US3526418A

US3526418A - Wellhead completion apparatus

Info

Publication number: US3526418A
Application number: US747708A
Authority: US
Inventors: Robert D Barnett
Original assignee: Rockwell Manufacturing Co
Current assignee: Rockwell Manufacturing Co; Smith International Inc
Priority date: 1968-07-25
Filing date: 1968-07-25
Publication date: 1970-09-01
Anticipated expiration: 1987-09-01
Also published as: GB1224430A; FR2013646A1

Description

Sept 970 R. 0. BARNETT 3,526,418

WELLHEAD COMPLETION APPARATUS Filed July 25, 1968 Foerf .0. Bar/7e f f INVENIOR.

A77 PA/EV United States Patent 3,526,418 WELLHEAD COMPLETION APPARATUS Robert D. Barnett, Houston, Tex., assignor to Rockwell Manufacturing Company, Houston, Tex., a corporation of Pennsylvania Filed July 25, 1968, Ser. No. 747,708 Int. Cl. F161 35/00 U.S. Cl. 28593 4 Claims ABSTRACT OF THE DISCLOSURE Wellhead completion apparatus comprising a tubing head with a vertical bore therethrough, a tubing hanger disposed in said bore and a lockscrew assembly afiixed to the tubing head. The bore of the tubing head is defined 'by an upper cylindrical portion joined to a lower cylindrical portion by upwardly facing annular shoulder. The tubing hanger exterior is defined by an upper cylindrical portion and a lower cylindrical portion joined by a downwardly facing surface in contact with the tubing bore shoulder to support the hanger. An annular groove is formed on the exterior of the hanger adjacent the lockscrew assembly. The lockscrew assembly includes a lockscrew laterally movable through the tubing head wall to engage the annular hanger groove. Annular sealing rings are provided on the upper hanger portion above the groove and on the lower hanger portion below the groove. These rings are in sealing contact with the tubing head bore walls.

BACKGROUND OF THE INVENTION Field of the invention This invention pertains to apparatus for use in well completion operations. More specifically, it pertains to apparatus for hanging and holding tubing within a well.

Background of the invention It is common practice in the completion of oil and gas wells to hang a production tubing string in a tubing head which is usually surmounted on a casing head. A tree assembly, normally including a master valve and other valves and fittings, is then mounted on the tubing head.

It is also common to use lockscrews, passing through the upper tubing head flange engaging the tubing hanger, to hold the tubing down. Unless special pack-01f nipples and seals are used the lockscrews are exposed to full well pressure at all times. Should a leak occur in the lockscrew packing, it would be necessary to kill the well for replacement, since the master valve is above the lockscrews. This, of course, is a very expensive procedure.

SUMMARY OF THE INVENTION The present invention provides a unique tubing head, hanger and lockscrew arrangement whereby the lockscrews are isolated from high well pressures. The invention comprises a tubing head having a vertical bore therethrough and an upwardly facing shoulder therein; a tubular hanger supported on the shoulder and having annular groove means on its exterior; lockscrew means on the tubing head, a portion of which is laterally movable through the walls of the tubing head to engage the annular groove means, preventing longitudinal movement of the hanger; and

3,526,418 Patented Sept. 1, 1970 annular sealing means on the hanger in sealing contact with the tubing head isolating the lockscrew means from pressure above and below the hanger. Thus, the likelihood of a costly leak is reduced. The arrangement also provides a simple testing method whereby the lockscrew packing and isolating seals may be easily tested at any time.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention will become apparent from the following description when taken into conjunction with the accompanying drawing in which:

FIG. 1 is a schematic representation of a typical wellhead and production tree assembly, and

FIG. 2 is an elevation view, partially in section of a tubing head, tubing hanger, tubing and lockscrew arrangement according to a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, a typical wellhead and production tree assembly is shown supported on a surface casing 2 penetrating the ground 3. A lowermost casing head 4 is attached to the surface casing 2 for supporting a casing hanger and another casing (not shown) therein. Depending on the casing program called for another casing head 5 may be mounted above casing head 4 to support an intermediate casing hanger and casing (not shown).

Mounted on casing head 5 is tubing head 6 which supports therein tubing hangers and tubing through which the well production will flow. Casing valve 7 gives flow access to the casing surrounding the production tubing. Surmounted on tubing head 6 is an adapter flange 8, master valve 9, tee 10 and tree top 11. A wing valve 12 is connected to one branch of T 10 through which production fluids pass to a choke 13 and eventually to a flow line 14.

The tubing head 6 shown in FIG. 1 is one typical of presently used equipment. It will be noticed that lockscrews 15 are provided in the upper flange. These lockscrews are used to engage tubing hangers (not shown) suspended within tubing head 6 to hold the hangers and their attached tubing strings in the well against any upward force that may be exerted on them. Occasionally these lockscrews are damaged on installation or due to the high internal well pressures to which they are subjected their packings begin to leak. Since they are below master valve 9, it is necessary to kill the well to replace or repair a lockscrew or its packing.

With the tubing head, tubing hanger, and lockscrew arrangement of the present invention the lockscrews are isolated from high wll pressures. Thus, it is less likely that a leak will occur. Furthermore, the invention provides a method of testing the lockscrew packing and isolating seals prior to bringing the well in. This gives assurance of a good seal before the Well begins to produce. A preferred embodiment of the invention is shown in FIG. 2 comprising tubing head 20, tubing hanger 30, tubing 40, and lockscrew assembly 50. The embodiment shown is for a single tubing completion. The invention may also be adapted for use with multiple completions, as can be understood.

Tubing head 20 is provided with a lower flange 21 for mounting on a casing head and an upper flange 22 on which a master valve and other production tree components may be surmounted. The bore 23 of tubing head is provided with an upwardly facing shoulder 24 on which tubing hanger 30 is supported. This support shoulder may be above or below lockscrew assembly 50. The bore of tubing head 20 immediately below shoulder 24 is of a smaller diameter than the bore thereabove for reasons to be subsequently understood.

Lockscrew assembly 50 comprises tubular housing 51, lockscrew 52, packing 53, inner packing gland 54, and outer packing gland 55. Tubular housing 51 opens into tubing head bore 23 and is provided with threads 56 for engagement of lockscrew threads 57 and threads 58 for engagement of outer gland threads 59. A nut member 60 is provided for rotating gland 55 to adjust or replace packing 53. Lockscrew 52 is provided with flats 61 for engagement of a wrench or the like allowing lockscrew 52 to be withdrawn from or projected into tubing head bore 23. The inner end of lockscrew 52 has a frusto-conical nose portion 62 which in the inwardly projecting position shown engages tubing hanger 30 preventing upward movement thereof.

Tubing hanger 30 is a tubular member with upper and lower inner connection means such as threads 28 and 29. A tubing string 40 is attached to the lower connection. The upper connection may be connected to a handling string for installation or removal of hanger 30 and its attached tubing string 40. The exterior of hanger 30 comprises an upper cylindrical portion 31 and a lower cylindrical portion 32. The diameter of lower portion 32 is slightly less than upper portion 31 so that a downwardly facing surface 33 is provided to cooperate with tubing head shoulder 24 for supporting hanger 30 within the head 20. Near the bottom of upper cylindrical portion 31 and above support surface 33 an annular groove 34 with bottom wall 35 and

side walls

36 and 37 is cut to cooperate with the frusto-conical nose 62 of lockscrew 52 to hold hanger 30 and tubing 40 against upward movement. Groove 34 could also be placed below support surface 33 if desired. Since the nose 62 of lockscrew 52 is usually of a harder material than hanger 30, lockscrew 52 may slightly deform hanger 30 near

groove walls

36 and 37. This may scratch the bore of tubing head 20 when the hanger is removed. To eliminate this problem annular

relieved areas

47, 48 are provided above and below groove 34. This allows some deformation without bore interference.

Immediately above hold down groove 34 are two adjacent annular grooves 38 in which are mounted annular sealing rings 39 and annular back-up rings 41. This upper sealing means isolates lockscrew assembly 50 from the high pressures existing in the upper part of tubing head 20. Immediately below support shoulder 33, on lower reduced diameter portion 32, are two more adjacent annular grooves 42 in which are mounted annular sealing rings 43 and annular back-up rings 44. This lower sealing means isolates lockscrew assembly 50 from the pressures existing in the lower part of tubing head 20 and casing therebelow. This pressure could become quite high if tubing string 40 should dev lop a leak, which is quite common. Thus, lock screw assembly '50 is completely isolated from high pressure environments by the upper and lower sealing means. Lockscrew packing 53 will be less likely to develop a leak and the lockscrew assembly 50 may be of a more economical design without sacrificing safety or performance.

A port 45 may be formed in the wall of tubing head 20 through which pressure can be applied to test both lockscrew packing 53 and the upper and lower sealing assemblies of tubing hanger 30. This can be done prior to bringing in a well so that a complete seal can be assured once production is b gu To install hanger 30 and tubing string 40 in a well a handling string would be attached to the upper inner connection means 28 of hanger 30 and the hanger 30 would be lowered into head 20, lockscrew 52 being fully retracted from the bore thereof until downwardly facing shoulder 34 contacts tubing head support shoulder 24. Since the lower portion 32 of hanger 30 is of a diameter smaller than the hanger upper portion 31, it is readily seen that the seal rings 43 of the lower sealing assembly are not in contact with the tubing head walls until they pass support shoulder 24. Thus, the likelihood of damaging the seal on installation is considerably reduced. Once the hanger 30 has been seated on support shoulder 24, lockscrew 52. may be turned until nose 62 fully engages the walls of hold down groove 34 restraining hanger 30 and its supported tubing string 40 against longitudinal displacement. Pressure may then be applied through port 45 to test the

seals

39, 43 and lockscrew packing 53. Assuming that the test is positive, the well can be brought in. The lockscrew, being isolated from high internal well pressures, will not be likely to develop a leak which would require a costly shutdown.

Although only one preferred embodiment of the invention has been described herein, many modifications thereof can obviously be made by one skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. Wellhead completion apparatus comprising:

a tubing head having a vertical bore therethrough, said bore defining an upper cylindrical portion and a smaller diameter lower cylindrical portion with an upwardly facing support shoulder therebetween;

a tubular hanger supported within said bore on said support shoulder, the exterior of said hanger comprising an upper cylindrical portion, a smaller diameter lower cylindrical portion and annular groove means;

lockscrew means attached to said tubing head, a portion of which is laterally movable through the walls of said tubing head engaging said groove means to prevent longitudinal movement of said hanger;

first annular sealing means on said hanger upper portion above said groove means in sealing contact with said tubing head upper portion;

second annular sealing means on said hanger lower portion below said groove means in sealing contact with said tubing head lower portion; and

at least one test port passing through the wall of said tubing head and communicating with said groove means to pressure test said first and second sealing means and said lockscrew means.

2. Wellhead completion apparatus as set forth in claim 1 characterized by annular relieved areas above and below said annular groove means immediately adjacent thereto.

3. Wellhead completion apparatus as set forth in claim 1 characterized in that said groove means is on one of said upper and lower cylindrical portions.

4. Wellhead completion apparatus comprising:

a tubing head having a vertical bore therethrough, said bore comprising an upper cylindrical portion and a lower cylindrical portion with an upwardly facing annular support shoulder therebetween;

a one piece tubular hanger disposed in said bore having on its exterior an upper cylindrical portion, a lower cylindrical portion, annular groove means and a downwardly facing support surface joining said upper and lower cylindrical portions and cooperating with said support shoulder to support said hanger on said tubing head;

a tubing string directly connected to said tubular hanger and supported thereby;

lockscrew means, attached to said tubing head, lateral- 1y movable through the walls thereof to engage said groove means preventing longitudinal movement of said hanger and tubing string relative to said tubing head;

first annular seal on said hanger above said groove means and second annular seal on said hanger below said groove means in sealing contact with said tubing head isolating said lockscrew means from the pressurized environment of said tubing head above said hanger and around said tubing string; and

a test port passing through the wall of said tubing head and communicating with said groove means to test said first and second seal.

References Cited UNITED STATES PATENTS Pinkard 285142 X Smith 285-404 X Roach et al 28593 X Parkhurst et al. 285-133 X Musolf 285133 X Rector 285-93 X Knight 285-27 DAVE W. AROLA, Primary Examiner US. Cl. X.R.