US3101118A

US3101118A - Y-branched wellhead assembly

Info

Publication number: US3101118A
Application number: US834095A
Authority: US
Inventors: Frederick H Culver; John A Haeber; Edward B Lagucki; Raymond F Perner
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1959-08-17
Filing date: 1959-08-17
Publication date: 1963-08-20
Anticipated expiration: 1980-08-20
Also published as: GB924903A

Description

. Augn ZO, 1963 F. H. CULVER 'ETAL 3,101,118

Y-BRANCHED WELLHEAD ASSEMBLY Filed Aug. 17, 1959- FIG. I

INVENTORS:

F. H. CULVER Y J. A. HAEBER E. B. L AGUCKI R. F. PERNER BY: H. 46

THEIR AGENT United States Patent Delaware Filed Aug. 17, 1959, Ser- No. 834,ll5 14 Claims. (Cl. 166-75) This invention relates to equipment used at the top of an oil or gas well and pertains more particularly to a wellhead assembly adapted to be secured to the top of a well casinghead for controlling the fluid flow from the well while providing apparatus by which the wellhead assembly can be entered vertically for work-over operations, while at the same time a side entry into the wellhead assembly is provided so that various tools, instruments or other devices can be circulated into the well.

A recent development in the drilling and completion of oil and gas wells has been the drilling and completion of underwater wells wherein the wellhead assembly and casinghead may be both positioned hundreds of feet below the surface of water at an offshore location, one such method being described in copending patent applica tion, Serial No. 830,583, filed July 30, 1959. In order to carry out maintenance or other operations on wells wherein the wellhead assembly is positioned a considerable distance below the surface of the watenmethods for carrying out these operations are being developed. One of these methods has been classified as a throughthe-flowline well maintenance technique. For performing the required operations involved in maintaining wells in this manner, certain tools and other devices which are capable of being pumped into and out of the wellbore through the production fluid flowline are being developed. Since these maintenance tools must be pumped into the wellbore, and since they are not able to pass around the right angle bends in the normal wellhead assembly, new types of wellhead fittings are required to carry out the proposed operations.

It is therefore a primary object of the present invention to provide a wellhead assembly provided with a production fluid flowline which joins the wellhead assembly in a manner such that tools, instruments, or other devices may be pumped through the fiowline down into the well.

Another object of the present invention is to provide a wellhead assembly adapted to be positioned under water and permit the passage of tools, instruments, or other devices which cannot move through a fiowline that is curved in a radius in less than from 5 to feet.

While simple well maintenance operations can be carvr-ie'd out by circulating tools through the flowline down into the well, the more important work-over operations require that the underwater wellhead assembly be entered from the top with tools passing vertically down through the wellhead assembly into the well. It is therefore a further object of the present invention to provide an underwater wellhead assembly which selectively permits the vertical entry into the well as well as the circulation of various devices through a substantially horizontal flowline lying on the ocean floor and into the wellhead assembly and thence to pass vertically down through the well.

Another object of the present invention is to provide apparatus by which the vertical conduits in an underwater wellhead assembly can be closed in a manner such that tools, instruments, or other devices may be circulated up through the Well and out through a side flowline conduit of the wellhead assembly without becoming lodged within the wellhead assembly.

Theseand other objects of the present invention will be understood from the following description taken with regard to the drawing, wherein:

3 ,l0 l,ll8 Patented Aug. 20, 1963 "ice FIGURE 1 is a schematic view illustrating many of the components which may be arranged as an underwater wellhead assembly;

' FIGURE 2 is a longitudinal view of a tool diverting plug adapted to fit within the vertical bore of a wellhead assembly in accordance with the present invention; and

:FIGURE 3 is' a view, taken partially in longitudinal cross-section of one form of an orienting device for positioning the tool diverting plug of FIGURE 2 within the wellhead assembly of FIGURE 1.

While the wellhead assembly of the present invention is described hereinbelow with regard to a well having two strings of production tubing suspended therein, it will be readily apparent that the present wellhead assembly can be modified so as to be employed on wells having a single string of tubing therein, or wells having three or more parallel strings of tubing suspended within a well casing.

Referring to FIGURE 1 of the drawing, a casinghead closure member 11 having an annular sealing element 12 carried on its outer surface is shown as positioned on the inner sloping seating surface 13 at the top of a casiughead 14, thus closing the casinghead 14 in a fluid-tight manner. The casinghead closure member 11 is provided with a 1 pair of vertical conduits centrally disposed in side-by-side side conduits.

arrangement and extending vertically down through the casinghead closure ll in register with a pair of strings of production tubing (not shown) suspended within the well. For purposes of illustration, it may be considered that the well casinghead l4 and the wellhead assembly of the present invention are mounted on an offshore Well and are positioned under water.

*Fixedly secured to the'top of the casinghead closure member 11, as by bolts 17, is a master valve 18 by which the well may be shut in upon closing of the valve 18. The valve 18 is preferably of the remotely-controlled fullopening type, that is, the gate or plug controlling flow within-the valve is of a type that, when open, furnishes a straight passageway through the valve ota diameter substantially equal to that of the vertical conduits 15 and 16. For this particular installation the master valve 18 would be one having two flow passageways and two closure members therein, since it is arranged to close both of the vertical conduits l5 and 16.

=Fixedly secured to the top of the master valve 18 is a Y spool piece 21 having a pair of

vertical conduits

22 and 23 therethrough in register, through master valve 18, with the vertical conduits 15 and 16 in the casinghead closure member 11.

Smooth-1y curving from the

vertical conduits

22 and 23 of the Y spool piece 21 are a pair of

side conduits

24 and 25 which branch upwardly and outwardly through the side wall of the spool piece 21. The curvature of the

side conduits

24 and 25 depends, to some extent, upon the length and flexibility of the tools, instruments, or other devices, to be circulated down into the well through the Thus, with the presently developed tools, the radius of curvature of the

side conduits

24 and 25 may be on the order of 5 to 10 feet.

The

side conduits

24 and 25 are provided with

flanges

26 and 27, respectively or other coupling means, for connecting control valves 30 and 31 to the

side conduits

24 and 25 respectively. A pair of

production llowlines

32 and 33 are connected to the other side of the control valves 3% and 31. The fiowl-ines 3-2 and 33 which lead to the top of the wellhead assembly eventually curve outwardly and downwardly to the ocean floor and then run along the ocean floor to shore or to some tank positioned offshore for collection or separation purposes. In the event that the sections of the production fiowlines 32 and 33 directly connected to the control valves 30 and 31 are metal, they should be smoothly curved in an arc of a radius no less than that which would permit objects to be o) circulated therethrough into the well. It is quite apparent that whether the

flowlines

32 and 33 are of a rigid or flexible material that all curves therein must have a minimum radius of not less than that required for circulation of objects therethrough.

From the construction of the present Wellhead assem bly it may be seen that tools and instruments may be readily circulated down through the production flowlines 32, the side conduit 24, and thence through vertical conduits 22 and down into the well. However, on circulating the tool (not shown) up from the bottom of the well, by reversing the circulation of fluid through

conduits

32 and 33, the tool would be driven up the vertical conduit 15 and conduit 22 and become lodged therein, rather than sweeping out the side conduit 24 and thence through the production flowline 32. It therefore has been found necessary to provide the

vertical conduits

22 and 23 of the Y spool piece 21 with

diverting plugs

34 and 35 which are remov-ably positioned therein to close the

vertical conduits

22 and 23 above the

side conduits

24 and 25. The

lower ends

36 and 37 of the

tool diverting plugs

34 and 35, respectively, are shaped in a manner such that the lower tapered face thereof forms a continuation of the inner wall of the smoothly

curved side conduits

24 and 25. That is, the lower end 37 of plug 35 is curved in a manner so as to bend in an arc of the same radius as side conduit 25, while at the same time having a concave face machined, cut, or formed so that a concave portion is curved in a radius equal to that of the inside of the

conduits

24 and 25.

The

tool diverting plugs

34 and 35 are provided with fishing heads 41} and 41 by which the

plugs

34 and 35 may be removed, as by means of a wire line fishing tool. The tool diverting plugs 34- and 35 are also provided with suitable retractable latching or stop means in a manner well known to the art for fixedly positioning the plugs in place so that well pressure does not force them upwardly out of alignment with the

side conduits

24 and 25. Retractable latching means 42 and 43 are well known to the art and are used on many wire line tools. One form of latching assembly is shown on a Type S tool manufaotured by Otis Engineering Corporation and disclosed in the, Composite Catalog of Oil Field Equipment 196 243 edition, page 3901. The

latches

42 and 43 may be withdrawn or set in any suitable manner, as by manipulation of the fishing heads 40 and 41 with wire line or other tools. If desired, the plugs may also be provided with O-

ri'ng seals

44 and 45.

One of the tool diverting plugs 35 is shown in FIGURE 2 with the latching means 43 in its retracted position. Suitable guide means are provided on the tool diverting plug 35 and on the interior wall of the vertical bore 23 of the Y spool piece 21 above the side conduit 25 for orienting the plug 35 to its proper position within the verical bore 23 of the Y spool piece 21. Precise location of the plug 35 within the conduit 23 is necessary in order to be able to circuit tools through the side conduit 25. If a Wellhead of the present invention were to be employed above the surface of the water, the

plugs

34 and 35 could be oriented into their proper position by hand with the use of suitable orienting markings on the top of the plugs. However, where generally the wellhead assembly of: the present invention is to be positioned under water where it is necessary to drop the plugs 34' and 35 into place or lower them by means of a wire line, it is essential that they be provided with guide means for their proper orientation. Any suitable guide means may be employed. For example, in FIGURE 2 the tool divertin'g plug 35 is shown as being provided with an outwardly extending pin 46 which is preferably spring-loaded so that most or all of its length may be retracted into the body of the plug 35 as the plug drops through a tubing string into place.

In FIGURE 3, a section of the Y spool piece 21 is shown with a portion of the vertical condiut 23 taken above the point where the side conduit 25 joins the spool body. In this particular embodiment the inner bore is provided with a sleeve 50 adapted to orient the tubing plug 35 of FIGURE 2 therein. The orienting sleeve 50 is provided with a longitudinal slot or keyway 51 from which diverging

shoulders

52 and 53 slant upwardly and meet at a point 54. The pin 46 in the tool diverting plug 35 of FIGURE 2 is arranged so that it projects horizontally a short distance over the

shoulders

53 and 52 of the orienting sleeve 50. As the tool diverting plug 35 is lowered or dropped into the vertical conduit 23 of the spool piece 21, the projecting pin 46 will engage a point on either

shoulder

52 or 53. Thereupon, the pin 46 will ride down the

shoulder

52 or 53 and cause the tool diverting plug 35 to rotate in the bore of the vertical conduit 23 until the pin 46 and the slot or keyway 51 are in vertical alignment so that the pin drops therein. In this position the curved lower end of the tool diverting plug 35 is in register with the inner curving wall of the side conduit 25, as shown in FIGURE 1. In well installations where there is no well pressure tending to force the diverting

plugs

34 and 35 out of place, the pin of the guide or orienting means also serves as the latching means, preventing the plugs from dropping below the desired position.

In the event that an object or device, such as a packer, is to be circulatde down the Well for permanent use therein and it is not meant to be circulated back to the surface, then it is apparent that no diverting

plugs

34 and 35 are needed in the spool piece 21 at that time.

Fixedly secured to the top of the Y spool piece 21 is a control valve 56 which is preferably of the identical design as the master valve 18, having dual passageways therethrough with full-opening plugs or gates therein. This valve 56 may be known as the swabbing valve since it is opened to allow the passage of tools therethrough during swabbing of a Well. However, with the use of a control valve 56 above the spool piece 21 the lower master valve 18 may be omitted in some installations with the spool piece 21 being connected directly to the top of the casinghead closure member 11. In such an arrangement the flow of fluid would be controlled by

valves

30, 31 and 56. Although it is preferred that the control or wing valves 33' and 31 in the side conduits 24 land 25 be attached directly to spool piece 21 or located close to the Wellhead assembly, in certain installations the

production flowlines

32 and 33 may be connected directly to the

side conduits

24 and 25 with the control of valves 30 and 31 being positioned at the other ends, i.e., the discharge ends, of the conduits 32 land 33, which may be located on land or above the surface of the Water. It is preferred, however, that the Wellhead assernbly of the present invention be provided with both a master and swabbing

valve

18 and 56, respectively, as well as control valves 30 and 31 located close to the wellhead assembly.

Fixedly secured to the top of a swabbing valve 56 is a vertical re-entry conduit having

vertical conduits

58 and 59 therein which are in register, through valve 56, With

vertical conduits

22 and 23 of the spool piece 21. The vertical re-entry conduit may be closed in a suitable fluidtight manner, such, for example, as described in copending patent application, Serial No. 830,587, filed July 30, 1959, or may be provided with a flexible joint whereby the major length of the re-entry conduit can be folded over the rest on the ocean floor, as described in copending patent application, Serial No. 834,096, filed Aug. 17, 1959. The well re-entry conduit 57 is shown as being provided with a pair of wire line

shiftable sleeve valves

60 and 61 for controlling the flow of a pressure fluid through

conduits

62 and 63 and thence through conduits 64 and 65 to lock, or unlock, the casinghead closure member 11 to the casinghead, as described in copending patent application, Serial No. 830,587, filed July 30, 1959.

The entire wellhead assembly of the present invention is preferably covered by a fluidtight chamber 66 to protect the component parts from the corrosive action of sea water and the accumulation of marine growth thereon. The

valves

18, 30, 31 and 56 may be either electrically, pneumatically or hydraulically actuated by any suitable valve system well known to the art. In this particular installation an electric cable 67 is provided for conducting electric signals to energize the series of electrically-actuated pilot valves 70-75 which control the flow of a hydraulic pressure fluid from electrically driven

pumps

76 and 77. The pressure fluid is contained in

reservoirs

78 and 79.

In the operation of the present wellhead assembly fluid may be produced from the well through

conduits

32 and 33 with

valves

30, 31 and 18 open while valve 56 is closed. In the event that it was desired to run a paraffin cleaning tool down through the tubing strings in the well that was connected to vertical conduit 15 of the casinghead closure member 11, the tool (not shown) would be inserted into the conduit 32' at its opposite end on land, or above the surface of the water, and a fluid would be pumped in the back of the tool to force it down through conduit 32, valveSti, side conduit 24-, vertical bore 22, valve 18, vertical conduit '15, and down into the tubing string (not shown). In the event that

conduits

32 and 33 were handling production fluid from the same production Zone in the well, fluid in the well could be returned up through conduits =16, 2,3, 25 and 33, as the tool was being pumped down the opposite conduit. However, in the event that

conduits

32 and 33 were handling fluids from separate production formations and were not in communication with each other within the well, the fluid already in the tubing string and in

conduits

15, 22, 24 and 3-2 at the time the paraflin cleaning tool was inserted therein, would be pumped downwardly and into the formation again during the paraffin cleaning operation. This could also be the mode of operation when the wellhead apparatus of the present invention was employed on a well using a single tubing string.

If remedial work requiring the use of wire line tools was needed in the well and it was necessary to go into the well tubing strings with tools that could not pass around the smoothly-curved side conduits 24 and 2510f the present wellhead assembly, it would be necessary to enter the well through the re-entry conduit 57. After controlling the Well by circulating packers through

conduits

32 and 33, 101' controlling the well by killing it with a drilling mud pumped through the same conduits, the valve 56 would be opened by remote control from the operational base above the surface of the Water and a wire line tool would be sent down through the re-entry conduit 57 to withdraw the [

tool diverting plugs

34 and 35 from the spool piece 21. It would then be possible to lower elongated sections of tool down through the re-entry conduit 57, through spool piece 21 and the casinghead closure member 11 and thence downwardly into the well. After the work-over operations have been completed and the tools withdraWn from said well may be established, and means for closing off the vertically-extending conduit means to maintain a full-opening path through said curved conduit means.

2. A well assembly adapted to be secured to the top of a well casinghead for controlling the fluid flow from said well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a casinghead closure connected to said well casinghead and having vertical conduit means there- .through, a spool piece secured to said casinghead closure, said spool piece having vertical conduit means therethrough in register with the vertical conduit means in said casinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, vertical conduit closure means carried by said spool piece for closing the vertical conduit means thereof, second independent conduit means through said casinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate well pipe strings with each other within the well, whereby well devices may be circulated into and out of said well through said smoothly-curved side conduit means, and vertical re-entry conduit means secured to the top of said wellhead assembly and in register with the vertical conduit means of said spool piece.

3. A wellhead assembly adapted to be secured to the top of a well casinghead for controlling the fluid flow from said Well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a casinghead closure connected to at least one producing formation, said assembly including said well casinghead and having vertical conduit means therethrough, a spool piece secured to the top of said casinghead closure, said spool piece having vertical conduit means therethrough in register with the vertical conduit means in said casinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, removable plug means closing the vertical conduit means in said spool piece above the side conduit means thereof, the lower end of said plug means being shaped so that the lower face thereof forms a continuation of the inner wall of the smoothly-curved side conduit means, full-opening valve means secured to the top of said spool piece for closing the vertical conduit means thereof, second independent conduit means through said casinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate well pipe strings with each other within the well, whereby well devices may be circulated into and out of said well through said smoothlyculrved side conduit mean-s, and vertical re-entry conduit means secured to the top of said valve means and in regsister therethrough with the vertical conduit means of said spool piece.

4. A wellhead assembly adapted to be secured to the top of a well casinghead for controlling the fluid flow from said well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a casinghead closure connected to said well casinghead and having vertical conduit means therethrou-gh, a spool piece secured to the top of said casinghead closure, said spool piece having vertical conduit means therethrough in register with the vertical conduit means in said casinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, removable plug means closing the vertical conduit means in said spoolpieceabove the side conduit means thereof, the lower end of said plug means being shaped so that the lower face thereof forms a continuation of the inner wall of the smoothly-curved side conduit means, first and second guide means, one of said means carried by the plug means and the other on the inner wall of the vertical conduit means of said spool piece whereby the engagement of said first guide means with said second guide means upon entry of said plug means into said vertical conduit means of said spool piece causes said plug means to rotate therein until the lower end thereof is curved to register with the inner curving wall of said side conduit means, full-opening valve means secured to the top of said spool piece for closing the vertical conduit means thereof, second independent conduit means through said oasinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate Well pipe strings with each other within the well, whereby well devices may be circulated into and out of said well through said smoothly-curved side conduit means, and vertical re-entry conduit means secured to the top of said valve means and in register therethrough with the vertical conduit means of said spool piece.

5. A wellhead assembly adapted to be secured to the top of a well oasinghead for controlling the fluid flow from said Well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a oasinghead closure connected to said well oasinghead and having vertical conduit means therethrough, a spool piece secured to the top of said casinghead closure, said spool piece having vertical conduit means therethrou-gh in register with the vertical conduit means in said oasinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, removable plug means closing the vertical conduit means in said spool piece above the side conduit means thereof, the lower end of said plug means being shaped so that the lower face thereof forms a continuation of the inner wall of the smoothly-curved side conduit means, fishing head means for inserting said plug means into the vertical conduit means of said spool piece and removing it therefrom, latch means in engagement between said plug means and said spool piece for fixedly positioning said plug means therein, registering first and second guide means, one of said means carried by the plug means and the other on the inner wall of the vertical conduit means of said spool piece whereby the engagement of said first guide means with said second guide means upon entry of said plug means into said vertical conduit means of said spool piece causes said plug means to rotate therein until the lower end thereof is curved to register with the inner curving wall of said side conduit means, full-opening valve means secured to the top of said spool piece for closing the vertical conduit means thereof, second independent conduit means through said oasinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate well pipe strings with each other within the Well, whereby well devices may be circulated into and out of said well through said smoothly-curved side conduit means, and vertical re-entry conduit means secured to the top of said third valve means and in register therethrough with the vertical conduit means of said spool 1ece. p 6. A wellhead assembly adapted to be secured to the top of a well oasinghead for controlling the fluid flow from said well while providing du-al conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a casinghead closure connected to said Well casinghead and having vertical conduit means therethrough, a spool piece secured to the top of said cars inghead closure, said spool piece having vertical conduit means therethrough in register with the vertical conduit means in said oasinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, first valve means in said side conduit means for controlling the fluid flow therethrough, removable plug means closing the vertical conduit means in said spool piece above the side conduit means thereof, the lower end of said plug means being shaped so that the lower face thereof forms a continuation of the inner wall of the smoothly-curved side conduit means, fishing head means for inserting said plug means into the vertical conduit means of said spool piece and removing it therefrom, registering first and second guide means, one of said means carried by the plug means and the other on the inner wall of the vertical conduit means of said spool piece for orienting said plug means therein whereby the lower end thereof is curved to register with the inner curving wall of said side conduit means, full-opening second valve means secured to the top of said spool piece for closing the vertical conduit means thereof, second independent conduit means through said oasinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate Well pipe strings with each other within the well, whereby well devices may be circulated into and out of said well through said srnbothlycurved side conduit means, and vertical re-entry conduit means secured to the top of said second valve means and in register therethrough with the vertical conduit means of said spool piece.

7. Awellhead assembly adapted to be secured to the top of a well oasinghead for controlling the fiuid flow from said well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a oasinghead closure connected to said well casinghead and having vertical conduit means therethrough, first full-opening valve means secured to the top of said casinghead for closing the conduit means therein, a spool piece secured'to the top of said first valve means, said spool piece having vertical conduit means therethrough in register through said first valve means with the vertical conduit means in said casinghead closure, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said spool piece from the vertical conduit means therein, second valve means in said side conduit means for controlling the fluid flow therethrough, removable plug means closing the vertical conduit means in said spool piece above the side conduit means thereof, the lower end of said plug mean-s being shaped so that the lower face thereof forms a continuation of the inner wall of the smoothly-curved side conduit means, fishing head means for inserting said plug means into the vertical conduit means of said spool piece and removing it therefrom, latch means in engagement between said plug means and said spool piece for fixedly positioning said plug means therein, registering pin means and guide means, one of said means carried by the plug means and the other on the inner wall of the vertical conduit means of said spool piece for orienting said plug means therein whereby the lower end thereof is curved to register with the inner curving wall of said side conduit means, full-opening third valve means secured to the top of said spool piece for closing the vertical conduit means thereof, second independent conduit means through said casinghead closure in communication between the interior of the well and the space outside thereof, said vertical conduit means and said independent conduit means adapted to communicate through separate well pipe strings with each other within the well, whereby well devices may be circulated' into and out of said well through said smoothlycurved side conduit means, and vertical re-entry conduit means secured to the top of said third valve means and in register therethrough with the vertical conduit means of said spool piece.

8. A wellhead for underwater wells. including at least one unitary member including conduit means adapted to extend vertically, and a curved flow conduit means smoothly branching upwardly and outwardly from said vertically-extending conduit means along a curve having a radius such that a well device can be pumped therethrough, and second conduit means through said unitary member adapted to communicate in the well with said curving conduit means, and means fior closing oil? the vertically-extending conduit means in said unitary member to maintain a full opening path through said curved flow conduit means.

9. A wellhead for an underwater well including at least one unitary member including first conduit means adapted to extend vertically, and curved flow conduit means smoothly branching upwardly and outwardly from said vertically-extending conduit means, the lower end of said first conduit means adapted to communicate through a first well pipe string with the interior of the well, means for closing oil the vertically-extending conduit means in said unitary member to maintain a toll opening path through said curved flow conduit means and into said well, and second independent conduit means in said wellhead adapted to communicate through a second well pipe string with the interior of the well and with said first pipe string, whereby well devices may be circulated into and out of said well through said curved flow conduit means.

10. The apparatus of claim 9 including closure means for closing said second conduit means.

11. The apparatus of claim 9 wherein said wellhead system is removably secured to the top of a well having a well casing and a tubing production string in communication with the producing formation of the well, said curved conduit means being in communication with the tubing string and said second conduit means in communication with the interior of said casing.

12. The apparatus of claim 9 wherein said wellhead system is removably secured to the top of a well having a well casing and a pair of tubing strings therein in normal open communication with the producing liormation of the well, said curved conduit means and said second conduit means being in communication with separate tubing strings in said well.

13. A wellhead assembly adapted to be secured to the top of a well easinghead for controlling the fluid flow from said well while providing dual conduit means selectively permitting the vertical entry of devices into the well as well as the circulation of :devices into a well, said wellhead assembly comprising a casinghe-ad closure connecti-ble to said well casinghead and having a plurality of conduit means therethrough, at least one of said conduit means being vertical conduit means, a tubing string in said well in register with the one vertical conduit means in said casinglhead closure and in communication with a production zone of the well, smoothly-curved side conduit means branching upwardly and outwardly through the side wall of said closure from the vertical conduit means therein, another cl said conduit means being in communication through said closure between the same production zone in the interior of a well and the outside thereof whereby well devices may be circulated into and out of said well through said curved side conduit means, and conduit closure means co-nnectible to said closure for closing at least the vertical conduit means thereof above the branching conduit means.

14. A wellhead assembly adapted to be secured to the top of a well casinghead for controlling the fluid flow from said well while providing dual conduit means selectively permitting the vertical entry of [devices into the well as well as the circulation of devices into a well, said wellhead assembly comprising a oasinghead closure connectible to said well casinghead and having a pair of vertical conduit means therethrough, and having smoothly-curved side conduit means branching upwardly and outwardly through the side wall thereof [from at least one of the vertical conduit means therein, said pair of vertical conduit means adapted to communicate through a pair of well pipe strings in communication with each other within the well, whereby well devices may be circulated into and out of said well through said curved side conduit means, and vertical conduit closure means carried by said closure for closing at least the vertical conduit means thereof above the branching conduit means, and vertical re-entry conduit means carried in the top of said wellhead assembly and in register with the vertical conduit means of said casinghead closure.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,047 Hindcnlite-r I an. 16, 1934 399,747 Edwards Mar. 19, 1889 1,851,319 McCoy et al. Mar. 29, 1932 2,532,341 Shannon Dec. 5, 1950 2,590,688 Crain Mar. 25, 1952 2,854,215 Cox et al. Sept. 30, 1958 2,859,773 Wallace Nov. 11, 1958 2,862,560 Bostocket et al Dec. 2, 1958 2,874,784 Baker et al. L Feb. 24, 1959 2,889,886 Gould June 9, 1959 2,903,066 Brown Sept. 8, 1959 3,012,608 McLaren Dec. 12, 1961

Claims

1. A WELLHEAD SYSTEM ADAPTED TO BE ARRANGED AT THE TOP OF A WELL CASING EXTENDING INTO THE GROUND AND TRANVERSING AT LEAST ONE PRODUCING FORMATION, SAID ASSEMBLY INCLUDING FIRST CONDUIT MEANS ADAPTED TO EXTEND VERTICALLY FROM SAID WELL CASING AND CURVED CONDUIT MEANS BRANCHING FROM SAID VERTICALLY-EXTENDING CONDUIT MEANS, SECOND CONDUIT MEANS IN SAID WELLHEAD SYSTEM IN COMMUNICATION BETWEEN THE INTERIOR OF THE WELL AND THE SPACE OUTSIDE THEREOF, SAID FIRST AND SECOND CONDUIT MEANS BEING ADAPTED TO BE IN COMMUNICATION WITH EACH OTHER WITHIN THE WELL WHEREBY A CIRCULATION PATH THROUGH THE WELLHEAD SYSTEM AND TO AND FROM SAID WELL MAY BE ESTABLISHED, AND MEANS FOR CLOSING OFF THE VERTICALLY-EXTENDING CONDUIT MEANS TO MAINTAIN A FULL-OPENING PATH THROUGH SAID CURVED CONDUIT MEANS.