thus the apparatus A is secured in fixed relationship with the casing B since the upper slips 31 prevent upward movement of the apparatus and the lower slips 51 prevent downward movement thereof. At this stage, the setting tool (not shown) may be removed by exerting with conventional means (not shown) a predetermined amount of tension upon release ring 11 until it shears at weakened region 15.

The valve member 'F and retainer means G, shown in FIGS. 1 and 2 at the lower end of the apparatus A below the gripping means C and packing means D, are used in conjunction with the valve member actuating means H to selectively open or close a fluid passage that extends from an axial passage 59 of body E to the exterior of the apparatus below packing means D and gripping means C. In some situations (for example, when pumping cement or other slurry down well tubing, through the packer apparatus and ultimately into communication with a formation) it is necessary that the valve member F be moved to an open position. In other situations (such as when testing the tubing for leaks) it is necessary that the valve member be moved to a closed position. The valve means illustrated in the drawing is particularly effective in accomplishing these results in an advantageous and reliable manner.

The floating valve member F is tubular, open-ended and coaxially aligned with the fluid passage 59 of body E. Valve member F has a beveled upper interior surface 61 vthat intersects a cylindrical surface 63. An annular groove 65 is formed at one region of cylindrical surface 63 and this groove has upper and lower camming surfaces 67, 69. The lower end of cylindrical surface 63 has an inwardly extending shoulder 71.

Referring especially to FIG. 2, the exterior of valve member F engages the interior of retainer means G and is axially slidable therein. The upper end of valve member F is adapted to engage a shoulder 73 formed on body E and an exterior shoulder 101 (see FIG. 2) of the valve member is adapt-ed to engage a shoulder on the interior of valve retainer means G. The interior end surface 75 of the valve member retainer means G is never engaged by the valve member F so that fluid can freely flow therebetween even when the valve member is in its open position. Retainer means G of FIGS. 1 and 2 has an upper section 77 and a lower section 79. Upper section 77 is joined to body E by threads 81, and a seal ring 83 is provided to prevent fluid flow through this threaded region. One or more fluid ports 85 are formed in the upper section 77 of retainer means G. The lower section 79 of retainer means G is secured by threads 87 to the upper section 77. A seal ring 89 is provided to prevent the flow of fluid between sections 77, 79.

The area of the downwardly facing surfaces of valve member F is greater than the area of its upwardly facing surfaces. Consequently, fluid pressure inside or outside the apparatus A urges the valve member to the upper closed position shown in FIG. l. The upper section 77 of valve member retainer means G is confronted with mating cylindrical surfaces on the exterior of valve member F, and upper and lower seal means 90, 91 extend between the cylindrical surfaces to prevent fluid flow therebetween when the valve is moved toward its upper closed position. An assembly ring 93 with interior and exterior seal rings 9S, 97 is secured to the lower end of valve member F. The resulting large, radially extending downwardly facing surface, when added to the other downwardly facing :surfaces is much larger in area than that of the combined :upwardly facing surfaces of the valve member F, Thus `the valve member is urged by the fluid pressure inside the vretainer means G toward the closed position seen in FIG. l.

The purpose in having assembly ring 93 formed of a separate piece is to permit assembly of the valve member F inside retainer means G. During assembly, upper and lower sections 77, 79 of retainer means G are separated and valve member F is inserted into upper section 77 through its upper end. This is necessary since valve member F has an upper cylindrical surface 98 that is larger in diameter than the diameter of the smallest interior cylindrical surface -99-of upper retainer section 77. Once valve member F is inserted into upper section 77, the adaptor ring 93 (its outer cylindrical surface 100 is larger in diam- `eter than the diameter of the smallest interior cylindrical surface- 99 of upper retainer section 77) may be secured to the lower end of valve member F by suitable means such as threads. Then, thelower section 79 of retainer means G is secured to the upper section 77 and finally, the entire retainer means G and the valve member F are secured to the lower end of body E of apparatus A.

From the above it may be seen that the valve member F is urged toward its upper closed position when seals 91 and 97 engage the mating interior cylindrical surfaces of upper section '77 of valve member retainer means G. Upon pushing valve member F downward until seals 91 and 97 are below the mating cylindrical surfaces of valve member retainer means G, the upwardly and downwardly directed forces exerted upon valve member F become equalized. Consequently, there is no tendency for valve member F to move under the influence of fluid pressures while in the open position.

When seals 91 and 97 engage the mating surfaces of retainer means G, however, the fluid pressure inside the apparatus pushes the valve member toward its closed position because the diameter of the lowermost region of the valve is larger than that of the uppermost region of the valve. That is, the downwardly facing area of those portions of the valve member exposed to the fluid pressure inside the apparatus is larger than that of the upwardly facing surfaces exposed to such pressure. Also, the diameter of the intermediate region of the Valve member (i.e., that region which communicates with fluid ports when seal 91 engages the retainer means G) is smaller than that of the upper region of the Valve. Hence, the pressure of the fluid external of the apparatus tends to move the valve member toward its closed positions when seal 91 engages its mating cylindrical surface.

To move the valve to its lower, opened position, the valve member actuator means H is lowered on a tubing string through axial passage 59 of body E into engagement with the valve F. The actuator means H includes a seal nipple 102 that has a plurality of seal rings 103 surrounding its exterior surface to scalingly engage the axial bore 59 of body E. Secured to the lower end of seal nipple 102 is a collet 105 having a plurality of resiliently expansible and retractable protrusions 107 with tapered surfaces for mating with the internally formed annular groove 65 of valve F. Resiliency is obtained by forming axially extending slots 109 on the collet, which is formed of an elastic material such as heat treated steel. The extremity of collet 105 rst engages the upper beveled surface 61 of valve F and is thereby centered with respect to the valve. The outside diameter of collet 105 except for protrusions 107 is smaller than the internal diameter of the bore 66 through valve member F so that the collet can be pushed through the valve member. The protrusions 107 move inwardly as they engage cylindrical surface 63 of valve member actuator means H and eventually expand into the annular groove 65 of valve member F. When the downward force exerted on valve F by the collet E05 exceeds the upward force on valve F caused by the fluid pressure (as explained above), the valve F will be moved to a downward, opened position. Movement of the collet is effected by raising or lowering the tubing string (not shown) which is secured to seal nipple 102 by a collar connector 111. With the apparatus positioned as shown in FIG. 2, fluid is pumped through the axial flow passage of actuator means H and to the exterior of apparatus A. Fluid flows through the space between the exterior of valve F and the interior of retainer means G and through valve ports S5 when valve F is in the open position shown in FIG. 2.

To move valve F to its upper, closed position, the tubing string (not shown) is raised so that collet 105 and the valve F (through engagement of protrusions 1.07 on the collet and the internal annular groove 65) are moved upward. When valve F is in its Lipper closed position, further upward movement of collet 105 causes the protrusions 107 to move radially inward due to engagement with upper cam surfaces 67 of valve F. Continued upward movement results in the complete separation of the collet S and valve F. Thereafter the collet 105 and the tubing string may be removed from the casing. Due to the imbalance in the upwardly and downwardly facing surface areas when the Valve member F is in or adjacent its closed position, the fluid pressure urges the valve to its closed position.

It should be .apparent from the foregoing that I have provided an invention having significant advantages. The above described well packer is an improvement over related prior art devices, and has a valve member that is easily and reliably moved between opened and closed positions to effectively control the flow of fiuid through the packer. The means for opening the Valve member is very simple, involving no complicated mechanisms or movements. Moreover, the configuration of the valve member F utilizes the pressure of the fluid to urge the valve member to a closed position. Thus, the use of springs or other mechanical elements for this purpose is eliminated; as a result the apparatus is further simplified.

Although I have shown my invention in only one form, it should be apparent to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

I claim:

1. In a well apparatus of the type to be disposed in a well casing on a running in string and wherein a body with an axial fluid passage is anchored to the well casing by gripping means, there being on the body packing means adapted to be expanded against the well casing, the combination therewith of (a) a tubular, open-ended, floating valve member coaxially aligned and communicating with the axial fiuid passage of said body and having upper closed and lower opened positions for closing oropening a fluid passage that extends from the axial fluid passage of said body to the exterior of said apparatus below said gripping and said sealing means, with said valve member having downwardly facing surfaces that are exposed to fiuid being larger in area than than the area of its upwardly facing surfaces that are exposed to fluid so that the pressure of the fluid urges said valve member toward its upper closed position, said valve member having an annular groove formed internally therein;

(b) valve member retainer means secured to said apparatus below said gripping and said sealing means to limit the axial movement of said valve member, said retainer means having at least one fluid port extending therethrough to permit fluid flow through said retainer means to the exterior of said apparatus when said valve member is in an opened position;

(c) seal means between said valve member and said retainer means to prevent fiuid flow therebetween when said valve member is in its closed position; and

(d) Valve member actuator means having an end portion engageable with the interior of said valve member, said actuator means end portion having resilientiy expansible and retractable protrusions for mating and unmating selectively with the internally formed annular groove of said valve member.

2. In a Well apparatus of the type to be disposed within a well and having a body which is to be fixed relative to the well bore, with said body having an axial fluid passage, and valve means operable to control fiuid fiow through said passage to or from a first zone from or to a second zone which is isolated from the first Zone except via said valve means, the improvement wherein:

(a) said valve means includes a floating valve member reciprocable Within valve retainer means;

(b) said retainer means having a bore including a rst cylindrical portion having a first diameter, a second cylindrical portion having a second diameter, and a third cylindrical portion having a third diameter, with said first diameter being greater than said Second diameter and said third diameter being greater than said first diameter, with said second cylindrical portion being disposed between said first and third cylindrical portions;

(c) first, second and third seal means on said floating valve member sealingly engageable with said first', second and third cylindrical portions respectively, With each said seal means engaging a corresponding cylindrical portion when the floating valve member is in the closed position, and with only the first seal means engaging a corresponding cylindrical portion when the floating valve member is in the opened position;

(d) first fluid passage means communicating from the exterior of said valve retainer means to its interior at the region between said first and second cylindrical portions so that fluid from said second zone impinges upon said first and second seal means when said fioating valve member is in the closed position;

(e) second fluid passage means communicating between said first zone and said first and third seal means when said fioating valve member is in the closed position;

(f) whereby, when said iioating valve member is in the closed position, pressure force unbalance on respective seals due to fiuid from either or both of said first and second zones, will act to maintain said valve member in the closed position.

References Cited UNITED STATES PATENTS 2,033,563 3/1936 Wells 166-126 3,163,225 12/1964 Perkins 166-128 3,306,363 2/1967 McZilkey 166-152 3,306,365 2/ 1967 Kammerer 166-224 JAMES A. LEPPINK, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2033563 *Aug 25, 1934Mar 10, 1936Technicraft Engineering CorpMeans for controlling well flow
US3163225 *Feb 15, 1961Dec 29, 1964Halliburton CoWell packers
US3306363 *Apr 22, 1964Feb 28, 1967Baker Oil Tools IncValve controlled well packer apparatus
US3306365 *May 13, 1963Feb 28, 1967Baker Oil Tools IncWell bore testing and displacing valve apparatus
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3433301 *Oct 5, 1967Mar 18, 1969Schlumberger Technology CorpValve system for a well packer
US3457994 *May 18, 1967Jul 29, 1969Schlumberger Technology CorpWell packer valve structure
US3483921 *Dec 16, 1968Dec 16, 1969Schlumberger Technology CorpWell packer having a selectively positionable valve means
US3485298 *Dec 16, 1968Dec 23, 1969Schlumberger Technology CorpRetainer packer valve system
US3570595 *Nov 22, 1968Mar 16, 1971Schlumberger Technology CorpHydraulically operable valves
US3633669 *Aug 24, 1970Jan 11, 1972Exxon Production Research CoApparatus for running in and operation of valves and the like
US3633670 *Jan 2, 1970Jan 11, 1972Brown Oil ToolsTool string assembly for use in wells
US3675718 *Sep 11, 1970Jul 11, 1972Exxon Production Research CoConducting operations in a well through a normally closed valve
US3732925 *Jan 18, 1972May 15, 1973Exxon Production Research CoApparatus for conducting operations in a well through a normally closed valve
US4252195 *Jul 26, 1979Feb 24, 1981Otis Engineering CorporationWell test systems and methods
US4372388 *Nov 24, 1980Feb 8, 1983Halliburton CompanySubsurface control valve
US4372390 *Sep 2, 1980Feb 8, 1983Hughes Tool CompanyWell valve
US4441552 *Jun 18, 1982Apr 10, 1984Halliburton CompanyHydraulic setting tool with flapper valve
US4470465 *Apr 22, 1983Sep 11, 1984Halliburton CompanyBall type shut in tool
US4487221 *Nov 16, 1981Dec 11, 1984Klaas ZwartDevice for temporarily sealing a pipe
US4648445 *Dec 13, 1985Mar 10, 1987Halliburton CompanyRetrieving mechanism
US4651829 *Dec 13, 1985Mar 24, 1987Halliburton CompanySubsurface control valve
US6712153Jun 27, 2001Mar 30, 2004Weatherford/Lamb, Inc.Resin impregnated continuous fiber plug with non-metallic element system
US7036602Jul 14, 2003May 2, 2006Weatherford/Lamb, Inc.Retrievable bridge plug
US7124831Apr 8, 2005Oct 24, 2006Weatherford/Lamb, Inc.Resin impregnated continuous fiber plug with non-metallic element system
US7389823Jan 31, 2006Jun 24, 2008Weatherford/Lamb, Inc.Retrievable bridge plug
US7779927Dec 23, 2009Aug 24, 2010Weatherford/Lamb, Inc.Non-metallic mandrel and element system
US7779928Aug 24, 2010Weatherford/Lamb, Inc.Non-metallic mandrel and element system
US7789135Dec 23, 2009Sep 7, 2010Weatherford/Lamb, Inc.Non-metallic mandrel and element system
US7789136Dec 23, 2009Sep 7, 2010Weatherford/Lamb, Inc.Non-metallic mandrel and element system
US7789137Dec 23, 2009Sep 7, 2010Weatherford/Lamb, Inc.Non-metallic mandrel and element system
US8002030Aug 23, 2011Weatherford/Lamb, Inc.Retrievable bridge plug
US8079413Dec 20, 2011W. Lynn FrazierBottom set downhole plug
US8307892Jan 24, 2012Nov 13, 2012Frazier W LynnConfigurable inserts for downhole plugs
US8459346Dec 16, 2011Jun 11, 2013Magnum Oil Tools International LtdBottom set downhole plug
US8496052Dec 23, 2008Jul 30, 2013Magnum Oil Tools International, Ltd.Bottom set down hole tool
US8505623 *Aug 11, 2009Aug 13, 2013Weatherford/Lamb, Inc.Retrievable bridge plug
US8783341 *Jul 2, 2010Jul 22, 2014W. Lynn FrazierComposite cement retainer
US8899317May 13, 2013Dec 2, 2014W. Lynn FrazierDecomposable pumpdown ball for downhole plugs
US9062522Jul 29, 2011Jun 23, 2015W. Lynn FrazierConfigurable inserts for downhole plugs
US9109428Jul 29, 2011Aug 18, 2015W. Lynn FrazierConfigurable bridge plugs and methods for using same
US9127527May 13, 2013Sep 8, 2015W. Lynn FrazierDecomposable impediments for downhole tools and methods for using same
US9163477Jun 5, 2012Oct 20, 2015W. Lynn FrazierConfigurable downhole tools and methods for using same
US9181772May 13, 2013Nov 10, 2015W. Lynn FrazierDecomposable impediments for downhole plugs
US9217319May 15, 2013Dec 22, 2015Frazier Technologies, L.L.C.High-molecular-weight polyglycolides for hydrocarbon recovery
US9279307Jul 29, 2013Mar 8, 2016Weatherford Technology Holdings, LlcRetrievable bridge plug
US9309744Dec 16, 2011Apr 12, 2016Magnum Oil Tools International, Ltd.Bottom set downhole plug
US20040177952 *Mar 29, 2004Sep 16, 2004Weatherford/Lamb, Inc.Resin impregnated continuous fiber plug with non-metallic element system
US20100263857 *Jul 2, 2010Oct 21, 2010Frazier W LynnComposite Cement Retainer
US20110036564 *Aug 11, 2009Feb 17, 2011Weatherford/Lamb, Inc.Retrievable Bridge Plug
USD657807Apr 17, 2012Frazier W LynnConfigurable insert for a downhole tool
USD672794Dec 18, 2012Frazier W LynnConfigurable bridge plug insert for a downhole tool
USD673182Dec 25, 2012Magnum Oil Tools International, Ltd.Long range composite downhole plug
USD673183Dec 25, 2012Magnum Oil Tools International, Ltd.Compact composite downhole plug
USD684612Jun 18, 2013W. Lynn FrazierConfigurable caged ball insert for a downhole tool
USD694280Jul 29, 2011Nov 26, 2013W. Lynn FrazierConfigurable insert for a downhole plug
USD694281Jul 29, 2011Nov 26, 2013W. Lynn FrazierLower set insert with a lower ball seat for a downhole plug
USD694282Jan 7, 2013Nov 26, 2013W. Lynn FrazierLower set insert for a downhole plug for use in a wellbore
USD697088Jul 29, 2011Jan 7, 2014W. Lynn FrazierLower set insert for a downhole plug for use in a wellbore
USD698370Jul 29, 2011Jan 28, 2014W. Lynn FrazierLower set caged ball insert for a downhole plug
USD703713Sep 27, 2012Apr 29, 2014W. Lynn FrazierConfigurable caged ball insert for a downhole tool
EP0123393A2 *Mar 8, 1984Oct 31, 1984Halliburton CompanyBall type shut in tool for wells
EP0226455A2 *Dec 11, 1986Jun 24, 1987Halliburton CompanySubsurface control valve
WO1982001736A1 *Nov 16, 1981May 27, 1982Klaas ZwartDevice for temporarily sealing a pipe
Classifications
U.S. Classification166/128, 166/332.1
International ClassificationE21B33/129, E21B33/12
Cooperative ClassificationE21B33/1294
European ClassificationE21B33/129N