US3802509A

US3802509A - Well head completion and control

Info

Publication number: US3802509A
Application number: US00355485A
Authority: US
Inventors: D Grable; B Laney
Original assignee: LANEY; Hydro Combo Corp
Current assignee: LANEY; Hydro Combo Corp
Priority date: 1973-04-30
Filing date: 1973-04-30
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

Well flow control apparatus comprises: A. FIRST TUBULAR MEANS IN THE WELL FOR RECEIVING AN ELONGATED CYLINDRICAL STRING TO BE VERTICALLY MOVABLE FROM THE WELL HEAD RELATIVE TO SAID TUBULAR MEANS, SAID FIRST TUBULAR MEANS ADAPTED TO PASS A FIRST STREAM OF PRODUCTION FLUID TO THE WELL HEAD, B. TUBULAR CASING INSTALLED IN THE WELL AND THROUGH WHICH THE FIRST TUBULAR MEANS EXTENDS AND ADAPTED TO PASS A SECOND STREAM OF PRODUCTION FLUID FOR DELIVERY TO THE WELL HEAD, SAID CASING HAVING A REDUCED BORE SECTION, AND C. A PLUG CARRIED ON THE FIRST TUBULAR MEANS BELOW THE LEVEL OF SAID REDUCED BORE SECTION AND ADAPTED TO ENGAGE SAID REDUCED BORE SECTION FOR BLOCKING UPWARD FLOW OF SAID SECOND STREAM OF PRODUCTION FLOW IN RESPONSE TO RELATIVE VERTICAL DISPLACEMENT OF THE PLUG AND FIRST TUBULAR MEANS.

Description

United States Patent [1 1 Grable et a1.

1 41 WELL HEAD COMPLETION AND CONTROL 175] Inventors: Donovan B. Grable, Long Beach;

Bill C. Laney, Torrance, both of Calif.

[73] Assignee: Hydro-Combo C0rp., Salt Lake City, Utah by said Laney [22] Filed: Apr. 30, 1973 [21] Appl. No.: 355,485

[52] US. Cl....- 166/315, 166/73, 166/226 [51] Int. CL; E2lb 43/00, E2lb 43/12 [58] Field of Search 166/315, 68, 73, 226

[56] References Cited UNITED STATES PATENTS 1,557,224 I 10/1925 Warnerm, 166/68 2,796,133 6/1957 En Dean..... 166/73 3,376,936 4/1968 Tomlin 166/73 Primary Ekaminer lames Leppink Attorney, Agent, or Firm-William W. Haefliger Apr. 9, 1974 I 57] ABSTRACT Well flow control apparatus Comprises:

a. first tubular means in the well for receiving an elongated cylindrical string to be vertically movable from the well head relative to said tubular means, said first tubular means adapted to pass a first stream of production fluid to the well head,

b. tubular casing installed in the well and through which the first tubular means extends and adapted to pass asecond stream of production fluid for delivery to the well head, said casing having a reduced bore section, and

c. a plug carried on the first tubular means below the level of said reduced bore section and adapted to engage said reduced bore section for blocking upward flow of said second stream of production flow in response to relative vertical displacement of the plug and first tubular means.

34 Claims, 11 Drawing Figures PATENTED APR 9 I974 sum 1ur WELL HEAD COMPLETION AND CONTROL BACKGROUND OF THE INVENTION This invention relates generally to the control of production fluid flow from and within wells; and more particularly concerns apparatus and methods for controlling such flow as well as enabling work-over of the well with minimum disturbance to well head equipment, connections and fluid column in the well bore.

As described in our co-pending application Control of Well Fluid Level Ser. No. 272,320, filed July 17, 1972, there is a need for simple and effective means to achieve shut-off of production flow in a pumped or flooding well in a very simple manner and also to provide down-hole blow-out prevention protection while the well is being pumped. There is further need, as for SUMMARY OF THE INVENTION It is a major object of the invention to satisfy the above needs, and to-provide' a well flow control system incorporating unusual advantages in construction, mode-of operation and results, as will be seen.

Basically, the invention is embodied in a system that includes-first tubular means in the well 'for receiving an elongated cylindrical string, as for example tubing or red string, to'be vertically movable from the well head, and adapted to pass a first stream of production fluid to the 'well head; tubular casing installed in the well through which the first tubular means extends, and

adapted topass a second stream of production fluid (as for example casing gas) for delivery to the well head, and a plug carried by the first tubular means below the level of a reduced bore section in the casing and adapted to be elevated to engage that bore section for blocking upward flow of the second stream of production gases during upward withdrawal of the first tubular means from the well. As will be seen, the first tubular means may be supported by a first spool at the well head, below the .level of a blow out preventer carried by tubular well head structure receiving and supporting that spool; the well head structure may also support a flange carrying the tubular casing referred to; a second spool may also be received in and supported by the well head structure and a stuffing box may be carried by the second spool to pass and seal off about the vertically reciprocable rod string.

It is another object of the invention to provide a stuffing box, including a pack-off assembly, characterized in that the latter may be removable from the well in response to retrieval of the rod string, the stuffing box being mounted on the second spool or carried downhole on second tubular means suspended by the second spool to hang within the first tubular means.

11 is a'fragmentary plan view, on lines lll1 It is a further object of the invention to provide for retrieval of the first and second spools and associated tubing strings via a blow-out preventer at the surface, after prior removal of the rod string, and While the well is maintained in secure condition. Another object concerns the elimination of Christmas tree connections at the well head, and concealment of all well head structure in a celler, as will be described.

Additional objects include provision of methods whereby all rod and tubing strings may be run into and retrieved from the pressurized well with minimum disturbance to surface connections as well as the fluid column in the well bore, and while the well is maintained secure against blow-out, as will be'seen.

These and other objects and advantages of the invention, as well as the details of illustrative embodiments, will be more fully understood from the following des'cription and drawings, in which:

DRAWING DESCRIPTION FIG. 1 is a vertical elevation showing a well installation incorporating the invention; FIG. 2 is an enlarged vertical section taken on'lines 2-2 of FIG. l;

FIG. 3 is an enlarged vertical section taken on lines 3-3 of FIG. 1; I 7

FIG. 4 is a vertical elevation showing a well installation incorporating a modified form of the invention;

FIG. 5 is an enlarged vertical section taken through well head structure;

FIG. 6 is aplan view taken on lines 6-6 of FIG. 5;

FIG. 7 is an elevation, partly in section, showing a stuffing box construction;

FIG. 8 is an enlarged fragmentary'elevation; and FIGS. 9 and 10 are fragmentary elevations, and FIG. of FIG. 10, showing a modification.

DETAILED DESCRIPTION includes first tubular means, as for example outer casing 26, in a well 11 (which may be cased at 10) and an internal seat thereon below the well head 12 in celler 12a. For example, the seat may take the form of the downwardly presented upper valve seat 13, better seenv in FIG. 3 as formed by upwardly tapered adapter section 14a of tubing 14; or, the seat may take the form of an upwardly presented lower valve seat 15 formed by downwardly tapered adapter section 14b of tubing 14. The seat or seats may be part of the tubing or separate seat structures carried thereby. The main extent of the tubing may have larger inner and outer diameterdimensions and those-of the tubing sections 16 connected in end-to-end relation therewith, for unusually advantageous purposes as will appear. characteristically, both

seats

13 and 15 will be provided. for production flow control purposes to be described. Connectors are provided at and 81. v

An elongated cylindrical string, as for example rod string 17, extends within the tubing to be vertically movable from the well head relative to the tubing. A plug 18 is carried by the rod string 17 to be moved between a first position or positions spaced from either seat (in which event well fluid flows upwardly within tubing 14 past the plug, as for example around the plug as indicated by arrows 19), and a second position in which the plug engages the seat for blocking such upward flow of well fluid. For example, the plug may be reciprocated in cavity 25 by the rod string 17, as during normal well pumping between upper and lower positions indicated at 18a and 18b in FIG. 1 respectively spaced from positions of engagement with either of the

seats

13 and 15, the rod stroke length or range indicated at 20. Well production fluid flows upwardly through tubing 14 during such stroking, the latter displacing a bottom hole sub-surface pump or swab 21 up and down in the bottom hole tubing. Means at the top of the well to reciprocate the rod string is generally indicated at 22, and may take the form of the counterbalancing drive means disclosed in either of U.S. Pats. Nos. 3,516,762 and 3,521,445 or in pending Grable application WELL PUMPING CONTROL Ser. No. 262,605 filed on or about June 13, 1972. The

broken lines

18c and 18d in FIG. 3 indicate alternative secondary" positions of plug engagement with the

seats

13 and 15, and in either of which upward flow of well fluid is blocked, for example to prevent well blowout. For this purpose, the plug may incorporate a body supported annular elastomer lip 22 adapted to flex outwardly as at 22a to seal against the inner wall of tube 14 when the plug is in either sealing

position

18c and 18d. Displacement of the plug to either of the latter positions may be quickly effected by manipulation of the rod string from the surface; thus if the string is moving up it may be lifted until the plug seats, and if the string is moving down, it may be lowered until the plug seats. Positions 18a and 18b may be less than 2 feet from seating positions as described.

Referring to FIGS. 1 and 2, the first tubular means such as outer casing 26 is shown to have a reduced diameter lowermost portion 26a supporting production tubing 16 as via pin and box connection 27. Casing 26 is suspended at the well head as by thread connection at 28 with a carrier in the form of an annular spool piece 29, the latter received in and supported by tubular well head structure 30 as by interior shoulder 130. Note that O-ring seals 31 seal off between the bore 30a of structure 30 and the spool piece outer diameter.

Second tubular means, as for example inner casing 32, extends within the outer casing 26 and in spaced relation thereto to form therewith an annulus 33 conducting production fluid upwardly to the well head. Sealing means is carried by the casing 32, as for example at the lower terminal of the latter, to pass and seal off about the rod string 17 above the plug 18 and also to seal off against the casing 32. Such sealing means may typically include a threaded box 34 removably receiving a threaded pin 35a of a stuffing box 35 passing the rod string. One important advantage of this construction lies in the fact that the stuffing box may float laterally with the lower terminal of casing 32, but as limited by engagement with the bore of casing 26, in response to lateral movement of the rod string during its up and down stroking, so as not to bind or inhibit such stroking. In addition, casing 26 may float laterally in the well annulus 90.

Inner or second casing 32 has upper extent 32a projecting upwardly through the outer or first casing at the well head, and annular structure extends about said upper extent 32a to form a well production flow receiving annulus 37 in direct communication with the annular space 33 between

casings

26 and 32. Such annular structure may include a second annular spool 38 removably supporting the second or inner casing as by thread connection at 39.

The second spool is received in and supported by the annular flange 41, which may be considered as part of the tubular well head structure; A shoulder 42 in the flange seats the spool, as shown; also annular O-ring seals 43 seal off between the spool outer diameter and the bore 43a of flange 41. The latter and structure 30 may be interconnected as by bolts 44. Note that a blow out preventer 45 is typically connected onto and above flange 41, as appears in FIG. 1, and while spool 38 is of larger outer diameter than spool 29, both are upwardly retrievable through the open blow-out preventer, as will be further described. The blow-out preventer may have the construction as described in U.S. Pat. No. 2,609,836 to Knox.

Flange 41 and structure 30 form upper bore sections and 51 between spools 29 and 38, and production fluid flows in a first stream 71 to those bore sections via annulus 33 for delivery to outlet pipes 52. The latter communicate with bore section 50 via side outlet passages 54 in the flange 41, as better seen in FIGS. 5 and 6. Valves 55 controls discharge via pipes 52. Structure 30 also forms a lower bore section 57 through which a second stream 72 of production fluid (as for example casing gas) flows from annulus 90 for delivery to outlet pipe or pipes 58. Control valve means 59 is connected in series with the latter.

Referring to FIGS. 2 and 7, the stuffing box 35 typically includes a cylindrical body 60 carrying a pack-off assembly including packing 61 for sealing off about the cylindrical rod string 17 as the latter is stroked up and down. The assembly is typically carried for upward removal away from the body (which is attached by pin 35a to box 34) in response to upward engagement of a collar 62 on the string with releasable retaining means also carried by the body. This allows the rod string, down hole pump and seal 18 to be pulled upwardly through the stuffing box body, as during well workover.

Such retaining means may include latch dog levers 65, pivoted at 66 to hold them in the position shown, the levers engaging body interior shoulder 67 to retain the pack-off assembly mandrel 63 against upward release. Spring 64 urges the mandrel downwardly against the levers. When the collar 62 exerts upward force in the mandrel, the latter rises in body 60 against spring resistance causing a part 68 on the mandrel to engage and swing the levers to disengage body shoulder 67, releasing the pack-off assembly for upward removal on the rod string. Sleeve 69 carries the packing 61 and mandrel 63.

In accordance with an important aspect of the invention, tubular casing is provided in the well as at 70 to pass the second stream of production fluid 72 for delivery to the well head. The casing 70 has an elongated, reduced bore section 75, as for example extends between flaring opposite ends 76 and 77 of the casing; and, a plug carried on the first tubular means, as for example at 78 below the level of the reduced bore section 75, is adapted to be elevated to enter, engage and plug that section for blocking upward flow of the second stream 72 of production fluid during upward withdrawal of the first tubular means 26 from the well (as for example during work-over). Such upward retrieval of string 26 may be carried out after removal of rod string 17, and of the second tubular means 32, as will be described; also, such upward withdrawal of string 26 may be effected by lowering a threaded pin member illustrated at 80 in FIG. 2 through the top-side blow-out preventer to connect to the spool thread 81, after which member 80 is elevated to carry the spool through the opened blow-out preventer during the time that plug ,78 seals off against bore 75 of casing 70, to maintain the well shut-in. Prior to upward exit of plug 78 from that casing, the preventer is closed on tubular string 26 after the spool 29 has passed through the preventer. A pin member 83 is similarly adapted to be lowered for attachment to spool 38 atthread 84, to withdraw that spool and its suspended string 32, in a similar manner, through the preventer, after withdrawal of string 17 but prior to withdrawal of string 26 as described.

The tubular casing 70 may with unusual advantage be carried or supported by a wide flange 86 in turn supported by the flange 87 on'well head stub casing 88. Bolts 89 are shown attaching flange 86 between flange 87 and a flange 90 integral with structure 30. Accordingly, casing 70 extends directly below spool 29 to direct the second stream 72 of production fluid into lower bore section 57.

In that form of the invention seen in FIG. 4, elements similar to those of FIG. 2 are given the same identifying numerals. The stuffing box 35 is here mounted on the second spool 110, and the second tubular string is eliminated. The bore 111 of the first spool 109 is reduced as is the box connection at 112, to receive a reduced diameter pin member 113 passed downwardly through the diametrically enlarged stuffing box body 60 after the pack-off assembly has been upwardly retrieved upon removal of the rod string'17, as previously described. Upon elevation of spool 109 by the member 1 13, the spool 110 is engaged and lifted out of the bore 43a in top flange 41. Preliminarily, however, anchor studs 114 are retracted radially outwardly so that their inner ends 114a are displaced out of anchoring relation to the spool 110. The anchor studs may have threaded connection to threaded bores 115 in the flange 41, as is clear from FIGS. 5 and 6.

As shown in the FIG. 8 detail view, the spool 110 and flange 41 have top surfaces 110a and 41a which are horizontally flush, to seat the high pressure sealing flange 116. Annular pressure seals at 117 and 118 seal off the clearance 119 between the spool and flange, and provide back-up sealing in addition to seals 43, to assure securing of the well. Flange 116 may be removed, and the blow-out preventer flange 45a installed, as seen in FIGS. 1, 2 and 4.

During installation of the FIGS. 1 and 2 equipment, the casing 70 is first installed as by installing flange 86, the flange 41 and the blow-out preventer 12 are also installed. Thereafter, the first tubular means 26 is installed through the preventer and spool 29 is landed;

the second tubular means 32 is run in the well with stuffing box body 60 attached and the spool 38 landed; and then the rod string 17 is lowered into the well along with bottom hole pump and the stuffing box pack-off assembly. The latter is run into the body 60 by the rod joint next about the pack-off assembly, and the latches 65 operate to retain the assembly in FIG. 7 position so that the rod string may be stroked through the packer 61. The plug 18 is also carried to the position seen in FIG. 1, on the rod string.

During work-over, the components are easily retrievable from the well while the latter is kept secured against blow-out. Thus, the rod string may first be elevated for retrieval of the bottom hole pump at the well surface, the plug 18 sealing off against the bore 16a during the time that the stuffing box packer is withdrawn through the blow-out preventer at the surface; at other times, the preventer is kept closed about the end string. Thereafter, the second tubular means 32 is withdrawn upwardly as by elevation of spool 38 as previously described, the preventer closing about the spool and string 32; and the first tubular means 26 is then elevated as by elevation of spool 29. During a portion of the elevation of string 26, as for example while spool 29 is withdrawn through the blow-out preventer, a subsurface pack-off is maintained between string 26 and casing 70, as by means of plug 78 as previously referred to. Also, after the sub-surface pack-off isterminated (Le. after plug 78 leaves the casing the surface preventer seals off about the string 26 being elevated.

The same modes of operation are applicable to that form of the invention seen in FIG. 4, excepting that spool 110 is lifted in response to elevation of spool 109,

as previously described; also, the sub-surface pack-off of packer 78 against casing 70 is maintained while both

spools

109 and 110 are elevated through the surface preventer.

FIGS. 2 and 4 show the provision on casing 70 of a heavy duty packer 150 having a skirt 151 responsive to upward pressure of gas in annulus 90 to flex outwardly and seal against well casing 90. The packer is removably installable with casing 70, and provides added hold-down security at the well head against gas leakage. I a

In the modification of the invention seen in FIGS. 9-11, elements corresponding to those described in FIG. 2 bear the same identifying numerals. The modification has to do with the provision of actuator means for displacing the tubular casing 70a downwardly in the well relative to the first tubular means (such as outer casing 26), thereby to engage the reduced bore section a of the casing 70a with the plug. This enables sealing off the annulus below modified flange 86a in a simple and unusually advantageous manner, without necessitating manipulation of the

strings

26 or 32, or the surface blow-out preventer. I

More specifically, the actuator means includes an an nular piston element carried on the tubular casing 70a, and-a cylinder 151 receiving the piston element, with slidable engagement of annular O-rings 152 on the piston with the cylinder bore 153. The modified annular flange 86a supports the cylinder to extend vertically within well head structure 88, as shown, O-r ings 154 sealing off between the flange bore and casing 70a whereas O-rings 155 seal off between the casing 7.0a and a bottom end annular cap 156 on the cylinder. Ducting in the flange communicates with

chambers

157 and 158 defined by the cylinder and piston at opposite sides of the piston for conducting actuating fluid pressure to those chambers. Thus, for example, duct 159 communicates between exterior pressure line 160 and chamber 157, whereas duct 161 in the flange and duct 162 in the cylinder communicate between exterior pressure line 163 and chamber 158. A four way valve 164 is operable to alternately interconnect a source of pressure 165 with

pressure lines

160 and 163, the other of those lines then communicating with a bleed outlet 166. If desired, mechanical actuator means (as for example a rack and pinion mechanism) may be provided as an alternative to the fluid actuator.

A passage 167 is provided in the flange to communicate vertically therethrough with

cavities

168 and 169 formed by the well head structure above and below the flange, for equalizing the fluid pressure in those cavities, as may be required. A suitable valve 170, controlled by manual actuator 171, controls passage 167. In addition a blow-out passage 172 may be provided in the flange to communicate between the upper cavity 168 above the flange and the exterior, in order to permit blow-out of any sand or other particles that tend to accumulate in that cavity. Means to control release through that passage may comprise a removable plug indicated at 173 in FIG. 11.

Referring back to FIG. 9, a wiper ring 175 may be carried by the flange 86a to wipe the tubular casing 70a as it reciprocates vertically relative to the flange.

We claim:

1. In well flow control apparatus,

b. tubular casing installed in the well and through which the first tubular means extends and adapted to pass a second stream of production fluid for delivery to the Well head, said casing having a reduced bore section, and

2. The apparatus of claim 1 including said elongated cylindrical string received in the well and through the first tubular means, and a bottom hole pump carried by said elongated cylindrical string.

3. The apparatus of claim 1 including a first spool at the well head supporting said first tubular means, and tubular well head structure containing and removably supporting the spool and forming upper and lower bore sections respectively above and below the spool, and via which the respective fluid streams are delivered to outlets formed by the tubular well head structure.

4. The apparatus of claim 3 including a blow-out preventer supported by said well head structure and through which the spool is upwardly removable while said plug engages said reduced bore section.

5. The apparatus of claim 1 including a flange supporting said tubular casing, and tubular well head structure supporting said flange.

6. The apparatus of claim 3 including a flange supporting said tubular casing, the casing having opposite flaring ends, and said tubular well head structure supporting said flange so that said tubular casing extends directly below said spool, said lower bore section located between said'first spool and said flange.

7. The apparatus of claim 3 including a second spool supported at the well head by said tubular well head structure, and a stuffing box carried by said second spool to pass and seal off about said elongated cylindrical string.

8. The apparatus of claim 7 wherein said stuffing box includes a cylindrical body, and a pack-off assembly carried by the body for upward removal in response to upward engagement of a collar on the cylindrical string with releasable retaining means also carried by the body.

9. The apparatus of claim 8 wherein the stuffing box body is mounted on the second spool.

10. The apparatus of claim 8 including second tubular means suspended by the second spool to extend within the first tubular means, with flow passing clearance between the first and second tubular means, the stuffing box carried by the second tubular means below the level of the first and second spools.

11. The apparatus of claim 7 wherein the upper bore section is located between the first and second spools.

12. The apparatus of claim 7 including a blow-out preventer supported by the well head structure and having a closable aperture to pass both said spools vertically therethrough.

13. The apparatus of claim 7 wherein said spools each have interior bore threads forming box connections accessible to threaded retrieval pin means advanced downwardly to said connections.

14. The apparatus of claim 7 including said cylindrical string in the form of a rod string passing downwardly through said stuffing box.

15. The apparatus of claim 14 including a downwardly presented seat on the first tubular means below the well head, the rod string having a range of vertical reciprocation to operate a well pump for pumping well fluid upwardly within said first tubular means, and a plug carried on the rod string to be reciprocated within said first tubular means in spaced relation to the seat as the rod reciprocates within said range while well fluid flows upwardly past the plug, and the plug sized to engage the upper seat and block said upward flow in response to upward displacement of the rod string beyond the upper limit of said range.

16. The apparatus of claim 15 wherein said first tubular means has a vertically elongated portion which is diametrically enlarged to form a cavity within which the plug is reciprocable vertically with flow passing clearance at the side of the plug. 7

17. The apparatus of claim 15 including an upwardly presented lower seat on the first tubular means and sufficiently below the upper seat as to normally remain out of engagement with the plug as the rod string reciprocates within said range, the plug sized to engage the lower seat and block vertical flow therethrough in response to downward displacement of the string below the lower limit of said range.

18. In the method of retrieving from a well a pump rod string, a bottom hole pump carried by the rod string, a stuffing box packer through which the rod string passes, and first tubular means in the well for receiving the rod string to be vertically movable from the well head and adapted to pass a first stream of production fluid to the well head, there being tubular casing in the well and through which the first tubular means extends, the casing adapted to pass a second stream of production fluid to the well head, the steps that include a. elevating the pump rod string and bottom hole pump and retrieving same at the well head,

b. elevating said first tubular means for retrieval at the well head,

c. and, during a portion of said elevation of the first tubular means, maintaining a sub-surface pack-off between said first tubular means and the casing.

19. The method of claim 18 that includes maintaining a pack-off at the well head about the first tubular means being withdrawn from the well after terminating said subsurface pack-off.

20. The method of claim 19 that includes also maintaining a pack-off at the well head about the rod string during elevation thereof. I

21. The method of claim 20 that includes elevating the stuffing box packer with the rod string for retrieval at'the surface.

22. The method of claim 21 that includes preliminarily suspending a stuffing box body in the well to releasably contain the packer, and retrieving said body following retrieval of the rod string.

23. The method of claim 18 that includes preliminarily installing a plug on the rod string to reciprocate therewith in said first tubular means allowing well fluid to pass therebetween, and displacing the rod string and plug to seat on the first tubular means to block said flow.

24. The method of claim 18 wherein the first tubular means is suspended in the well by a first spool at the well head, and the stuffing box is carried by a second spool above the first spool, and within well head tubular structure, and wherein the first tubular means is elevated by elevating the first spool, the second spool and stuffing box being elevated in response to first spool elevation.

25. The apparatus of claim 1 including a packer carried by said tubular casing to seal off against the well bore in response to gas pressure in the well outside said casing and below the packer.

26. The apparatus of claim including a packer carried by said tubular casing below said flange to seal off against the well bore in response to gas pressure in the well outside said casing and below the packer.

27. The method of claim 18 including the step of supporting said tubular casing at the well head, and sealing off between said tubular casing and the well bore.

28. The apparatus of claim 1 including means for elevating said first tubular means in the well so as to elevate the plug into engagement with said reduced bore section.

29. The apparatus of claim 1 including actuator means for displacing said tubular casing downwardly in the well relative to said first tubular means, thereby to engage said reduced bore section with the plug.

30. The apparatus of claim 29 wherein said actuator means includes an annular piston element carried on the tubular casing and acylinder receiving said piston element, there being an annular flange supporting said cylinder to extend vertically at the well head and about said tubular casing.

31. The apparatus of claim 30 including ducting in the flange in communication with chambers defined by the cylinder and piston at opposite sides of the'piston for conducting actuating pressure to said chambers.

32. The apparatus of claim 31 including tubular well head structure supporting the flange and also extending thereabove, there being a passage in the flange to communicate with cavities formed by the well head structure above and below the flange, valve means to control said passage, and means sealing off between the flange and tubular casing.

33. The apparatus of claim 32 including a blow-out passage in the flange and communicating between the cavity formed by the well head structure above the flange, and the exterior of the flange, and means controlling said passage.

34. The method of claim 18 that includes the step of v displacing the tubular casing downwardly relative to the first tubular means, andestablishing a sub-surface pack-off therebetween in response to said downward displacement.

Claims

1. In well flow control apparatus, a. first tubular means in the well for receiving an elongated cylindrical string to be vertically movable from the well head relative to said tubular means, said first tubular means adapted to pass a first stream of production fluid to the well head, b. tubular casing installed in the well and through which the first tubular means extends and adapted to pass a second stream of production fluid for delivery to the well head, said casing having a reduced bore section, and c. a plug carried on the first tubular means below the level of said reduced bore section and adapted to engage said reduced bore section for blocking upward flow of said second stream of production flow in response to relative vertical displacement of the plug and first tubular means.

6. The apparatus of claim 3 including a flange supporting said tubular casing, the casing having opposite flaring ends, and said tubular well head structure supporting said flange so that said tubular casing extends directly below said spool, said lower bore section located between said first spool and said flange.

16. The apparatus of claim 15 wherein said first tubular means has a vertically elongated portion which is diametrically enlarged to form a cavity within which the plug is reciprocable vertically with flow passing clearance at the side of the plug.

18. In the method of retrieving from a well a pump rod string, a bottom hole pump carried by the rod string, a stuffing box packer through whIch the rod string passes, and first tubular means in the well for receiving the rod string to be vertically movable from the well head and adapted to pass a first stream of production fluid to the well head, there being tubular casing in the well and through which the first tubular means extends, the casing adapted to pass a second stream of production fluid to the well head, the steps that include a. elevating the pump rod string and bottom hole pump and retrieving same at the well head, b. elevating said first tubular means for retrieval at the well head, c. and, during a portion of said elevation of the first tubular means, maintaining a sub-surface pack-off between said first tubular means and the casing.

20. The method of claim 19 that includes also maintaining a pack-off at the well head about the rod string during elevation thereof.

21. The method of claim 20 that includes elevating the stuffing box packer with the rod string for retrieval at the surface.

26. The apparatus of claim 5 including a packer carried by said tubular casing below said flange to seal off against the well bore in response to gas pressure in the well outside said casing and below the packer.

30. The apparatus of claim 29 wherein said actuator means includes an annular piston element carried on the tubular casing and a cylinder receiving said piston element, there being an annular flange supporting said cylinder to extend vertically at the well head and about said tubular casing.

31. The apparatus of claim 30 including ducting in the flange in communication with chambers defined by the cylinder and piston at opposite sides of the piston for conducting actuating pressure to said chambers.

34. The method of claim 18 that includes the step of displacing the tubular casing downwardly relative to the first tubular means, and establishing a sub-surface pack-off therebetween in response to said downward displacement.