INSERT FOR DUAL STRING HANGER ASSEMBLY

Description

FIELD OF THE INVENTION

This invention relates to an apparatus for hanging a production tubing string and an auxiliary tubing string within a well casing.

BACKGROUND OF THE INVENTION

A “dual string” well is a well that includes both a production tubing string and an auxiliary tubing string located within the well casing.

Applicant's dual string hanger assembly, as described in US 2022/0282589 published on Sep. 8, 2022 provided an excellent solution for a dual string well. The solution of US 2022/0282589 was useful where the auxiliary tubing string was jointed tubing or coil tubing.

It is apparent, however, that setting up a dual string well with coil tubing may result in operational difficulties and extra costs. For example, coil tubing is difficult to handle and difficult to bend around sharp radiuses. Further, the tendency for coil tubing to assume a spiral shape can create problems during installation.

SUMMARY OF THE INVENTION

The invention therefore provides a dual string tubing hanger insert and assembly for a production tubing and an auxiliary line.

In accordance with one broad aspect of the invention, there is provided a dual string tubing hanger insert comprising: a cylindrical body including an upper surface, a lower surface and an outer wall shaped to taper downwardly; a bore extending from the upper surface to the lower surface of the cylindrical body, the bore having an inner diameter; a hanging profile for engaging an auxiliary line of a dual string well, the hanging profile including an inner facing wall surface about a long axis extending from the upper surface to the lower surface of the cylindrical body, wherein the hanging profile includes (a) a diameter less than the inner diameter of the bore and (b) an upwardly facing shoulder on the inner facing wall surface on which a shoulder of the auxiliary line is supported, wherein the cylindrical body is separated into a first part and a second part at a split that extends from the upper surface to the lower surface and the split bisects the hanging profile along the long axis of the hanging profile.

In accordance with another broad aspect of the invention, there is provided a wellhead installation comprising: a tubing head on a well casing; the insert as described above positioned in the tubing head, with the first part and the second part coupled to form therebetween the hanging profile; an adaptor for hanging a production tubing string within the well casing, the adaptor including: a main body with an outer surface and an interior open area extending from an upper end to a lower end, the lower end defining an annular mounting flange through which the adaptor is mounted on the tubing head; a production string tubing hanger profile in the interior open area, the production string tubing hanger profile being offset non-concentrically relative to the annular mounting flange; and a port for auxiliary line fluid communication, the port extending from the outer surface to an inner opening and positioned aligned over the hanging profile; a tubing string longitudinally suspended from the production string tubing hanger profile and hanging down through the bore of the insert; and an auxiliary line suspended from the hanging profile and in fluid communication with the port.

In accordance with another broad aspect of the invention, there is provided a method for wellbore operations, the method comprising: positioning an upper end of an auxiliary line in a tubing head of a well; assembling a first part and a second part of an insert for a dual string in the tubing head to create a hanging profile for the auxiliary line, wherein the insert for a dual string well comprises: a cylindrical body including an upper surface, a lower surface and an outer wall shaped to taper downwardly; a bore extending from the upper surface to the lower surface of the cylindrical body, the bore having an inner diameter; the hanging profile for engaging the auxiliary line, the hanging profile including an inner facing wall surface about a long axis extending from the upper surface to the lower surface of the cylindrical body, wherein the hanging profile includes (a) a diameter less than the inner diameter of the bore and (b) an upwardly facing shoulder on the inner facing wall surface, wherein the cylindrical body is separated into the first part and the second part at a split that extends from the upper surface to the lower surface and the split bisects the hanging profile along the long axis of the hanging profile; supporting a shoulder of the auxiliary line on the upwardly facing shoulder with a length of the auxiliary line extending down into the well; hanging a tubing string for longitudinal support from a tubing hanger profile spaced above the tubing head, the tubing string extending down through the tubing head and the bore of the insert and extending down into the well alongside the auxiliary line; and configuring the auxiliary line to be connectable into fluid communication with an exterior source of fluid and sealed from fluid communication with the tubing head and the tubing string.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show the preferred embodiments of the present invention in which:

FIG. 1A is a top plan view of a wellhead installation;

FIG. 1B is a section along line M-M through the wellhead installation of FIG. 1A. Specifically, the section is taken along a radius toward the center axis of a wellhead installation and along the long axis of the auxiliary line;

FIG. 2 is a top, side isometric view of an insert for a dual string hanger assembly;

FIG. 3 is another top, side isometric view of the insert of FIG. 2;

FIG. 4 is a top plan view of one of the parts of the insert of FIGS. 2 and 3;

FIG. 5 is a top, side isometric view of the part of FIG. 4, showing the face side;

FIG. 6 is a side elevation of the part of FIG. 4, showing the face side;

FIG. 7 is a detail from FIG. 1B of the auxiliary line installed within the insert;

FIG. 8 is a detail of the bottom of the insert adjacent the auxiliary line in FIG. 7;

FIG. 9 is a section through another wellhead installation, the section passing through the center axis of a wellhead installation and along the long axis of the auxiliary line;

FIG. 10 is a top, side isometric view, partially cut away, of an insert for a dual string hanger assembly;

FIG. 11 is a section along line B-B of FIG. 9;

FIG. 12 is a section along line C-C of FIG. 9; and

FIG. 13 is a detail of the insert and the auxiliary line from FIG. 11.

DESCRIPTION OF EMBODIMENTS

The present insert is for a dual string hanger. The present insert is configured for installation in a tubing head of a wellhead and for supporting an auxiliary line in a well alongside a production tubing string. The insert is particularly able to support an auxiliary line of jointed tubing, such as non-upset end (NUE) tubing, but can also handle coil and other types of tubing. The auxiliary line is sometimes called a flushing line.

The insert may be used in a dual string hanger assembly. In use, the auxiliary line is supported in a hanger profile that is part of the insert, which is installed within the tubing head. The production string is supported hanging alongside the auxiliary line, for example, in a tubing hanger profile built into an adaptor above the existing tubing head. In one embodiment, a dual string hanger wellhead installation includes the insert and an adapter. The insert is installed within the inner diameter of the tubing head and the adaptor is coupled over the top of the tubing head. The insert, therefore, becomes sealed within the interior space between the tubing head and the adaptor.

A dual string tubing hanger insert comprises a cylindrical body including an upper surface, a lower surface and an outer wall shaped to taper downwardly. A bore extends from the upper surface to the lower surface of the cylindrical body. The insert also includes a hanging profile for engaging an auxiliary line of a dual string well. The hanging profile includes an inner facing wall surface about a long axis and the hanging profile extends from the upper surface to the lower surface of the cylindrical body. Generally the hanging profile includes (a) a diameter less than the inner diameter of the bore and (b) an upwardly facing shoulder on the inner facing wall surface on which a shoulder of the auxiliary line can be supported. To facilitate operations, for example during installation of the insert, the cylindrical body described herein is separated into a first part and a second part at a split. The split extends from the upper surface to the lower surface and bisects the hanging profile along the long axis of the hanging profile.

In one embodiment of the present dual string tubing hanger insert, the split bisects the bore as well as the hanging profile (FIGS. 1A to 8). In another embodiment of the present dual string tubing hanger insert, the split bisects only the hanging profile but does not pass through the bore (FIGS. 9 to 13).

An first embodiment of an insert for a dual string tubing hanger assembly is described with reference to FIGS. 1A to 8. The insert 12, in use, is installed within an existing tubing head 2 and is configured to support the auxiliary line 4. Insert 12 is part of a dual string tubing hanger assembly that includes a hanging profile 28 for the production tubing 5 such as in an adapter 10 that is installed on the tubing head 2.

Insert 12 is configured, for example shaped and sized, to be positioned in the existing tubing head 2 of a well head. Insert 12, for example, has an annular outer wall 12′ extending between its upper surface 12″ and its lower surface 12″′. The annular outer wall is shaped for hanging in the tubing head. For example, the annular outer wall 12′ may have a radially outwardly projecting shoulder, such as a frustoconical, downwardly tapering outer diameter surface shape that is sized to be hung in the frustoconical, downwardly tapering bowel 2b of the tubing head.

Insert 12 is further configured to support the small diameter auxiliary tubing in a dual string well. In particular, the insert contains a hanging profile 12a. The hanging profile 12a is a bore, that extends from the insert's upper surface 12″ to the insert's lower surface 12″′.

The auxiliary line is supported hanging straight down from the hanging profile 12a. The hanging profile 12a is positioned off center, non-concentric relative to the outer diameter of the insert outer wall 12′. The hanging profile is close to the outer diameter surface 12′ and there is a thin insert body portion 12a′ between the inner cylindrical wall defining the hanging profile and annular outer wall 12′.

Insert 12 also includes a bore 12b that extends from the insert's upper surface 12″ to the insert's lower surface 12″′. This bore 12b provides an open passage through insert 12 through which the production tubing can pass. The bore 12b has a larger open inner diameter than the inner diameter of hanging profile 12a. The open inner diameter of bore 12b may also be larger than the production tubing outer diameter, which is larger than the diameter of the auxiliary line. Bore 12b is also positioned off center, non-concentric relative to the outer diameter of the insert outer wall 12′. Bore 12b is positioned diametrically opposite hanging profile 12a. Bore 12b is close to the outer diameter surface 12′and there is a thin insert body portion 12b′ between the inner wall of the bore 12b and annular outer wall 12′.

When considering the insert in plan view (best seen in FIG. 2), the offset location of bore 12b leaves a crescent-shaped portion 21 of the insert body remaining within wall 12′. Hanging profile 12a is located in that crescent-shaped portion 21 of the insert body.

Insert 12 is a cylindrical structure that is separated at a split from upper surface to lower surface into two parts 12c, 12d that are each part of a cylinder. In the illustrated embodiment of FIGS. 1A-8, the parts are semi-cylindrical. The split ensures that insert 12 can be introduced into a tubing head after the auxiliary line is already extending into the tubing head. The split that separates the two parts, therefore, passes through at least hanging profile 12a and bore 12b. The two semicircular parts 12c, 12d, therefore, each include a face 12c′, 12d′ where the body is split. The faces 12c′, 12d′ come into close proximity when the insert body is assembled. Each face includes a portion, such as about half, of the inner wall defining hanging profile 12a and a portion, such as about half, of the inner wall defining bore 12b. Each face, therefore, also includes a face portion 12ca′, 12da′ that spans across thin insert body portion 12a′ between the inner wall of the hanging profile and annular outer wall 12′ and a face portion 12cb′, 12db′ that spans across the thin insert body portion 12b′ between the inner wall of the bore 12b and annular outer wall 12′.

Insert 12 is configured to secure auxiliary line 4 (see FIGS. 1B, 7 and 8) that has a structure 23a, sometimes referred to as a coupling, at its upper end, where the structure 23a has a larger outer diameter than the outer diameter of the main auxiliary line conduit 23b. The structure 23a, having a larger diameter than the main conduit, creates an annular downwardly facing shoulder 23a′ on the auxiliary line. The larger diameter structure could, for example, be a coupling or a threaded box that is used to threadedly connect lengths of tubing together. In one embodiment, for example the auxiliary line is a NUE tubing string and the larger diameter structure 23a is a NUE coupling with threaded box ends that receive and engage threaded pin ends of the NUE tubing joints 23b. The NUE coupling creates annular downwardly facing shoulder 23a′ between the outer diameter of the coupling and the outer diameter of the NUE tubing joint.

Insert 12 is, in particular, (a) configured to hold the weight of the auxiliary line hanging down below and (b) configured to engage the structure 23a against rotation (i.e. such that the enlarged structure cannot rotate while being engaged by the insert).

To hold the weight of the auxiliary line hanging down below the insert, hanging profile 12a for auxiliary line 4 includes an inwardly stepping shoulder 13 where the inner diameter ID of the upper end of hanging profile is greater than the inner diameter of the lower end of hanging profile. Inwardly stepping shoulder 13 defines an upwardly facing, support surface 13′within the inner diameter of hanging profile. As the outer diameter dimensions of structure 23a and main tubing structure 23b will be known or readily ascertained, the inner diameter ID of hanging profile 12a above shoulder 13 and at lower end, can be constructed to accommodate auxiliary line 4 in a hanging position, supported on insert 12. For example, hanging profile 12a at the lower end can have an inner diameter larger than the outer diameter dimension of main tubing structure 23b, but smaller than the outer diameter dimension of structure 23a. As such, structure 23a can be supported on upwardly facing, support surface 13′within the inner diameter of hanging profile 12a. No slips between line 4 and insert 12 or other separate hanging apparatus are required.

As noted, insert 12 is also configured to engage the structure 23a against rotation. This engagement can be achieved in any of various ways.

In one embodiment, there can be a faceted region 23a″ on structure 23a and the inner surface of hanging profile 12a above the shoulder 13 can have a faceted region 12a′″ corresponding to faceted region 23a″. The faceted regions can then fit together such that structure 23a cannot rotate within profile 12a. The faceted region can include a key/keyway configuration, as shown, splines, hex shaping, etc.

In another embodiment shown in FIGS. 1A-8, the semicircular parts 12c, 12d are configured to have a gap g there between near hanging profile 12a, when assembled, such that the semicylindrical parts at least near profile 12a can be squeezed together to urge the insert to engage structure 23a. Thus, while the annular outer wall 12′ defines a complete circle, there is a gap g between the faces 12c′, 12d′ of semicircular parts 12c, 12d. In other words, each part 12c, 12d is just less than ½ of the overall annular body, with a portion of the face removed to create the gap.

Insert 12 includes a raised portion 12e on at least one of the face portions 12cb′, 12db′ that prevents the face portions 12cb′, 12db′ from coming into close contact. Raised portion 12e acts as a shim that ensures that gap g is maintained between faces 12cb′, 12db′ even when the parts 12c, 12d are assembled with the faces aligned. Together, gap g and raised portion 12e permit room for the insert to be squeezed inwardly to vary inner diameter ID and close it into engagement with structure 23a.

It is noted that there may be no raised portion at face portions 12ca′, 12da′, such that there is nothing to stop the gap g from being closed at the interface of those face portions 12ca′, 12da′.

To facilitate handling, the insert may include a cable or strap for holding parts 12c, 12d together. For example, a groove 12f is provided encircling annular outer wall 12′ that is configured to receive a cable, a strap, etc. to hold the two pieces of the split hanger together and in place during installation

In operation to secure an auxiliary line 4, the auxiliary line can be introduced into the well with a length extending through the tubing head 2. Insert 12 is then introduced to the tubing head 2 by positioning the semicircular parts 12c, 12d in the tubing head bowl 2b. Each part's portion of hanging profile 12a is positioned about line 4. A strap can be tightened in groove 12f to hold the parts together.

Then, auxiliary line 4 can be lowered to set shoulder 23a′ of structure 23a on upwardly facing, support surface 13′ within the inner diameter of hanging profile 12a. The weight of line 4, can therefore be supported through shoulder 13 by insert 12.

Structure 23a can also be engaged against rotation within the inner diameter of hanging profile 12a. This can, for example, be achieved by interlocking the faceted regions 12a′″, 23a″. Alternatively, parts 12c, 12d can be squeezed inwardly to reduce inner diameter ID of profile 12a and close it into engagement with structure 23a. This squeezing can be via tightening lag bolts 29, for example.

Once the auxiliary line is engaged by the insert, a communication tube 30, also called an NUE adapter, can be fit into the upper end of structure 23 through which fluid communication can be made from outside to the auxiliary line. Because structure 23 is held against rotation, communication tube 30 can be threaded into and out of structure.

Another insert 100 is disclosed in the embodiment of FIGS. 9 to 13. Insert 100 is similar to insert 12, but has a few differences, as described below.

Insert 100 is also bisected into a two-part structure with parts 100c, 100d. In particular, insert 100 is separated at a split 100A that extends from the upper surface to the lower surface. Split 100A, however, only bisects the hanging profile 12a. In particular, split 100A bisects the hanging profile 12a without intersecting or passing through the bore 12b through which production tubing 5 extends. As such, bore 12b is spaced from the split and the insert around bore 12b is continuous. The arrangement of split 100A in this embodiment facilitates coupling of the auxiliary line 4 into insert 100, but does not overly complicate installation of the insert into the tubing head and machining of the parts.

Split 100A renders the cylindrical form of the insert into (i) a larger part 100c, with bore 12b and half of hanging profile 12a and (ii) a smaller part 100b defining the other half of hanging profile 12a. The two parts, therefore, each include a face 100c′, 100d′ at split 100A where the insert body is separated. Since the split does not pass through the center axis of the cylindrical form of insert 100, the top plan shape of the smaller part 100d is, according to geometry, a circular segment (i.e. having an arc along the outer diameter of the insert and a chord along the split face 100d′).

Each face 100c′, 100d′ defines about half the hanging profile 12a. For example, each face includes a groove or channel thereon extending from upper surface to the lower surface. When the faces are brought together, the grooves align and together define the hanging profile 12a. The faces come into close proximity when the insert body is assembled, but there is a gap therebetween, such as described above in respect of gap g. For example, with reference to FIG. 13, each groove has a width W from side to side and a depth D from the inner facing surface to the plane across the face and width W from side to side is more than twice the dimension of depth D. As such, parts 100c, 100d can be squeezed together to configure hanging profile 12a to be out of round, such as to have an inner diameter from part 100c to part 100d across hanging profile 12a that is less than the width W from side to side across the groove defining half of hanging profile 12a on each part. This allows insert 100 to be configured to engage auxiliary line 4 or the couplings thereon within hanging profile 12a, when the parts 100c, 100d are brought together.

To assemble the insert, the faces 100c′, 100d′ are brought together to align the channels and clamping screws 103 are inserted through apertures 103a in the smaller part 100d to engage and thread into the larger part 100c. There is at least one clamping screw 103 on each side of the hanging profile.

Insert 100 is configured to secure auxiliary line 4 that has a structure 23a, sometimes referred to as a coupling, at its upper end, where the structure 23a has a larger outer diameter than the outer diameter of the main auxiliary line conduit. The structure 23a, having a larger diameter than the main conduit, creates an annular downwardly facing shoulder 23a′ on the auxiliary line. The larger diameter structure could, for example, be a coupling or a threaded box that is used to threadedly connect lengths of tubing together.

Once structure 23a is located in between the parts of the insert 100, clamping screws 103 can be threaded in to clamp the two parts together with structure 23a between them. The gap at split 100A ensures that the parts 100c, 100d can be tightly clamped about the structure 23a.

Communication tube 30, also called an NUE adapter, can be fit into the upper end of structure 23a through which fluid communication can be made from outside to the auxiliary line.

Bolts 103 clamp the insert onto the OD of the circulation string hanger 23a so that the tube 30 can be screwed into the hanger or unscrewed from the hanger once the insert is set into the tubing head. Because structure 23a is held against rotation by the clamping action, communication tube 30 can be threaded into and out of structure.

In the illustrated embodiment, communication tube 30 is configured with a bend along its length, wherein the upper opening thereof is out of alignment with its lower opening. The bend in communication tube therefore configures the conduit through tube with an offset such that the bottom fits into the auxiliary tubing hanger and the upper end is offset to align with an upper connection or port that is closer to the outer diameter of tubing head. In the illustrated embodiment, the bend offsets the connection tube toward the annular side wall of the insert.

In one embodiment, communication tube 30 can include one or more, for example, three, visible alignment features 30A such as markings, indents or notches. The visible alignment features 30A are useful to align with physical features or indications on insert 100, to ensure that communication tube 30 is properly installed. For example, one or two visible alignment features 30A can be positioned on an exterior surface of communication tube 30 to align with split 100A, as it extends away from hanging profile 12a on both sides.

Insert 100 may include a further alignment indicator such as alignment marker 100B that is offset 10-90° from the split 100A and there may be a visible alignment features on the exterior surface of communication tube 30 to align with marker 100B.

As noted, insert 12, 100 is part of a dual string tubing hanger assembly that also includes a hanging profile for the production tubing. In one embodiment, an adapter 10 is installed on the tubing head 2 and includes a hanging profile for the production tubing.

Insert 12, 100 is configured to support the small diameter auxiliary tubing and the adapter is configured to support the production tubing in a dual string well. In particular, there is a hanging profile 28 on the adapter 10, which includes a bore in which the production string is supported.

Referring more closely to FIGS. 1A, 1B and 9, the adapter 10, when installed on the top of the tubing head, creates a sealed interior space between the interior of the tubing head and the underside of the adapter. The insert 12, 100 is contained within the interior space.

Adapter 10 is installed on top of the tubing head 2 above the insert 12, 100. The installation seals flange 20a to flange 2a of the tubing head. Auxiliary line 4 is installed in insert 12, 100 prior to installing the adaptor. After installation of the adapter 10, the insert 12, 100 is protected within the internal area common between adapter 10 and tubing head 2. In other words, insert 12, 100 in use, is installed within the inner diameter of the tubing head and below the underside of adapter, which is a sealed area.

The adapter includes a fitting 15 through which fluid communication is made to the auxiliary line. In particular, adapter 10 has an exterior wall and fitting 15 extends through the wall and defines a fluid port therethrough. Fitting 15 is positioned on the adapter such that when the adapter is installed above the insert, fitting 15 can be installed in substantially vertical alignment over the small diameter hanging profile 12a of insert 12, 100. For example, fitting 15 is positioned off-center, non-concentric relative to the outer diameter of the flange 20a, such that it is positioned to be alignable above hanging profile 12a. In one embodiment, the fitting 15, or as noted above in respect of FIG. 13, the communication tube 30 are configured with an offset such that the bottom fits into the auxiliary tubing hanger 12a and the upper end can align with the fluid port in the adaptor. As such, the fluid port through the adapter can be positioned at a greater distance from the tubing head center line. This is advantageous since positioning the fluid port further from the center line provides more space to make room for fitting 15 or alternatively to increase the bore 28 through the adaptor to run larger tools.

The dual tubing string assembly includes seals for sealing communication tube 30 to adapter 10 or fitting 15. Seals may be carried, for example, in glands on a port through the wall of adapter 10. Thus, an end of communication tube 30 can be inserted and sealed to adapter into communication with fitting 15.

The fitting 15 may have an end configured, such as by threading or with a quick lock detent, for receiving connection of external piping, etc., for communication to auxiliary line. The fitting may be integral with adaptor 10 or coupled thereto (as shown). Auxiliary line 4, therefore, is directly or indirectly coupled to the lower flange 20a of the adaptor and sealed by the seals to be isolated from annular pressure, but able to receive fluid communication and flow through fitting 15 from outside fluid supplies.

The production string 5 is supported in the dual string adaptor 10 by a hanging profile 28 that is elevated above the insert 12, 100. The production string is larger diameter than the auxiliary line, so the production string hanging profile 28 is a larger diameter than the auxiliary line hanging profile. The hanging profile 28 is positioned non-concentric, off center relative to flange 20a, which is also off center relative to the tubing head 2 and casing 6. Production string 5 hangs down from hanging profile 28, through the adapter and tubing head 2 and into the casing. Insert 12, 100 does not affect passage of string 5 through head 2. In particular, bore 12b in insert 12, 100 is aligned below profile 28 and bore 12b is large enough to allow string 5 to pass. In other words, crescent-shaped area 21 is offset from under the profile 28. The production tubing is not in any way supported by or directly coupled to, the insert.

The current embodiment, allows 3½″ production tubing and 1¼″ auxiliary line all within a 7″ casing and tubing head. The production string can be pulled without disturbing the auxiliary line. In other words, the auxiliary line can stay in place while the production string is removed, serviced and run back in. Once the auxiliary line is in place, it can be accessed by removing the production tubing 5 and dual string adaptor 10. As such, this dual string hanger semi-permanently hangs the auxiliary line 4, but permits the production string 5 to be pulled when required to fix holes in tubing, replace the pump, etc. This is achieved by having a production tubing hanging profile separate from that for the auxiliary line. Also, the production string hanger 28 is spaced above the existing tubing head 2 and above the auxiliary line hanger profile 12a.

The dual string hanger assembly can, but does not necessarily, use a tubing rotator. The rotator is a separate function added by putting a rotating tubing hanger into the adaptor hanging profile 28 and then bolting a rotator drive on top of the adaptor 10 or alternately, adding an independent tubing rotator to the top flange of the adaptor that has its own tubing hanging profile.

While the lengths of tubing string 5 and auxiliary line 4 extend alongside each other through at least a portion of the well, the tubing string 5 is installed to extend along one side of the well while the auxiliary line extends along the other side.

The auxiliary line can extend down to the toe of the well. A continuous auxiliary flow can maintain the well free of sand and debris during production.

The dual tubing string hanging assembly may be configured to operate with any or all of a BOP, an auxiliary line hanger, a rotating hanger and a tubing rotator, as desired.

The present dual string hanger assembly offers several key attributes, including at least:

• • 1. The production string and the auxiliary line, such as coiled tubing, are supported and oriented with sufficient spacing therebetween to avoid interference between them.
  • 2. The production string can be pulled without disturbing the auxiliary line. In other words, the auxiliary line can stay in place while the production string is removed, serviced and run back in. This is useful because the production string is serviced more often than the auxiliary line.
  • 3. The auxiliary line is sealed to the dual string adaptor so it can stay in place and remain isolated from the production string and from the annulus between the production string and the casing during production string servicing operations.
  • 4. Because the second, smaller diameter hanger profile, and thereby the connection between the hanger profile, hanging apparatus and the auxiliary line, is positioned within the inner diameter of the tubing head and within the interior space, no seals are required at the hanging profile and hanging apparatus for the auxiliary line.
  • 5. No special purpose tubing rotator is required, as the dual string adaptor can be configured to accommodate various rotators at the production string hanger.
  • 6. No special wellhead is required.

It is to be understood that what has been described are preferred embodiments of the invention and that it may be possible to make variations to these embodiments while staying within the broad scope of the invention. Some of these variations have been discussed while others will be readily apparent to those skilled in the art.