US2863511A - Back circulating valve - Google Patents
Back circulating valve Download PDFInfo
- Publication number
- US2863511A US2863511A US528585A US52858555A US2863511A US 2863511 A US2863511 A US 2863511A US 528585 A US528585 A US 528585A US 52858555 A US52858555 A US 52858555A US 2863511 A US2863511 A US 2863511A
- Authority
- US
- United States
- Prior art keywords
- sleeve
- diameter portion
- sub
- ports
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000013013 elastic material Substances 0.000 description 7
- 230000000717 retained effect Effects 0.000 description 4
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 239000003129 oil well Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/10—Valve arrangements in drilling-fluid circulation systems
- E21B21/103—Down-hole by-pass valve arrangements, i.e. between the inside of the drill string and the annulus
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/06—Valve arrangements for boreholes or wells in wells
- E21B34/063—Valve or closure with destructible element, e.g. frangible disc
Definitions
- This invention relates to an oil well tool. More particularly, the invention relates to a back circulating valve adapted to be inserted in a well string.
- valves are available but, in general, these have been operable only when the well string was bottomed or set in the well by means of a packer or slips or the like, these valves being operable by relative rotational or longitudinal movement between the lower portion of the well string which is fixed in the well and carries one part of the valve, and the upper free portion ofthe well string which carries the other part of the valve.
- the back circulation valve When the necessity for reverse circulation arises, the back circulation valve must be opened quickly to enable immediate control over the well to avoid damage and waste. In many instances there is not time, nor is it practical or in some cases possible, to reset a packer or again bottom the well string to enable opening of a back circulation valve.
- Fig. 1 illustrates a sectional view of a valve embodying the principles of the invention, the valve being shown in its closed positon.
- Fig. 2 is a similar view of the valve shown in Fig. 1 and illustrates the valve after it has been opened.
- valve sub 10 indicates generally a tubular valve sub comprising upper and lower sections 11 and 12, respectively, threadedly connected together as indicated at 13.
- the upper end of the valve sub 10 is provided with a threaded box 14 and the lower end with a pin 15 to facilitate the insertion of the valve sub into a well string.
- the lower end of the upper section 11 is counterbored as shown at 16 and a sleeve 17 is slidably received in said counterbore and retained therein by a shear pin 18 extending inwardly from the wall of the section 11 into an annular notch 19 cut into the lower outer edge of the sleeve 17.
- a pipe plug 29 is threaded into the outer surface of the tubular section 11 behind the shear pin 18 to retain said pin in position.
- the sleeve 17 has a downwardly and inwardly tapered inner surface 21 for purposes hereinafter described.
- the tubular bore 22 in the lower section 12 is slightly larger in diameter than the counterbore 16 in the upper section 11.
- the upper section 11 is provided with a plurality of radially extending ports 23 adjacent the counterbored portion thereof.
- a sealing plug 24of rubber or other suitable elastic material is held in each of the ports 23 by a tubular seal retainer 25 which surrounds the plug 24 and is threaded into said port 23.
- Each of the plugs 24 has an external annular flange 26 which is confined between the tubular seal retainer 25 and the sleeve 17.
- Each of the plugs 24 has a conical depression 27 formed in its outer end.
- the elements are assembled into a well string.
- the hydrostaticpressure acting on the outer end of the plugs 24 tends to force the plugs inwardly and because of the conical depression 27 tends to expand the plug outwardly into tight sealing engagement with the retainer 25.
- a suitable sinker bar (not shown) is dropped through the string.
- suitable projections thereon contact the tapered surface 21 of the sleeve 17 and force the sleeve downwardly into the larger bore 22 in the lower sub section 12 breaking the shear pin 18.
- the sleeve 17 When the sleeve 17 is moved downwardly out of the way, the pressure surrounding the well string forces the plugs 24 inwardly out of the ports 23 to permit circulation therethrough. Since the sleeve 17 is of smaller external diameter than the bore 22 in the lower sub section 12, the sleeve 17 will tilt therein and is thereby prevented from re-entering the counterbore 16 and interfering with the flow through the ports 23 in the manner shown in the dot-dash lines in Fig. 2.
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller diameter portion and an enlarged diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, releasable means normally retaining said sleeve in said smaller diameter portion, at least one lateral port in said sub adjacent said sleeve, and a substantially cylindrical plug of elastic material in each port, the inner end of each plug being against said sleeve, said sleeve being movable downwardly into said enlarged diameter portion and prevented from re-entry into said smaller diameter portion by engagement with said downwardly facing shoulder.
- a back circulating apparatus comprising a tubular 3.
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, said sleeve having an upper shoulder, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said smaller diameter portion opposite said sleeve, and a substantially cylindrical plug of elastic material retained in each of said ports to seal the same while the inner end of each of said plugs bears against said sleeve, said sleeve being slidable into said larger diameter portion to unseal said ports and retained therein by engagement of said shoulders.
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve mounted in said smaller diameter portion and movable into said larger diameter portion, said sleeve being prevented from reentry into said smaller diameter portion by engagement with said downwardly facing shoulder, a plurality of lateral ports in said smaller diameter portion opposite said sleeve, a cylindrical plug of elastic material in each of said ports to seal the same while the inner end of each of said plugs bears against said sleeve, said sleeve being slidable into said larger diameter portion to uncover said ports and retained therein by engagement of said shoulders, and a conical depression formed in the outer end of each of said plugs.
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow, a sleeve mounted in said smaller diameter portion and slidable into said larger diameter portion, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said sub adjacent said sleeve, a cylindrical plug of elastic material in each of said ports, the inner end of each of said plugs being against said sleeve, an external radial flange adjacent the inner end of each of the plugs, and a tubular seal retainer surrounding each of said plugs and threaded into said ports, said retainers 4 being adapted to confine said plug flanges between said retainers and said sleeve to seal said ports until said sleeve slides into said larger diameter portion.
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, an upwardly facing shoulder at the lower end of said enlarged diameter portion, a sleeve slidably mounted in said smaller diameter portion and movable into said larger diameter portion, said sleeve having upper and lower shoulders engageable with said downwardly and upwardly facing shoulders for retention in said larger diameter portion, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said sub adjacent said sleeve, a cylindrical plug of elastic material in each of said ports, the inner end of each of said plugs being against said sleeve, an external radial flange adjacent the inner end of each of the plugs, a tubular seal retainer surrounding each of said plugs and threaded into said ports, said retainers being adapted to confine said plug flanges
- a back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller diameter portion and an enlarged diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, retarding means normally retaining said sleeve in said smaller diameter portion, at least one lateral port in said sub adjacent said sleeve, and a plug of elastic material in each port, the inner end of each plug being against said sleeve, said sleeve being movable downwardly into said enlarged diameter portion and prevented from re entry into said smaller diameter portion by engagement with said downwardly facing shoulder.
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- Multiple-Way Valves (AREA)
Description
United States Patent Ofitice Patented Dec. 9, 1958 BACK CIRCULATING VALVE Jack A. Moosman, Glendale, Califl, assignor, by mesne assignments, to Johnston Testers, Inc., Houston, Tom, a corporation of Texas Application August 16, 1955, Serial No. 528,585
7 Claims. (Cl. 166-424) This invention relates to an oil well tool. More particularly, the invention relates to a back circulating valve adapted to be inserted in a well string.
In oil well production practice, it is necessary at various times to circulate drilling mud or other fiuid down the annular space between a well string and a casing or well bore, through a valve in the well string and up through the well string. Sometimes this reverse circulation is performed to back scuttle gas and oil under control from the well string; for instance, to eliminate a fire hazard. Also, sometimes during the pulling of a well string, it is necessary to reverse circulate to maintain control over the well which may get somewhat out of control for various reasons; for example, because the hydrostatic head in the well drops due to the removal of the well string from the region of the well fluid, allowing high pressure areas previously controlled by the hydrostatic head to get somewhat out of control.
Various other back circulating valves are available but, in general, these have been operable only when the well string was bottomed or set in the well by means of a packer or slips or the like, these valves being operable by relative rotational or longitudinal movement between the lower portion of the well string which is fixed in the well and carries one part of the valve, and the upper free portion ofthe well string which carries the other part of the valve.
When the necessity for reverse circulation arises, the back circulation valve must be opened quickly to enable immediate control over the well to avoid damage and waste. In many instances there is not time, nor is it practical or in some cases possible, to reset a packer or again bottom the well string to enable opening of a back circulation valve.
It is therefore the principal object of this invention to provide a reverse circulating valve adapted to be connected between sections of Well string, which valve can be opened when the well string is oif bottom without setting a packer or similar device.
A preferred form of the invention is described in the following detailed specification and illustrated by way of example in the accompanying drawings, wherein:
Fig. 1 illustrates a sectional view of a valve embodying the principles of the invention, the valve being shown in its closed positon.
Fig. 2 is a similar view of the valve shown in Fig. 1 and illustrates the valve after it has been opened.
Referring now to the drawings, indicates generally a tubular valve sub comprising upper and lower sections 11 and 12, respectively, threadedly connected together as indicated at 13. The upper end of the valve sub 10 is provided with a threaded box 14 and the lower end with a pin 15 to facilitate the insertion of the valve sub into a well string.
The lower end of the upper section 11 is counterbored as shown at 16 and a sleeve 17 is slidably received in said counterbore and retained therein by a shear pin 18 extending inwardly from the wall of the section 11 into an annular notch 19 cut into the lower outer edge of the sleeve 17. A pipe plug 29 is threaded into the outer surface of the tubular section 11 behind the shear pin 18 to retain said pin in position. The sleeve 17 has a downwardly and inwardly tapered inner surface 21 for purposes hereinafter described. The tubular bore 22 in the lower section 12 is slightly larger in diameter than the counterbore 16 in the upper section 11.
The upper section 11 is provided with a plurality of radially extending ports 23 adjacent the counterbored portion thereof. A sealing plug 24of rubber or other suitable elastic material is held in each of the ports 23 by a tubular seal retainer 25 which surrounds the plug 24 and is threaded into said port 23. Each of the plugs 24 has an external annular flange 26 which is confined between the tubular seal retainer 25 and the sleeve 17. Each of the plugs 24 has a conical depression 27 formed in its outer end.
In the use of the device, the elements are assembled into a well string. As the well string is lowered, the hydrostaticpressure acting on the outer end of the plugs 24 tends to force the plugs inwardly and because of the conical depression 27 tends to expand the plug outwardly into tight sealing engagement with the retainer 25.
When it is desired to open the ports 23 to permit back circulation, a suitable sinker bar (not shown) is dropped through the string. When the bar reaches: the valve, suitable projections thereon contact the tapered surface 21 of the sleeve 17 and force the sleeve downwardly into the larger bore 22 in the lower sub section 12 breaking the shear pin 18.
When the sleeve 17 is moved downwardly out of the way, the pressure surrounding the well string forces the plugs 24 inwardly out of the ports 23 to permit circulation therethrough. Since the sleeve 17 is of smaller external diameter than the bore 22 in the lower sub section 12, the sleeve 17 will tilt therein and is thereby prevented from re-entering the counterbore 16 and interfering with the flow through the ports 23 in the manner shown in the dot-dash lines in Fig. 2.
While I have shown and described the preferred form of my invention, it is obvious that various changes may be made in its construction by those skilled in the art, without departing from the spirit of the invention as defined in the appended claims.
Having thus described my invention, what I claim and desire to secure by Letters Patent is:
1. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller diameter portion and an enlarged diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, releasable means normally retaining said sleeve in said smaller diameter portion, at least one lateral port in said sub adjacent said sleeve, and a substantially cylindrical plug of elastic material in each port, the inner end of each plug being against said sleeve, said sleeve being movable downwardly into said enlarged diameter portion and prevented from re-entry into said smaller diameter portion by engagement with said downwardly facing shoulder.
2. A back circulating apparatus comprising a tubular 3. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, said sleeve having an upper shoulder, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said smaller diameter portion opposite said sleeve, and a substantially cylindrical plug of elastic material retained in each of said ports to seal the same while the inner end of each of said plugs bears against said sleeve, said sleeve being slidable into said larger diameter portion to unseal said ports and retained therein by engagement of said shoulders.
4. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve mounted in said smaller diameter portion and movable into said larger diameter portion, said sleeve being prevented from reentry into said smaller diameter portion by engagement with said downwardly facing shoulder, a plurality of lateral ports in said smaller diameter portion opposite said sleeve, a cylindrical plug of elastic material in each of said ports to seal the same while the inner end of each of said plugs bears against said sleeve, said sleeve being slidable into said larger diameter portion to uncover said ports and retained therein by engagement of said shoulders, and a conical depression formed in the outer end of each of said plugs.
5. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow, a sleeve mounted in said smaller diameter portion and slidable into said larger diameter portion, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said sub adjacent said sleeve, a cylindrical plug of elastic material in each of said ports, the inner end of each of said plugs being against said sleeve, an external radial flange adjacent the inner end of each of the plugs, and a tubular seal retainer surrounding each of said plugs and threaded into said ports, said retainers 4 being adapted to confine said plug flanges between said retainers and said sleeve to seal said ports until said sleeve slides into said larger diameter portion.
6. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller internal diameter portion and a slightly larger diameter portion therebelow defining a downwardly facing shoulder therebetween, an upwardly facing shoulder at the lower end of said enlarged diameter portion, a sleeve slidably mounted in said smaller diameter portion and movable into said larger diameter portion, said sleeve having upper and lower shoulders engageable with said downwardly and upwardly facing shoulders for retention in said larger diameter portion, releasable means for normally retaining said sleeve in said smaller diameter portion, a plurality of lateral ports in said sub adjacent said sleeve, a cylindrical plug of elastic material in each of said ports, the inner end of each of said plugs being against said sleeve, an external radial flange adjacent the inner end of each of the plugs, a tubular seal retainer surrounding each of said plugs and threaded into said ports, said retainers being adapted to confine said plug flanges between said retainers and said sleeve, and a conical depression formed in the outer end of each of said plugs, whereby said plugs seal said ports until said sleeve slides into said larger diameter portion.
7. A back circulating apparatus comprising a tubular sub adapted to be inserted in a well string, said sub having a smaller diameter portion and an enlarged diameter portion therebelow defining a downwardly facing shoulder therebetween, a sleeve slidably mounted in said smaller diameter portion, retarding means normally retaining said sleeve in said smaller diameter portion, at least one lateral port in said sub adjacent said sleeve, and a plug of elastic material in each port, the inner end of each plug being against said sleeve, said sleeve being movable downwardly into said enlarged diameter portion and prevented from re entry into said smaller diameter portion by engagement with said downwardly facing shoulder.
References Cited in the file of this patent UNITED STATES PATENTS 2,185,522 Rollins Ian. 2, 1940 2,630,865 Baker Mar. 10, 1953 2,645,288 Deters et a1 July 14, 1953
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US528585A US2863511A (en) | 1955-08-16 | 1955-08-16 | Back circulating valve |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US528585A US2863511A (en) | 1955-08-16 | 1955-08-16 | Back circulating valve |
Publications (1)
Publication Number | Publication Date |
---|---|
US2863511A true US2863511A (en) | 1958-12-09 |
Family
ID=24106297
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US528585A Expired - Lifetime US2863511A (en) | 1955-08-16 | 1955-08-16 | Back circulating valve |
Country Status (1)
Country | Link |
---|---|
US (1) | US2863511A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3205948A (en) * | 1962-04-05 | 1965-09-14 | Baker Oil Tools Inc | Well bore casing releasing apparatus |
US3211232A (en) * | 1961-03-31 | 1965-10-12 | Otis Eng Co | Pressure operated sleeve valve and operator |
US3360047A (en) * | 1965-05-18 | 1967-12-26 | Bob J Burnett | Well drilling device |
US4320800A (en) * | 1979-12-14 | 1982-03-23 | Schlumberger Technology Corporation | Inflatable packer drill stem testing system |
US5014780A (en) * | 1990-05-03 | 1991-05-14 | Uvon Skipper | Long distance section mill for pipe in a borehole |
US20110017448A1 (en) * | 2008-01-11 | 2011-01-27 | Douglas Pipchuk | Zonal testing with the use of coiled tubing |
US8991492B2 (en) | 2005-09-01 | 2015-03-31 | Schlumberger Technology Corporation | Methods, systems and apparatus for coiled tubing testing |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2185522A (en) * | 1937-10-28 | 1940-01-02 | Leon F Rollins | Well flow controlling device |
US2630865A (en) * | 1949-02-25 | 1953-03-10 | Baker Oil Tools Inc | Hydraulically operated well packer |
US2645288A (en) * | 1951-07-23 | 1953-07-14 | Johnston Testers Inc | Back circulator device |
-
1955
- 1955-08-16 US US528585A patent/US2863511A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2185522A (en) * | 1937-10-28 | 1940-01-02 | Leon F Rollins | Well flow controlling device |
US2630865A (en) * | 1949-02-25 | 1953-03-10 | Baker Oil Tools Inc | Hydraulically operated well packer |
US2645288A (en) * | 1951-07-23 | 1953-07-14 | Johnston Testers Inc | Back circulator device |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3211232A (en) * | 1961-03-31 | 1965-10-12 | Otis Eng Co | Pressure operated sleeve valve and operator |
US3205948A (en) * | 1962-04-05 | 1965-09-14 | Baker Oil Tools Inc | Well bore casing releasing apparatus |
US3360047A (en) * | 1965-05-18 | 1967-12-26 | Bob J Burnett | Well drilling device |
US4320800A (en) * | 1979-12-14 | 1982-03-23 | Schlumberger Technology Corporation | Inflatable packer drill stem testing system |
US5014780A (en) * | 1990-05-03 | 1991-05-14 | Uvon Skipper | Long distance section mill for pipe in a borehole |
US8991492B2 (en) | 2005-09-01 | 2015-03-31 | Schlumberger Technology Corporation | Methods, systems and apparatus for coiled tubing testing |
US20110017448A1 (en) * | 2008-01-11 | 2011-01-27 | Douglas Pipchuk | Zonal testing with the use of coiled tubing |
US8763694B2 (en) | 2008-01-11 | 2014-07-01 | Schlumberger Technology Corporation | Zonal testing with the use of coiled tubing |
US9581017B2 (en) | 2008-01-11 | 2017-02-28 | Schlumberger Technology Corporation | Zonal testing with the use of coiled tubing |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2121002A (en) | Cement retainer and bridge plug for well casings | |
US2998075A (en) | Subsurface well apparatus | |
US3013612A (en) | Casing bottom fill device | |
US3148731A (en) | Cementing tool | |
US2919709A (en) | Fluid flow control device | |
US3163225A (en) | Well packers | |
US4176717A (en) | Cementing tool and method of utilizing same | |
US3356140A (en) | Subsurface well bore fluid flow control apparatus | |
US3811500A (en) | Dual sleeve multiple stage cementer and its method of use in cementing oil and gas well casing | |
US4185689A (en) | Casing bridge plug with push-out pressure equalizer valve | |
US3995692A (en) | Continuous orifice fill device | |
US2999545A (en) | Retrievable plug | |
US2925865A (en) | Full flow packer cementing shoe | |
US3044553A (en) | Well packer | |
US3095040A (en) | Access valve for completing oil wells | |
US3306365A (en) | Well bore testing and displacing valve apparatus | |
US3223160A (en) | Cementing apparatus | |
US3338311A (en) | Stage cementing collar | |
US2128253A (en) | Hydraulic lock dry pipe valve with well testing and well flowing apparatus | |
US2379079A (en) | Well cementing device | |
US4089548A (en) | Hydraulic releasing tool with plug | |
US2863511A (en) | Back circulating valve | |
US3392785A (en) | Retractable packer | |
US2737247A (en) | Well packer apparatus | |
US3543849A (en) | Cement retainer valve for well packers |