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Publication numberUS2757741 A
Publication typeGrant
Publication dateAug 7, 1956
Filing dateNov 12, 1954
Priority dateNov 12, 1954
Publication numberUS 2757741 A, US 2757741A, US-A-2757741, US2757741 A, US2757741A
InventorsO'reilly Wallace M
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Back pressure regulator for wells
US 2757741 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

W. M. O'REILLY BACK PRESSURE REGULATOR FOR WELLS Filed Nov. l2... 1954 Aug. 7, 1956 United States Patent 2,757,741 BACK PRESSURE REGULATOR FoR WELLS f Application November l12, 1954, 'Serial No. 468,301

'12 Claims. (Cl. 1664-118) The present invention is directed to a retrievable back pressure regulator. directed to a throttling-type subsurface back pressure regulator which is adapted to be arranged in a tubing string. In its more specilic aspects, the invention is directed to a device useful in conducting subsurface operations and in maintaining pressure in a well tubing.

The present invention may be briefly described as a retrievabie throttling-type subsurface back pressure regular which is adapted to be arranged in sealing relationship in a well tubing string. The back pressure regulator comprises a tubular body member having a 'cylindrical bore yand provided with vertically spaced apart first and second ports fluidly communicating the bore With the exterior surface of the body member. A packing means is arranged on the exterior` surface of the body member for packing off between the interior of the tubing and the body member and a seating orsupporting `means is arranged on the exterior surface of the body member for supporting or seating the body member in the tubing.

Spaceti apart first andsecond sealing means are arranged within the bore and a slidably mounted body member is arranged in sealing relationship' to the first and second sealing means within the bore, the body member having iirst and second differential surface areas and is provided also with first and second longitudinalvpassageways. A third sealing means is carried by the slidable body member in sealing relationship to the bore.

Fig. l shows the arrangement `of the apparatus of the present invention in a tubing string; and I )e i Fig. 2 is a detail in partial section of the 'apparatus'of the present invention.

Referring now to the drawing in which similar numerals will be employed to designate identical parts and particularly to Fig. l, numeral 11 designates a well bore drilled from earths surface 12 to penetrate at least an eil productive interval 13. In this instance production may be obtained from one of a plurality of intervals,- Zones, strata, horizons or formations below interval 13. The well bore 11 has a'casing string 14 arranged therein which is cemented in place with primary cement'r15. Also arranged in the casing 14 is a tubing string` 16 formed of a plurality of sections 17 which are coupled together by a pipe connecting means 18.

A well head or Christmas treearrangement, such aS Morelparticularly,.the invention is ICC 2 19 closes in the tubing and casing and valves 20, such as usually foundon Christmas tree installations, are also provided.l The tubing has connected thereto a lubricator 21 of the conventionalndesign provided with valves 22.

Connected to'the tubing 1.6 and to one of the valves 20 by a conduit 23 is a pump24 which imposes fluid pressure on the tubing.

A device in accordance withy theh present invention generally indicated by the numeral 3i) is arranged in the lower end ofthe tubing 16 and supported thereon in a landing nipple 25,theback pressure regulator valve 30 being seatedin the landing ynipple 25 by meansiof latch- -ing dogsl 26 on the exterior surface of the valve 30. An illustration of'v a landing nipple suitable in the practice of the present invention may be found 'in Figf`49, page 4000, vol..2,` 20th edition, Composite Catalog of Oil Field and Pipeline Equipment, 1954-55.

The annulus A between the tubing 16 and the casing 14 is sealed olf by a packer 10, a description .of which may be .found at page 4819of Vol. 2 of the Composite Catalog supra.

, Referring nowto Fig. 2, the back pressure regulator 3i) is described in more detail and comprises a body member 31 defining with its interior surface a cylindrical bore A.32. The upper end of the body .member 31 has a fishing neck 33 for engagementwith a fishing tool carried on a wire line. Arranged on the exterior surface of the bodymember 31 below the latching dogs 26 is a suitable packer or sealing means 34 for sealing between the interior of the tubing 16 and the exterior of the body `member 31. The packing or sealing means may be either yabove or below the latching dogs 26 but must be above the ports 3.5. Spaced lbelow the packing means 34 is a rst port 35 whichcommunicates the cylindricalbore 32 with the interior of the tubing` 16 and spaced apart from the first port 35 isa second port 36 Which'also communicates the cylindrical bore 32 with the tubing. i y A The cylindrical ybore 32 has a restricted portion 37 of smaller cross-sectional area than the upper portion of the cylindrical bore 32, Arranged within the smaller portion 37 of the cylindrical bore 32 are spaced apart packing means 38Y and 39 which enclose a space S in Athe portion 37 of the cylindrical bore 32. Slidably arranged Within the cylindricalubore 32 and the portion 37 thereof is a slidable plug 40 which carries a packing means 41 on its upper end in sealing relationship with the upper portion of the cylindrical bore 32. The lower end 42 of the slidable plug 40 is of reduced cross-sectional area and is sealingly arranged for sealing engagement with the sealing means 38 and 39. l

Extending longitudinally the greater length of the f slidable plug 40 is a iirst longitudinal passageway 43 which communicates a'surface area 44 with the space S through an opening 45. Communicating a surface area 46 of, the lower end 42 of the slidable plug 40 with the port 35 is a second longitudinal passageway 47 which has an opening 48 normally positioned above sealing means 38. The lower end of the passageway 47 is always below the packing means 39.

Normally urging the 'slidable plug 40 in sealing relationship with the first port 35 is a biasing means, such as a helical coil spring 62,.which bears against the surface 46 and is confined by an adjustable annular plate member 63 which is threadably engaged with the body member by mating threads 49.

The annular plate vmember 63 has an orifice 50 which defines a conical seating surface for the adjustable valve Patented Aug. 7, 1956 31,and it will be further seen that the adjustable valve member 51 is provided with a hexagonal nut 54 for adjustment thereof either to open the orifice 50 or to throttle same.

The apparatus of the present invention is suitably used n maintaining a pressure on a tubing string at a predetermined point but is quite useful in injecting sealing compound and the like for use in sealing leaking pipe connec tions, such as 18.

In this operation, which will be described in more detail hereinafter, a thread sealing compound may be used which may be composed of of equal amounts of 100 to 140 mesh silica, 140 to 200 mesh silica, and 200 plus mesh silica and 90% of a lubricating oi-l base or grease. Further thread sealing materials may suitably be used, such as compounds of finely divided particles dispersed in a lubricating base or grease. Descriptions of suitable lubricating bases are found in U. S. Patents 2,205,990, Nelson et al., 2,065,248, Smith and in Abstract 165,377, entitled Thread Lubricant," 662, O. G. 4, page 1188.

In the use of the device of the present invention different types of thread sealing compounds may be used for different types of leakages; for example, one sealing cornpound may seal certain types of leaks while other types will seal larger or smaller `type holes in the tubing string. For example, two different types of thread sealing compounds with different average particle sizes in the lubricating vehicle may be used together or separately.

Prior to the introduction of a thread sealing compound, the device of the present invention is employed to retain the uid contents of the tubing under pressure and pressure relief from the tubing is directed through the device of the back pressure regulator 30. In other words, the back pressure regulator contains the contents of the tubing as surface pumping with pump 24 effects the internal pressure increase. Thereafter a sealing compound, such as a body 60, is introduced into the tubing.

In practicing the present invention, a body of a thread sealing compound, such as indicated by the numeral 60, is lubricated into the 'tubing through the lubricator 21. Before introducing the body 60 of the thread sealing compound of the type mentioned, a plug 27 provided with sealing members 28 and a fishing neck 29 may be introduced into the lubricator and into the tubing. After the body of sealing material 60 has been lubricated into the tubing after the plug 27, it is confined by a second plug 27 of a similar type. As the sealing compound is injected into the tubing, pressure is imposed through pump 24 and the sealing compound is pumped downwardly as a slug between the plugs 27, leaving depositions in existing crevices and apertures as the compression of the tubing contents is accomplished. When the tubing pressure` has increased to a predetermined magnitude, acting on the upper surface 44 of the reciprocating or slidable plug 40, the device opens to permit passage from the tubing of some of its contents to release the pressure. As the pressure increases beneath the plug through the longitudinal passageways in the plug 40, the plug reciprocates in the opposite direction to close and thereafter the throttling-type continuous movement of the plug 40 maintains the internal pressure of the tubing at its predetermined magnitude. At this condition of maximum pressure, a second slug or body 61 of the sealing compound is injected into the tubing 16 through lubricator 21 or through well head or Christmas tree connections, the body 61 being confined between plugs 27 of the nature described supra. Both body members 60 and 61 are then moved simultaneously through the tubing squeezing the sealing compound into existing leaks at a constant pressure which is maintained by the pressure regulator. In other words, the pressure regulator allows the build up of pressure in the well tubing and the maintenance of the pressure.

The body member 31 is suitably run into the tubing through the lubricator on a wire line, not shown, attached to the fishing neck 33 and landed in the landing nipple 25 with the latching dogs 26 in engagement with the landing nipple 25.

In operation, the plug 40 is held in its normal position, as shown, in the drawing, by the helical coil spring 62 of predetermined tension. Thus in this position, the packing means 41 `isolates the port or ports 35 from the tubing contents above the regulator 30 by virtue of the packer 34 on the exterior of the body member 31. The force of the -spring 62 determines the operating pressure in the tubing 16 and, of course this force is adjustable by a mechanical manipulation of the annular plate member 63 relative to the body member 3l. As pressure is increased on the differential surface 44 to overcome the force of the spring 62, the plug 40 is caused to move downwardly establishing communication between the ports 35 and the contents of the tubing above the plug 40. This causes the port 45 and the longitudinal passageway 43 to move from the space S between the packing means `38 and 39 into the lower portion 37 of the cylindrical bore 32 between the packing means 39 and the plate 63. The port 48 of the longitudinal passageway 47 is then moved into thc area or space S between the packing members 38 and 39 and pressure from the tubing 16 which is admitted through the port 35 down between the body member 31 and the tub ing into the lower well bore is thus directed to the passageway 43 into the lower portion` 37 of the cylindrical bore 32 between the sealing means 39 and the plate 63. This increase of pressure then acts on the surface 46 which is less in area than the surface 44 and in conjunction with the energy of the compressed spring 62 will cause a reversal of movement of the plug 40 or a reciprocation thereof to its normal position; thus the assembly is prepared for another cycle operation as described. The port 48 of passageway 47 permits pressure in the lower portion of the bore 37 below the packing means 39 to escape through the ports 35 into the lower well bore. The rate of pressure buildup on surface 46, which determines the rate of cycling action, may be governed by manipulation of the adjustable valve member 51 which controls the cscape of pressure through alternate lower port 36.

The maintenance of a predetermined pressure in the tubing as described in the next paragraph is obtained by the series of movement of plug 40 to effect opening and closing of the ports 35. The rate of operational cycling may be regulated by positioning of the screw-type adjustment valve 51 to establish a desired orifice in the port 50 in annular plate member 63. Pressure from below the packing means 39 escapes through the orifice or port 50 into the zone Z between the annular plate 63 and the closure plate 52 and this pressure is then bled through port 36 into the lower well bore. This escape of pressure determines the rate of pressure increase on the area 46 to cause reciprocation upwardly of the plug 40 to complete the cycle as described.

h The present invention is of considerable use in conducting operations, such as described in sealing leaking threads, couplings and other holes or orifices in tubings. The pressure setting and position of the device 30 may be selected for individual wells and is based on the bottomhole pressure, the gradient of the contents of the tubing and the annulus of the well, and the rated working pressures of the well equipment. As an example, in a well of a depth of 8000 feet `and having a bottom hole pressure of approximately 3800 pounds per square inch is may be desirable to set the regulator 30 at a level of approximately 7800 feet. Experience has indicated that the landing nipple ordinarily available near the bottom of the tubing string is a convenient location for which the other factors may be adjusted and the landing nipple is thus ordinarily utilized where available. The pressure maintained on the well may be substantially in excess of normal well pressure and suitably in the range from about 3000 to 7500 pounds per square inch; a suitable pressure for wells extendingtofabout 16,000 feet may -be in the range from 5000'to 15,000 poundsV per squareinch." The-lower range of pressures is dependent on working pressure of well head equipment. The upper range'may be those exemplified plus approximately one pound per foot of well depth.

The amount of thread sealing material used for a 10,000 foot well may comprisevabout 1000 feet of the thread sealing material in a tubing of eitherxZ or 21,/2 in diameter. As a minimum, the body of thread sealing material should occupy approximately 50 yfeet of the tubing bore and, as a maximum, Iapproximately of the length of the complete `string yof tubing and such an amount that the hyrostatic pressure is less than the well pressure if the body is to be removed by liowing it from the well. In short, the body or plug of thread sealing compound occupies only a small percentage of the total length of the tubing through which it is passed in intimate contact with the tubing walls at a pressure `substantially in excess of the natural pressure of the well.

After the well has been treated by passing the thread sealing compound either a-s a separate body `or as a plurality of bodies 'substantially through the length of the tubing, the back pressure regulator 30 and the plugs 27 may be retrieved from the tubing 18 by engagement with a fishing tool carried on a wire line and thereafter tion from the well may be renewed.

The present invention is very-useful in conducting such operations in that it remains in a closed position until a predetermined internal pressure is built up in the tubing resulting lfrom pumping from the surface which applies a hydrostatic head to compress the contents of the tubing.

When .the predetermined pressure is obtained, the device opens asufiicient amount to allow passage from the tubingy of the contents of the tubing at a rate such that the pressure inside the tubing will be maintained at a substantially constant ligure. If the pumping rate is decreased, the device closes off with a minimum of hysteresis to maintain the predetermined pressure within the tubing.v

While numerical `values have been given in vthe examples, it is to be understood that these values are illustrat-ive only. and are not given by way of limitation;

The nature and objects of the present invention having been completely described and illustrated, what `I wish to claim as new` and useful 'andto' secure by Letters Patent is:

1. A retrievable back pressure regulator adapted to be arranged sealingly in a well tubing string which comprises,

in combination, a tubular'body member having a cylindrical bore and provided with vertically spaced apart vupper and lower ports fiuidly communicating the bore with the exterior surface of the body member, spaced apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means within said bore having first and second longitudinal passageways, said first and second'sealingl means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to saidV bore, biasing means normally urging said slidable body memberl and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, and an adjustable valve member arranged within said cylindrical bore having an orifice fluidly communicating the lower portion of the cylindrical bore with said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body member sufficient to exceed the force of the biasing means, said iirst longitudinal passageway normally communicating the space between said first and second sealing meanswith the upper end of the slidable body member and said second longitudinal passageway normally communicating said producupper port with member; l Y Y i 2. A retrievable back pressure regulator adapted to be arranged in a well tubing'string which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upper and lower ports iiuidly communicating the bore with the exterior surface of the body member, a packing means and aA seating means arranged on the exterior surface of said body member vertically spaced above said first port, spaced apart upper and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means'within said bore having first and second differential surface areas and provided with first and second longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to said bore, biasing means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, and an adjustable valve member arranged within said cylindrical bore having an orifice iiuidly communicating the lower portion of the the lower end `of -the slidable body cylindrical bore with said lower port, said slidable body l member being slidable downwardly to seal o the lower portion of the bore below the upper port on .exertion of pressure on the upper end of the slidable body member suflicient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said rst and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with the second differential surfacey area.

3. A retrievable back pressure-regulator adapted to be arranged in a well tubing string Which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upper and lower ports fluidly communicating the bore with the exterior' vsurface of the body member, a packing means and a seating means arranged on the exterior surface of said body member vertically spaced above said upper port, spaced apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means within said bore having first and second differential surface areas and provided with first and second longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, lthird sealing means carried'v by said slidable body member in sealing relationship to said bore and vertically spaced above said firstv and second sealing means, biasing means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, means closing the lower end of said cylindrical bore, and an adjustable valve member arranged within said cylindrical bore having an orifice iiuidly communicating the lower portion of the cylindrical bore withy said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body member sufficient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said first and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with the second differential surface area.

4. A retrievable back pressure regulator adapted to be arranged sealingly in a well tubing string which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upperand lower ports iluidly communicating the bore apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said firstand second sealing means within said bore having first and second differential surface areas and provided with first and second longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to said bore, biasing means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, means for adjusting tension of said biasing means, means closing the lower end of said cylindrical bore, and an adjustable valve member arranged within said cylindrical bore having an orifice fluidly communicating the lower portion of the cylindrical bore with said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body member sufficient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said first and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with the second differential surface area.

5. A retrievable back pressure regulator adapted to be arranged in a well tubing string which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upper and lower ports fiuidly communicating the bore with the exterior surface of the body member, a packing means and a seating means arranged on the exterior surface of said body member vertically spaced above said upper port, spaced apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means within said bore having first and second differential surface areas and provided with first and second `longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to said bore, biasing means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, means for adjusting tension of said biasing means, means closing the lower end of said cylindrical bore, and an adjustable valve member arranged within said cylindrical bore having an orifice fluidly communicating the lower portion of the cylindrical bore with said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body .ember sufficient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said first and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with the second differential surface area.

6. A back pressure regulator adapted to he arranged in a well tubing string which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upper and lower ports tiuidly communicating the bore with the exterior surface of the body member, a packing means and a supporting means arranged on the exterior surface of said body member vertically spaced above said upper port, spaced apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means within said bore having first and second differential surface areas and provided with first and second longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to said bore, biasing means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, means for adjusting tension of said biasing means, means closing the lower end of said cylindrical bore, an adjustable valve member ar ranged within said cylindrical bore having an orifice fiuidly communicating the lower portion of the cylindrical bore with said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body member sufficient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said first and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with the second differential surface area, and means for retrieving said back pressure regulator from the well tubing string.

7. A retrievable back pressure `regulator adapted to be arranged sealingly in a well tubing string which comprises, in combination, a tubular body member having a cylindrical bore and provided with vertically spaced apart upper and lower ports fiuidly communicating the bore with the exterior surface of the body membenspaced apart first and second sealing means arranged within said bore between said ports, a slidable body member arranged in sealing relationship to said first and second sealing means within said bore having first and second differential surface areas and provided with first and second longitudinal passageways, said first and second sealing means isolating a space around the slidable body member, third sealing means carried by said slidable body member in sealing relationship to said bore, means normally urging said slidable body member and said third sealing means in sealing relationship with said tubular body member to seal off the upper portion of the bore above the upper port, and an adjustable means arranged within said cylindrical bore having an orifice fiuidly communicating the lower portion of the cylindrical bore with said lower port, said slidable body member being slidable downwardly to seal off the lower portion of the bore below the upper port on exertion of pressure on the upper end of the slidable body member sufficient to exceed the force of the biasing means, said first longitudinal passageway normally communicating the space between said first and second sealing means with the first differential surface area and said second longitudinal passageway normally communicating said upper port with thc second differential surface area.

8. A retrievable back pressure regulator adapted to be arranged sealingly in a well tubing string which comprises, in combination, a tubular body member having a cylindrical bore and provided with upper and lower ports fiuidly communicating the bore with the exterior surface of thc body member, a slidable body member arranged within said bore, first sealing means within said bore for isolating a space around said slidable body member between said body members and second sealing means within said bore cooperating with said slidable body member for sealing off the upper portion of the bore above the upper port when the slidable body member is in `a first position and for sealing off the lower portion of the bore below the upper port when the slidable body member is in a second position, and means urging said slidable body member into the first position, said slidable body member being moved into the second position by sufficient fluid pressure acting on said slidable body member to exceed the force of the urging means, said slidable body member being provided with separate passageways one of which normally communicates the said space with the bore of the tubular member above the upper end of the slidable body member and the other of said passageways 11. A back pressure regulator in accordance with claim normally communicates the lower port with the upper 8 in which the urging means is a spring. port when the slidable body member is in ts rst position. 12. A back pressure regulator in accordance with k 9. A back pressure regulator in accordance with claim claim 8 which is provided with means for retrieving same 8 in which the second sealing means is carried by the 5 from the Well tubing string. body member above the mst seaimg means' v References Cited in the le of this patent 10. A back pressure regulator 1n accordance w1th clalm 8 provided with an adjustable valve member having an UNITED STATES PATENTS orifice iluidly communicating the lower portion of the 1,769,240 Smith July 1, 1930 bore with the lower port. 1 2,246,811 f Oris June 24, 1941

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1769240 *Aug 27, 1927Jul 1, 1930Aerometric Valve CorpInflating means
US2246811 *May 22, 1937Jun 24, 1941Otis Herbert CWell flowing device
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2906342 *Mar 21, 1956Sep 29, 1959Jersey Prod Res CoWell assembly for production of fluids from a plurality of zones
US2909227 *Jan 16, 1956Oct 20, 1959Otis Eng CoWell tools
US3050132 *Jul 1, 1957Aug 21, 1962Page Oil Tools IncFluid pressure operated shut-off valve for wells
US3987848 *Mar 6, 1975Oct 26, 1976Dresser Industries, Inc.Pressure-balanced well service valve
US4050516 *Jun 24, 1976Sep 27, 1977Dresser Industries, Inc.Method of injecting fluids into underground formations
US4063594 *Jun 11, 1976Dec 20, 1977Dresser Industries, Inc.Pressure-balanced well service valve
US4260020 *Sep 4, 1979Apr 7, 1981The Dow Chemical CompanyMethod and tool for controlling fluid flow from a tubing string into a low pressure earth formation
US8590629 *Feb 16, 2009Nov 26, 2013Pilot Drilling Control LimitedFlow stop valve and method
US8752630Oct 18, 2012Jun 17, 2014Pilot Drilling Control LimitedFlow stop valve
US8776887Apr 8, 2013Jul 15, 2014Pilot Drilling Control LimitedFlow stop valve
US20110036591 *Feb 16, 2009Feb 17, 2011Pilot Drilling Control LimitedFlow stop valve
Classifications
U.S. Classification166/118, 137/102, 166/142, 166/325, 137/624.14
International ClassificationE21B34/00, E21B33/13, E21B34/08, E21B33/14
Cooperative ClassificationE21B33/14, E21B34/08
European ClassificationE21B34/08, E21B33/14